Supermarket group Tesco, which pumps out some four million tonnes of carbon a year, today opened its first zero carbon store as part of its bid to be a carbon ­neutral company by 2050.

The shop, in Ramsey, Cambridgeshire, is timber-framed rather than steel, and uses skylights and sun pipes to cut lighting costs. It also has a combined heat and power plant powered by renewable bio-fuels, exporting extra electricity back to the national grid. In addition the refrigerators – one of the biggest blackspots for food retailers trumpeting their green credentials – have doors to save energy and harmful HFC refrigerant gases have been replaced.

Tesco chief executive Sir Terry Leahy said: "It shows that you can dramatically alter how much carbon you use and life can go on".

The new store, he said, "cost 30% more to build, but it uses 50% less energy, and with oil at $70 a barrel it is a business case in itself".

To coincide with the Ramsey opening, the supermarket chain said it intended to spend more than £100m with green technology companies, although Leahy was unsure of the level of supermarket's current spend on this.

Tesco has been at the forefront of the grocers' race to be green. The UK's biggest supermarket has provided £25m of funding for the University of Manchester to set up a sustainable consumption institute, and has a 10-point community plan, with pledges to increase local sourcing and to consult local communities in an attempt to be viewed as a good neighbour.

Separately, new market research data released today showed that Tesco's bid to lure back shoppers with double clubcard points and a surprise pre-Christmas mail-out of money-off vouchers has paid dividends and put pressure on Asda.

The Kantar Worldpanel data, formerly known as TNS, shows Tesco's market share climbed from 30.4% to 30.5% in the 12 weeks to 24 January compared to the same period a year ago. Asda meanwhile, has slipped from 17% to 16.9% over the same period. Last weekend Asda broke with tradition and offered discount vouchers in a bid to entice lost shoppers.

Morrisons recorded a more than 10% sales improvement, resulting in a market share of 12.5%, up from 11.8% a year ago. Waitrose is the biggest winner, with growth of 17.5%, taking the upmarket grocer to a market share of 4.1%, compared to 3.5% a year ago.

At the other end of the scale the discounters – led by Aldi and Lidl – are now losing market share after a boom at the start of the recession.