Expert View: Don't dump your waste in the lake, npower – recycle it

The word "sustainable" crops up a lot in press releases, marketing literature and company reports. Nevertheless, nobody quite knows what it means.

In its latest annual report on corporate responsibility, the energy supplier npower uses the word 38 times. And while we may not be sure what sustainability is, we can certainly recognise when npower's actions don't match its words.

Last week the company began preparations to drain a lake near its power station in Didcot, Oxfordshire. This lake is a much-loved local beauty spot. Despite its closeness to myriad human activities, the area around the water is rich in rare wildlife. Two weeks ago nature lovers saw a peregrine falcon wheel high above the lake edge as it searched for prey.

Npower needs a lake to dump some of the half million tons of ash produced every year by its coal-fired station. Few would describe landfill as "sustainable" but the group fiercely defends its actions. If we want cheap electricity, it says, the generating firms need to continue to operate their coal-fired stations 24 hours a day. And when coal is burnt, it produces ash. There is very little they can do about this.

But the story does not end there. Power station ash is a very useful product when actively recycled. In particular, it can be incorporated in many construction materials, such as bricks and concrete. Didcot's ash needs to be processed to meet the quality requirements of some of these applications, but the cost of this low. The vast bulk of the ash could be productively reused.

Tens of thousands of homes will be built in the area round the station in the next decade. If npower was really trying to behave sustainably, Didcot ash should be helping to build the walls and floors of these homes. The benefits of using waste in this way are far greater than simply avoiding the destruction of local beauty spots. For example, ash incorporated in construction materials replaces cement, which generates huge amounts of carbon dioxide in its production process. Simple calculations suggest recycling a ton of ash would reduce emissions by a similar amount. Full recycling of Didcot's waste might save around half a million tons of CO2 each year.

Other power station owners have begun to accept that burning coal and landfilling the resulting ash are not compatible with a responsible stance on climate change. E.ON managed to recycle 93 per cent of its ash last year. Scottish Power's ash marketing subsidiary has won awards for its innovative construction products made from power station waste.

Most importantly, Scottish and Southern is investing in a new technology, commercialised by Bristol-based RockTron, which splits the ash into valuable by-products as well as construction materials. These include tiny glassy spheres that can be used for heat insulation in the most demanding conditions, such as the nose cone of the Space Shuttle. Separating the ash into different fractions substantially increases its value, so Scottish and Southern will almost certainly make money out of the RockTron investment.

Ignoring the good examples set by its main competitors, npower has pressed on with its plans for dumping Didcot's ash.

Building a truly sustainable business – however one defines this – is always going to involve difficulties, and possibly a significant increase in short-term costs. But we need the world's big corporations to take the lead because the scale of their operations is so vast. Npower's coal-fired power stations are some of the biggest CO2 producers in the country. Didcot alone is responsible for more than 1 per cent of the UK's carbon emissions. And the volume of ash produced by the station each year is 50 per cent greater than the amount of domestic waste produced by the whole of Oxfordshire.

Householders are entitled to ask why they should bother to recycle their own waste, or cut their emissions, when Oxfordshire's largest polluter continues to avoid its obligations.

Chris Goodall publishes 'Carbon Commentary', a bi-weekly newsletter on climate change issues and business chris@carboncommentary.com