The impact of fuel cell vehicles and electric battery vehicles on Ontario’s electricity grid

By: Donald Jones, P.Eng., retired nuclear industry engineer, 2014 November 24

Major automobile manufacturers are continuing their development of cars powered by fuel cells using hydrogen (reference 1). Like cars powered by electric batteries the cars themselves will emit no greenhouse gas (GHG). Bulk quantities of hydrogen are mainly derived from natural gas (increasingly frackgas) but the process results in the production of carbon dioxide, a GHG, so fuel cell cars will not reduce overall GHG emissions. However hydrogen can also be produced from the electrolysis of water using electricity. If this electricity is generated from a power grid of non-fossil fuelled generation then zero overall GHG emissions can be achieved – this applies to battery cars as well as fuel cell cars.

Since fuel cell cars and battery cars can significantly reduce GHG emissions in at least part of the transportation sector the market for such vehicles could expand and one of the key questions will be how will these cars affect the demand for electricity and the stability of the grid. Battery cars and fuel cell cars will affect the power grid in different ways. Battery charging is uncontrolled and people will charge their car batteries when convenient, day and night. Fast battery charging at home from a dedicated house circuit can overload the street transformers. Smart controls at the distribution level may alleviate this but ultimately the distribution system might need upgrading to handle the extra demand. All ratepayers will pay for this including those without battery cars. Increasing the day time peak loads on the grid by uncontrolled battery charging will require an increase in generating capacity, likely from frackgas-fired GHG emitting units. Ideally battery charging should be done overnight when surplus generation is available at the lowest carbon dioxide emission intensity and at lowest cost.