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UMass Amherst Libraries

Renewable Energy

Overview

Solar Energy

Solar energy is the cleanest, most abundant, renewable energy source available, and the U.S. has ample supplies. States are already taking advantage of this natural resource with California, Nevada, New Jersey, and Colorado leading the way in domestic solar installations. In fact, in January 2006, the California Public Utility Commission approved the California Solar Initiative, which dedicates $3.2 billion over 11 years to develop 3,000 megawatts of new solar electricity, equal to placing photovoltaic (PV) systems on a million rooftops (One MW of solar PV capacity can power 150 to 250 homes).

Despite the small percentage of overall power derived from solar energy, solar energy electricity generation more than tripled between 2000 and 2008. In addition, there are currently 80 MW of concentrating solar power (CSP) plants under construction or with financing secured. All of this activity has the solar PV industry aiming to provide half of all new U.S. electricity generation by 2025.

How Does it Work?

Solar technologies allow us to capture the sun's energy in two principal ways. Solar PV panels, which frequently sit atop buildings, convert sunlight directly into electricity. These solar panels are made of cutting-edge silicon materials, similar to those used in computer chips. As light passes through the panels, it creates a current which generates electricity.

This process of converting light (photons) to electricity (voltage) gives us the photovoltaic effect. Also currently in use are solar thermal systems, which use the sun's heat to warm water for our businesses and homes.

Large-scale CSP systems can also produce energy at a central power plant. These allow us to reduce the construction of new coal fired power plants. CSP technologies use mirrors to reflect and concentrate sunlight onto receivers that collect the solar energy and convert it to heat. This thermal energy can then be used to produce electricity via a steam turbine or heat engine driving a generator.

From Sierra Club