Alternative energy discussions usually miss the point. They almost always focus on variations on a theme - come up with a chemical means of transporting energy from one point to another, and burning it on demand to do useful things. That's a cycle and paradigm keeping us stuck in a rut, but it's pretty much driven by a lack of an attractive and inexpensive technological alternative. For generating portable mechanical power, we simply have come up with NOTHING more efficient than starting and stopping a controlled and contained explosion using a mixture of petroleum fuel and the oxygen found in our atmosphere.
Considering the entire cycle, from pumping oil from the ground to burning it in your SUV or lawn mower, NOTHING we have nowadays is more efficient and useful that that, period. And that's pretty sad.
We need a few things.
Higher conversion rate from energy to work. (ie. less waste heat).
Higher energy storage density. (ie. MUCH better batteries or more energetic fuels) Or a way to avoid storage and just pull it from thin air, because hauling your fuel around is necessary but inherently wasteful.
High adoption rate (ie. attractive reasons to switch from old to new)
Less wasteful production - consumption cycle (ie. halting rate of increase of use of a non-renewable source)
All the BS about veggie oil, alcohol, and electric power run against one or more of these problems. But if you don't solve ALL of these problems, you're just trading one crappy way of doing things for another, and the alternative is going to cost more than the way we're doing things now.
Personally, I think that the only thing that will fix our energy problems are massive improvements on conversion rate and storage density. Efficiently using what energy you have available is always a good idea, but the efficiency increase must pay for the cost of the changeover including both pure research/development and replacing all the old crap with new crap. And although there are gigawatts of energy just sitting around in our nuke powerplants, getting that energy to where it's actually needed is just as much a problem now as it was 200 years ago. Yea we're using power lines and supertankers to move energy from one point to another instead of hauling wood and coal one donkey-cart at a time, but a lot of energy is still wasted getting that energy to whoever consumes it to do work.
Guess what - NONE of the current alternative fuel sources do ANYTHING about those two problems - efficient conversion to work and storage density. If anything, they are steps backwards. As just one simple example, I'll pick on alcohol. First, it has terrible energy density compared to petroleum fuels. A gallon of gas has somewhere around 25% more stored energy than a gallon of alcohol (this is why alcohol-spiked fuel lowers your gas mileage). Second, since it burns cooler than petroleum you can't create as great of a pressure or temperature differential within a powerplant, and that means the powerplant itself is less efficient. Maximizing a pressure or temperature differential is one of the single most important requirements when designing a powerplant that converts one kind of energy to another. It's why hotter engines produce more power, and it's why really BIG dams make electricity more efficiently than a series of little dams. Third, transmission of alcohol based fuels is less efficient because it mixes with water, it must be transported and stored in more expensive sealed and climate controlled containers and may even need to be processed to remove excess water before it can be used. All of that uses even more energy spent just in the process of getting your fuel from the production source to the end user.
Electricity is even worse, but I think it will gradually get better. Solar cells are nothing more than a battery (look it up), and the energy required to create a solar cell is more than the energy you'll ever get out of it. The question is if the loss is worth it. If you're in the middle of the desert (or out in space) and there are no power lines around, then yea it's worth it. If you're in the middle of a city on a plentiful power grid and you can buy electricity and use it yourself with the same inherent transmission losses as a factory that builds solar cells, then no way in hell is it worth it. Conventional batteries have the same problem. When they develop a battery the weight, size, and shape of a full gas tank that equals the storage density of a tank of gas, then we'll be getting somewhere. Until then, you're simply using the same energy in a different manner and transporting that energy is going to remain your main problem. And electrical motors get hot just like combustion engines, meaning that they're still wasting a significant percentage of the energy as heat.
