Wal-Mart, the largest US retailer, on Wednesday publicly set itself the goal of selling 100 million low-energy light bulbs in the coming year, in a potentially industry-changing move that is part of a broader effort to improve its environmental reputation.

If successful, the retailer would double the current US market for the bulbs, which use about 75 per cent less energy than traditional incandescent bulbs, and can last more than six times longer.

Currently low energy bulbs make up only about 5 per cent of the total US bulb market, compared to around 11 per cent in the United Kingdom.

A Wal-Mart spokesman said the retailer would double shelf space devoted to the bulbs. It will also develop displays aimed at educating customers about the potential long term savings from buying the bulbs, which have in the past cost far more than the conventional equivalents.

Wal-Mart estimates that selling 100m bulbs could save its customers $3bn in energy costs, and produce a significant reduction in greenhouse as emissions.

Lee Scott, Wal-Mart's chief executive, has been an advocate of the bulb programme, which is part of an overall push to focus the retailer on environmental issues that he launched in late 2005.

Wal-Mart has also worked closely with General Electric, which currently dominates the market for the compact fluorescent bulbs.

Over the past year, the price of the bulbs at Wal-Mart's discount stores has fallen 20 per cent to just over $2.50.
Its Sams Club membership warehouses are currently selling eight 13 watt low-energy bulbs for a unit price of $1.36, only roughly twice the cost of the equivalent conventional 60 watt bulb.

Wal-Mart said earlier this month it will install LED low energy lighting in refrigerators at 500 of its stores, to replace fluorescent lighting.

The company has said it will spend up to $500m a year to achieve a 30 per cent reduction in energy use and a 20 per cent reduction of greenhouse gas emissions at its stores.