Using electric vehicles as storage for large offshore wind power

Offshore wind now appears to be a huge resource--sufficient to provide most of the electricity for many of the world's heavily populated coastal states. This long-term resource promise may be constrained because wind’s power fluctuations lead to grid integration problems. At small scales of wind implementation, existing mechanisms of grid regulation are sufficient. However, existing mechanisms cannot support wind at the penetration levels needed to, for example, meet British or Danish renewable energy targets or to make a significant impact on CO2 emissions. Storage has been proposed as a solution, but dedicated storage adds significant cost to wind power. This paper reviews existing storage technologies, and then proposes vehicle-to-grid power (V2G) as a storage resource for large-scale offshore wind power. V2G uses the distributed storage inherent in electric-drive vehicles (here we consider battery and plug-in hybrid vehicles) to stabilize wind generation. We model large-scale wind with V2G storage based on prototype V2G electric vehicles already built. These vehicles charge from the grid and discharge to the grid at 15 kW, with storage of 30 kWh; incremental capital cost to add V2G is approximately € 400 (€22/kW or US$33/kW). Using two different models as a cross-check, we calculate that wind generation meeting 50% of electrical energy needs could be stabilized by 8 - 38% of the vehicle fleet with V2G capability. Since offshore wind sites are often near cities with large vehicle fleets, V2G offers an exceptionally low-capital-cost means of simultaneously stabilizing wind power and reducing petroleum needs of the light vehicle fleet. Prototype vehicles with this capability (at 20 kW/vehicle) have been built, driven and provided charge or discharge on signal from the grid operator.