EV batteries can contribute to grid stability, study says

A new academic study claims that batteries used in plug-in electric vehicles (PEVs) could be used to stabilise electrical grid networks, as well as for providing houses and businesses with backup power.

Concepts such as the ‘smart home’ have regarded the use of EV batteries as a charge and discharge station for the entire building as technically feasible for some time. The latest study led by a team in Macedonia and published earlier this month in the New Journal of Physics aims to show the potential for EV batteries to provide stability when the grid is subjected to “large disturbances” and to sudden large changes in the load.

Led by a team at the Macedonian Academy of Arts and Sciences, a simulation was run of a New England power system which incorporated the plugging in of so-called “vehicle-to-grid” buses.

The study aimed to bring together two separate energy conversion and management systems from the last century, electric utility systems and light vehicle fleets, which the journal’s authors described as “exceptionally complementary”.  The report asserts a view that the two systems “will merge at some level in this century”.

“The electric utility system has essentially no storage, and therefore, energy/power generation and transmission must be continuously managed to match fluctuating customer load,” the report says.

“The light vehicle fleet, however, inherently has storage, since both the vehicle and its fuel must be mobile.”

The use of power from EVs is also available at a cheaper cost per unit than the high capital cost involved in developing large generation facilities, the report points out.

Grid integration of renewables could be assisted further by energy storage in EVs, beyond the already recognised capabilities which include providing backup power. Image: wikimedia User: M.O. Stevens.
A key element of the study is that information from PEVs to the grid and vice versa could be relayed using high-speed internet connections, which are capable of providing responsive control within 10 to 20 milliseconds. Under the simulated control strategy, a power shortage will call for additional power to be drawn into the grid from connected EVs, while in a surplus the EVs act as loads and absorb the excess.

At present, the potential for using PEVs for backup for renewable energy sources, providing reactive power support, active power regulation, peak shaving and load balancing is recognised, as well as its potential to reduce operating costs incurred by utilities and generating revenue. The team behind the new report claims however that PEVs with a regulated power output can reduce speed and voltage fluctuations caused by disturbances by up to 80%. PEVs can also extend the critical clearing time (CCT) of a grid network, which is the maximum amount of time a disturbance can be applied to a network without compromising inherent stability, by 20% to 40%.

The study acknowledges that technical barriers to this sort of use of EVs exist in addition to the already recognised existing barriers to widespread adoption of EVs, such as lack of customer acceptance, cost of investment and resistance from the incumbent automotive and energy industries.

“…the vehicle-to-grid (V2G) concept faces several challenges that should be addressed before the V2G technology becomes widely accepted. The increased number of PEVs may impact power distribution system dynamics and performance through overloading of transformers, cables, and feeders.”

Battery costs and the need for the high-speed information technology infrastructure may also prove further barriers, the report concedes.

On a related note, in a recent interview with PV Tech Storage, Ray Noble, a stalwart of the British renewable energy and an advisor on topics including solar, storage and EVs, spoke of the potential he saw for reducing costs for both the automotive and renewable energy industries by recycling EV batteries for use in stationary storage. Talking about the UK, he said he believed that the market for EV batteries could prove to be a strong driver for energy storage adoption as a whole.

“…the driver of storage at this point in time, particularly the storage that’s probably going to be used with solar initially, is the EV market. The batteries that are being developed for EV to give them greater range, that’s where the motor manufacturers in mass production can drive down the costs very, very, rapidly,” Noble said.

“…there will be a large number of batteries coming onto the market which will be second hand, in effect. So if you could find a use for these batteries, a second use, say putting them into a cassette and putting them into peoples’ houses, in buildings and putting them onto the grid or whatever, it’s a way of actually helping the motor industry but also bringing forward storage at a rapid rate.”

The study, led by a team at the Macedonian Academy of Arts and Sciences, claims light vehicle fleet and electric utility systems, which are "exceptionally complementary", will "merge at some point".