Residual - or "waste" - heat and energy recuperation: a growing trend

August 20, 2010

Existing power plants sometimes rely on technologies that are a bit dated by today’s standards, yet re-designing the whole power generation systems from scratch is not an option. A transition period is necessary before renewables and more efficient plants come of age, and re-using residual heat is one of the ways to achieve this transition.

Multiple applications A closed loop model considers that there should be no such thing as a useless by-product, and this founding principle amounts to simple common sense. It’s therefore not surprising to see major businesses putting it into practice, whether they openly subscribe to the philosophy or not. Northern Europe has been a testing ground, with credible examples first appearing some 25 years ago, and today waste heat recuperation is often used as a complement for district heating or commercial applications. From horticulture to municipal heating, a few examples: Germany • 6 commercial greenhouses have been established at the Niederaubetaem power station in Cologne (Germany) since 1987, and their heating is provided by the water from the cooling tower of the coal-fired plant. • This energy was previously wasted and now heats a greenhouse area of approximately 53,000 m2. • During the winter of 1991, the system was able to keep an indoor temperature of up to 22 °C, even with an outside temperature of -14 °C. The Netherlands • Almere, one of Europe’s youngest municipalities, will soon see the opening of its “Sun Island”, made up of 7,000 square metres of solar collectors. • This technology will provide 10% of the city’s heating needs • Promoters of the project have taken a global approach and decided to use residual heat from the existing Almere power plant to optimise its results. • These two combined initiatives will result, for every home that uses district heating, in a CO2 reduction of 50%.

Canada (L'Oréal) * A study by the company's engineering team highlighted the fact that the effluents, the boilers and the compressors were generating a great quantity of re-usable residual energy. * This heat is now re-used to preheat the plant’s washing waters. * Another system was installed to recover the heat generated by the compressors and this heat is now used to heat the warehouses. * The recovery of the effluents’ heat has reduced the boilers operation by 15% and proportionally the same for greenhouse gas. CSR Europe See also Power from residual heat: International Society for Horticultural Science: