Tesco adopts new approach to trigeneration
As part of its plans to halve its energy use by 2020 compared with 2006 Tesco has installed a CHP system that can use biofuel and an adsorption [not absorption] chiller at its supermarket at Colney Hatch to the north of London. This is said to be the first installation to combine cooling, heating and power using an adsorption chiller.
This trigeneration system can generate 800 kW of electricity, up to 100% of the store’s demand, and it simultaneously produces chilled water for air-conditioning and refrigeration systems.
The adsorption chiller uses recovered heat from generating electricity to drive the refrigeration cycle. Water is adsorbed onto a bed of silica gel and boiled off under low pressure to generate chilled water at temperatures as low as 4°C. The energy saving for refrigerators alone is 30% compared with traditional arrangements.
Weatherite has the sole manufacturing rights for this adsorption chiller in Europe from a Japanese manufacturer. Managing director John Whitehouse says, ‘It is a viable alternative to the absorption chiller, which is currently used in other CHP systems on the market. It is more reliable and does not contain lithium bromide or other refrigerants, which means no crystallisation, no corrosion, no chemical testing and no hazardous leaks.’
This technology was first introduced into the UK by consultancy Scott Wilson with air-conditioning specialist Weatherite, installation and refrigeration specialist Space Engineering and Cogenco.
This CCHP technology can use various fuels, including gas, vegetable oil and rapeseed oil. It can be modified to adapt to new fuel in the future.
Peter Sutcliffe, a director with Scott Wilson, says, ‘Tesco is the first UK retailer to incorporate tri-generation technology to significantly reduce its carbon footprint per store. The engines can be installed in new and existing developments and go a long way to helping meet carbon-saving targets.’
At Colney Hatch, CCHP technology is being used alongside solar thermal heating and solar photo-voltaic. Four solar-thermal panels generate hot water for the staff changing area and customer toilets. Photo-voltaic panels on the roof provide enough electricity to power half the checkouts.