We hear a lot about “alternative energy”, meaning environmentally friendly substitutes for fossil fuels –  coal, oil, and natural gas.  But while each alternative has its virtues, each also has downsides.  Which one seems the most promising, and which have the most liabilities?  Join Phil Pryde, author of Nonconventional Energy Resources, for a slide show that will illustrate various forms of alternative energy sources, both those now in use and those that aren’t, and the advantages and disadvantages of each.