heat pumps

 

Heat Pumps for Process Heat

Heat pumps can take heat from the environment or from waste heat streams and supply it to industrial applications without the need to burn any fuel. In applications where the pumping energy input is in the form of electricity produced from renewable energy sources, heat pumps are a fully renewable energy technology. Where the electricity is generated from fossil fuels, only part of the energy output of heat pumps can be regarded as renewable. So, for example, if the electricity comes from fossil fuel generation with an efficiency of 40%, the coefficient of performance12 of the heat pump needs to be higher than 2.5 if the pump is to save primary energy and be considered as providing renewable heat. The amount of useful heat provided must be higher than the primary energy consumed.

Two other factors, the capital cost of the equipment and its performance, are also important in determining the competitiveness of heat pumps. Performance is expressed in terms of the number of units of energy the heat pump can move from the lower temperature of the source to the higher temperature needed, using one unit of electricity. In most normal operating conditions, the amount of electricity required is considerably less than the amount of heat provided, particularly in applications demanding relatively low temperature process heat. The main thermodynamically limiting factor in the use of heat pumps for high temperature process heat, however, is that their performance decreases the greater the difference in temperature between the input source and the output demanded. So heat pumps are more efficient in delivering low temperature process heat demands. And air heat pumps are more efficient in warmer climates. This factor has been taken into account in analysing the cost of the process heat in individual regions.

Supply cost curves have been calculated for 2007 and 2050 for the same temperature range categories as in the supply cost curve for solar thermal, using the cost per unit of useful energy based on the cost of electricity, an indicative capital cost of the heat pump and its performance coefficient. The performance coefficient of pumps decreases as the temperature lift increases. It is much lower for the 60 - 100C range than for temperature lifts less than 60C. Electricity costs are taken from the IEA Energy Prices and Taxes database, using the data for the final price of electricity for the industrial sector. For those regions not in the database, the data of a representative country have been used as a proxy, notwithstanding the very significant differences in electricity prices among different countries in the same region. For those countries for which historical data are missing, a 2007 figure has been calculated using the OECD price in 1996 as base and rescaling as a proportion of the OECD 2007 figure. The resulting cost curve for the food and tobacco sector.

Heat pumps can already provide a competitive alternative to fossil fuels for low temperature process heat in several regions. One of the driving factors, for example in China, is the availability of cheap electricity. But where this electricity is generated by low-efficiency or coalfired power plant, this can completely offset the potential CO2 emission reductions associated with the use of heat pumps.

 

The competition for low-temperature renewable process heat production between heat pumps and solar thermal will be heavily dependent on regional and local conditions.






The Innovator

Gurmit Singh, New Delhi

Dr. Gurmit Singh is a research scientist and an environmentalist, his profound enthusiasm and passion for renewable energy technologies has been for 28 years now. He holds both his Bachelors and Masters degrees from 'Rheinisch-Westfalische Technische Hochschule Aachen.' In Germany and spent 14 years in Germany working as a research Scientist and then 8 years in Florida, USA in Solar Research. He is winner of 'Lockheed Martin Innovation Award 2008' in renewable energy, also won the '2010 BuildArch Award'and recently won the 'i3 India Innovates Award 2011'. His professional career started with a technology assessment of the carbon abatement potential of specific industrial technologies in the EU, and the evaluation of national and international policies and measures in the areas of climate change, energy efficiency and renewable energy. Currently he is a Visiting Faculty for 'Renewable Energy' at Amity University, Noida

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