As my individual assignment - Site Planning I wanted to design a renewable energy power plant in Sri Lanka.. I wish to clarify the possibility of implementing a such project.
I think that utilization of geothermal energy "GTE" is one of the best alternatives for the traditional energy derived from fossil fuels. Many times in the past, I read articles about this subject when I taught a course that was entitled "Applied Chemistry". My personal judgment was that GTE is scientifically fine on account of "validity & feasibility" and those who object it do so for nonscientific reasons. Please see this article which is high quality science, in my opinion.
Perera seems some very old Portuguese reminescence...no, Shalomi?
Geo thermal is part of the 'menu' of energy sources in Nature. But as it happens with fuels, the fact that is taken from the soil is not a garantee that is clean. It must be exploited, of course, - no doubt- about that - as Nizar wrote because it is agile and local and is good for several applications around from electricity to some direct uses as heat.
Ive been reading some articles about GTE though it may seems as a better energy portion on earth, but the releasing gases are really harmful. May be in near future if they can invent some transformation mechanism for green house gases into earth friendly elements, GTE would be one good option than others.
We have good geothermal sources in Australia, and there are firms attempting to exploit them commercially. But they are struggling because of the low return on investment. The plants are costing far more than originally hoped and don't yield as much energy as hoped. I doubt very much if the situation in Sri Lanka will be better than here (which is among the best in the world). Are there studies on the rock temperatures, depths, general geological nature of the strata to drill through?
I am all for your idea but I don't think geothermal is a good one to put in the mix of technologies. Go for solar (PV and thermal), wind, hydro (which you already have on the Mahaweli)l, tidal.