battery round trip efficiency formula

• Sustainable
• Energy Economy
• Energy Services

What is Round Trip Efficiency?

Energy storage systems function by taking in electricity, storing it, and subsequently returning it to the grid. The round trip efficiency (RTE), also known as AC/AC efficiency, refers to the ratio between the energy supplied to the storage system (measured in MWh) and the energy retrieved from it (also measured in MWh). This efficiency is expressed as a percentage (%).

The round trip efficiency is a crucial factor in determining the effectiveness of storage technology. A higher RTE indicates that there is less energy loss during the storage process, resulting in a more efficient overall system. Grid systems engineers strive for energy storage systems to achieve an 80% RTE whenever feasible, as it signifies a desirable level of efficiency and minimizes energy losses.

What Factors Can Affect the Round Trip Efficiency of an Energy Storage System?

The RTE of an energy storage system can be influenced by various factors, including:

1. Technology: Different storage technologies have varying round-trip efficiencies. For example, hydro storage typically ranges from 65% in older installations to 75-80% in modern deployments, while flywheels have efficiencies of about 80% to 90%. Some battery technologies can have round-trip efficiencies ranging from 75% to 90%.

2. Storage duration: Some technologies may experience leakage or energy loss over long-term storage, which can affect round-trip efficiency. It is important to consider the specific characteristics and limitations of the storage technology when evaluating its efficiency.

3. Age and condition of the system: Older storage systems may have lower round-trip efficiencies compared to newer ones. Factors such as wear and tear, component degradation, and maintenance practices can impact the overall efficiency of the system.

4. Charging and discharging rates: The speed at which energy is charged into and discharged from the storage system can affect its efficiency. Certain technologies may have lower efficiencies at high charging or discharging rates.

5. System design and control: The design and control strategies implemented in the energy storage system can influence its round-trip efficiency. Optimal system design, efficient power electronics, and effective control algorithms can improve the overall efficiency of the system.

6. Temperature: Temperature can have an impact on the performance and efficiency of energy storage systems. Extreme temperatures can affect the efficiency of certain storage technologies, such as batteries, leading to lower round-trip efficiencies.

Considering these factors is crucial when evaluating the round-trip efficiency of an energy storage system, as they can significantly affect its performance and effectiveness in storing and retrieving energy.

Must Read: What is Power Conversion Efficiency?

Elliot is a passionate environmentalist and blogger who has dedicated his life to spreading awareness about conservation, green energy, and renewable energy. With a background in environmental science, he has a deep understanding of the issues facing our planet and is committed to educating others on how they can make a difference.

Related Posts

What is Heating Seasonal Performance Factor (HSPF)?

What is Annual Fuel Utilization Efficiency (AFUE)?

What is Grid Parity?

Save my name, email, and website in this browser for the next time I comment.

Type above and press Enter to search. Press Esc to cancel.

Today in Energy

• Recent articles
• liquid fuels
• natural gas
• electricity
• oil/petroleum
• production/supply
• consumption/demand
• exports/imports
• international
• forecasts/projections
• steo (short-term energy outlook)

Utility-scale batteries and pumped storage return about 80% of the electricity they store

Electric energy storage is becoming more important to the energy industry as the share of intermittent generating technologies, such as wind and solar, in the electricity mix increases. Electric energy storage helps to meet fluctuating demand, which is why it is often paired with intermittent sources. Storage technologies include batteries and pumped-storage hydropower , which capture energy and store it for later use. Storage metrics can help us understand the value of the technology. Round-trip efficiency is the percentage of electricity put into storage that is later retrieved. The higher the round-trip efficiency, the less energy is lost in the storage process. According to data from the U.S. Energy Information Administration (EIA), in 2019, the U.S. utility-scale battery fleet operated with an average monthly round-trip efficiency of 82%, and pumped-storage facilities operated with an average monthly round-trip efficiency of 79%.

EIA’s Power Plant Operations Report provides data on utility-scale energy storage, including the monthly electricity consumption and gross electric generation of energy storage assets, which can be used to calculate round-trip efficiency. The metrics reviewed here use the finalized data from the Power Plant Operations Report for 2019—the most recent year for which a full set of storage data is available.

Pumped-storage facilities are the largest energy storage resource in the United States. The facilities collectively account for 21.9 gigawatts (GW) of capacity and for 92% of the country’s total energy storage capacity as of November 2020.

In recent years, utility-scale battery capacity has grown rapidly as battery costs have decreased. As batteries have been increasingly paired with renewables , they have become the second-largest source of electricity storage. As of November 20, 2020, utility-scale battery capacity had 1.4 GW of operational capacity. Another 4.0 GW of battery capacity is scheduled to come online in 2021, according to EIA’s Preliminary Electric Generator Inventory .

Although battery storage has slightly higher round-trip efficiency than pumped storage, pumped-storage facilities typically operate at utilization factors that are currently twice as high as batteries. Increasing durations among battery applications could shift battery operations toward services that reward longer output periods. For example, in 2015, the weighted average battery duration was a little more than 46 minutes, but by 2019, weighted average battery durations had doubled to 1.5 hours. The role of batteries and their capability to provide high levels of round-trip efficiency may become more important as batteries continue to be deployed and as the intermittent renewables share of the electricity mix grows.

Tags: storage , electricity

This is the UK domain, to see the EU or other regions, please click below

• Visit the GivEnergy cloud

• All in One – battery plus inverter
• AC coupled inverter
• Hybrid inverter
• Battery storage
• Full energy ecosystem overview
• Start your journey
• Power conversion system (PCS)
• Battery packs
• Commercial battery rack
• SME battery system
• Battery storage container

Energy management software

• GivEnergy app
• GivEnergy portal
• Home battery storage
• Commercial battery storage
• Sustainable construction projects
• Wholesalers
• Energy suppliers – E.ON partner
• Energy suppliers – Octopus
• Energy aggregators
• Solar industry – Open Solar
• Solar industry – Easy PV
• Giv-Gallery
• Case studies
• Support hall of fame
• Why choose GivEnergy?
• Refer a friend
• Find a distributor
• Knowledge base
• Community forum

Documentation

• Resource hub
• Product brochure 2024
• GivEnergy API
• Server status
• View all posts

GivEnergy appoints Brian Beaver as Sales and Marketing Director

What is long duration energy storage?  

GivEnergy 3-phase: an easy, ideal stepping stone into the high-profit...

• FIND AN INSTALLER
• Home-owners

• January 30, 2024
• Blog , Commercial battery storage , Domestic battery storage , Explain like I’m 5

What is round trip efficiency in battery storage?

Round trip efficiency (RTE) is a measure of how efficiently a battery can store and discharge energy. Find out why it’s crucial in the world of BESS.

Terminology in the world of battery storage can seem daunting to the average Joe.

Luckily, we’re here to help.

Round trip efficiency (RTE) is something you may have come across in relation to batteries.

In a nutshell, RTE measures how efficiently a battery can store and discharge energy.

How is RTE calculated? Why are there no batteries with 100% RTE? How has RTE in storage batteries improved in recent years?

Read on to find the answers to these questions.

How to calculate the RTE of a battery?

The RTE of a battery can be calculated as a percentage using a simple formula shown below:

Energy output ÷ energy input x 100 = RTE

Let’s demonstrate what this means in practical terms with an example.

Mrs Jones installs a storage battery for her home . As she and her family typically use 10 kWh of electricity per day, she opts for a 10 kWh storage battery.

As someone who is both eco-conscious and has an above-average income, Mrs Jones installs both solar panels and a wind turbine to power her battery storage system. This means she can charge her 10 kWh battery from renewable sources.

However, Mrs Jones soon realises that she isn’t getting 10 kWh per day from her storage battery.

In reality, she gets 8 kWh per day. That’s because her 10 kWh battery has 80% round trip efficiency.

If she had opted for a 10 kWh battery with 90% round trip efficiency, she would get… yep… 9 kWh per day.

For her remaining 2 kWh per day of electricity needs, she draws energy from the grid.

Why do batteries lose energy?

Unfortunately, batteries always lose a small amount of energy during operation.

This is usually because of heat loss, self-discharge, high internal cell resistance or other factors.

Are there any batteries with 100% RTE?

You can think of it like this: if anyone ever tries to sell you a 100% RTE battery, run a mile because they’re almost certainly lying.

What is the RTE of a typical battery?

RTE varies among different types of storage batteries .

For older battery systems, 80% round trip efficiency would have been considered a good standard. Some evidence suggests the typical lithium-ion battery – a popular choice for modern battery energy storage systems and electric vehicles – has round trip efficiency of around 83%.

