Possible workable renewable energy?

[Ronin13]

Burning trash normally is pretty yucky. However there are Gassifiers that I think someone else mentioned. They burn trash and use the heat to pre-heat the trash before they burn it. That preheated trash releases gasses that are flammable, and are used to burn the trash at a much higher temperature. The net result is you end up with mostly carbon and black glass-like shards. There isn't a lot of surplus energy out of the system, and it still produces CO2. http://en.wikipedia.org/wiki/Incineration

I saw a neat system that uses the CO2 rich gas coming out of a power plant and funneling it through clear plastic bags filled with pond water. The algae bloomed in the sunlight (bags hung in greenhouses). The algae was then processed into an oil. Essentially the algae took the CO2 from the power plant, hydrogen from water, and sunlight for power to produce a hydrocarbon. Presumably it could run on any source of CO2.

Well our idea, and I'd like to get an engineer input on it, was not focused on burning trash- hydro electricity from heating water to turn a turbine. But the algae/water filter was kind of what we were playing around with the idea of since most toxins can be absorbed through water and not pollute the air.
Here is a concept drawing we did (I'm no artist and there is not much detail- simple concept art from MSPaint):

[Hoosier]

This article seems to sum up the pros and cons of what you're talking about:

http://blogs.forbes.com/energysource...ash-for-power/

Another interesting technology for turning a temperature differential into power is the Sterling engine. It's a closed cycle heat engine that works by having hot on one side and cold on the other. Anywhere you have a thermal gradient you can use this technology.

H.