Solar Energy News  
SOLAR DAILY
Solar energy farms could offer second life for electric vehicle batteries
by David L. Chandler for MIT News
Boston MA (SPX) May 25, 2020

An MIT study shows that electrical vehicle batteries could have a useful and profitable second life as backup storage for grid-scale solar photovoltaic installations, where they could perform for more than a decade in this less demanding role. This image shows a 'cut-away' view of a lithium-ion battery over a background of cars and solar panels.

As electric vehicles rapidly grow in popularity worldwide, there will soon be a wave of used batteries whose performance is no longer sufficient for vehicles that need reliable acceleration and range. But a new study shows that these batteries could still have a useful and profitable second life as backup storage for grid-scale solar photovoltaic installations, where they could perform for more than a decade in this less demanding role.

The study, published in the journal Applied Energy, was carried out by six current and former MIT researchers, including postdoc Ian Mathews and professor of mechanical engineering Tonio Buonassisi, who is head of the Photovoltaics Research Laboratory.

As a test case, the researchers examined in detail a hypothetical grid-scale solar farm in California. They studied the economics of several scenarios: building a 2.5-megawatt solar farm alone; building the same array along with a new lithium-ion battery storage system; and building it with a battery array made of repurposed EV batteries that had declined to 80 percent of their original capacity, the point at which they would be considered too weak for continued vehicle use.

They found that the new battery installation would not provide a reasonable net return on investment, but that a properly managed system of used EV batteries could be a good, profitable investment as long as the batteries cost less than 60 percent of their original price.

Not so easy
The process might sound straightforward, and it has occasionally been implemented in smaller-scale projects, but expanding that to grid scale is not simple, Mathews explains. "There are many issues on a technical level. How do you screen batteries when you take them out of the car to make sure they're good enough to reuse? How do you pack together batteries from different cars in a way that you know that they'll work well together, and you won't have one battery that's much poorer than the others and will drag the performance of the system down?"

On the economic side, he says, there are also questions: "Are we sure that there's enough value left in these batteries to justify the cost of taking them from cars, collecting them, checking them over, and repackaging them into a new application?" For the modeled case under California's local conditions, the answer seems to be a solid yes, the team found.

The study used a semiempirical model of battery degradation, trained using measured data, to predict capacity fade in these lithium-ion batteries under different operating conditions, and found that the batteries could achieve maximum lifetimes and value by operating under relatively gentle charging and discharging cycles - never going above 65 percent of full charge or below 15 percent. This finding challenges some earlier assumptions that running the batteries at maximum capacity initially would provide the most value.

"I've talked to people who've said the best thing to do is just work your battery really hard, and front load all your revenue," Mathews says. "When we looked at that, it just didn't make sense at all." It was clear from the analysis that maximizing the lifetime of the batteries would provide the best returns.

How long will they last?
One unknown factor is just how long the batteries can continue to operate usefully in this second application. The study made a conservative assumption, that the batteries would be retired from their solar-farm backup service after they had declined down to 70 percent of their rated capacity, from their initial 80 percent (the point when they were retired from EV use).

But it may well be, Mathews says, that continuing to operate down to 60 percent of capacity or even lower might prove to be safe and worthwhile. Longer-term pilot studies will be required to determine that, he says. Many electric vehicle manufacturers are already beginning to do such pilot studies.

"That's a whole area of research in itself," he says, "because the typical battery has multiple degradation pathways. Trying to figure out what happens when you move into this more rapid degradation phase, it's an active area of research."

In part, the degradation is determined by the way the batteries are controlled. "So, you might actually adapt your control algorithms over the lifetime of the project, to just really push that out as far as possible," he says. This is one direction the team will pursue in their ongoing research, he says. "We think this could be a great application for machine-learning methods, trying to figure out the kind of intelligent methods and predictive analytics that adjust those control policies over the life of the project."

The actual economics of such a project could vary widely depending on the local regulatory and rate-setting structures, he explains. For example, some local rules allow the cost of storage systems to be included in the overall cost of a new renewable energy supply, for rate-setting purposes, and others do not. The economics of such systems will be very site specific, but the California case study is intended to be an illustrative U.S. example.