GivEnergy’s own batteries – using LiFePO4 (lithium iron phosphate) – have achieved 93% round trip efficiency .

RTE – not to be ignored

Grid-level battery storage is becoming increasingly common to accommodate the growth in renewables, especially solar and wind.

Round trip efficiency is a factor that decision-makers need to take into account when assessing the overall efficiency of an energy storage system.

And it’s something YOU also need to bear in mind when installing your own battery storage system for your home or business.

Remember: 100% round trip efficiency is a lie! However, 93% round trip efficiency with a GivEnergy battery using LiFePO4 technology is not a lie.

Looking to play your part in the energy storage revolution? Get started by finding an approved GivEnergy installer today.

Further reading

• Explain like I’m 5: depth of discharge
• LiFePO4 battery: what is it & why is it best for BESS?
• The superior choice: embracing LiFePO4 batteries over NMC technology

Quick Links

Getting started with...

Product images used are for illustrative purposes. The finished setup will vary from installation to installation, and will include all your needed cable connections, metering, any (outdoor) canopies, etc.

Utility-Scale Battery Storage

The 2021 ATB represents cost and performance for battery storage across a range of durations (2–10 hours). It represents lithium-ion batteries only at this time. There are a variety of other commercial and emerging energy storage technologies; as costs are well characterized, they will be added to the ATB.

The NREL Storage Futures Study has examined energy storage costs broadly and specifically the cost and performance of lithium-ion batteries (LIBs)  (Augustine and Blair, 2021) . The costs presented here (and for distributed residential  storage and distributed commercial storage) are based on this work. This work incorporates current battery costs and breakdowns from  (Feldman et al., 2021) , which works from a bottom-up cost model. We would note though that, during the elapsed time between the calculations for the Storage Futures Study and the ATB release, updated values have been calculated as more underlying data have been collected. Though these changes are small, we recommend using the data presented here in the ATB rather than what was previously published with the Storage Futures Study.

Current costs for utility-scale battery energy storage systems (BESS) are based on a bottom-up cost model using the data and methodology for utility-scale BESS in  (Feldman et al., 2021) . The bottom-up BESS model accounts for major components, including the LIB pack, inverter, and the balance of system (BOS) needed for the installation. Using the detailed NREL cost models for LIB, we develop current costs for a 60-MW BESS with storage durations of 2, 4, 6, 8, and 10 hours, shown in terms of energy capacity ($/kWh) and power capacity ($/kW) in Figure 1 and Figure 2 respectively. Current installed capital costs for BESS in terms of $/kWh decrease with duration, and costs in $/kW increase. This inverse behavior is observed for all energy storage technologies and highlights the importance of distinguishing the two types of battery capacity when discussing the cost of energy storage.

Figure 1. 2019 U.S. utility-scale LIB storage costs for durations of 2–10 hours (60 MW DC ) in $/kWh

EPC: engineering, procurement, and construction

Figure 2. 2019 U.S. utility-scale LIB storage costs for durations of 2–10 hours (60 MW DC ) in $/kW

Scenario Descriptions

Battery cost and performance projections in the 2021 ATB are based on a literature review of 13 sources published in 2018 or 2019, as described by Cole et al.  (Cole et al., 2021) . Three projections from 2019 to 2050 are developed for scenario modeling based on this literature. 

• Conservative Technology Innovation Scenario (Conservative Scenario): The conservative projection is comprised of the the maximum projection in 2020, 2025, and 2030 amongst the 13 cost projections from the literature review  (Cole et al., 2021) . Defining the 2050 points is more challenging because only four data sets of the 13 from the literature review extend to 2050; they show cost reductions of 19%, 25%, 27%, and 39% from 2030 to 2050. A 25% cost reduction is assumed for the moderate and conservative scenarios. In other words, the Conservative Scenario is assumed to decline by 25% from 2030 to 2050.
• Moderate Technology Innovation Scenario (Moderate Scenario): The moderate projections are taken as the median point in 2020, 2025, and 2030 of the 13 projections reviewed. Defining the 2050 points is more challenging because only four data sets of the 13 from the literature review extend to 2050; they show cost reductions of 19%, 25%, 27%, and 39% from 2030 to 2050. A 25% cost reduction is assumed for the moderate and conservative scenarios. In other words, the Moderate Scenario is assumed to decline by 25% from 2030 to 2050.
• Advanced Technology Innovation Scenario (Advanced Scenario): The advanced projections are taken as the as the lowest cost point in 2020, 2025, and 2030 from the 13 projections reviewed. Defining the 2050 points is more challenging because only four of the reviewed data sets extend to 2050; they show cost reductions of 19%, 25%, 27%, and 39% from 2030 to 2050. The 39% cost reduction is used for the Advanced Scenario. In other words, the Advanced Scenario is assumed to decline by 39% from 2030 to 2050.

Methodology

Projected Utility-Scale BESS Costs: Future cost projections for utility-scale BESS are based on a synthesis of cost projections for 4-hour duration systems in  (Cole et al., 2021)  and the Bloomberg New Energy Finance (BNEF) cost projections for utility-scale BESS  (Bloomberg New Energy Finance (BNEF), 2019b) (Frith, 2020) . The Cole et al. cost projections are based on a literature survey that includes results from 13 studies of BESS costs. The BNEF cost projections are based on learning rates and deployment projections for utility-scale BESS that are broken down at the system component level. Both projections extend to 2050.

Projected costs for battery components tend to decrease much more quickly than projected costs for other system components such as the inverter, BOS, installation, and soft cost components  (Electric Power Research Institute (EPRI), 2018) (Bloomberg New Energy Finance (BNEF), 2019b) (Bloomberg New Energy Finance (BNEF), 2019a) (Schmidt et al., 2018) . Thus, projected total system costs decrease more quickly for longer-duration battery storage than shorter-duration battery storage. However, the duration is not captured in the BNEF cost projections, which only project a 4-hour system. The  (Cole et al., 2021)   projections contain information for both power and duration, so costs can be calculated for any storage duration; however, they do not account for how different BESS component costs (particularly, the LIB pack cost) change over time  (Cole et al., 2021)  . Therefore, to account for storage costs as a function of storage duration, we apply the BNEF battery cost reduction projections to the energy (battery) portion of the 4-hour storage and use the Cole and Frazier summary for the remaining component costs to develop combined Moderate Scenario projections for future years. In this way, the cost projections capture the rapid projected decline in battery costs and account for component costs decreasing at different rates in the future. Figure 3 shows the resulting utility-scale BESS future cost projections for the Moderate Scenario for 2–10 hours in terms of both $/kWh and $/kW. For the Advanced and Conservative BESS cost scenarios, we apply the normalized cost reductions for the corresponding scenarios from  (Cole et al., 2021)   to the current costs for all storage durations.

Figure 3. Utility-scale BESS Moderate Scenario cost projections, on a $/kWh basis (left) and a $/kW basis (right) Projections assume a 60-MW DC project. Note that 2019 costs correspond to Figure -1 and Figure 2.

Capital Expenditures (CAPEX)

Definition:  The bottom-up cost model documented by  (Feldman et al., 2021)  contains detailed cost components for battery only systems costs (as well as combined with PV). Though the battery pack is a significant cost portion, it is a minority of the cost of the battery system. These costs for a 4-hour utility-scale stand-alone battery are detailed in Table 1.

Table 1. Capital Cost Components for Utility-Scale Storage (4-Hour Duration, 240-MWh) 

Base Year : The Base Year cost estimate is taken from  (Feldman et al., 2021)  and is currently in 2019$.

Within the  ATB Data  spreadsheet, costs are separated into energy and power cost estimates, which allows capital costs to be constructed for durations other than 4 hours according to the following equation:

Total System Cost ($/kW) = Battery Pack Cost ($/kWh) × Storage Duration (hr) + BOS Cost ($/kW)

For more information on the power versus energy cost breakdown, see  (Cole et al., 2021)  .

Future Projections : Future projections are based on the same literature review data that informs  (Cole et al., 2021)  , which generally used the median of published cost estimates to develop a Moderate Technology Cost Scenario and the minimum values to develop an Advanced Technology Cost Scenario. However, as the battery pack cost is anticipated to fall more quickly than the other cost components (which is similar to the recent history of PV system costs), the battery pack cost reduction is taken from  (Bloomberg New Energy Finance (BNEF), 2019b)  and  (Frith, 2020)  and reduced more quickly. This tends to make the longer-duration batteries (e.g., 10 hours ) decrease more quickly while short duration (e.g., 2 hours) decrease less quickly into the future. All durations trend toward a common trajectory as battery pack costs decrease into the future. 

