Electric Cars: Opportunity and Risk
It’s been five years since I’ve written about electric cars. In those years the Leaf has replaced the Prius as the environmental car of choice and the Tesla Model S has won more automotive awards than Bryon Cranston has won Emmys. As I expected, electric cars are driving down the road towards the mainstream.
While the cost, range, and quality of electric cars has improved dramatically, the way those cars are charged has remained relatively unchanged. Sure Tesla has installed a network of fast chargers that in twenty minutes can add sufficient charge that road trips are now possible and many businesses have installed charging stations in their parking lots, but most electric cars are still changed at home overnight. The driver gets home, plugs in the car and in the morning the car is ready for another day of driving. Depending on your system and how far you’ve driven, charging may take from two to ten hours. Currently, the electric grid treats an electric car just like a blender.
As electric cars become mainstream, there will be a new rush hour on the grid right after the rush hour on the roads: millions of cars plugging in around 6 p.m., drawing power at the same time as stoves and heaters and TVs are firing up. This is a challenge not just to produce the electricity, but also to distribute it to all of those garages. If we don’t deal with this intelligently, then we might see a gridlock of electrons (i.e. brown-outs).
But this challenge is also an opportunity to make the grid better. The electric grid needs to be sized for peak demand. The rest of the day, those resources are underused. Creating off-peak demand helps the utility.
Very few drivers need their car charged up as soon as possible, but just want it ready for their daily commute by the next morning. How do we build a system that does the bulk of the changing when the grid has underused capacity (i.e. the middle of the night)? There are several approaches, each with advantages and disadvantages:
- Time-of-day metering, where the retail price of electricity drops during the time of day when the wholesale price of electricity is low and the grid is operating at much less than capacity (e.g. 11 pm to 8 am). This is fairly straightforward to implement, but is inflexible to events (e.g. a transformer goes down). This only requires advanced power meters and chargers that know what time it is and what time they should start charging.
- Real time pricing, where the utility can set the price based on the current situation and sends a message that appliances (e.g. car chargers) can respond to (e.g. delaying charging). This requires a much smarter system (i.e. the Smart Grid), but allows the utility to manage challenges like a substation fire or high wind-production during a time of low demand.
- Build a system that can handle increased peak loads; more generators, wires, transformers, poles… This is almost certainly the most expensive and dirtiest way to meet the challenge.
Currently in Seattle, we’re not doing any of these things. The cost of electricity is the same at 6p.m. as it is at 2 a.m. and the chargers that people are installing in their garages don’t know what time it is, much less the cost of electricity at that moment. I expect electric car growth to follow a hockey-stick pattern, which is common for new technology adoption (think smart phones): sales will grow linearly and moderately for a few years, then the next time that gasoline prices hit $5.00 a gallon, electric car sales will explode. Are we building the electric network that can handle this opportunity?