Turning waste heat into energy

Once thought of as expensive and inefficient, in recent years heat pumps have come in from the cold and have taken their place as a viable source of green energy.  So much so that within the Government’s Green deal, Ground and Water source heat pumps qualify for a £1,250 grant; ahead of biomass boilers at £950, air source heat pumps at £850 and solar thermal hot water at £300.

But whilst heat pumps may simply be an effective heating option for our homes, at the other end of the scale taking steps to reuse waste heat can transform some businesses.  This was certainly the case for Shree Cement Limited of Rajasthan.  Making cement is an extremely heat intensive business requiring temperatures of 1400-1450°C.  Normally around 55% of the heat generated is used in the process with the rest being vented as waste gas.

Shree Cement Ltd took the decision to install a waste heat recovery system which would not only make use of the excess heat from the main process but also capture the low temperature heat from the air quenching cooler.  With the plant installed in a record time, Shree Cement Ltd is looking for a payback time of between seven and eight years.  Along the way the waste heat recovery system has completely eliminated the need to purchase power from the grid.

Other benefits include a reduction in Co2 emissions of approximately 1,312 tons per day, a reduction in SOx emissions of 30 tons per day and a reduction in water usage of 1,250kl per day.  Shree Cement Ltd say that their waste heat recovery system has not only helped the business financially it has also added to its sustainable development with natural resource conservation and a reduction in emissions.  The company also believe that in the long term it will benefit from an improved brand image and that the system has given it a competitive advantage.

So successful has the project been that the World Economic Forum nominated Shree Cement Ltd as a sustainability champion and in its report the Forum said that “The company has become the global benchmark: leading cement companies from around the world visit Shree to learn from its innovations.”  We were happy to add our own accolade with a Green Apple Award.