Supermarket Waitrose has announced it is to trial rape seed oil as a green means of powering its delivery vans.

The six-month trial will see the company modify five of its lorries to run on rape seed oil with a view to rolling the technology out across its fleet of 300 vehicles if it proves successful.

The company said that despite the engine and fuel tank modifications it would have to make it had opted to trial rape seed oil as opposed to more conventional biodiesels because it boasts a cleaner production process and can be sourced from UK and German farms as opposed to tropical plantations that may have contributed to deforestation.

According to Waitrose, rape seed oil does not have to undergo a chemical process to change its molecular structure before it can be used to power vehicles and as a result it has a carbon footprint 20 per cent lower than the production process for biodiesels.

"As a responsible retailer we aim to look at alternative fuels that are more sustainable across the whole cultivation and manufacturing process, as well as on the road," said Waitrose supply chain director Mark Williamson. "The future potential for rape seed oil as a fuel is certainly worth exploring - and we will be doing just that during this six-month trial."

The trials are currently using fuel from Germany and the UK, but Waitrose said that were it to extend the trial it would look to cut the fuel's carbon footprint further by identifying UK sources for all the fuel, potentially including its own farm at Leckford in Hampshire.

However, despite the care Waitrose has taken to ensure the trial avoids the concerns over deforestation and the negative environmental impacts associated with other forms of biofuel, the supermarket is still likely to face criticism from some environmentalists who have been calling for a full moratorium on all biofuels until second-generation fuels relying on waste crops or algae are developed.

Critics of biofuels - such as the authors of a recent Oxfam report into the humanitarian impact of increased biofuels - maintain that regardless of the type of biofuel used financial subsidies and increased demand for fuel crops has led to agricultural land being switched from growing food to growing fuel crops, directly contributing to food shortages and soaring prices.

However, a spokeswoman for Waitrose insisted the company was doing everything possible to ensure the trial was genuinely sustainable. "We are acutely aware of the need for rapeseed oil to be sourced sustainably, if we were to use it on a broader scale," she said. "We believe there is the potential for this because rapeseed can be grown as a 'break crop' between conventional crop cycles - so could complement conventional agriculture… We don't have all the answers at this stage, but…we will be fully assessing its environmental footprint and its performance during this trial."