Operation and Maintenance (O&M) Costs

Base Year :  (Cole et al., 2021)  assume no variable O&M (VOM) cost. All operating costs are instead represented using fixed O&M (FOM) costs. They include augmentation costs needed to keep the battery system operating at rated capacity for its lifetime. In the 2020 ATB, FOM is defined as the value needed to compensate for degradation to enable the battery system to have a constant capacity throughout its life. According to the literature review  (Cole et al., 2021)  , FOM costs are estimated at 2.5% of the capital costs in dollars per kilowatt. 

Future Years : In the 2021 ATB, the FOM costs and VOM costs remain constant at the values listed above for all scenarios.

Capacity Factor

The cost and performance of the battery systems are based on an assumption of approximately one cycle per day. Therefore, a 4-hour device has an expected capacity factor of 16.7% (4/24 = 0.167), and a 2-hour device has an expected capacity factor of 8.3% (2/24 = 0.083). Degradation is a function of this usage rate of the model and systems might need to be replaced at some point during the analysis period. We use the capacity factor for a 4-hour device as the default value for ATB.

Round-Trip Efficiency

Round-trip efficiency is the ratio of useful energy output to useful energy input.  (Mongird et al., 2020)  identified 86% as a representative round-trip efficiency, and the 2021 ATB adopts this value.

The following references are specific to this page; for all references in this ATB, see References .

Augustine, Chad, and Nate Blair. “Energy Storage Futures Study: Storage Technology Modeling Input Data Report.” Golden, CO: National Renewable Energy Laboratory, 2021. https://www.nrel.gov/docs/fy21osti/78694.pdf .

Feldman, David, Vignesh Ramasamy, Ran Fu, Ashwin Ramdas, Jal Desai, and Robert Margolis. “U.S. Solar Photovoltaic System and Energy Storage Cost Benchmark: Q1 2020.” National Renewable Energy Lab. (NREL), Golden, CO (United States), January 27, 2021. https://doi.org/10.2172/1764908 .

Cole, Wesley, Will A. Frazier, and Chad Augustine. “Cost Projections for Utility-Scale Battery Storage: 2021 Update.” Technical Report. Golden, CO: National Renewable Energy Laboratory, 2021. https://www.nrel.gov/docs/fy21osti/79236.pdf .

Frith, James. “Energy Storage System Costs Survey 2020.” Bloomberg New Energy Finance, December 16, 2020.

Schmidt, Oliver, Sylvain Melchior, Adam Hawkes, and Iain Staffell. “Update 2018 - The Future Cost of Electrical Energy Storage Based on Experience Rates.” Figshare, 2018. https://doi.org/10.6084/M9.FIGSHARE.7012202 .

Bloomberg New Energy Finance (BNEF). “Energy Storage System Costs Survey 2019,” October 14, 2019a.

Bloomberg New Energy Finance (BNEF). “2019 Long-Term Energy Storage Outlook,” July 31, 2019b. https://www.bnef.com/core/insights/21113 .

Electric Power Research Institute (EPRI). “Energy Storage Technology and Cost Assessment: Executive Summary,” 2018. http://membercenter.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=000000003002013958 .

Mongird, Kendall, Vilayanur Viswanathan, Jan Alam, Charlie Vartanian, Vincent Sprenkle, and Richard Baxter. “2020 Grid Energy Storage Technology Cost and Performance Assessment.” USDOE, December 2020. https://www.energy.gov/energy-storage-grand-challenge/downloads/2020-grid-energy-storage-technology-cost-and-performance .

Performance Analysis of Lithium-Ion Battery Considering Round Trip Efficiency

Ieee account.

• Change Username/Password
• Update Address

Purchase Details

• Payment Options
• Order History
• View Purchased Documents

Profile Information

• Communications Preferences
• Profession and Education
• Technical Interests
• US & Canada: +1 800 678 4333
• Worldwide: +1 732 981 0060
• Contact & Support
• About IEEE Xplore
• Accessibility
• Terms of Use
• Nondiscrimination Policy
• Privacy & Opting Out of Cookies

A not-for-profit organization, IEEE is the world's largest technical professional organization dedicated to advancing technology for the benefit of humanity. © Copyright 2024 IEEE - All rights reserved. Use of this web site signifies your agreement to the terms and conditions.

Empowering Innovations: The Bright Future of Round Trip Efficiency of Battery

Round Trip Efficiency of Battery

The concept of round trip efficiency of battery is pivotal in energy storage technologies. This section will provide an extensive introduction to what round trip efficiency means in the context of batteries. We'll explore its importance in various applications, ranging from small-scale electronics to large-scale energy systems. Understanding the round trip efficiency of battery is essential for assessing the performance and sustainability of these energy storage devices.

The Science Behind Round Trip Efficiency

Delving deeper into the technicalities, this part will explain how the round trip efficiency of battery is determined. It will cover the fundamental principles of battery operation, including charge and discharge cycles, energy losses during these cycles, and how they affect overall efficiency. Factors like temperature, charge rate, and battery age, which significantly impact round trip efficiency, will be discussed in detail.

Components Affecting Round Trip Efficiency

In this subsection, we will explore the various components of batteries, such as electrodes, electrolytes, separators, and casings, and how each contributes to or detracts from the round trip efficiency. The material composition of these components, their engineering, and how they interact with each other play a critical role in the efficiency of the battery.

The Role of Battery Design

This part will discuss how the physical and chemical design of a battery influences its round trip efficiency. Topics like battery size, shape, internal architecture, and the arrangement of cells within a battery pack will be covered. The section will also explore how innovative design strategies are being employed to enhance efficiency.

Types of Batteries and Their Round Trip Efficiency

This section will provide a comparative analysis of different battery types, such as lithium-ion, lead-acid, and nickel-metal hydride, focusing on their round trip efficiencies. Each battery type's unique characteristics, advantages, and limitations in terms of efficiency will be discussed.

Lithium-Ion Batteries and Efficiency

Focusing on lithium-ion batteries, this subsection will delve into why they are widely regarded for their high round trip efficiency. We will examine the factors that contribute to this efficiency and the challenges that still exist. The latest advancements in lithium-ion technology aimed at improving efficiency will also be highlighted.

Other Battery Technologies

This part will look at alternative battery technologies, comparing their round trip efficiencies with that of lithium-ion batteries. It will cover emerging technologies like solid-state batteries, flow batteries, and others, discussing their potential to rival or surpass the efficiency of traditional battery types

Improving the Round Trip Efficiency of Battery

This section will explore the various strategies and technological advancements aimed at enhancing the round trip efficiency of battery. It will cover research and development efforts in new materials, battery chemistry, and manufacturing techniques. Discussion will include how these advancements could potentially increase efficiency, reduce costs, and extend the life of batteries.

Innovations in Battery Materials

Delving into the realm of materials science, this subsection will explore new and innovative materials being developed to increase the round trip efficiency of battery. This includes advancements in electrode materials, electrolyte formulations, and separator technologies. We'll look at how these new materials can reduce energy losses during charging and discharging, thereby improving overall efficiency.

The Future of Battery Efficiency

In this part, we will explore the cutting-edge research and future directions aimed at pushing the boundaries of round trip efficiency in battery technology. This will include a discussion on potential breakthroughs, the challenges researchers face, and the implications these advancements could have on the global energy landscape.

Applications and Importance of High Round Trip Efficiency

Discussing the wide range of applications where high round trip efficiency in batteries is critical, this section will cover areas like electric vehicles, renewable energy storage, grid management, and consumer electronics. We'll explore how improvements in battery efficiency can impact these fields, leading to more sustainable and efficient energy usage.

Impact on Electric Vehicles

Focusing on electric vehicles (EVs), this subsection will discuss how the round trip efficiency of battery affects the performance, range, and cost-effectiveness of EVs. We'll explore current challenges, the importance of efficiency improvements in the context of EV adoption, and how advancements could shape the future of transportation.

Renewable Energy Storage Systems

In this part, the role of battery efficiency in the effectiveness and viability of renewable energy storage systems will be examined. We'll discuss how higher round trip efficiency can enhance the storage and release of energy from sources like solar and wind, making renewable energy more reliable and accessible.

Battery Round Trip Efficiency Definition: Understanding the Concept

The definition of battery round trip efficiency is a fundamental concept in the realm of battery technology and energy storage. This section aims to elucidate the battery round trip efficiency definition and its relevance in practical applications.

Exploring the Battery Round Trip Efficiency Definition

Battery round trip efficiency is defined as the ratio of the energy output of a battery to the energy input required to recharge it. This definition provides a quantitative measure of how effectively a battery stores and then releases the energy put into it. It's a critical parameter for evaluating the performance of a battery, as it directly influences the efficiency and cost-effectiveness of the battery in its practical application.

