San Antonio’s Southwest Research Institute (SwRI) brings Texas the latest example of an intelligent, demand-side resource that can play an active role in the power grid and offset the use of fossil-fuel power plants. Late last month, SwRI announced that its innovative vehicle-to-grid system got the green light from the Electric Reliability Council of Texas (ERCOT), the grid operator, to participate in the state’s electricity market. This system is able to control the charging and discharging for a fleet of electric delivery trucks, meaning that when the supply of electricity struggles to meet demand, the intelligent vehicle charging system can simply stop charging (thus lowering demand). This technology will significantly increase grid reliability, thanks to its quick response time, and effectively deter the need for firing up another dirty power plant.
In order to avoid a blackout, the supply of electricity to the power grid must equal the electric demand from customers. Conventionally, this balance is maintained by power plants that remain on stand-by, ready to respond at a moment’s notice. Every hour of the day, ERCOT precisely controls these power plants to keep the grid balanced. In the process, a power plant has to rapidly increase or decrease its power output, which decreases its efficiency and increases its carbon and pollution footprint, much like an a car revving its engine.
To modernize our electric system, experts have proposed using demand-side resources – defined here as energy efficiency, demand response, renewable energy, energy storage, and even electric vehicles – to balance the electric grid in place of power plants. Smart power technologies enable ERCOT to reduce demand for energy through programs like demand response, where a customer is compensated for temporarily conserving energy use. For the first time, a customer reducing their need for electricity can provide the same service as a power plant generating more electricity. These customer-powered “negawatts” (the amount of energy not used) are advantageous because they offset power plant emissions, rather than increase them.
SwRI’s intelligent delivery truck charging system provides negawatts to ERCOT by temporarily suspending vehicle charging. During the day, electric delivery trucks carry goods to their intended destination, and then return to “refuel” with electricity in the evening, when Texas’ wind farms are most productive. SwRI’s charging management system ensures that all of the trucks are recharged before they have to make their next trip. At the same time, it counts up how many trucks are charging, and sends that information to ERCOT. If ERCOT senses a sudden shortfall in power supply, the management system interrupts charging for some of the trucks to quickly rebalance the grid.
Beyond just reducing emissions by offsetting power plants, SwRI’s system also increases the overall reliability of Texas’ power grid. Because power plants are such enormous and complex machines, it often takes them several minutes or longer to rebalance the grid. On the other hand, demand-side resources, like SwRI’s charge management system, can respond instantaneously. Studies show that these fast-responding resources fundamentally improve the grid. That’s why ERCOT is carrying out a major pilot project to evaluate the benefits of quick, highly flexible resources like demand response. And Texas isn’t the only place where this technology is being tested.
In Japan, Nissan conducted a pilot connecting six of its electric Leafs to the Nissan Advanced Technology Center in Atsugi City. The results: the building reduced its energy usage during peak summer periods (when electricity is most expensive) by 2.5% by simply controlling the EV-charging time. Nissan saved an estimated annual $4,900, without impacting the workers' daily commute.
In collaboration with the University of Delaware and NRG Energy, Honda is also in the vehicle-to-grid game. With a pilot involving its Accord plug-in hybrid, Honda is “showcasing how [vehichle-2-grid] technology could be used to sell energy storage from electric vehicles into the PJM Interconnection Regulation Market.”
SwRI’s qualification to participate in the electricity market is a signal that the flexibility and cost benefits expected from demand-side resources can be realized in practice. As smart power technologies develop, we hope that more commercial, industrial, and residential energy users will offer their negawatts to the power grid. Doing so reduces the need for fossil-fuel power plants and improves the economics for technologies like electric vehicles and energy storage. When all of the pieces of the energy system talk to each other in an intelligent way, we can unlock new ways to save energy, reduce emissions, and improve the electric grid.