Prototype system converts exhaust heat to hot water

An innovative system that uses waste vehicle exhaust heat to provide hot water was on show at NextGen, part of the “Power of 3” event at Stoneleigh Park, Warwickshire, last week.

The prototype Landrover Freelander features a high density thermal store unit that sits between the catalytic convertor and the silencer box to capture heat from the exhaust pipe while the engine is running.

When the vehicle is parked, separate water hoses are connected to the system. These pipes pass through a conductive heat transfer block, which uses heat from the thermal store to heat water circulating through the pipes, to around 60C. Hot water can then be piped into a separate tank for use in household radiators, or hot tap water.

The Thermal Energy Storage & Saving Automobile (TESSA) project director Patrick Byrd said the prototype system used half of all waste exhaust heat produced, but this could be increased to 60% or 70% with further refining. “Within five minutes of running, a typical exhaust pipe will be up to about 500C and one 40-mile trip could heat enough hot water to supply a domestic house for a day,” he said.

While the prototype weighed a hefty 80kg, he was confident this could be reduced to nearer 30kg and was keen to work with investors and car manufacturers to develop the system. Further work was also required to meet stringent health and safety regulations.

The most immediate commercial potential was likely to be on delivery vehicles, possibly within two years, but there could also be scope to use it on farm vehicles, Mr Byrd said.

But EU regulations were a potential stumbling block to future development. The system does not reduce CO2 emissions from the vehicle itself, but it could result in lower fuel consumption in the home. However, vehicle manufacturers cannot claim the CO2 savings against the vehicle, and Mr Byrd said this policy would need to change if car manufacturers were to put more resource into developing the system. “We estimate this system has the potential to save 8% of the nation’s CO2,” he added.