Transcript Slide 1
The Environmental Impact of Solar Photovoltaic Cells The Energy Challenge and How to Solve it with Solar Cells Original Presentation by J. M. Pearce, 2006 Email: [email protected] The Energy Challenge • World population is expanding rapidly and will likely reach more ~9 billion before stabilizing • Energy use is directly proportional to standard of living • Energy demand is skyrocketing • Standard methods of producing energy have a limited supply and have unacceptable impacts on the environment The Population Explosion Human Development Index HDI: longevity (life expectancy), educational attainment, and standard of living (gross domestic product per capita) World Energy Consumption By Fuel Type 1970-2015 Future Energy Needs How to Produce Electricity? • Conversion of mechanical energy into electricity (dynamo) • Conversion of chemical energy into electricity • Conversion of nuclear energy into electricity • Conversion of photon energy into electricity Energy Sources – Global Primary Energy Supplies U.S. Production Peak - 1970 • • Measured in 1000 barrels per day World energy reserves and peak under considerable debate… U.S. and World Natural Gas Supplies World and U.S. Coal Reserves Even if we discover more fossil fuels…. We can not burn what we already have. Atmospheric Carbon Dioxide Concentration From 1860 to 1990 the industrial nations released 185 billion tons of carbon into the atmosphere from burning fossil fuels. Today 6 + billion tons of CO2 are released into the air every year! 370ppmv Global Warming This is the Consensus View The Intergovernmental Panel on Climate Change In 1995, over 2,500 scientists representing more than 80 countries analyzed over 20,000 articles from the relevant literature It is now quite clear that certain gases, such as carbon dioxide, play a crucial role in determining the earth's climate by preventing heat from escaping the atmosphere. Now predicting temp. gains up to 14oF!!! Potential Consequences : Manageable to Catastrophic • In 50 years Earth will be ~3-5 degrees hotter, leading to a rise of up to 14 ft in global sea levels. (3ft floods Florida & NYC) • Weather patterns disrupted: droughts in some places and torrential rain in others – disturbing agricultural production. • EPA estimates that by 2050 the southern boundary of forest ecosystems could move northward by 600km. • Thus we face massive forest death and species extinction. Potential Effects of 21st-Century Warming on the Summer Climate of Illinois Solar Photovoltaic Energy as a Solution to the Energy Challenge Environmental Benefits • During use - PV produce no : – atmospheric emissions – radioactive waste • During use PV produce no greenhouse gases so it will help offset CO2 emissions and global climate destabilization – PV does have an embodied energy and embodied CO2 emissions • PV curtails air pollution, which produces acid rain, soil damage, and human respiratory ailments. Environmental Benefit of a 4 kWp PV system This solar energy array would prevent: • 2.4 tons of coal from being burned • 6.2 tons of CO2 = decreasing the greenhouse effect • over 3,600 gallons of water from being used • ~34 pounds each of NOx and SO2 from polluting the atmosphere • 1.8 pounds of particulates from causing a health hazard (and no nuclear waste) EACH YEAR - FOR 30+ YEARS! Busting PV Related Myths Myth 1: PV use more energy to make than they produce over their lifetime For cells in production now the energy payback is between 6 months and 5 years! Net Energy for 1kW-hr invested in PV Roof in Detroit, MI 15 14 13 12 Net Energy (kW-hrs) 11 10 9 8 7 c-Si Low c-Si High p-Si Low p-Si High a-Si Low a-Si High 6 5 4 3 2 1 0 -1 0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930 Time (Years) 14+ breeds Built in PV Integrated into the roof. Integrated into an awning over a back porch California, generates electricity while shading the family's outdoor activities Additional BIPV Solar Shingles Aesthetic Applications A Canadian team fashioned a window with solar electric cells and a motif of autumn leaves Myth 2: There is Not Enough Land • Each day the sun casts more energy on the earth than all people would consume in 27 years. • The entire world’s energy needs could be provided by ½ the area of the Gobi desert covered with PV. What about in the USA? • 100 miles by 100 miles in Nevada would provide the equivalent of the entire US electrical demand • Distributed (to sites with less sun) it would take less than 25% of the area covered by US roads. Solar Cell Land Area Requirements for the World’s Energy with Solar PV 6 Boxes at 3.3 TW Each Solar Cells Myth 3: We do not have Enough Raw Materials • Si - 2nd most abundant element in Earth’s crust • The amorphous silicon cells manufactured from one ton of sand could produce as much electricity as burning 500,000 tons of coal. • Philadelphia home Solar Photovoltaics is the Future Acknowledgements • This is the fifth in a series of presentations created for the solar energy community to assist in the dissemination of information about solar photovoltaics. • This work was supported from a grant from the Pennsylvania State System of Higher Education. • The author would like to acknowledge assistance in collecting information for this presentation from Heather Zielonka.