The owners of electric vehicles (EVs) are used to plugging in charging stations at home or at work and filling their batteries with energy from the grid. However, in the near future when they plug their vehicles into charging stations, they will also have the capability in reverse of electrons and transmit them into the grid. As the amount of EVs grows the batteries of the fleet could be a cost-effective, large-scale energy source with potential for dramatic effects on the transition to renewable energy, according to a recent research paper released in the journal Energy Advances by the MIT group in Energy Advances.
“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,” claims Jim Owens, lead author and a doctoral candidate at the MIT Department of Chemical Engineering. Other contributors are Emre Gencer, who is a principal researcher in MITEI. MIT Energy Initiative (MITEI) as well as Ian Miller, a research specialist at MITEI at the time of the study.
The team’s work is the first thorough analysis of systems-based power systems based on a unique combination of models that incorporate the carbon emission targets and Variable Renewable Energy (VRE) generation and the costs associated with creating energy storage production, transmission and infrastructure.
“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,” Gencer says. Gencer. “The results were surprising; I personally didn’t believe we’d have so much potential here.”
Displaces new infrastructure
While the United States and other nations strive to achieve strict goals to reduce carbon emissions, electrification in transportation is taking off and the pace of EV adoption rapidly increasing. (Some projections suggest EVs outshining internal combustion engines within thirty years time.) As more people opt for emission-free vehicles there will be a higher need for power. “The challenge is ensuring both that there’s enough electricity to charge the vehicles and that this electricity is coming from renewable sources,” Gencer says. Gencer.
However, the power of wind and solar is intermittent. Without a reliable backup plan for these sources, like permanent energy storage systems that use lithium-ion batteries, for example or massive, natural gasor hydrogen-fueled power plants, meeting green energy targets will be difficult. The cost of construction of the needed new infrastructure for energy is in thousands of billions.
As the researchers noted, this is exactly the situation where V2G could play a crucial and important role. In their study of a hypothetical New England power system meeting strict carbon standards For instance, the team discovered that only 13.9 percent of 8 million low-duty (passenger) EVs displaced 14.7 gigawatts of energy storage in stationary units. The result was $700 million in savingsthe expected cost of constructing new storage capacity.
The paper also discussed the role that batteries from EVs could serve during times of high demand, like scorching summer temperatures. “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,” Owens 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.”
Modeling power
To study the effects of V2G on their imagined New England power system, researchers combined their V2G and EV travel models using two existing MITEI modeling tools which include The Sustainable Energy System Analysis Modeling Environment (SESAME) to predict the future of electric vehicle fleets and expansion as well as GenX which analyzes the operating and investment costs of storage, electricity generation along with transmission system. They also incorporated inputs like the various EV levels of involvement, the cost of generation for both conventional and renewable power sources and charging infrastructure upgrades the demand for travel by vehicles and changes in demand for electricity and EV battery cost.
The study showed benefits of V2G application in the power system (in terms of displacement of power storage, and also firms generation) in all carbon emissions levels limits even one that has no emissions caps whatsoever. Their models show that V2G provides the most value in the energy system at times when carbon-related constraints are the most agressive at the rate of 10 grams carbon dioxide per Kilowatt hour load. The total savings to the system due to V2G was between $183 million up to $1,326 million which reflects an EV participation rate between 5 and 80 percent.
“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,” Owens says. Owens.
Harnessing V2G
For those who are looking to cut carbon emissions with the dream that millions of EVs stored in garages or in offices and connected in to grids for 90%% of their operational lives is an irresistible challenge. “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,” Gencer says. Gencer.
It is not an unattainable goal. Startup companies are testing software that allows two-way communication between electric vehicles as well as grid operators or other organizations. If the algorithms are right, EVs would charge from and distribute power to the grid in accordance with the specific profiles for each vehicle owner’s requirements, without depleting the battery or threatening an errand.
“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,” Gencer says. Gencer. Gencer believes that the different schedules of drivers who drive electric vehicles will have enough battery power available to handle the spikes in electricity usage during a typical 24 hours. There are also other possible source of power from batteries on the road, for instance electric school buses, which are used only for short intervals throughout the day, and then sat at a standstill.
The MIT team is aware of the challenges of consumer buy-in to V2G. Although EV owners love an environmentally friendly, clean driving experience, they might not be as eager to hand access to their car’s battery over to the utility company or an aggregator who works with the operators of power systems. Incentives and policies could help.
“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,” Gencer says. Gencer.
“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,” Owens 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?” Gencer adds. Gencer. “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.”
Practical insights
Owens who is currently writing his dissertation on research into V2G and is currently examining the possible impact of electric vehicles that are heavy-duty in reducing carbon emissions from the energy system. “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 dedicated his time to “providing insights that are actionable by system planners, operators, and to a certain extent, investors,” he states. Owens’ work could be used to determine what type of charging infrastructure should be constructed and in which location.