Implications of Battery Round Trip Efficiency in Energy Systems

Understanding the battery round trip efficiency definition is vital for anyone involved in the design, manufacture, or use of battery systems. This efficiency metric is particularly important in applications where energy conservation and efficiency are paramount, such as in electric vehicles, renewable energy systems, and portable electronic devices. A higher round trip efficiency means more of the stored energy is available for use, which is crucial for the overall efficiency and sustainability of these systems.

Environmental Impact of Battery Efficiency

This new section will explore the environmental implications of the round trip efficiency of battery. It will discuss how increased efficiency can lead to reduced energy waste and lower carbon footprints. This part will also cover the lifecycle of batteries, including manufacturing and recycling processes, and how efficiency plays a role in minimizing environmental impact.

Economic Aspects of Battery Efficiency

In this section, we'll delve into the economic aspects of round trip efficiency in batteries. It will cover how higher efficiency can lead to cost savings for consumers and businesses, and its impact on the overall economy. This part will also discuss the investment in research and development for more efficient batteries and how this drives innovation in the battery industry.

Safety and Reliability Concerns

This part will address how the round trip efficiency of battery relates to their safety and reliability. We'll explore the challenges that arise when trying to balance high efficiency with safety, especially in high-demand applications like electric vehicles and energy storage systems. This section will also discuss the measures taken to ensure that efficiency improvements do not compromise the safety and longevity of batteries.

Regulatory and Policy Frameworks

This new section will examine the role of regulatory and policy frameworks in shaping the development and adoption of efficient battery technologies. It will cover current regulations and standards related to battery efficiency, and how these policies impact the industry. Additionally, this part will discuss potential future policies that could encourage or mandate improvements in battery efficiency.

BatteryRound Trip Efficiency Calculation: Methods and Importance

The calculation of battery round trip efficiency is a critical aspect in assessing the performance of battery systems. This section delves into the methodologies and significance of accurately performing batteryround trip efficiency calculation.

Understanding the Basics of Battery Round Trip Efficiency Calculation

To begin with, battery round trip efficiency calculation involves determining the ratio of the energy outputted by the battery to the energy inputted into it during charging. This calculation is crucial for understanding how much energy is lost in the process of charging and discharging a battery. These energy losses typically occur due to factors like internal resistance, heat generation, and the inefficiencies in the battery's chemical processes.

Step-by-Step Process of Battery Round Trip Efficiency Calculation

To calculate battery round trip efficiency, one must first measure the amount of energy inputted into the battery during the charging process. This is typically done in watt-hours (Wh) or kilowatt-hours (kWh). Following this, the energy outputted by the battery during discharge is measured. The round trip efficiency is then calculated by dividing the energy outputted by the energy inputted and multiplying the result by 100 to obtain a percentage. A higher percentage indicates a more efficient battery with less energy loss.

The Significance of Accurate Calculation

Accurate battery round trip efficiency calculation is crucial for several reasons. Firstly, it allows for the comparison of different battery technologies on a uniform basis, aiding in the selection of the most efficient and suitable battery for a specific application. Secondly, understanding the efficiency of a battery helps in estimating its operational costs and its impact on the overall efficiency of the system it powers, such as an electric vehicle or a renewable energy storage system.

Battery Storage Round Trip Efficiency: Key Aspects and Evaluation

The concept of battery storage round trip efficiency is crucial in the context of energy storage systems. This section focuses on defining and understanding the nuances of battery storage round trip efficiency and its impact on energy storage solutions.

Defining Battery Storage Round Trip Efficiency

Battery storage round trip efficiency is a measure that indicates how efficiently a battery can store and then release the energy it has been charged with. This efficiency is calculated by comparing the amount of energy input into the battery during charging to the amount of usable energy output during discharge. A higher battery storage round trip efficiency signifies that a larger portion of the input energy is available for use, making the battery more effective and economical for energy storage purposes.

Importance of Battery Storage Round Trip Efficiency in Energy Systems

In the field of energy storage, especially in systems like grid storage or electric vehicles, battery storage round trip efficiency plays a pivotal role. It directly affects the viability and performance of the storage system. High-efficiency levels mean more energy is available for use from each charging cycle, which is crucial for the overall energy efficiency and operational cost of the system. As such, battery storage round trip efficiency is a key parameter in the selection and design of battery systems for various applications.

Round Trip Efficiency Battery Storage: A Brief Overview

The term roundtrip efficiency in battery storage is a vital metric in the energy sector. This section provides a succinct overview of what round trip efficiency battery storage entails and its significance.

Understanding RoundTrip Efficiency Battery Storage

Round trip efficiency in battery storage refers to the measure of how effectively a battery can store and then return the energy that is put into it. It is a crucial indicator of a battery's performance, affecting the viability and efficiency of energy storage systems. This efficiency is especially important in applications where energy conservation and effective storage are key, such as in renewable energy systems and electric vehicles.

The Role of Round Trip Efficiency in Battery Storage Systems

The significance of roundtrip efficiency battery storage cannot be overstated. It directly influences how much stored energy is actually usable, impacting the overall effectiveness and cost-efficiency of the storage system. High round trip efficiency battery storage means more energy is available for use, reducing waste and improving the sustainability of the system.

Round Trip Efficiency of Battery Formula: Essential Calculation

The round trip efficiency of battery formula is a fundamental equation in battery technology. This section is dedicated to explaining the round trip efficiency of battery formula and its application in measuring battery performance.

The Basic RoundTrip Efficiency of Battery Formula

At its core, the roundtrip efficiency of battery formula involves a simple calculation: dividing the energy output of the battery (measured in watt-hours or kilowatt-hours) by the energy input required to charge the battery, and then multiplying by 100 to express it as a percentage. This formula is critical for determining how much energy a battery can effectively use out of the total energy it consumes during the charging process.

Practical Applications of the Formula

In practical terms, the round trip efficiency of battery formula is used extensively by engineers and technicians to assess the performance of different types of batteries. This formula helps in comparing the efficiency of various battery technologies and designs, playing a crucial role in battery research and development. A higher percentage obtained from this formula indicates a more efficient battery, with less energy lost during charging and discharging cycles.

The round trip efficiency of battery formula is not just a theoretical tool; it has significant practical implications in the development and selection of batteries for various applications, from small electronics to large-scale energy storage systems.

Tesla Battery Round Trip Efficiency: Insights into Performance

Tesla battery round trip efficiency is a key metric that highlights the effectiveness of Tesla's battery technology. This section aims to shed light on the specifics of Tesla battery round trip efficiency and its implications.

Understanding Tesla Battery Round Trip Efficiency

Tesla battery round trip efficiency refers to the efficiency with which Tesla's batteries can store and then release energy. This efficiency is a critical aspect of Tesla's battery technology, reflecting how much energy is retained and available for use after charging. The higher the round trip efficiency, the more effective the battery is at minimizing energy losses during charge and discharge cycles.

Significance of Tesla Battery Round Trip Efficiency in Electric Vehicles

Tesla battery round trip efficiency is particularly important in the context of their electric vehicles (EVs). High round trip efficiency means that more of the energy stored in the vehicle's battery is available for driving, enhancing the vehicle's range and overall performance. Tesla's focus on optimizing battery round trip efficiency has been a significant factor in their EVs' success, as it directly impacts driving range, charging times, and the overall user experience.

Frequently Asked Questions (FAQs) About Battery Efficiency

What is Round Trip Efficiency of Battery?

Round trip efficiency of a battery refers to the measure of how effectively a battery can store and then release the energy that is put into it during charging. It is calculated by dividing the energy output during discharge by the energy input during charging, then multiplying by 100 to get a percentage. A higher value indicates that the battery is more efficient, losing less energy in the process of charging and discharging.

How Does Temperature Affect Battery Efficiency?

Temperature can significantly impact the efficiency of a battery. Extreme temperatures, both hot and cold, can affect the chemical reactions within a battery, thereby impacting its ability to store and release energy efficiently. Typically, high temperatures can accelerate degradation, while low temperatures can reduce the battery's effective capacity.

Can the Round Trip Efficiency of a Battery Improve Over Time?

Generally, the round trip efficiency of a battery decreases over time as the battery undergoes wear and tear from repeated charging and discharging cycles. However, advancements in battery technology, materials, and management systems can lead to improvements in newer batteries. Ongoing research is focused on developing batteries with longer lifespans and better efficiency retention over time.

What Factors Influence the Round Trip Efficiency of Electric Vehicle Batteries?

