As consensus builds on transitioning to renewable energy to cut greenhouse gases, a growing number of businesses and governments are evaluating the carbon footprint of the various energy sources from cradle to grave. These analyses, known as life cycle, show that every energy technology produces emissions--be it coal, nuclear, solar or wind energy. That is true for the latter two resources because oil, natural gas, or coal is used to make and transport materials used in solar panels and windmills. Thus, until renewable energy technology is made with renewable power--still a distant prospect--it cannot become fully renewable, according to some clean energy advocates. Solar energy developers, however, are working to make sun power systems petroleum free. \u201cUsing more petroleum in [solar] cells goes against the principle of green energy,\u201d said David Lee, president and chief executive officer of BioSolar, a company based in suburban Los Angeles. \u201cOur mission is to replace the petroleum-based material in photovoltaic cells.\u201d To do that, the Santa Clarita-based company has developed a plant-derived material to use as the \u201cbacksheet\u201d on which crystalline solar cells are mounted. The product is known as BioBacksheetTM. The company also works on bio-based substrate material for thin film solar technology, as well as biomaterials to replace the glass used on top of the solar cells in today\u2019s panels. Bio-housing and packaging material for solar panels is another area of research for Lee and his firm. The company estimates that such biomaterials are likely to cost about half of the traditional materials used in panels, as well as reduce greenhouse gases. BioSolar has developed a way to use plants with a minimal amount of what Lee, a former aerospace engineer, calls chemical manipulation. \u201cIt is not made from sources that compete with food,\u201d he quickly adds. The backsheet has the physical properties--including thermal characteristics--needed for use in solar panels, which sit on rooftops that are blazing hot during the day and can freeze at night. The product is being submitted for patenting and is in the midst of the Underwriters Laboratory certification process. On a life-cycle basis, photovoltaic power produces about 0.04 kilograms of carbon dioxide\/kWh, according to an analysis by Ambiente Italia presented last fall at a renewable energy conference in Chiba, Japan. Researchers see that level declining dramatically by mid-century with improvements in the materials used to make solar equipment. Some of today\u2019s emissions result from making the plastic used in solar panels themselves. The plastic also is a significant cost factor, according to Lee, along with non-renewable glass and metal. They account for 25 percent of the material costs and much of the fossil fuel burned to make the average panel. While the cost of the silicon material used in the panels may be coming down, the cost of the fossil fuels used to make panel components is going up, according to Lee. BioSolar is ready to move from the research and development phase to pilot manufacturing of the backsheet, Lee added. Unlike many other startup manufacturing operations, he said, BioSolar plans to open a facility in the U.S. rather than overseas, particularly since the cost of the raw material is small and most of the work to produce the backsheet is done by machine, rather than workers. Lee is convinced that such innovations in the non-silicon components used to make solar panels are ultimately important in lowering the cost of solar energy. \u201cWe\u2019re getting closer and closer to making the solar panel financially feasible,\u201d he concluded.