Solar power is emerging as a popular alternative to fossil fuels. And while it will still be some time before solar power is a widely adopted, cost-effective alternative, the chemistry to help convert heat into electricity exists. At two major installations, high temperature heat transfer fluid already is being used in processes to capture energy from the sun and convert it to steam for generating electricity.
Heat transfer fluids from the Dow Chemical Co.'s Performance Fluids business are enabling solar plants in Spain and Nevada to explore and exploit solar heating. In Spain, three large solar power plants collect heat and convert it to electrical energy. Taking advantage of the sunny climate and favorable tax incentives, Spain is pioneering large, commercially viable solar power plants.
The Midland, Mich.-based chemical company delivered more than 2,000 metric tons of Dowtherm A, specialized heat transfer fluid, to the Andasol I Solar Energy plant in Guadix, located in southern Spain, near Granada. Also, according to the company, in just a few months, Dow will fill the Iberdrola Renovables plant in Ciudad Real with nearly 1,000 metric tons of Dowtherm A. Later still, another 2,000 metric tons of the same heat transfer fluid will be delivered to Andasol II, also located near Guadix.
Each plant will supply 50 MW of electrical power, for a total of 150 MW, or enough electricity for about 90,000 homes. All three solar plants will collectively save approximately 450,000 tons of carbon dioxide per year that would have been released to the atmosphere had traditional fuels been burned.
Dow also is supplying Dowtherm A to a solar plant near Boulder City, Nev. Nevada Solar One will generate 64 MW of electricity, enough electricity to power about 45,000 average homes for a year. Plants like Nevada Solar One are ideal for areas such as the Southwest that use a significant amount of electricity to run air-conditioning. With the land and sun resources available in places like Nevada, and state regulations mandating that at least 5 percent of electric power come from solar energy by 2015, it is likely that even more solar power plants will be built.
At each of the solar plants, Dowtherm A is used to collect heat energy and transport it to a power-generating station. The transported heat converts water to steam, which in turn drives turbines to make electricity. Dowtherm A is a mixture of special fluids that have the high temperature stability needed to collect, transport and store heat. It is suitable for systems that use liquid- or vapor-phase heating.
Sidebar:Trough solar systems use parabolic curved, trough-shaped reflectors to focus the sun's energy at 30 to 60 times its normal intensity onto a receiver pipe. The concentrated energy heats a thermal fluid flowing through the pipe. This fluid then is used to generate steam, which powers a turbine driving an electric generator. The collectors are aligned on an east-west axis, and the trough is rotated to follow the sun and maximize the solar energy input onto the receiver tube.
Get Acquainted With Parabolic Trough Solar Systems
New solar power generating plants are being built around the world. In countries like Spain, solar power plants currently provide electricity at a cost of $0.10 to $0.12 per kilowatt-hour (kWh). A target has been set to reduce the cost to $0.035 to $0.043 per kWh by 2020.
Trough collector solar power systems, also called solar electric generating systems (SEGS), represent the most mature concentrating solar power (CSP) technology. Nine of these plants were built in California's Mohave Desert between 1984 and 1991, offering 354 MW of installed capacity. The plants are still operating and producing power for the electrical grid at 99 percent availability.
For more information from Dow Performance Fluids, part of the Dow Chemical Co., Midland, Mich., call (800) 447-4369 or visit www.dow.com/heattrans.