The burning of fossil fuels such as coal to create electricity typically wastes about 70 percent of potential total energy in the form of heat that is released into the air, rivers or lakes. Making up for that inefficiency may require burning more fossil fuels, creating even more greenhouse gas emissions in the process. Milwaukee-based Johnson Controls offers some insights into heat recovery and waste heat use.
Industrial facilities as well as cities, campuses and hospitals are capturing that previously wasted heat to meet power process operations, hot water needs, control humidity or warm or cool buildings, notes the company. By doing so, they are increasing energy efficiency, alleviating the need for additional boilers and helping to clean the environment.
Heat recovery is not a new concept, but government mandates, higher energy costs and improved technology are making it more attractive to large energy users.
Waste heat from power generation, often in the form of hot water, can be captured in a continual process and used directly if there is a need for lower temperature hot water. In most cases, it is boosted in temperature by heat pumps that operate much more efficiently than boilers. This recycled energy is then used for other useful purposes or to heat buildings. Depending upon the type of facility, a large percentage of the heat normally discarded to the atmosphere can be captured and recycled, improving the overall energy efficiency from 30 percent to more than 85 percent.
Heat recovery plays an important role in China’s 12th Five-Year Plan on Energy Conservation and Emission Reduction. The Chinese government has made a major commitment to reduce pollution from the burning of fossil fuels, especially coal. Waste heat is viewed as a major energy source for urban heating. The technology was put to the test in a municipal heating facility in Northeast China. There it successfully saved more than $1.2 million annually in energy costs while alleviating the need to burn 9,200 tons of coal during the most recent heating season. This is equivalent to removing 4,000 passenger vehicles from the road for a year.
Heat recovery technology is now spreading throughout other countries, Johnson Controls notes. In the United States, tax credits are being offered for waste-heat recovery projects and systems. And the federal Environmental Protection Agency is working with energy users, state and local governments and other clean energy stakeholders in a voluntary program to facilitate the development of new heat-recovery projects. These new projects are helping industrial facilities to lower costs. College campuses and medical centers are using heat-recovery technology to become more energy resilient through the creation of self-sustaining microgrids. And cities are finding new ways to create energy islands that keep energy costs lower.
Learn more about heat recovery technologies from Johnson Controls Inc. by visiting www.johnsoncontrols.com.