According to new research on V2G technology from an MIT team published in the journal Energy Advances, as the number of EVs rises, the collective fleet’s batteries might function as a cost-effective, large-scale energy source, with potentially significant effects on the energy transition. Electric vehicle (EV) owners are used to connecting their electric vehicles to charging ports at home and at work to refuel their batteries with energy from the power grid. These electric vehicles will also be able to reverse the flow and deliver electrons back to the grid when they plug in.
“At scale, vehicle-to-grid (V2G) can boost renewable energy growth, displacing the need for stationary energy storage and decreasing reliance on firm [always-on] generators, such as natural gas, that are traditionally used to balance wind and solar intermittency,” says Jim Owens, lead author and a doctoral student in the MIT Department of Chemical Engineering. Additional authors include Emre Gençer, a principal research scientist at the MIT Energy Initiative (MITEI), and Ian Miller, a research specialist for MITEI at the time of the study.
The work of the group represents the first comprehensive systems-based analysis of future power systems, and it is founded on a novel combination of computational models that incorporate goals for carbon emission reduction, the production of variable renewable energy (VRE), and the costs related to developing infrastructure for energy storage, production, and transmission.
“We explored not just how EVs could provide service back to the grid — thinking of these vehicles almost like energy storage on wheels — but also the value of V2G applications to the entire energy system and if EVs could reduce the cost of decarbonizing the power system,” says Gençer. “The results were surprising; I personally didn’t believe we’d have so much potential here.”
The electrification of transportation has boomed, with the rate of EV adoption significantly increasing as the US and other countries pursue strict goals to reduce carbon emissions and consumers respond with high interest in EVs. (According to some predictions, EVs will displace internal combustion engines over the next 30 years.) But there will be more need for electricity as the popularity of emissions-free driving increases. “The challenge is ensuring both that there’s enough electricity to charge the vehicles and that this electricity is coming from renewable sources,” says Gençer.
Solar and wind energy, however, are not steady 24/7. Achieving clean energy objectives will be difficult without sufficient backup for these sources, such as large-scale natural gas power plants (dirty) or stationary energy storage facilities using lithium-ion batteries, for example. It will cost hundreds of billions of dollars to create the necessary new energy infrastructure. However, there are also other options on the table. …
According to the researchers, this is precisely the situation where V2G may play a crucial and valued role. For example, the team discovered that involvement from only 13.9% of the region’s 8 million light-duty (passenger) EVs eliminated 14.7 gigawatts of stationary energy storage in their case study of a hypothetical New England power system satisfying strong carbon limitations. That also meant savings totaling $700 million, which was equal to the estimated cost of adding new storage.
In their paper, they also discussed the potential use of EV batteries during periods of high demand, such as hot summer days. “V2G technology has the ability to inject electricity back into the system to cover these episodes, so we don’t need to install or invest in additional natural gas turbines,” says Owens. “The way that EVs and V2G can influence the future of our power systems is one of the most exciting and novel aspects of our study.”
The researchers combined their EV travel and V2G service models with two of MITEI’s existing modeling tools, including GenX, which simulates the investment and operating costs of electricity generation, storage, and transmission systems; and SESAME, which projects growth in the vehicle fleet and electricity demand. This allowed them to analyze the effects of V2G on their fictitious New England power system. They took into account factors such as various EV participation rates, electricity generation costs for conventional and renewable power suppliers, updates to the infrastructure for charging, vehicle travel demand, shifts in electricity demand, and the price of EV batteries.
They observed that V2G applications in power systems were favorable at all levels of carbon emission controls, even one scenario with no emissions caps at all. But according to their calculations, V2G benefits the electricity grid best when carbon restrictions are the strictest — at 10 grams of carbon dioxide per kilowatt-hour load, for example. The range of $183 million to $1,326 million in total system savings from V2G reflects EV participation rates between 5% and 80%.
“Our study has begun to uncover the inherent value V2G has for a future power system, demonstrating that there is a lot of money we can save that would otherwise be spent on storage and firm generation,” says Owens.
The idea of millions of EVs being parked in garages or offices and being connected to the grid for 90% of their useful lives proved to be an enticing temptation for scientists looking for ways to decarbonize the economy. “There is all this storage sitting right there, a huge available capacity that will only grow, and it is wasted unless we take full advantage of it,” says Gençer.
This is a very real possibility. Software that would enable two-way communication between EVs and grid operators or other entities is now being tested by startup businesses. With the correct algorithms, EVs would never run out of battery or jeopardize a commute because they would always be able to charge from and provide energy to the grid in accordance with profiles customized to each car owner’s needs.
“We don’t assume all vehicles will be available to send energy back to the grid at the same time, at 6 p.m. for instance, when most commuters return home in the early evening,” says Gençer. He thinks there will be enough battery power available to offset spikes in electricity use over an average 24-hour period because EV users have such diverse schedules. Additionally, there are additional future battery power options, such as electric school buses that are used for brief periods of time during the day before being left idle.
The MIT team is aware of the difficulties in getting V2G consumer buy-in. While EV owners enjoy a clean, environmentally friendly trip, they might not be as eager about granting a utility or distributor working with power system operators access to their car’s battery. Policies and incentives would be desirable.
“Since you’re providing a service to the grid, much as solar panel users do, you could be paid for your participation, and paid at a premium when electricity prices are very high,” says Gençer.
“People may not be willing to participate ’round the clock, but if we have blackout scenarios like in Texas last year, or hot-day congestion on transmission lines, maybe we can turn on these vehicles for 24 to 48 hours, sending energy back to the system,” adds Owens. “If there’s a power outage and people wave a bunch of money at you, you might be willing to talk.”
“Basically, I think this comes back to all of us being in this together, right?” says Gençer. “As you contribute to society by giving this service to the grid, you will get the full benefit of reducing system costs, and also help to decarbonize the system faster and to a greater extent.”
Owens is currently examining the possible role of heavy-duty electric vehicles in the decarbonization of the power system as he bases his dissertation on V2G research. “The last-mile delivery trucks of companies like Amazon and FedEx are likely to be the earliest adopters of EVs,” Owen says. “They are appealing because they have regularly scheduled routes during the day and go back to the depot at night, which makes them very useful for providing electricity and balancing services in the power system.”
Owens is committed to “providing insights that are actionable by system planners, operators, and to a certain extent, investors,” he says. His research may be used to decide where and what kind of infrastructure for charging should be constructed.
“Our analysis is really timely because the EV market has not yet been developed,” says Gençer. “This means we can share our insights with vehicle manufacturers and system operators — potentially influencing them to invest in V2G technologies, avoiding the costs of building utility-scale storage, and enabling the transition to a cleaner future. It’s a huge win, within our grasp.”
The research for this study was funded by MITEI’s Future Energy Systems Center.
While V2G technology is still at an early stage of evaluation concerning how much it can be used to manage energy use and grid capacity, it is already being adapted and tested in places like NYC, as reported by Zachary Shahan back in August. The researchers there claim that the costs associated with creating infrastructure for energy storage, production, and transmission have never been thoroughly analyzed on a systems-based basis as in this study, which examines future power systems. The more these various alternatives are examined and compared from large systems-level, long-term viewpoints, the more that might bolster the argument that the costs and challenges of V2G are worth it. If V2G can beat out alternatives in net cost, utilities and policymakers might be pushed more seriously to set up V2G policies and programs that strongly incentivize automakers and/or customers. We shall see.
Source: MIT
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