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Donald – good points as ever. With regard to motorway charging, I see a halfway house. Essentially, I think our services could look a lot like they do at the moment – but every parking space will have a charger. Each car will have the option of charging, if it needs it, during the time the driver is in the services going to the loo, getting a meal, etc.
With regard to electricity consumption, I haven’t checked your figures – I’m sure you’re right. But it ignores the massive gains we would make by not refining fossil fuels. I have read that a western nation uses something like 30% of its total energy consumption on fossil fuel support, particularly refining. I’m sure you’ve heard too that an EV can drive something like 100 miles on the energy it takes just to get a conventional car’s fuel from the ground to the pump.
I haven’t checked your figures…it ignores the massive gains we would make by not refining fossil fuels. …I’m sure you’ve heard too that an EV can drive something like 100 miles on the energy it takes just to get a conventional car’s fuel from the ground to the pump.
Good point, though I am not quite sure the impact that has on the particular calculations I made, as I’m only presuming to discuss extra expansion of electricity delivery for EVs from non-fossil fuels.
Not sure what the relative energy overhead is to shift oil from well to wheel, I would have to go look it up. Clearly the overhead losses get bigger over time too as the field become more marginal, whereas we can hope to imagine that ‘cleaning up’ the electricity generation will be the opposite and only get better.
services could look a lot like they do at the moment – but every parking space will have a charger
That’s how I tend to see it in the future too. I can’t really see much of an alternative, if it is going to happen at all. But my picture has only (or ‘mainly’) inductive chargers. Each parking spot will have a little mound, but that is all and otherwise are usable by any cars.
[Unfortunately, my vision of en-route inductive charging is a pipe-dream seeing as Highways Agency can’t even keep the motorways from failing into deep potholes, so any hope for something more technically complex is unimaginable on any time-scale right now.]
Plug-in or inductive, you also have the question over total power delivery to a large charging site. If each charging point is a 50kW station and you have, just for illustration, 200 cars charging at once, then the site needs 10MW power delivery. That’d be 3 wind turbines running, or 100 acres of solar panels. My preference would be for a small modular buried nuclear power source, which is a concept rapidly gaining technical credibility albeit lacking political interest!
So, based on what I have found;
http://www.eia.gov/dnav/pet/pet_pnp_capfuel_dcu_nus_a.htm
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http://www.eia.gov/dnav/pet/pet_pnp_capprod_dcu_nus_a.htmit would seem to me that each gallon (imperial duly converted) is matched by the consumption of 3kWh, so about 10 EV miles.
Other studies show that about 6 kWh of energy is needed for each US gal of refined road fuel. However, there will be a mix of energy sources, some from the fuel itself. 3 kWh of electricity seems reasonable, in that context.
The figure of merit is not transparent because refining consumes many other forms of energy inputs, and has many varied product outputs. I think it is therefore a ‘reasonable’ 1st approximation to simply match the electricity inputs with the road fuel outputs.
So if we assume 40mpg as a whole fleet average (?guesstimate?) and save 10 EV miles for every ICE gallon we displace, then we reduce the electricity ‘burden’ by a quarter. So I think that means my 120 TWh estimate for annual EV electricity demand reduces to 90 TWh.
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