Solar Thermal Energy: Heating our homes while cooling our planet Chris Mayor and Stephen Mizera

What is solar thermal energy? A technology for harnessing solar energy for heat Uses mirrors and lenses to concentrate sunlight onto heat collectors Used to produce electrical power

Collectors Can be categorized into three different types: Low-temperature, medium-temperature, and high-temperature Used to concentrate and harness the power of the sun

Low-temperature Collector Made up of flat plates Most often used in the heating of swimming pools Can use the sunlight to heat water for houses Began appearing in the United States in the 1890’s Thermal mass materials such as stone and cement can be used to maintain comfortable temperatures within a household Another use of this is in evaporation ponds, where dissolved solids are concentrated through evaporation Evaporation ponds are the oldest application of solar thermal energy usage

Medium-Temperature Collector Produces 50% of hot water needed for commercial and residential usage A solar cooker is the most well known type of medium-temperature collector Solar cookers use reflectors for concentrating light on a cooking container Solar stills are used to disinfect water by extinguishing the chemicals in the water

High-Temperature Collector When temperatures are above 95 degrees Celsius, flat plate collectors are used without concentrating the solar rays The types of collectors vary with how high the temperature is Steam and gas turbines are the most prevalent

Types of System Designs for High-Temp Collectors Parabolic trough designs: direct solar radiation goes to receivers at focal point of parabolic curve Power Tower: use movable, flat mirrors to focus the sun’s rays on the receiver of the tower Dish designs: use one large, parabolic dish to focus the sunlight into a receiver Fresnel Reflectors: long, narrow, shallow-curvature mirrors focus the sun’s rays onto receivers Fresnel Lenses: not in use currently; cheaper than mirrors for Fresnel Reflectors MicroCSP: designed mainly for rooftop installation

Benefits of Solar Thermal Energy The sun produces large and unlimited quantities of energy The sun delivers about 300 BTUs per square foot to anything on the earth’s surface that is facing it directly on a clear day Solar radiation arrives on the surface of the earth with a maximum power of approximately 1 kilowatt per square meter (kW/m2). Easily harnessed by many different types of collectors.

Disadvantages of Solar Thermal Energy Only certain regions of the world receive adequate amounts of direct sunlight Difficulty in storage of heat Costs a large amount of money to produce the materials necessary to harness the energy Solar thermal energy plants can harm desert ecosystems if not properly managed Solar thermal energy farms require a large amount of space

Financial Impacts of Solar Thermal Energy Because it does not rely on fuel, costs consist mainly of constructing plants Minor operational and maintenance costs Tax incentives for installing solar thermal systems

Environmental Impacts of Solar Thermal Energy Produces no air or water pollution in the process of harnessing it Takes up a lot of much needed space in the desert for the farms Creates some indirect impacts to environment, such as manufacturing the photovoltaic cells used to convert sunlight into electricity, consumes silicon and produces some waste products

Progress of United States in producing solar thermal energy Currently, the United States does not utilize solar thermal energy as a major energy source Less money will be used to buy oil for gas, which will make the United States less dependent on foreign oil

Statistics on Solar Thermal Energy

Statistics on Solar Thermal Energy (cont.) Solar Thermal Collector Average Price,

Statistics on Solar Thermal Energy (cont.) Low-temperature collectors contributed 75% of the total shipments of collectors in 2006, medium-temperature collectors 6.5%, and high-temperature collectors 18.5% Largest gain in market share from 2005 to 2006 was high-temperature collectors, which went from nearly a negligible amount of shipments to 18.5% of the total collector shipments Total shipment revenue nearly tripled from $45.8 million in 2005 to $121.1 million in 2006