"A lot of states are really starting to see the benefit that storage can provide," Mathews says. "And this just shows that they should have an allowance that somehow incorporates second-life batteries in those regulations. That could be favorable for them."

A recent report from McKinsey Corp. shows that as demand for backup storage for renewable energy projects grows between now and 2030, second use EV batteries could potentially meet half of that demand, Mathews says. Some EV companies, he says, including Rivian, founded by an MIT alumnus, are already designing their battery packs specifically to make this end-of-life repurposing as easy as possible.

Mathews says that "the point that I made in the paper was that technically, economically, ... this could work." For the next step, he says, "There's a lot of stakeholders who would need to be involved in this: You need to have your EV manufacturer, your lithium ion battery manufacturer, your solar project developer, the power electronics guys." The intent, he says, "was to say, 'Hey, you guys should actually sit down and really look at this, because we think it could really work.'"

The study team included postdocs Bolum Xu and Wei He, MBA student Vanessa Barreto, and research scientist Ian Marius Peters. The work was supported by the European Union's Horizon 2020 research program, the DoE-NSF ERF for Quantum Sustainable Solar Technologies (QESST) and the Singapore National Research Foundation through the Singapore-MIT Alliance for Research and Technology (SMART).

Research Report: "Technoeconomic model of second-life batteries for utility-scale solar considering calendar and cycle aging"


Related Links
MIT News Office
All About Solar Energy at SolarDaily.com


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


SOLAR DAILY
Next-generation solar cells pass strict international tests
Sydney, Australia (SPX) May 22, 2020
Australian scientists have for the first time produced a new generation of experimental solar energy cells that pass strict International Electrotechnical Commission testing standards for heat and humidity. The research findings, an important step towards commercial viability of perovskite solar cells, are published in the journal Science. Solar energy systems are now widespread in both industry and domestic housing. Most current systems rely on silicon to convert sunlight into useful energy ... read more

Comment using your Disqus, Facebook, Google or Twitter login.



Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

SOLAR DAILY
Chemical recycling makes useful product from waste bioplastic

Researchers turn algae leftovers into renewable products with flare

Can renewable energy really replace fossil fuels?

Solve invasive seaweed problem by turning it into biofuels and fertilisers

SOLAR DAILY
Next generation of soft robots inspired by a children's toy

E-commerce startup banks on robotics, AI to win consumers

UCLA and Carnegie Mellon researchers develop real-time physics engine for soft robotics

'Steering wheel' brain neurons control if mouse turns left, right

SOLAR DAILY
US wind plants show relatively low levels of performance decline as they age

Wave, wind and PV: The world's first floating Ocean Hybrid Platform

Supercomputing future wind power rise

Wind energy expansion would have $27 billion economic impact

SOLAR DAILY
Uber says slashing jobs and trimming investment

Tesla, California appear to end standoff over restarting factory

Uber to require face masks for drivers, riders

China car sales begin recovery after virus plunge

SOLAR DAILY
Surrey unveils fast-charging super-capacitor technology

Skoltech scientists show a promising solid electrolyte is 'hydrophobic'

Electrons break rotational symmetry in exotic low-temp superconductor

Coordination polymer glass provides solid support for hydrogen fuel cells

SOLAR DAILY
US awards two projects utilizing the BWRX-300 Small Modular Reactor Design

Study reveals single-step strategy for recycling used nuclear fuel

Framatome and the Technical University of Munich to develop new fuel for research reactor

Are salt deposits a solution for nuclear waste disposal?

SOLAR DAILY
Global CO2 emissions to drop 4-7% in 2020, but will it matter

New map highlights China's export-driven CO2 emissions

COVID-19 to cause record emissions fall in 2020: IEA

Europe's banks not doing enough on climate: pressure group

SOLAR DAILY
With attention on virus, Amazon deforestation surges

Brazil to deploy army to fight Amazon deforestation

Look beyond rainforests to protect trees, scientists say

Deforestation in Africa accelerates: UN food agency









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.