Electric Transportation and Our Power Grid
Here’s an article that discusses the rise of electric transportation and the effects that this will have on the grid. I have two issues with it:
1) The author erroneously notes that EV charging could cause a 43% increase in electricity consumption. No, the entirety of transportation is only about 40% of our energy consumption, and, because the conversion of electrical to kinetic energy is three times more efficient than the conversion of chemical (gasoline) energy in our internal combustion engines, we could change out all 230 million cars and trucks on our roads to electric, and the total increase in demand on our grid would be no larger than 14%.
2) The author avoids the subject of environmentalism. That’s the real point here, isn’t it? Why not bring it up at all? The issue, of course, is coal. As long as coal is our least expensive base load power, an incremental load on the grid in the middle of the night is most likely to be met by burning more. That’s not a boon to the environment; it fact, it’s aggravated assault.
Craig,
We agree, obviously, on the issue with coal. But the linked article was probably more concerned with last-mile issues than with overall grid balance issues.
If you are in a neighborhood that has ~100 houses, you might have a transformer that could handle a few hundred kW… Because it’s highly unlikely that more than x% of the houses might be operating their dryers at any given time, and it’s unlikely that more than y% of the houses will be cooking and Z% will have more than one large TV on… etc…
But if 10 of those homes were to get an EV, then the car charging for those 10 EV’s will require ~20-80 kW (depending on the charging infrastructure) for the entire evening. That compresses the amount of power that the other houses can draw before running into problems with the transformers on the lines feeding your neighborhood.. So now if X% of the houses ran their dryers and Y% of the houses were watching multiple TV’s while z% of the houses were cooking (the same ratios as intended in the initial estimates), you’d experience brownouts and/or blackouts within the neighborhood… So the electric company would have to replace all of the transformers and upgrade all of the lines running to your neighborhood because ~10% of the homes got plug-in vehicles…
It might not happen at 10%, but it WOULD happen at 20%, then happen again at 40-60%… then happen again at 80-100%. These upgrades are EXTREMELY expensive, and would force electric bills to be much higher for all customers to amortize the cost. Requiring a smart-charging system would eliminate that threat (or at least push the threat to much higher penetration levels) by ensuring that the car charging was lower priority and would not take place while other activities (TV watching, cooking, drying clothes) were happening at high rates in the neighborhood.
The same, obviously, could be said for large malls, commercial parks and industrial parks… there will be many places where the last-mile power handling of the grid has a narrow margin… In the Blue Cross/Blue shield building a few miles away, they won’t let employees plug in a small (4″) personal fan in their cubicles, and the employees are limited to 1 phone/tab charger. In places like that someone plugging in an EV in the parking lot could easily cause a brownout to occur the next time someone inside the building starts a pot of coffee… Smart charging would be pretty important in those places as well.