Background
Hawai‘i, like many other states, has an energy policy that calls for reducing dependence on imported fossil fuels by increasing energy efficiency and the use of renewable energy resources. Despite innumerable plans and studies of energy options over the last three decades, Hawai’i’s dependence on imported fossil fuels has actually increased. This is partly due to the closing of sugar plantations, which burned bagasse for energy. It is also partly due to the cost and pricing structure of alternative energy compared to imported fossil fuels, and the way energy production and sales are regulated in Hawai‘i.

It is clear that to attain a preferred energy future for Hawai‘i, a collaborative effort of government, business, and community is necessary. Thus, the University of Hawai‘i convened Hawai‘i’s major energy stakeholders as the Hawai‘i Energy Policy Forum in May 2002. The purpose of the Forum is to develop an energy vision for the year 2030 and to formulate a strategy to ensure its implementation. The Forum is a unique experiment in collaborative energy policy making. It includes representatives of the electric utilities; oil and natural gas suppliers; environmental groups; the renewable energy industry; the state legislature; federal, state and county agencies; the general business community; and major energy consumers (see Forum Members).

The Forum is designed to facilitate discussion of a preferred energy future and the relevant issues and constraints. In addition to the usual energy economics and technology questions, the Forum considers the roles of energy planning agencies, the Public Utilities Commission, and the Legislature in energy decision-making. The intent is to incorporate as many different perspectives and the broadest possible experience into the design of a flexible, forward-looking energy strategy that provides environmentally friendly, renewable, safe, reliable, and affordable energy for the State.

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Executive Summary
The major share of energy which is needed in industrial production processes is below 250°C – a temperature level, which could be well supplied by solar thermal technologies. The lower temperature level (< 80°C) can already be provided today with commercially available solar thermal collectors. Most solar applications for industrial processes are on a relatively small scale and are mostly experimental in nature. There are currently about 85 solar thermal systems supplying heat for industrial processes. These plants have a total installed capacity of 27 MWth (38,500 m²)4. Solar Heat for Industrial Processes (SHIP) is still in its infancy and yet, as discussed
in the market potential section of this report, there is potentially an enormous range of Solar Thermal applications within this sector which can supply a large portion of
our total energy demand. Current SHIP applications are based on presently available technologies. RD&D is performed both on developing new components with a quality suitable for specific industrial applications, e.g. higher temperatures, and on refining configurations of products which are already available. As new developments become available, more SHIP applications will become viable. Because solar industrial process heat is not yet widely available, it is important to understand its specific barriers to growth and consequently the best strategies to help overcome these barriers. The following short list will help policy-makers develop and implement suitable support policies for SHIP. A more detailed list can be found at the end of this document.

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Solar Process Heat

A transpired collector is installed at a FedEx facility in Denver.

Commercial and industrial buildings may use the same solar technologies—photovoltaics, passive heating, daylighting, and water heating—that are used for residential buildings. These nonresidential buildings can also use solar energy technologies that would be impractical for a home. These technologies include ventilation air preheating, solar process heating, and solar cooling.

Many large buildings need ventilated air to maintain indoor air quality. In cold climates, heating this air can use large amounts of energy. A solar ventilation system can preheat the air, saving both energy and money. This type of system typically uses a transpired collector, which consists of a thin, black metal panel mounted on a south-facing wall to absorb the sun’s heat. Air passes through the many small holes in the panel. A space behind the perforated wall allows the air streams from the holes to mix together. The heated air is then sucked out from the top of the space into the ventilation system.

Solar process heating systems are designed to provide large quantities of hot water or space heating for nonresidential buildings. A typical system includes solar collectors that work along with a pump, a heat exchanger, and/or one or more large storage tanks. The two main types of solar collectors used—an evacuated-tube collector and a parabolic-trough collector—can operate at high temperatures with high efficiency. An evacuated-tube collector is a shallow box full of many glass, double-walled tubes and reflectors to heat the fluid inside the tubes. A vacuum between the two walls insulates the inner tube, holding in the heat. Parabolic troughs are long, rectangular, curved (U-shaped) mirrors tilted to focus sunlight on a tube, which runs down the center of the trough. This heats the fluid within the tube.

The heat from a solar collector can also be used to cool a building. It may seem impossible to use heat to cool a building, but it makes more sense if you just think of the solar heat as an energy source. Your familiar home air conditioner uses an energy source, electricity, to create cool air. Solar absorption coolers use a similar approach, combined with some very complex chemistry tricks, to create cool air from solar energy. Solar energy can also be used with evaporative coolers (also called “swamp coolers”) to extend their usefulness to more humid climates, using another chemistry trick called desiccant cooling.

Find out about NREL solar technologies research for nonresidential buildings from its Advanced Desiccant Cooling & Dehumidification Program and High Performance Buildings Research Program.

The U.S. Department of Energy’s Consumer Guide has in-depth information on Active Solar Heating.

For more information, you might want to see Advanced Buildings Technologies and Practices.