I answered
Solar Energy
I think all of them should be pursued, obviously, but of the ones listed solar might be our best bet. Hydro wont work in landlocked states and nations, wind requires significant open land which can be hard to find around urban areas and geothermal is cool, but I don't know enough about it to chose it. Solar works no matter where you are (except near the poles which have extremely low population densities) on land, on water, in the middle of nowhere there can be huge solar fields and in urban areas they can cover roofs and parking structures without being eyesores.
Interestingly, solar has really improved in the past decade. There are now solar tiles for the roof that look snazzy (and are much more effective) and there is a research team in the midwest US working on solar panels that are strong enough to be roads. I myself have installed a few panels to run my work computers and I must admit that they are great money savers!
It has! When I was in college my physics prof was super anti-solar (and in favor of other renewables) because of the low yields. He predicted it would never be cost efficient. I follow him on facebook and he has very happily walked back his position over the past few years as solar capacity has exploded.
I can understand how he felt. You still need very large panels for larger yields, although if you have more wiggle room in the budget there are better quality panels and batteries available now.
Thanks for the great comment. Something I don't understand is why Solar wouldn't work near the poles?
My guess would be that the nearer to the poles you get, the more severe the daylight difference is. For example, the 40 days of darkness in areas of populated Canada during the winter. Here is where we really need to work on mixing the types of alternate power, i.e. having solar, but also a windmill for dark, rainy days. And batteries, lots of batteries.
Makes sense. Thanks for the explanation!
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Yeah, like @jennswall said mostly the extreme shifts in day lengths and the long periods without light. In order to be effective you would either need huge battery capacity to store the energy for the months that pass without sunlight or you would need huge infrastructure overhauls to bring solar power in from closer to the equator. I don't know very much about batteries or power lines, but I do know that in general the more you use of each, the lower your energy yields are as you lose a good amount to heat. Also, I believe batteries still require the use of a lot of precious metals that we get through pretty exploitative methods in poorer countries. So imo why not just throw up a bunch of windmills in the arctic circles and save the headache?
Like in pretty much everything else, diversification is our best bet.
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