Several factors influence the round trip efficiency of electric vehicle (EV) batteries. These include the battery's chemical composition, design, the efficiency of the battery management system, and operational conditions such as temperature and charging habits. Additionally, the way the vehicle is driven and the efficiency of other vehicle systems can also impact the overall round trip efficiency of the battery.

Conclusion: The Future of Round Trip Efficiency in Battery

This concluding section will summarize the critical importance of round trip efficiency in batteries, reflecting on the discussed topics. It will envision the future of battery technology with a focus on efficiency, considering the potential impacts on various industries, the environment, and society at large.

Round Trip Efficiency

Energy Storage System Efficiency

Related Posts

Energy efficient outdoor heating: achieve unmatched comfort and savings, ultimate guide to ohio electric vehicle incentives in 2024, efficiency vermont led light bulbs: save energy, save money, maximizing flow battery efficiency: the future of energy storage.

Type above and press Enter to search. Press Esc to cancel.

Sign In or Register

Welcome back.

Login to your account below.

how to calculate battery storage round trip

How to Calculate Battery Storage Round Trip

Understanding Battery Storage Round Trip

The formula for calculating round trip efficiency.

Example Calculation

Factors impacting round trip efficiency, importance of round trip efficiency calculation.

In conclusion, calculating battery storage round trip efficiency is essential for evaluating the performance and cost-effectiveness of battery storage systems. By using the appropriate formula and considering the various factors that impact round trip efficiency, you can make informed decisions about the selection and optimization of battery storage systems.

Leave a Comment Cancel Reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

Notify me via e-mail if anyone answers my comment.

WhatsApp us

• POWER Plant ID
• POWER Events
• Connected Plant
• Distributed Energy
• International
• COVID-19 Coverage
• Carbon Capture
• Climate change
• Cybersecurity
• Distributed Power
• Electric Vehicles
• Energy Storage
• Environmental
• Instrumentation & Controls
• Legal & Regulatory
• Legislative
• Ocean/Marine
• Physical security
• Plant Design
• Power Demand
• Research and Development
• Supply Chains
• Tidal Power
• Waste to Energy
• About POWER
• Privacy Policy
• Cookie Settings
• Diversity, Equity, Inclusion & Belonging
• Accessibility Statement

Don’t Neglect Round-Trip Efficiency and Cost of Charging When Considering Levelized Cost of Storage

The world is moving toward renewable sources for electricity generation in an attempt to reduce fossil-fuel reliance. But wind and solar can’t provide a consistent flow of power 24/7, and grid operators have realized that new electricity generation needs to be paired with storage to manage periods with no sun or wind.

The decreasing cost of lithium-ion batteries has made battery energy storage systems (BESS) more affordable; however, the cost of battery storage systems represents only 20%-25% of any project’s lifetime cost. Power equipment, land, site work, cabling, project design and management, grid integration, transportation, and other related up-front costs represent another 25%.

So, what makes up the other ~50%? Operations and maintenance, otherwise known as O&M, represent a few percentage points. O&M generally includes expenses associated with maintaining, repairing, and operating energy storage systems over their lifespan. The rest comes from the cost of electricity to charge the system, which is significantly affected by the system’s overall round-trip efficiency (RTE).

Why RTE and Cost of Energy Matter

Levelized cost of storage (LCOS) is a metric used to determine the cost per unit of energy discharged from an energy storage system. The calculation is usually expressed in dollars per megawatt hour (MWh) and includes initial costs plus operating costs divided by the energy discharged over the asset’s service life.

There are dozens of potential variables that may be used to determine the true levelized cost of storage, and different vendors will add, omit, or adjust different ones to put their products in the best light. This is why it’s so important to understand the role of RTE and cost of energy in a storage system, because they often have the biggest impact. These are also components that vendors with low-RTE technologies will most often discount (or omit altogether).

Round-trip efficiency is a measure of the amount of energy put into a system compared to the amount dispatched, and is expressed as a percentage. A system with a high RTE (75%+) is able to dispatch most of the energy fed into it. A low RTE indicates that the system loses a considerable amount of energy, often to heat arising from irreversible side reactions or high internal cell resistance. Many long-duration energy storage systems have RTEs below 50%, creating a significant amount of energy waste.

For example, lithium-ion batteries generally have RTEs of 90%+. In contrast, lead-acid batteries have lower RTEs of around 70%, meaning that approximately 30% of charge energy is lost. RTEs for flow batteries can range from 50%–75%, while metal-air batteries could have RTEs as low as 40%.

If the electricity used to charge low-RTE batteries was free, efficiency might not matter much. But electricity always comes with a cost. Some might argue that during periods where supply exceeds demand, renewables could be used to charge batteries when they would otherwise be curtailed. There’s a logic to that, but curtailment periods can’t always be predicted.

Even if you’re using electricity that would otherwise be curtailed, you have to assign a monetary value. If a turbine is spinning or a solar panel is generating electricity and a battery system is storing that electricity, every component in the system is subject to normal wear and tear plus maintenance and replacement protocols—all of which have costs associated. Factors at play include:

Technology lifespan and degradation rate. An energy storage system’s service life is determined by technology and cycles. All energy storage systems deteriorate over time, making them less efficient at storing and discharging energy. The same goes for generation sources. From solar to wind to flow batteries to lithium-ion, the more the components are used, the shorter the lifespan and the sooner the need for repair, replacement or augmentation.

Maintenance costs. Solar panels, wind turbines, battery systems, transmission lines, and power equipment all have to be maintained. The more they’re used, the more often components need to be serviced or replaced.

Long-Duration Doesn’t Always Mean Lower LCOS

The latest buzzy term in the energy space is “long-duration energy storage,” or LDES for short. While there’s no single definition of what the term means, the term has generally come to describe a non-lithium storage technology that can provide energy for anywhere from 8 to 160 hours at a lower installed cost per MW than lithium-ion batteries or a standard natural gas turbine.

LDES isn’t confined to battery storage; non-battery technologies include compressed air, latent heat, flywheels, and more. In fact, pumped hydro currently accounts for the vast majority of all LDES capacity in the US, and will likely remain in that position for an extended time. Battery technologies being positioned for LDES use include flow batteries, zinc-based chemistries, metal air, nickel hydrogen, and more.

These technologies all work well and are generally safer than lithium-ion batteries, but they come with trade-offs. Many have high up-front costs and must be amortized over 30–40-year periods to be cost competitive. Some have very low energy densities, requiring significant amounts of land for installations above a few megawatt hours. Some are rate-limited and can’t discharge as quickly as needed for specific applications. Some have very restricted siting requirements. And maybe most importantly, many have RTEs below 60%, with a few at 40% or lower.

So, what does this all mean? The race is on to build a better storage system, and with no universal standard for calculating LCOS, every vendor is using a model that plays to the strength of their own technology. If you’re investigating a new storage technology, be sure to ask a few questions when LCOS numbers come up, such as:

How many years are they calculating when it comes to system life? Lithium-ion batteries usually have to be augmented or replaced somewhere between 10 and 15 years of use; vendors with low densities or high installed costs may calculate over 30–40 years to lower their LCOS while factoring in two or more replacement cycles for lithium-ion.

What are they using for the cost of electricity to charge the system, and how does that compare with your actual costs? Even if you’re only planning to charge the system during periods you’d normally be curtailing renewables, remember that there’s still a cost to running those systems. A system with a low RTE may end up having a much higher LCOS even when you’re paying very little for electricity.

Are they including the cost of land in their calculations? If you’re installing a storage facility in a rural area where land is cheap, this may not matter so much. But if you need to place storage in or near a high-cost-of-living area, cost of land (and availability) could be one of your primary concerns and should definitely play a role in the LCOS calculation.

Are they including installation tax credits (ITCs) or production tax credits (PTCs) in their calculations? If so, be sure that the numbers are correct for your projects, and that the same are being applied to any other technologies you’re evaluating.

— Mukesh Chatter is the CEO of Alsym Energy , a technology company developing a low-cost, high-performance rechargeable battery chemistry that is free of lithium and cobalt.

SHARE this article

Thunder Said Energy

the research consultancy for energy technologies

Round Trip Battery Efficiencies

This data-file derives the ‘net round trip efficiency’ of nine different battery solutions for storing energy. Rough costs are also estimated.

Net round trip efficiency is calculated as the energy efficiency of the battery (kWh recovered per kWh fed in) divided by the energy efficiency of the displaced energy source.

We see great potential in “good batteries” , for example, electrification of the vehicle fleet, which can achieve c3.5x uplifts in efficiency.  We see less potential in “bad batteries”, for example, backing up the grid with hydrogen, which reduces total system efficiency by c35%.

