Tubaryan12 wrote:rocksanddirt wrote:On a personal note....we have a GEM electric car (basically an oversize golf cart) and it's perfectly fine for around town, and increased use of it has cut our use of a gas car to almost nothing (from three tank fulls of gas a month to less than one).
Now imagine if he had a solar cell on the top of the house to charge the car. Imagine if 25% of the folks in this country that could afford to buy the electric car also bought the solar cell as well? Lots of individuals cutting their gasoline use to a third of what it used to be would be a step in the right direction.
Let's think about that a bit. The typical large solar panel is 5 feet by 2 feet (10 square feet) and nominally produces 100 watts in full sun. With an assumption of six hours of full sun, that panel will produce 600 watt-hours at a nominal 16 volts. Charging a storage battery produces heat, so that means there is inefficiency--I don't know how much but I'll guess 30% with expectation that it's really worse than that.
The typical gasoline-engined car does about 25% better on the highway than in the city, and the typical power requirement for a very small and light car to cruise at 50 mph may be as little as 4900 watts (6.5 horsepower at 100% efficiency). For a 30-minute commute that is all cruise each way, that requires 4900-watt-hours of sustained power at the wheels. We can increase that to 6100 to account for a few stops and starts, and 7700 to account for transmission and power conversion inefficiency (assuming a
very favorable 80% efficiency of the electric drivetrain).
Thus, to top off the charge, we need 7700/(600*70%) = 19 of those panels. The panels cost about $700 each, plus the controller, and they take up 190 square feet. And it takes a full day of sunlight to charge the car, so the panels have to be at work and not at home, unless you work at night. And that doesn't account for unplanned trips, overcast days, etc., etc. For every case where a person could make this work, there would be 100 people who, for one of many reasons could not do it. And don't forget that I'm talking just about moving the vehicle, not about running the radio, lights, or any climate control. And to be that efficient, the windows will have to be rolled up.
Of course, there's nothing stopping you from doing it right now, since you already own an electric vehicle.
(My Subaru will drive 71,000 miles, at $4 a gallon, for just what those panels would cost new, not including the controller or the significant maintenance.)
Electric vehicles, if they are the same size and shape as regular cars, will require less power because they are more efficient than internal combustion engines, but they still have to make the same hole in the air as they move and that's what consumes more power than anything. Any advantage they have is that instead of burning fuel at the vehicle to produce that power, they use power produced somewhere else and transported to and stored in the vehicle. In some situations, this might be a desirable tradeoff, but it uses grid power. Doing it off-grid will be a challenge, to say the least.
I have considered buying one of those panels for my motorhome. My usage is far less than what it would take to actually move the beast. I may consume as much as 500 or 1000 watts of 12-volt power in a day. The panel would top up the battery on some days but not on others. In my case, it would keep me from having to run my generator as much, and on some days I'd be able to avoid running it at all to keep the house batteries topped up. But the motivation is not the price of fuel, but rather the reduction in noise and odor. Generally, though, I still have to run the generator to make hot water or to run the air conditioner, and the battery usually gets charged because of that. So, it really isn't worth it for my typical usage.
For sure, though, high fuel prices are what make these alternatives more desirable, and if fuel is expensive enough, our free market economy will drive those developments faster than any government mandate or incentive, and we won't have to coerce people into using it.
Rick "whose automotive air conditioner alone probably consumes at least half of the horsepower mentioned above" Denney
And if we do use, say, tea, what happens to the parts of the tea that aren't water? I don't want to clean that out!
