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Generate your own electrical power, cut warehouse energy costs in half.

Generate Your Own Electrical Power, Cut Warehouse Energy Costs in Half

Cogeneration and options from the PRW operator's perspective discussed by Los Angeles Cold Storage engineer at TRRF Convention in Colorado Springs.

Cogeneration? It's not just some Southern California hippie trying to hook his windmill into Pacific Electric: it can be a real energy and money-saver for refrigerated warehouses.

Los Angeles Cold Storage Co. isn't even trying to sell power to the public utility, but John S. Scherer, manager of engineering, expects a new cogeneration facility to cut energy costs in half at the company's downtown refrigerated warehouse complex.

The system, just being put into operation at press time, is called an Integrated Cascade Refrigeration System (ICRS). Although it now seems like an obvious idea, Scherer said, nobody else has done it -- Los Angeles Cold Storage had to design and patent some components.

The ICRS, he explained in a speech to The Refrigeration Research Foundation (TRRF) in Colorado Springs this past April, comprises three basic components:

* A conventional compression refrigeration circuit

* An absorption refrigeration circuit

* An engine-generator combination

The compressor and other equipment load the engine-generator, the water jacket and exhaust heat of which are used to run the absorption refrigeration circuit. The absorption circuit, in turn, is used to condense the compression refrigerant at low temperature, which has the effect of reducing the compression ratio and enhancing the efficiency of the compressor.

At the same time, electricity is produced at a lower cost than that purchased from the utility -- Scherer estimates Los Angeles Cold Storage will produce 98% of its own electric needs at the downtown complex. Overall plant efficiency is 80%, vs. only 30% at conventional refrigerated warehouse energy systems, and 70% of the engine-generator's useful output is refrigeration-related -- being either electricity to run the compressor and other refrigeration equipment, or heat for the absorption circuit.

In a hypothetical, but plausible (possibly even conservative) example, Scherer later told Quick Frozen Foods International, the cost of electricity from a public utility might be eight cents a kilowatt hour, with compressors running at 900 kilowatts. With the ICRS, it might cost only 5.5 cents a kilowatt hour to generate the power, but the compressors could also run at only 600 kilowatts. The same amount of power, 720,000 kilowatt hours, would thus cost only $23,760, instead of $51,840 -- less than half as much.

The key to the success of the operation is the absorption circuit, Scherer told QFFI, and Los Angeles Cold Storage had to design that for itself -- after learning the closest place anything like it could be sourced was West Berlin, and the German company wanted to charge 50% more than L.A. Cold Storage was willing to pay. "We learned quite a few new tricks about absorption, and filed two patents in Europe as well as here in the U.S.," he said. As far as he knows, the engineering manager added, the system is unique.

Cogeneration projects, although given legal status by the Public Utilities Act of 1978, aren't popular with utilities -- traditionally they have involved people trying, in effect, to go into the electric business without being subject to the same sort of regulations the utilities themselves must observe. They do this by setting up some sort of token industrial plant, which is supposedly the purpose of the generating plant -- but the generating plant itself, and the income from selling "excess" power back to the utility, is the real point.

A combined cycle cogeneration system could be used in a refrigerated warehouse, Scherer said, and generate far more power than needed for the plant -- but it would cost $20 million to $70 million to install, and take up 15,000-20,000 square feet, for its capacity of 10 to 50 megawatts. A refrigerated warehouse might find it advantageous to simply purchase the refrigeration produced by such a plant; that would avoid the burden of capital investment -- but there would still be the risk of getting locked into a longterm contract for more refrigeration than the user might need.

A power plant producing refrigeration requires a gas turbine as the main driver to produce electricity. The heat from that is recovered to produce high-pressure steam to run a second turbine, which generates additional power. The exhaust from the second turbine is fed into the absorption refrigeration system (a cooling tower for the excess is also required).
COPYRIGHT 1989 E.W. Williams Publications, Inc.
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Copyright 1989 Gale, Cengage Learning. All rights reserved.

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Publication:Quick Frozen Foods International
Date:Jul 1, 1989
Previous Article:Scholler sales up nearly 10% to DM 962-M getting on track for 1992 united Europe.
Next Article:German cold storage industry sputters following 10-year period of expansion.

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