Privacy Overview

GridProjectIQ Documentation

Energy Storage System Efficiency

The round trip efficiency (RTE) of an energy storage system is defined as the ratio of the total energy output by the system to the total energy input to the system, as measured at the point of connection. The RTE varies widely for different storage technologies. A high value means that the incurred losses are low.

Reference Information

The typical RTE values for different technologies along with the source of information are provided below. If the reference provides a range of values instead of a single value, the median value of the range has been used.

• Lithium-ion (83%) : W. G. Manuel, “Energy Storage Study 2014”, 2014.
• Vanadium redox flow (75%) : V. Viswanathan, M. Kintner-Meyer, P. Balducci and C. Jin, “National Assessment of Energy Storage for Grid Balancing and Arbitrage, Phase II, Volume 2: Cost and Performance Characterization”, Sept. 2013.
• Sodium sulfur (75%) : W. G. Manuel, “Energy Storage Study 2014”, 2014.
• Advanced lead-acid (85%) : IEC, “Electrical Energy Storage: White Paper”, 2011.
• Flywheel (81%) : V. Viswanathan, M. Kintner-Meyer, P. Balducci and C. Jin, “National Assessment of Energy Storage for Grid Balancing and Arbitrage, Phase II, Volume 2: Cost and Performance Characterization”, Sept. 2013.
• Compressed air (50%) : IEC, “Electrical Energy Storage: White Paper”, 2011.
• Pumped hydro (81%) : V. Viswanathan, M. Kintner-Meyer, P. Balducci and C. Jin, “National Assessment of Energy Storage for Grid Balancing and Arbitrage, Phase II, Volume 2: Cost and Performance Characterization”, Sept. 2013.

Everything you want to know about batteries, and more!

Round Trip Efficiency in Batteries: A Critical Matter

When we depart for a hike in the mountains, we are full of excitement over the gorgeous views that lie ahead. However, when we return home late in the afternoon our energy is exhausted. Even after a good night’s sleep, we are still not fully ourselves. Our round trip has robbed ourselves of something. This happens with battery storage too. We call this phenomenon the “round trip efficiency”.

Comparing Round Trip Efficiency in Energy Storage

Battery storage saves surplus energy by absorbing it, and releasing it later typically to a power grid. However, the process itself expends some of the power. We call the net ratio of power retention round trip efficiency.

This ratio is critical to the success of energy storage, and by definition renewable energy sources too. We would be on the back foot were we to lose too much potential in the process. Energy Mag advises storage batteries are slightly behind flywheels that have 80 to 90% round trip efficiency. However, batteries are catching up with 75 to 90%, and every month science gains more traction.

Using Battery Storage to Manage Grid Loading

Grid managers face the challenge of matching supply and demand. Previously, they did so by throttling generators or even bringing power stations on and off line. But the dwell time between step changes could take hours – not good for our desk tops at all …

Battery storage has potential to make these adjustments in nano seconds, thereby avoiding power fluctuations that plague electronic equipment. However, domestic consumers are unwilling to accept the additional costs ensuing. Hence, the rate of mass battery storage implementation depends on the cost-efficiency of batteries.

Round trip efficiency in turn depends on battery performance , as do our efforts to reduce global warming. Thus, round trip efficiency is a critical success factor for our overall progress towards a greener future.

Will New Technologies be able to Increase Solar Power Efficiency?

Battery Longevity And How Size Matters

Preview Image: Recharging an Electric Bus in Shanghai

Video Share Link: https://youtu.be/-I87Qg24tMk

About Author

I tripped over a shrinking bank balance and fell into the writing gig unintentionally. This was after I escaped the corporate world and searched in vain for ways to become rich on the internet by doing nothing. Despite the fact that writing is no recipe for wealth, I rather enjoy it. I will not deny I am obsessed with it when I have the time. I live in Margate on the Kwazulu-Natal south coast of South Africa. I work from home where I ponder on the future of the planet, and what lies beyond in the great hereafter. Sometimes I step out of my computer into the silent riverine forests, and empty golden beaches for which the area is renowned. Richard

Related Posts

Things To Remember About Lithium-Ion

Iron Metal Reactivity Transformed By Scientists

Integrating Gravity Batteries in Buildings

Leave a reply cancel reply.

Save my name, email, and website in this browser for the next time I comment.

HOMER Pro 3.15

• Zoom Window Out
• Larger Text  |  Smaller Text
• Hide Page Header
• Show Expanding Text
• Printable Version
• Save Permalink URL

The battery round-trip efficiency is the round trip DC-to-storage-to-DC energy efficiency of the storage bank, or the fraction of energy put into the storage that can be retrieved. Typically it is about 80%. HOMER assumes the storage charge efficiency and the storage discharge efficiency are both equal to the square root of the round-trip efficiency.

Battery Charge Efficiency

Battery Discharge Efficiency

• GridTECH Connect

Calculating the True Cost of Energy Storage

When evaluating whether and what type of storage system they should install, many customers only look at the  initial cost of the system — the first cost or cost per kilowatt-hour (kWh). Such thinking fails to account for other factors that impact overall system cost, known as the levelized cost of energy (LCOE) , which factors in the system’s useful life, operating and maintenance costs, round-trip efficiency, and residual value.

Looking only at the initial cost of the system also fails to account for other factors, such as the revenue side of the equation, where a versatile battery that can be used for multiple applications can generate multiple revenue streams. When considering an energy storage purchase, it is essential that customers consider all these factors if they hope to secure an understanding of the true costs — and value — of the energy storage system they plan to purchase.

A simple calculation of LCOE takes the total life cycle cost of a system and divides it by the system’s total lifetime energy production for a cost per kWh. It factors in the system’s useful life, operating and maintenance costs, round-trip efficiency, and residual value. Integrating these factors into the cost equation can have a significant impact on the real cost of the battery.

For example, storing energy in a battery is no free lunch. Some of the energy you store in the battery is lost to due heat or other inefficiencies. Round-trip efficiency looks at how much of this energy is lost in a “round trip” between the time the energy storage system is charged and then discharged. You can almost think of it as a toll for getting on the highway. The question is how big the toll is. Most energy storage systems that use flow-batteries have round trip efficiencies of 75 percent or more, meaning that if you charge the battery with 100 kWh, you would be able to discharge 75 kWh of electricity from the battery. By integrating round-trip efficiency into the LCOE calculation these efficiency losses are accounted for, and you can have a better apples to apples comparison between two energy storage systems with different round-trip efficiencies.

Lithium advocates sometimes claim that their technology has a higher round trip efficiency, but the answer is not that simple. Lithium battery systems can have an 85 percent round trip efficiency for shallow cycles, but efficiency is relative to the charge and discharge rates of the battery, the depth of discharge, and even temperatures.  In the case of certain flow batteries, round trip efficiency doesn’t vary much at all, irrespective of depth of discharge, and charge or discharge rates.  In other words, depending on the use cases and various charge rates and depths of discharge or duty cycles, the lithium battery efficiency benefit disappears.

A system’s useful life is also factored into the LCOE calculation. This is calculated in years, but it is not as simple as that because batteries do not age based on time only — they also age based on use. Specifically, many batteries can only support a certain number of charge/discharge cycles before their performance either begins to degrade or they fail. Therefore the expected use pattern for a battery can have a significant impact on its useful life. One of the advantage of flow batteries is their useful life is not determined by charge/discharge cycles, as they can be charged and recharged nearly an unlimited number of times without degradation. For long-term, high-use applications, this capability lowers a flow-battery’s LCOE versus other battery technologies, as the flow battery does not have to be replaced due to frequent cycling.

Another factor to consider is operating and maintenance costs. The cost of an energy storage system is not final when you purchase it—there are also the costs involved in keeping it up and running. These can be high, especially for certain batteries which require frequent maintenance. By integrating these costs into the LCOE calculation, you obtain a truer understanding of a battery’s actual cost over its entire life.

And while powerful, LCOE is also not perfect. LCOE does not measure the reliability of a battery, or the impact of the sourcing of its components on the environment. And while it looks at the cost side of the equation, it fails to look at the other side — revenue. Batteries do not have to be used solely for a single application, like peak-shaving, renewable firming or frequency regulation. Versatile battery systems have the performance capabilities necessary to perform a diverse set of applications, allowing them to secure revenue from each of these applications. Thus a battery with a higher initial cost that is versatile enough to perform multiple applications could generate additional revenue that makes up for the initial cost.

Because it measures the cost of a battery over its overall life, LCOE is a powerful metric, and should be on any energy storage developer’s checklist when evaluating various battery storage technologies. In addition, energy storage developers need to look beyond this single number to a battery’s other characteristics — reliability, sustainability and versatility — if they hope to understand not just the raw cost, but the true value delivered by the battery.

