Concentrated Solar Power Energy & Sustainability Presentation PHYS3150- Petra Huentemeyer By: Matthew Baird

Alternatives to Photovoltaics? Collecting Solar Power is favorable Research still required for PV to be efficient One solar technology has already been around for hundreds of years

Ways we've used solar power.... Solar Kitchen in Auroville, India Fixed reflector One-axis receiver tracking Flexible reflecting coating to change curvature for seasonal variations Generates enough steam to cook 2,000 daily meals

Solar Furnace in Odeillo, France  Located in the French Pyrenees, this collector can achieve temperatures of 3,800 degrees Celsius  The heat is used to for large commercial buildings

Concentrated Solar Power (CSP) or, Solar Thermal Magnifying Glass trick Archimedes, in 216 B.C., allegedly helped protect Syracuse from the Romans by focusing light. Heating systems for swimming pools, commerce, and homes Evaporation ponds are the most used of all solar technologies.

Where CSP stands today Programs ongoing in the US DOE, grants for research and improvements of the technology There are four typical designs of CSP now being utilized  Tower of Power-- >  Parabolic Trough Systems  Fresnel reflectors  Dish/Stirling type

State of CSP cont. Link for current DOE funded R&D projects  y_projects.html#thermal y_projects.html#thermal Link for projects through NREL(National Renewable Energy Laboratory)  DOE/NREL has an initiative to install 1000MW of new CSP systems in the southwestern US by 2010  With this level of deployment, analyst predict consumer costs to be $0.07/kWHr which would make it compete in those markets.

Solar Resource Map of Utah Filtered by solar resource and land availability Represent locations that are economically viable to develop large scale CSP systems Full SW US map on next slide...

Parabolic Trough Systems Utilize parabolic mirrors to concentrate light onto a receiver that runs parallel to the mirror.  All mirrors manufactured by Flabeg  Second surface silvered glass Low iron glass, 4mm thick, with very high transmittance Solar weighted reflectivity ~93.5% Each mirror is ~2m^2 The 80MW SEGS powerplant has 888 collector assemblies, with a total close to 200,000 individual mirrors

Parabolic Trough Systems Synthetic oil is used for heat transfer usually  Oil is heated to 400 degrees Celsius  Using oil, instead of water to directly make steam, keeps pressures at a manageable level throughout the collector system Some stats on the SEGS I-IX plants  354MW capacity, with a capacity factor of 21%, total average gross output is 75 Mwe  Natural Gas can be burned during night to continue utilizing turbines  Claimed 232,500 homes are powered, with 3,800 tonnes of CO2 displaced each year  Total area coverage of 6.5 km^2

Parabolic Trough Systems

Fresnel Reflectors Similar to Trough Design Easy to cover ground area and track the sun effectively, single axis An entire row of mirrors reflect to a single overhead receiver

Fresnel Reflectors

Tower Of Power Many large, flat mirrors reflect to a receiver on top of a tower Water/steam or oil for heat transfer to drive turbine From Solar One in Barstow,CA produced 38 million kWh of electricity

Tower Of Power Solar II (retrofitted solar I) now has the capacity of using molten salt as heat transfer fluid and for thermal storage Developments are under way for a fresnel/TOP combination

Dish/Stirling Designs Large(5-7m dia) individual parabolic dish mirrors reflect onto a thermal receiver and stirling engine which powers a generator Advantage for distributed power Typically, same fluid is used for heat transfer and in engine 3-25 kW each unit typical electricity generation Net 30% efficiency achieved

Future Improvements Advanced optical materials are key  Reflective flexible coatings with ultra high reflectance and which are durable and easy to clean Materials which have high heat capacities and good thermal conductance Continued optimization of design to drive down capitol costs and increase efficiency Clever heat transfer fluids which also double for thermal storage so plant can generate electricity at night

Benefits of using CSP Extremely limited environmental impacts, essentially no CO2/NO2 emissions Evolutionary instead of revolutionary technology, resembles and uses much of the same equipment as current fossil fuel plants, easy to incorporate into the existing electricity infrastructure Already proven to be dependable and efficient(SEGS) Though initial investments are larger than other forms, the fuel used is unlimited, we don't have to mine or discover more which leads to heavy environmental impacts Fast approaching costs of fossil fuels

Sources U.S. Dept. of Energy  National Renewable Energy Laboratory  International Energy Agency 