Sustainability

West Chester University

 

Solar

According to the U.S. Department of Energy (DOE), the power of the Sun's irradiation of the Earth is approximately 1.2x1017 watts. Current worldwide power consumption is 1.3x1013 watts. In other words, the Sun provides more energy to the Earth in an hour than we use in a full year. Covering 0.16% of the US land area with 10% efficient solar cells (an efficiency easily obtained by commercial cells) would provide more than the current energy demand of the world. Solar is the only renewable energy source with this capacity... and it's falling on the US every day for free!

Solar energy is different from fossil fuels in that its cost is not related to securing the fuel, but to converting it to useful forms. The Solar America Initiative is a DOE effort to accelerate the development of advanced solar energy technologies. The goal is to make solar electricity from photovoltaics (PV) cost-competitive with conventional forms of electricity from the utility grid by 2015.

Light from the sun can be harnessed either to generate heat, electricity or chemicals (just like plants do in photosynthesis). Direct conversion of solar energy into electricity is performed by photovoltaic cells. This online tutorial describes all aspects of the production of solar photovoltaic cells as well as describing relevant aspects of solar radiation.

Solar radiation can also be used in a photothermal system in which the light heats a fluid. Heat exchangers extract the thermal energy from the fluid. This heat is used to generate steam that drives a turbine, just as in a conventional combustion or nuclear electrical generator.

There are numerous issues involving chemistry as it relates to solar power applications. Recently the NSF opened a center for chemical innovation called Powering the Planet. This Center is located at Caltech and focuses on the efficient and economical conversion of solar energy into stored chemical fuels. Their Education Page contains further information.

Here are a couple of links to some cool frontier ideas about integrating solar power production into building designs

The National Renewable Energy Lab (NREL) has lots more information on solar power.

If you are thinking about installing solar power or water heating, you can look to Philly Solar.org for more information.

Solar has great potential for both on-grid (hooked up to the wires that deliver electricity to homes and businesses) and off-grid applications. Off-grid applications are important to isolated communities: islands, remote villages, low population density areas, nomadic populations and the developing world. Small-scale off-grid solar energy capture, storage and use has the promise of allowing such areas to develop without having to build up an extensive (and expensive) infrastructure that may be inpracticable and difficult to maintain. The Lighting a Billion Lives project seeks to reach out to such populations and deliver basic solar lighting to them.

Founded by TERI, this campaign aims to bring light into the lives of one billion rural people by replacing kerosene and paraffin lanterns with solar lighting devices. This will facilitate education of children; provide better illumination and a kerosene-smoke-free indoor environment for women to do household chores; and provide opportunities for livelihoods both at the individual level and at the village level. Each solar lantern in its useful life of 10 years displaces the use of about 500-600 litres of kerosene, thereby mitigating about 1.5 tonnes of CO2.