Lead image: Calculator via Shutterstock

Related Posts

Latest Renewable Energy World News

You are using an outdated browser. Please upgrade your browser or activate Google Chrome Frame to improve your experience.

• Commercial & industrial PV
• Grids & integration
• Residential PV
• Utility scale PV
• Energy storage
• Balance of systems
• Modules & upstream manufacturing
• Opinion & analysis
• Opinion & analysis guidelines
• Press Releases
• Technology and R&D
• Sustainability
• 50 States of Solar
• pv magazine UP initiative
• pv magazine Hydrogen Hub
• Magazine features
• US module maker directory
• pv magazine Roundtables & Insights
• pv magazine Webinars
• Event calendar
• Past events
• Special Edition Las Vegas 2023
• OMCO Solar white paper
• Print archive
• pv magazine test
• pv magazine team
• Newsletter subscription
• Magazine subscription
• Community standards

Iron flow battery tech shows promise for mid-duration energy storage

The ESS battery systems have a prescribed design life of 25 years, but the battery modules, electrolyte, plumbing, and other components may well last for decades longer with proper maintenance.

• Energy Storage

An ESS battery Energy Warehouse.

Iron flow battery manufacturer ESS Inc. has been in the news lately, most recently for releasing an updated version of its product guarantee.

Munich RE, one of the world’s largest reinsurance companies, also updated its insurance policy for ESS to address customer concerns over technology risk. ESS told pv magazine USA that the new policy covers the battery modules and electrolyte management system, as well any needed repairs or replacement for the first 10 years of the system’s life. ESS manufactures these components itself.

The product’s pump and motor drives have an expected lifetime of 19-22 years. The industrial computer, which was described as “inexpensive,” can be expected to be replaced every 5-7 years. ESS offers an O&M service contract after the 10-year mark.

But even more striking is the battery’s expected longevity. Much like the grid’s oldest assets, (some of which were first built in the 1890s), ESS batteries show the potential to soldier on for many decades. While the ESS battery systems have a prescribed design life of 25 years, the battery modules, electrolyte, plumbing, and other components may well last for decades longer with proper maintenance.

For one thing, the battery is expected to experience zero degradation over 20,000 cycles. By design, iron flow batteries circulate liquid electrolytes to charge and discharge electrons using a process called a redox reaction, which represents a gain of electrons (reduction), and a loss of electrons (oxidation). ESS uses the same electrolyte on both the negative and positive sides, eliminating possible cross-contamination and degradation. As a result, ESS chemistry remains stable for an almost unlimited number of deep-cycle charge and discharge cycles.

Another reason for the expected long operating life is that ESS batteries use a “proton pump” to balance and maintain electrolyte health over the life of the asset.

The pump connects to the tank and passively mixes unwanted hydrogen back into the solution. Doing so maintains the balance of pH and states of charge in the liquid electrolyte circulating through the system.

In human terms, the battery is the heart, the electrolyte is the blood, and the proton pump is the kidney, which keeps everything in balance.

The pump itself is expected to be a key commercial differentiator for ESS. Other flow chemistries need to come offline regularly to rebalance their electrolytes. Not so with the ESS design.

In the unlikely event that the battery is to be decommissioned, the system and all of its components can be substantially recycled.

Any non-ESS manufactured system components come with third-party warranties. The full warranty wasn’t available to be distributed via pv magazine USA .

The company currently offers two products, the single shipping container Energy Warehouse and a string of warehouse units in an Energy Center.

Image: ESS Energy

One Energy Warehouse shipping container holds 400-600kWh of storage capacity and can be configured with variable power to provide storage durations of 4-12 hours. That makes the power rating configurable from 50-90 kW. The round-trip efficiency is 70-75%, DC-DC. Each battery weighs 16,000 kg dry, and as much as 38,000 kg after it’s filled with the electrolyte.

For larger volumes of energy storage, ESS will string together multiple batteries in what it calls an Energy Center . At this larger scale, ESS batteries take up some real estate. One acre of batteries holds up to 6 MW/90 MWh, providing up to 12 hours discharge at rated power. These large battery centers are expected to have fast, easy permitting due to the lack of hazmat concerns as well as non-flammable, non-explosive materials.

But the most important news of the day – product sales news – shows that ESS has been busy.

• The company recently announced that it entered into a framework agreement with SB Energy, a unit of SoftBank Group Corp., to deploy 2 GWh through 2026.  As part of the agreement, the first ESS system has already been delivered to an SB Energy location in Davis, California, and will be commissioned in October.
• An order with Enel Green Power España of 17 Energy Warehouse units with a combined capacity of 8.5 MWh will support solar farms in Spain as a part of a broader EU-wide engagement, providing resilience for the local power grid.

To support its growth, ESS announced that they were to become a publicly listed company through a SPAC merger with ACON S2 Acquisition Corp this past May. And in a great coup, the company will be listed on the NYSE under the ticker symbol “GWH.”

This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com .

John Fitzgerald Weaver

More articles from John Fitzgerald Weaver

DOE wants to power 5 million homes with community solar by 2025

Green hydrogen mou signed by intersect power and electric hydrogen, related content, elsewhere on pv magazine....

Please clarify why the storage of a flow battery is limited to 12 hours. My understanding of a generic flow battery is that the energy is stored in the flow/electrolyte. Ideally that charged electrolyte can be stored for years, at least for days or weeks so the energy from a PV array is stored to be available throughout an extended period of bad weather, not just for the evening. If the energy storage is just for a few hours, why not use a super capacitor.

It’s not limited to 12 hours, but just so happens that these batteries have been manufactured at that size. Form Energy offers a 150 hour flow battery.

Leave a Reply Cancel reply

Please be mindful of our community standards .

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

Notify me of follow-up comments by email.

Notify me of new posts by email.

By submitting this form you agree to pv magazine using your data for the purposes of publishing your comment.

Your personal data will only be disclosed or otherwise transmitted to third parties for the purposes of spam filtering or if this is necessary for technical maintenance of the website. Any other transfer to third parties will not take place unless this is justified on the basis of applicable data protection regulations or if pv magazine is legally obliged to do so.

You may revoke this consent at any time with effect for the future, in which case your personal data will be deleted immediately. Otherwise, your data will be deleted if pv magazine has processed your request or the purpose of data storage is fulfilled.

Further information on data privacy can be found in our Data Protection Policy .

pv magazine USA offers daily updates of the latest photovoltaics news. We also offer comprehensive global coverage of the most important solar markets worldwide. Select one or more editions for targeted, up to date information delivered straight to your inbox.

• Select Edition(s) * Hold Ctrl or Cmd to select multiple editions. Tap to select multiple editions. U.S. (English, daily) Global (English, daily) Germany (German, daily) Australia (English, daily) China (Chinese, weekly) India (English, daily) Latin America (Spanish, daily) Brazil (Portuguese, daily) Mexico (Spanish, daily) Spain (Spanish, daily) France (French, daily) Italy (Italian, daily)
• Read our Data Protection Policy .

Subscribe to our global magazine

Most popular

Keep up to date

Help | Advanced Search

Electrical Engineering and Systems Science > Systems and Control

Title: round-trip energy efficiency and energy-efficiency fade estimation for battery passport.

Abstract: The battery passport is proposed as a method to make the use and remaining value of batteries more transparent. The future EU Battery Directive requests this passport to contain the round-trip energy efficiency and its fade. In this paper, an algorithm is presented and demonstrated that estimates the round-trip energy efficiency of a battery pack. The algorithm identifies round trips based on battery current and SoC and characterizes these round trips based on certain conditions. 2D efficiency maps are created as a function of the conditions `temperature' and `RMS C-rate'. The maps are parameterized using multiple linear regression, which allows comparison of the efficiency under the same conditions. Analyzing data from three battery-electric buses over a period of 3.5 years reveals an efficiency fade of up to 0.86 percent point.

Submission history

Access paper:.

• Other Formats

References & Citations

• Google Scholar
• Semantic Scholar

BibTeX formatted citation

Bibliographic and Citation Tools

Code, data and media associated with this article, recommenders and search tools.

• Institution

arXivLabs: experimental projects with community collaborators

arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website.

Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them.

Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs .

Swiss startup Neural Concept raises $27M to cut EV design time to 18 months

As pressure from Chinese competitors intensifies and the EV market stalls , major U.S. and European auto manufacturers are racing to cut the cost of producing electric vehicles so they can get to the price tags and profit margins of ICE cars. But to do that, they must find ways to make the design process faster and more efficient.

Now, a company spun out from the Swiss Federal Institute of Technology in Lausanne (EPFL), has raised $27 million in a Series B funding round to apply AI to solve that exact pain point. 

