Joshua E. Richardson Industrial High Temperature Solar Thermal Power Plants

Definition Industrial High Temperature Solar Thermal Power Plants are systems for industrial scale use only that utilize solar heat energy to power a turbine in order to produce electricity.

Main Goals To successfully provide a fuel that is: –Clean –Efficient –Cost-effective Energy used specifically for industry-scale uses.

Overall Potential By using only 1% of the earth’s deserts, more clean solar electric power could be produced than is currently produced worldwide with fossil fuels. It is theoretically possible that over 90 percent of the nation’s electricity and most of the transportation sector’s energy needs, could be supplied by solar thermal technology within the next 50 years. Estimated that by 2010, systems will exceed 5,000 MW…enough to serve needs of 7 million people and save the equivalent of 46 million barrels of oil each year.

How does it work? Five types with different models. All operate somewhat alike: –Use lenses and reflectors to concentrate solar power. –Heat drives thermal power plant.

What happens at night? Power is stored during the daytime in molten salt at approximately 1050°F Salt sometimes used to heat graphite which would be used as a heat storage medium  night-time operations are possible! Storage of heat from solar power plants can allow solar power plants to operate around the clock –unique because they can generate power when it is needed…day or night…rain or shine

Designs Solar “Power Towers” Parabolic trough Solar Dish/Engine Systems CSP plants Fresnel Reflectors

Comparison of Major Solar Thermal Technologies (tower, dish, trough) Power Tower Parabolic Dish Parabolic Trough ApplicationsGrid-connected electric plants; process heat for industrial use. Stand-alone small power systems; grid support Grid-connected electric plants; process heat for industrial use. AdvantagesDispatchable base load electricity; high conversion efficiencies; energy storage; hybrid (solar/fossil) operation. Dispatchable electricity, high conversion efficiencies; modularity; hybrid (solar/fossil) operation. Dispatchable peaking electricity; commercially available with 4,500 Gwh operating experience; hybrid (solar/fossil) operation. [Source: Status Report on Solar Thermal Power Plants. Pilkington Solar International GmbH: Cologne, Germany,1996.]

“Power Towers” The first large-scale solar energy project in the U.S. –1982 –DOE and individual corporations Solar plant with a field of computerized mirrors called heliostats that follow the sun. Heliostats reflect rays towards a central tower where heat is used to produce steam. Steam turns a turbine like in more traditional plants.

Power Towers, cont’d Power Tower 1- original trial. –Success! Power Tower 2- 10MW second generation station –1926 heliostats –300 ft. tower –Power for 10,000 homes Discussion about a 30 to 100 MW tower in Nevada.

Parabolic Trough Made of long rows of concentrating mirrors Only curved in one direction Track the sun from East to West with surface that focuses sun’s energy Heat transfer fluid runs through pipe that is at the focus of the troughs Heat is transferred to working fluid (usually water) and used to power or drive turbine

An Acciona solar thermal power plant, located south of Las Vegas. r=1&em&ex= &en=2d73a651a7216de1&ei=5087%0A&oref=slogin Parabolic Trough

Still under development Consists of parabolic shaped concentrators that track sun in two-axis Cycle heat engine mounted on receiver generates electricity, or sunlight heats fluid that is transmitted to a central engine Parabolic Dish/Engine Systems

Political/Economic Obstacles Currently not economical –high cost of building facilities needed –currently can only lengthen the amount of time you have energy by a few hours –would require more high voltage DC lines to carry the electricity from the southwestern U.S. to the rest of the country Funding will be needed to bring solar thermal electric into large scale development

Political/Economic Opportunities Can create 2 and ½ times as many skilled high paying jobs as conventional power plants that use fossil fuels Moderate net energy Moderate environmental impact Costs reduced with natural gas turbine backup

Technological Obstacles Needs back up or storage system Storage: the solar thermal plans would need just 16 hours of storage to continuously generate electricity Low efficiency –increasing efficiency by 20-30% could significantly reduce the cost of electricity

Technological Breakthroughs Future solar collectors will be mass-produced using… –lower cost flat mirrors, rather than curved troughs –and sit low to the ground reducing wind loads Fast construction (1-2 years)

Land Use Issues Takes lots of area requiring high land use Works best in desert or other areas with lots of sun

Negative Environmental Impacts May disturb desert areas Could potentially endanger wildlife Take up at least nine square miles of space

Positive Environmental Impacts No CO 2 emissions –reduces air pollution Less use of fossil fuel

Costs of Use 15 – 20 cents per kilowatt-hour (kwh) –Comparison to wind…8 cents per kwh Costs to produce facility –One-half (50%) the cost of solar power tower is associated with mirrors that focus light on the receivers – Less than one-third (33%) is associated with power cycle and heat storage

Additional Benefits The peak demand period - during the hottest part of the day, when air conditioners are running in the office and home - coincides with the period of time when the solar thermal power plant is at peak production Steam is emitted rather than greenhouse gases

Conclusions Solar thermal energy could lead the United States into a renewable future. Cost reduction of producing solar thermal energy could make this the most viable type of available energy.

Bibliography &idtype=cvips&gifs=yeshttp://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO &idtype=cvips&gifs=yes a651a7216de1&ei=5087%0A&oref=sloginhttp:// a651a7216de1&ei=5087%0A&oref=slogin Living in the Environment (textbook)