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Texas Solar Energy

Solar power is friendly to our environment because no fuels are combusted, which means that emissions associated with generating electricity from solar technologies are negligible. The most common technologies used to actively convert solar energy into electricity are photovoltaics and concentrating solar power (solar-thermal) which includes parabolic trough systems, the lowest cost solar electric option for large power plant applications. Unlike solar photovoltaic, solar thermal projects tend to be large-scale and in remote areas.

Though we can capture solar energy, concentrate it, store it and convert it into other useful forms of energy, solar technologies must be further developed and profitably marketed to successfully harness the sun's power on a large commercial scale and to provide cost-effective, reliable energy services. NREL collaborates with industry to further the research and development of concentrating solar power (CSP) plant and solar thermal technologies and supports DOE in its concentrating solar power deployment efforts.

In its 2008 Annual Energy Outlook (pdf), The U.S. Department of Energy's Energy Information Administration projected thermal power generation to increase more than fourfold by 2030, while grid-connected solar power, which provided a miniscule share of the country's power in 2006, is projected to experience a 73-fold increase.

Solar Radiation in Texas

Texas has a virtually unlimited solar energy supply, ranking first in the nation in solar resource potential, with high levels of direct solar radiation. This radiation is more than suitable to support large-scale solar power plants concentrated in West Texas, which has 75 percent more direct solar radiation than East Texas. This makes Texas an ideal location for utility-scale concentrating solar power (CSP) technologies.

The Solar Energy Laboratory at the University of Texas at Austin emphasizes research on solar radiation measurements at several sites across Texas compiled as the Texas Solar Radiation Data Base. The database information includes monthly solar radiation averages for these locations.

Texas is one of seven states that partnered with DOE and the Western Governors Association in 2010 to install concentrating solar power (CSP) systems. The program's overall goal was to install 1,000 megawatts (MW) of new CSP systems in the southwestern United States by 2010. For additional information, see the DOE National Renewable Energy Laboratory (NREL) web site, Southwest Concentrating Solar Power 1000-MW Initiative.

Texas is Exceptional in Solar Energy Potential!

Chart, showing renewable energy potential.

The energy from sunshine falling on a single acre of land in West Texas is capable of producing the energy equivalent of 800 barrels of oil each year.

Active & Passive Solar Energy

Solar energy is the most democratic of renewable energy resources. It is available everywhere on the earth in quantities that vary only modestly. Only a very small percentage of the sun's energy strikes the earth but that is still enough to provide all our energy needs. Solar energy can be active (direct) or passive (indirect).

Active

Active photovoltaic solar systems collect, store and convert the sun's energy either as photovoltaic (PV) electricity or thermal (heating) energy.

Inside collector panels, air or water circulates, directing the sun's heat to a direct use for electric power, or a heat storage device. Typical uses for active solar collection systems are space and water heating.

Image of a solar active system

Passive

Passive solar design uses the sun's energy for the heating and cooling of living spaces, making use of building materials and building siting to take advantage of the sun's heat and light without using mechanical means.

In this approach, the building itself or some element of it takes advantage of natural energy characteristics in materials and air created by exposure to the sun. Passive systems are simple, have few moving parts, and require minimal maintenance and require no mechanical systems.

Image of a solar passive system

Land & Water Needs for Solar Power

Solar radiation has a low energy density relative to other common energy sources, so it requires that a large total acreage be utilized to gather an appreciable amount of energy. While the construction of large facilities like solar power plants are within the realm of successfully implemented projects, their size requires that a host of social and environmental issues be considered.

Typical solar-to-electric power plants require 5 to 10 acres for every megawatt (MW) of generating capacity. A 200 MW solar plant in West Texas would need about 1,300 acres of land.

Solar thermal electric technologies typically require considerable water supplies. While the quantity of water needed per acre of use is similar to or less than that needed for irrigated agriculture, dependability of the water supply is an important issue in the sunny, dry areas of the state favored for large-scale solar power plants.

Demonstration of solar thermal power
Solar Two thermal power demonstration, 1995-1999

Photovoltaic systems do not require the use of water to create electricity; and though solar-thermal technologies may tap local water resources, the water can be re-used after it has been condensed from steam back into wate. Systems off ering this flexibility sometimes are called distributed power generators. By contrast, utility-scale concentrating solar power plants use centralized power plants and transmission lines to distribute electricity to customers.

Texas Renewable Energy Resource Assessment

In the mid-1990's, SECO performed a study to evaluate Texas's renewable energy resource base, including solar, wind, biomass, water and geothermal. The following chart is included in the study, Texas Renewable Energy Resource Assessment (pdf). One of the main efforts of this project was to estimate the size of each of Texas' renewable energy resources.

In the following chart (Figure 1), the total physical energy for each resource is the amount available within the entire state per year. The accessible resource is the amount of the total resource that is technically feasible to extract with existing or near-term technology. Energy density compares the relative concentration of the resources at a prime Texas location for each. Measurement units are in quads per year. For reference, one quad is enough to serve all annual energy needs for about 3,000,000 people. Clearly then, the 4,300 quads of solar energy incident on the state each year is an immense resource.

Figure 1. Quantification of Texas renewable energy resource base
and identification of primary uses
Resource Total physical resource (quads/yr) Accessible resource (quads/yr) Energy density: Good Texas site (MJ/m2/yr) Primary energy uses * Non-energy uses
elec heat mech trans
Solar 4,300 250 8,000 y y
Wind 12 4 15,000 y
Biomass 13 3 45 y y y Food feed fiber
Water 3 1 10 y y y Water supply; flood control
Geothermal 1
(2,300,000 quads)
1 3 y y y
Building climatology 0.6 0.26 430 y y
* where elec is electricity, mech is mechanical, trans is transportation, and y is yes
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