In simple terms, Neural Concept lets designers model how components will perform before they can be manufactured — it’s no use just having the design of a component, you need to know how it’s going to behave as part of an engine, for instance. That’s where this platform comes in. The application could be useful across a large range of industries, such as automotive, micro-electronics, aerospace and energy. 

The company says it uses deep learning in a 3D environment, and combines data analysis with machine learning to speed up development times by up to 75% and product simulation by as much as 10 times.

Pierre Baqué, co-founder and CEO at Neural Concept, said the platform rapidly accelerates what is currently a manual process. “Let’s say I have a design for a battery, and I would like it to perform better to increase its thermal efficiency. Our software will suggest some improvements on how to make it more efficient, because the software is aware of the property of the materials,” he explained.

“Prior to our software you have, typically, a CAD designer drawing 3D designs who sends it to someone to do very complex numerical simulations. That can take a very long time to run or might require physical tests. But now, our platform can guide the designer directly.”

Baqué thinks his platform could reduce the development time of an EV from four years to 18 months.

The startup’s product is currently being used by Airbus, Bosch, General Electric, Mubea, Subaru, and four Formula 1 racing teams. The company is working with NVIDIA to optimize the graphics card maker’s GPUs and CUDA software.

Neural Concept is going up against much larger ‘component simulation’ giants such as ANSYS , which has been attempting to move into this ‘deep learning’ space with its own platforms.  

The Series B was led by Forestay Capital , with existing investors  Alven ,  Constantia New Business ,  HTGF ,  Aster Group  and D.E. Shaw group also participating. The round follows a $9 million Series A in March 2022 and a $2 million seed round in 2020. The new money will be used for recruitment and expansion into Europe, APAC and the U.S.

In a statement, Deborah Pittet, senior principal at Forestay Capital said, “Neural Concept has pioneered 3D Deep Learning – the leading-edge of AI – and demonstrated phenomenal traction and results with customers in various industries around the world.”

More TechCrunch

Get the industry’s biggest tech news, techcrunch daily news.

Every weekday and Sunday, you can get the best of TechCrunch’s coverage.

Startups Weekly

Startups are the core of TechCrunch, so get our best coverage delivered weekly.

TechCrunch Fintech

The latest Fintech news and analysis, delivered every Tuesday.

TechCrunch Mobility

TechCrunch Mobility is your destination for transportation news and insight.

Cloudera acquires Verta to bring some AI chops to its data platform

Cloudera, the once high flying Hadoop startup, raised $1 billion and went public in 2018 before being acquired by private equity for $5.3 billion 2021. Today, the company announced that…

Spend management startup SiFi raises $10M to grow further in Saudi Arabia

The global spend management sector is experiencing a tailwind of sorts. North America is arguably the biggest market in this space, but spend management companies have seen demand rise across…

Neural Concept lets designers model how components will perform before they can be manufactured.

Don’t miss StrictlyVC in DC next week

The StrictlyVC roadtrip continues! Coming off of sold-out events in London, Los Angeles, and San Francisco, we’re heading to Washington, D.C. for a cozy-vc-packed, evening at the Woolly Mammoth Theatre…

X tweaks rules to formally allow adult content

X will now allow users to post consensually produced NSFW content as long as it is prominently labeled as such.

Ashby injects recruiting with a dose of AI

Ashby consolidates existing talent acquisition tools and leans heavily on AI to automate the more repetitive steps in the recruitment pipeline.

Spotify to increase premium pricing in the US to $11.99 per month

Spotify has announced it’s hiking subscriptions for customers in the U.S., the second such price increase in the space of a year. The music-streaming giant reports that premium pricing will…

UK neobank Monzo reports first full (pre-tax) profit, prepares for EU expansion with Dublin hub

Monzo has announced its 2024 financial results, revealing its first full-year pre-tax profit. The company also confirmed that it’s in the early stages of expanding into the broader European market…

Featured Article

Inside Apple’s efforts to build a better recycling robot

Last week, TechCrunch paid a visit to Apple’s Austin, Texas manufacturing facilities. Since 2013, the company has built its Mac Pro desktop about 20 minutes north of downtown. The 400,000 square foot facility sits in a maze of industry parks, a quick trip south from the company’s in-progress corporate campus. In recent years, the capital…

Binit is bringing AI to trash

Early attempts at making dedicated hardware to house artificial intelligence smarts have been criticized as, well, a bit rubbish. But here’s an AI gadget-in-the-making that’s all about rubbish, literally: Finnish…

Temasek, Fidelity buy $200M stake in Lenskart at $5B valuation

Temasek has previously invested in Lenskart, and this new funding follows a $500 million investment by the Abu Dhabi Investment Authority last year.

French startup ten ten reinvents the walkie-talkie

Less than one year after its iOS launch, French startup ten ten has gone viral with a walkie talkie app that allows teens to send voice messages to their close…

Unicorn-rich VC Wesley Chan owes his success to a Craigslist job washing lab beakers

While all of Wesley Chan’s success has been well-documented over the years, his personal journey…not so much. Chan spoke to TechCrunch about the ways his life impacts how he invests in startups.

Trump takes off on TikTok

Presumptive Republican presidential nominee Donald Trump now has an account on the short-form video app that he once tried to ban. Trump’s TikTok account, which launched on Saturday night, features…

Iceland’s startup scene is all about making the most of the country’s resources

With fewer than 400,000 inhabitants, Iceland receives more than its fair share of tourists — and of venture capital.

Kobo’s new e-readers are a sidegrade most can skip (with one exception)

Kobo put out a handful of new e-readers a few weeks back: color versions of the excellent Libra 2 and Clara, as well as an updated monochrome version of the…

Unity co-founder David Helgason’s next act: Gaming the climate crisis

In an interview at his home near Reykjavík, the entrepreneur-turned-VC shared thoughts on his ventures and the journey that led him from Unity to climate tech, a homecoming of sorts.

Fisker collapsed under the weight of its founder’s promises

Welcome back to TechCrunch’s Week in Review — TechCrunch’s newsletter recapping the week’s biggest news. Want it in your inbox every Saturday? Sign up here. Over the past eight years,…

What is AI? We’ve put together this non-technical guide to give anyone a fighting chance to understand how and why today’s AI works.

President Biden vetoes crypto custody bill

President Joe Biden has vetoed H.J.Res. 109, a congressional resolution that would have overturned the Securities and Exchange Commission’s current approach to banks and crypto. Specifically, the resolution targeted the…

Industries may be ready for humanoid robots, but are the robots ready for them?

How large a role humanoids will play in that ecosystem is, perhaps, the biggest question on everyone’s mind at the moment.

VCs are selling shares of hot AI companies like Anthropic and xAI to small investors in a wild SPV market

VCs are clamoring to invest in hot AI companies, and willing to pay exorbitant share prices for coveted spots on their cap tables. Even so, most aren’t able to get…

Deal Dive: How (Re)vive grew 10x last year by helping retailers recycle and sell returned items

The fashion industry has a huge problem: Despite many returned items being unworn or undamaged, a lot, if not the majority, end up in the trash. An estimated 9.5 billion…

You can no longer use Tumblr’s tipping feature 

Tumblr officially shut down “Tips,” an opt-in feature where creators could receive one-time payments from their followers.  As of today, the tipping icon has automatically disappeared from all posts and…

AI training data has a price tag that only Big Tech can afford

Generative AI improvements are increasingly being made through data curation and collection — not architectural — improvements. Big Tech has an advantage.

This Week in AI: Can we (and could we ever) trust OpenAI?

Keeping up with an industry as fast-moving as AI is a tall order. So until an AI can do it for you, here’s a handy roundup of recent stories in the world…

General Catalyst-backed Jasper Health lays off staff

Jasper Health, a cancer care platform startup, laid off a substantial part of its workforce, TechCrunch has learned.

Live Nation confirms Ticketmaster was hacked, says personal information stolen in data breach

Live Nation says its Ticketmaster subsidiary was hacked. A hacker claims to be selling 560 million customer records.

Inside EV startup Fisker’s collapse: how the company crumbled under its founders’ whims

An autonomous pod. A solid-state battery-powered sports car. An electric pickup truck. A convertible grand tourer EV with up to 600 miles of range. A “fully connected mobility device” for young urban innovators to be built by Foxconn and priced under $30,000. The next Popemobile. Over the past eight years, famed vehicle designer Henrik Fisker…

Hugging Face says it detected ‘unauthorized access’ to its AI model hosting platform

Late Friday afternoon, a time window companies usually reserve for unflattering disclosures, AI startup Hugging Face said that its security team earlier this week detected “unauthorized access” to Spaces, Hugging…