As renewable energy technologies become more commonplace, more questions emerge as to the practicality and other problematic side-effects from otherwise promising approaches. Even solar technologies have come into question with problems related to disposing of spent photovoltaic panels.

　　Solar locating guides calculate available energy based on average "sun hours," or the number of hours per day where irradiance is at least 1 kW per square meter. While the two plants in the study are in m

　　The Electric Power Research Institute (EPRI) assists the electric utility industry by researching new technologies related to the generationCONTROL ENGINEERING China版权所有, delivery, and use of electric power. Its member utilities are responsible for more than 90% of the electricity generated in the U.S., with international participation from 40 countries. The group has researched many environmental and renewable projects控制工程网版权所有, guiding development from concept through evaluation, texting, and commercialization.
　　As one of its renewable energy projects控制工程网版权所有, EPRI is in the evaluation phase with two new projects to study solar steam generation that can supplement conventional thermal technologiesCONTROL ENGINEERING China版权所有, allowing utilities to increase output or reduce fossil fuel consumption. The objectives of the studies are to determine the practicality and effectiveness of adding solar steam generation to existing natural gas combined cycle plants and conventional coal-fired plants.
　　Solar technologies have been a major area of interest for renewable power generationCONTROL ENGINEERING China版权所有, however the biggest drawbacks have been efficient power conversion. The amount of solar energy hitting the earth is far greater than we could ever need, but we simply do not have practical technology to harness it. Considering that fossil fuels were formed from ancient plant life, all sources of energy on the earth (with the exception of nuclear and geothermal) are ultimately solar.