Arizona Approves Solar HVAC Pilot Program

First State to Include Solar HVAC in Renewable Portfolio

November 10, 2004

One of the most famous project examples of solar absorption technology, the Arnold Schwarzenegger Stadium in Graz, Austria. Schwarzenegger was instrumental in getting the solar HVAC system installed here.

Photo: New World Solar

"Adding solar HVAC to the portfolio mix provides new options for power-hungry industrial users."

- Commissioner Jeff Hatch-Miller

Three years ago, Arizona became one of the leading states in the nation to support the use of renewable energy sources for electric power generation. Beginning in 2002, their Environmental Portfolio Standard required regulated utilities to generate a minimum percentage of their total retail energy sales from renewable sources.

"Arizona has been on the leading edge in requiring the use of renewable sources of energy," Commissioner Bill Mundell said. "This pilot program is designed to encourage the installation and operation of five solar HVAC systems as part of the Environmental Portfolio Standard. We need to encourage these new technologies if we are going to wean ourselves off of fossil fuels."

Unlike technologies that generate electricity, solar HVAC technology saves energy that the customer would otherwise need to draw from the electrical grid. Arizona's energy use spikes in the summer due to the intense demand for air conditioning and the power necessary to run these systems. A solar HVAC system would provide summertime cooling without straining the electrical grid. In other seasons, energy captured by this technology can be used for space heating or to heat water for various applications within a building.

"For example, a high school could have a solar HVAC system to provide air conditioning in the warmest months," Commission Chairman Marc Spitzer explained. "During the cooler months, the system could provide hot water for dishwashing and cooking in the cafeteria or for showers in the gym."

Traditionally, solar thermal or solar hot water technologies are used only for heating. Configuring the system for cooling and air-conditioning is the real trick.

These solar HVAC systems operate using the process of "absorption cooling." According to the U.S. Department of Energy, absorption cooling is the first and oldest form of air conditioning and refrigeration. An absorption air conditioner or refrigerator does not use an electric compressor to mechanically pressurize the refrigerant. Instead, the absorption device uses a heat source, such as natural gas or a large solar collector, to evaporate the already-pressurized refrigerant from an absorbent/refrigerant mixture. This takes place in a device called the vapor generator.

Although absorption coolers require electricity for pumping the refrigerant, the power amount is small compared to what is consumed by a compressor in a conventional electric air conditioner or refrigerator. When used with solar thermal energy systems, absorption coolers must be adapted to operate at the normal working temperatures for solar collectors, between 180 to 250 degrees F (82 to 121 degrees C). It is even possible to produce ice with a solar powered absorption device, which can be used for cooling or refrigeration.

Solar HVAC systems are in use in Israel, Japan, China and some European countries according to Lori Glover, president of New World Solar, formerly So Cool Energy. Glover attended the Commission meeting to speak in favor of approving this technology. The Commission order does not specify the vendor or specific design criteria. Glover's firm is one of several companies that could supply a solar HVAC system under the program approved by the Commissioners. Arizona would be the first state to acknowledge this emerging technology as a qualifying project under a renewable energy portfolio, according to Glover.

"The kilowatt hours saved through the pilot program would be eligible to meet the solar electric requirements of the Environmental Portfolio Standard," Glover said.

Commissioner Mike Gleason said the kilowatt hours saved through the pilot program would be eligible to meet the solar electric requirements of the Environmental Portfolio Standard. Utilities or electric service providers wishing to participate in the solar HVAC pilot program are required to file notice with the Utilities Division that identifies the specific proposed project.

"In February 2004, we unanimously voted to continue increasing the percentage derived from renewable sources," Commissioner Jeff Hatch-Miller said. "Adding solar HVAC to the portfolio mix provides new options for power-hungry industrial users."

The Environmental Portfolio Standard covers solar technologies such as solar generation, solar water heating and solar air conditioning. Non-solar technologies such as landfill-gas generators, wind generators and biomass generators are also qualifying technologies. Unlike many other states, Arizona's definition of environmentally friendly, renewable technologies currently does not include hydroelectric generation or geothermal power.

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