jmw,
haha, yes, I stand corrected.
zdas04,
The two major concerns are how fast EV's gain in popularity and how people charge them.
We are expecting to see about 80,000 EV's by 2030, resulting in 195 GWh increase. This is not an issue for generation because that increase is spread out over 20 years. Another study showed that a 10% switch over from light-duty vehicles to EV's could increase the load by 4.7%. So, if you had a sudden, mass injection of EV's (such as that described in the article) then, yes, it could be a problem for generation capacity. However, the bigger issue is probably distribution and localized brown outs.
The more complicated (and maybe more important) problem is how people will charge them, namely uncontrolled versus smart charging.
Uncontrolled charging means people can plug in whenever they want, into any suitable outlet. Here people will most likely come home after work and plug in their car, during peak hours. This will cause an even greater spike to occur during this time, magnifying the possibility for brown outs. It may also force utilities to turn on higher cost forms (or dirty forms) of generation to meet the spikes. An utility wants nice flat demand profiles so that you can have generating stations running and near optimum levels for the majority of the time. The greater the peaks and valleys, the less efficient your generation is.
On the other hand, smart charging means that charging is regulated to smooth out the demand. This allows utilities to keep plants running at near optimum efficiency and also means that non-controllable renewables, such as wind/solar, can be used to curtail the increase caused by EV's. The result is lower cost to the utility (on a per kW basis) and lower total emissions. However, implementation is much more difficult/costly here.
A study on a fictional utility, with only small amounts of renewable generation, found that the uncontrolled charging strategy would increase the cost of generation (per kW) by 24% while increasing emissions per miles to 284 g/mile. While smart charging would reduce the cost of generation (per kW) by 19% and decrease the emissions per mile of EV's to 220 g/mile. Note an average light-duty vehicle has emits about 412 g/mile and a prius is about 176 g/mile. If the study was changed to a utility with 100% natural gas CCGT plants, the emissions from the EV would be 144 g/mile, and much lower for nuclear, wind, hydro or solar.
However, these numbers would be much different depending on the base load profile for the utility and the method of generation. The true benefit is different location to location; this is an important concept for people to think about when talking about EV's, that often gets overlooked.
For example, the utility I work for is:
- primarily hydro power
- publically owned (low domestic cost/kWh, higher incentive to be a corporate citizen)
- a big exporter of power, which is a huge contributor to our revenues.
So with that in mind, EV's in our area:
- Greatly reduce overall emissions
- Are attractive to local clients due to very low domestic electricity costs (but cold weather climate is a hindrance to EV's)
- Increases are local demand which reduces are exports = reduced revenues, for the same generation (however, with the US economy in the toilet, the cost of electricity has dropped which effects the severity of this reduction and possibly provides more stable revenues)
