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View Subscription Details: Letter ( 12/16/2010 ) - HTML Format

Electrical Energy is Cheap


In some areas of North America electrical energy can cost as low as 1 - 2 cents/KWh. Some companies in these areas believe that any investments in energy efficiency will have payback longer than 2 years.

This is true if you do capital investments. However, this is not true if you do optimization of the refrigeration plant operation. This optimization does not require significant investments and it has 10 - 20 times shorter payback than investment in energy saving equipment. However, I have heard from several companies that their operators have optimized operation of their refrigeration plants. Reviews of the operation of these plants have shown that only the initial steps of optimization were implemented. In industrial refrigeration every next step of energy saving process is harder and harder.

Assume that total potential energy savings for a refrigeration plant is 30%. To achieve the first 10% of these savings a company implemented initial steps of optimization and $2,000 was invested. To achieve a second 10% of energy savings, this company should invest $20,000 in the final optimization of refrigeration plant operation. Unfortunately, many companies do not see the difference between initial and final optimizations. This is understandable, because optimization of refrigeration plant operation is a relatively new approach in industrial refrigeration and there is no literature about this issue. A few consultants focused on the optimization, rely on the results of their own researches in this area of energy savings. However, results of these researches can be very different. Choose the right consultant for the final optimization of the refrigeration plant operation.



During winter operation, to maximize energy savings of the refrigeration plant condensing pressure should be kept as low as possible. Initially, a plant was operated at minimum condensing pressure of 120 psig. Operators reduced this pressure to 110 psig. They did not go below 110 psig because of concerns about hot gas defrosting. One consultant reviewed operation of this plant and he agreed with operators that 110 psig is minimum allowable condensing pressure for this refrigeration plant. However, another consultant has done in depth analysis of hot gas supply, hot gas condensation and ammonia condensate draining. He determined that properly balanced defrosting can be done at 90 psig of condensing pressure. This step has saved an additional 8% of the energy costs.


To achieve the third and final 10% of energy savings, the mentioned company should invest $200,000 in energy saving equipment. Very often investments in this equipment will have payback longer than 2 years. However, I believe that sooner rather than later the government of every country will demand certain energy savings from every company. It will be easier to achieve required savings if you initiate energy saving process as early as possible. I think that today initial and final optimizations of the refrigeration plant operation can be implemented. Regardless of energy cost, these optimizations will have payback less than 1 year. Hopefully in the future, generous government incentives will help you to invest in energy saving equipment and acceptable payback will be achieved. 


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