How can we bring solar power energy to our streets?

Alternative source of energy?

• One of the alternative source for energy is by using geothermal power.. but here's the problem.. the contruction of those geothermal power plants can cause increase of seismic activity to occur... please suggest a way to reduce this impact so that we can use geothermal power as an alternative source of energy.. NOTE: do not bring in other alternative source of energy... geothermal and geothermal only... just suggest a way to not make that problem (mentioned above) a problem.

• Answer:

  I think the cart has been placed before the horse, so to speak. Geothermal generators occur in places where there are forces which bring material from the earth's mantle closer to the crust. The best example is most likley Iceland on the mid atlantic ridge. These enormous forces generate volcanos and earthquakes on a regular basis. Humans constructing a power plant impact the geology in such a small way I don't think it can be said that the construction actually increases seismic activity. However, it is still present, and 20th century construction is designed on the premice of a stable environment, geologically speaking. The most straightforeward solution would be to build geothermal plants in stable areas. However, this is a situation in which the mantle is miles underground and human technology is not advanced enough to drill 6 miles into the crust. However, African gold mines are about 1.5 miles deep and at this depth, the rocks are about 120 degrees F. Water from such a geothermal plant might not be boiling, but it is still much warmer than surface water. A heat exchange system could be used to turn the heat into mechanical energy. Water might not boil at 120F, but many organic solvents do. Methylene chloride might be a good candidate to use in a piston driven engine which recycled the solvent between the cylinder and a large radiator. The amount of useful work can be precisely calculated using Gibb's and Carnot's formulas. They were developed for steam engines, but there is no reason why they could not be used just as well with something other than steam. The factors to concider in the construction of this engine is the amount of heat input into the system, the boiling point of the solvent used and the entropy of the system. The entropy is going to be the amount of heat lost in actually bringing the solvent to a boil. This heat can not be used to generate work. There is a conciderable amount of entropy involved in bringing water to a boil, but organic solvents tend to vaporize much easier than water does. Methylene chloride was chosen because it is relatively non-flamable compared to most solvents. It is also much less toxic than something like benzene. It is also liquid around 70F.