> How can unconventional technologies like wind or solar thermal (the "power tower" concept)have substantial public risk? The answer is simple. The

> How can unconventional technologies like wind or solar thermal (the "power tower" concept)have substantial public risk? The answer is simple. The production of the metals needed in many unconventional technologies requires that coal is burned I get the feeling that this study from the 70s doesn't have all the facts that are relevant today.