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Battery bravado

The rapid uptake of electric vehicles in California brings with it an increase in electricity storage capacity that perhaps calls into question the need to invest separately in batteries to support the bulk supply of electricity

California likes to be out front on the road to the energy transition, but in one case the US state may have taken a wrong turn, at least according to a research paper published in May 2018. It calls into question the need to continue investing billions of dollars in large-scale banks of batteries to support the grid when sufficient battery capacity for the job may be available in electric cars parked around the state and already paid for by consumers.

California has made a huge commitment to electric vehicles (EVs). State drivers have bought half of all plug-in vehicles ever sold in the US and 15% of the global total. Governor Jerry Brown recently raised the state’s goal from 1.5 million EVs by 2025 to five million on the road by 2030. The state’s Advanced Clean Cars law, known as ZEV-LEV, requires car makers to get at least 16% of their sales from zero-emission vehicles by 2025. An annual budget of $100 million to support ZEV projects has been supplemented by $800 million over ten years from Volkswagen’s dieselgate” settlement fund, created when California regulators caught the car company cheating on emissions tests for their diesel vehicles. On May 31, 2018 utility regulators approved another $768 million for investments in charging infrastructure and rebates for heavy-duty electric vehicles. On top of these investments in electric vehicles, California is also spending billions on banks of batteries to provide grid services, known as stationary batteries in the jargon. In theory, however, sufficient battery capacity could be available in the state’s EVs to provide the needed grid support, according to a paper published in Environmental Research Letters by a group of researchers at the state’s Lawrence Berkeley National Laboratory (LBNL). The authors question the need to invest in both batteries for grid support and batteries for mobility. Our results show that substantial capital investment, as much as several billion dollars, can be avoided if electric vehicles are used in lieu of stationary storage,” they write_._The California legislature has already passed two energy storage mandates, first in 2010 for 1325 megawatts (MW) in a variety of configurations (on the transmission grid, distribution grid, or behind the meter) and ownership models (utility, customer and third party owned), and again last year for another 500 MW of behind-the-meter storage. The battery industry is back again this year seeking another 2000 MW of mandates. This is on top of a state fund that will spend almost $400 million on batteries over the next two years. At least some of the preoccupation with batteries in California is a reaction to the major and infamous gas leak in 2015 that put the Aliso Canyon natural gas storage facility near Los Angeles offline. More than 60% of the battery power capacity now serving the grid was installed to meet local reliability needs in southern California after the leak. Experience with those batteries suggests they can help resolve another California problem, the electricity generated by solar panels in the middle of the day that is excess to immediate demand.

Managing solar

California has 704 utility-scale solar power facilities with an installed generating capacity of 10,830 MW, which in 2017 provided 11.8% of the state’s total electricity production. The state regularly sees hours when over a third of its power comes from utility-scale solar power. Added to that is the generation by another 6500 MW of distributed solar systems, mainly on rooftops, which is not tracked by the state’s grid operator. The future promises even more solar. Power companies are required by state law to get half of their power from renewables, not counting large hydropower, by 2030, but have said they may hit that goal ten years early. A recent decision by state building regulators to require solar on new homes could boost annual installations by 250 MW. All of this is pushing conventional generators off the grid on sunny days, resulting in a sudden dearth of supply as the sun goes down. The difference between net power demand at midday and gross power demand in the evening is getting bigger, creating a load profile that when shown as a graphic illustration has been dubbed the duck curve,” due to its rough similarity to a swimming duck. Battery suppliers are touting the potential of their technology to move the supply of solar energy from midday, when it is not needed, to the evening when it is. For their part, solar companies see electricity storage as so essential to continued growth of their market that the state Solar Energy Industries Association recently rebranded itself as the California Solar and Storage Association. Batteries in cars can provide services to the grid network in the same way as stationary batteries, according to the LBNL researchers. Since the batteries have already been paid for to provide mobility, the additional investment in controls and communications needed to make them controllable from a grid perspective is modest, perhaps $100 per vehicle, according to the paper.

Different scenarios

The researchers model daily demand profiles for 2025, with a growing share of solar power and 1.5 million electric vehicles. They calculate that 1.5 million vehicles, a mix of battery electric and plug-in hybrids, would have a storage capacity of 72 gigawatt-hours (GWh). Current summertime demand in the state is about 600 GWh a day. The researchers consider three scenarios: uncontrolled charging where drivers plug in whenever they want and charge until the battery is full; a one-way or V1G scenario where vehicle charging is controlled; and full integration with the grid, with controlled two-way power flows (called V2G). Uncontrolled charging would make the duck curve a little worse, raising the evening peak, but mostly it would be a substantial lost opportunity if vehicles are not integrated with the grid,” they conclude. With one-way controls, or V1G, cars can be charged at midday instead of during the evening peak in demand, reducing the size of the ramp between the two. V1G would reduce extremes by 2 GW at an incremental cost of $150 million, only 10% of the cost of a comparable amount of stationary batteries, according to the paper. If the 1.5 million vehicles had V2G capabilities, with controlled charging and discharging, they could provide services equal to about 5 GW of stationary storage, saving between $12.8 billion to $15.4 billion of investment. In other words, the California Storage Mandate can be accomplished through the ZEV Mandate, provided that controlled charging is also widely deployed.” Moreover, the money saved can instead be redirected to further accelerate the deployment of clean vehicles and vehicle-grid integration,” write the researchers.

Time and place

The argument put forward by the authors rests on the probability that a sufficient number of cars will be parked and available for grid services at a given moment. Whether owners would be willing to sacrifice the convenience they purchase through car ownership is left unanswered. The study simply maintains that cars spend 96% of their time parked. The authors contend that paying car owners for their services will encourage greater participation in grid support schemes. But there is no guarantee that the cars will be plugged in at the right time and place to provide reliability services. Study co-author Jeff Greenblatt thinks EVs will be like any other grid resource, with a certain statistical probability of being available, depending on time, place, and the amount of incentives offered. There will be millions of vehicles statewide by the mid-2020s,” he says. If vehicle owners receive a tangible or intangible benefit from being grid-connected, they will [participate] and we should be able to statistically predict this behaviour once there is sufficient data.”

Second life

While there may be millions of EVs on the road in ten years, there will also be a growing stream of used batteries coming out of those cars. Before they have to be recycled, there is potential for them to be given a second life” as stationary batteries. When EV batteries lose 20% of their capability they can no longer meet the heavy performance demands of a car, such as acceleration and climbing. But batteries can still perform well enough to provide grid services, which are less taxing. Car maker BMW has been busy testing this possibility. It opened a second life facility at a car factory in Leipzig, Germany in autumn 2017 to house up to 700 used battery packs from their i3 vehicle. The batteries are integrated with wind turbines on site and are able to contribute to balancing the local grid. BMW partnered with Pacific Gas & Electric in California in 2015 and 2016 on the so-called Charge Forward project, testing 100 BMW i3 vehicles and a second-life stationary battery system with 209 demand response events. A University of California study found that if the battery packs from half of the 92,000 EVs on the road in California in 2014 could be repurposed for stationary use, they could store and dispatch 850 MWh of electricity and 425 MW of power. Ten years from now, those batteries will likely be degraded enough to be switched over to stationary use, creating a great business opportunity for entrepreneurs — and a grave threat to the stationary battery market. Between grid-integrated vehicles and second life batteries, the long term prognosis for stationary batteries may be much weaker than it seems.

Writer: Bentham Paulos