bartelby said:
I thought all hydro-electric power stations, that use reservoirs, do this. That's what I was taught when I was at school anyway.
Nope, virtually all reservoirs are filled by rain and input rivers/streams.
This pumping scheme only works if you have thermal powerplants that are 'wasting' capacity because you cannot turn them off or down when demand is low.
Obviously, if your only source of electricity was hydro, you wouldn't use that pump water uphill, you'd just restrict the amount going downhill throught the turbines in the first place - because there's so much loss in the pumping process - I bet they're getting only about 2 watts net for every 10 they spend pumping.
What Mr. Run Car on Water dude is doing is simply snake oil marketing. It comes around every 10 years or so. Yeah, lets call it dihydrogen oxide instead of water. Lets invent new and non existent forms of matter to explain why this isnt the same as ever other scam, perpetual motion machine, and 'you get out more than you put in' scheme.
The whole question is about storage and distribution, not about generation.
You have a source of energy - it doesn't matter much what it is -- solar energy collected through photovoltaics, wind turbine, wave turbine, hydro electric, organic thermal or ethanol crops -- or millenia-old solar collected through coal and oil, or fission energy from uranium, or geothermal, or gravitaitonal through tidal turbines.
The whole challenge is how do you package that and transport it to the consumer, safely and with minimum loss and expense? For vehicles, the density of the fuel and its storage/motor system are key - how many kWH of power will you get from each kilo of fuel and powerplant.
At the one extreme, nuclear is completely non-viable small scale. It will only work in large, central generation.
Hydrogen has huge transportation issues. Cracking water at home makes no sense, because it's better just to use the electricity directly. As a vehicular fuel, safety and storage (pressure cylinders, etc) are the issue. Question is whether, if the storage can be solved, will a hydrogen combustion or hydrogen fuel cell prove to have greater energy density than advanced batteries?
Petroleum fuels and ethanol are relatively safe to transport, and infrastructure is in place. The fuels are relatively dense. The main problem is the efficiency of energy conversion/generation at each consumer's location - emissions, efficiency, cost of equipment.
Electricity has initial capital cost for infrastructure, but cheap to transport after. Benefits from higher efficiency of large scale generation. Problem with portability, though, once you get to the end of the driveway... addressible with better battery technologies, ultimately. Local generation (photovoltaic, wind) has low efficiency and long capital payback periods.
