A project to reduce the carbon dioxide emissions from oil refineries by using the gas as "fertiliser" in commercial greenhouses has been so successful it is being extended. The project, which adds new meaning to the term "greenhouse gas", is the first in the world. It distributes CO2 from Shells Pernis refinery outside Rotterdam to 400 greenhouses, saving a large amount of natural gas each year, which is equivalent to 170,000 tonnes of CO2.

The companies behind the venture, Hoek Loos and Voker Wessels are now expanding the operation to supply a further 100 greenhouses. Before the project was launched last year the greenhouses, which grow vegetables and flowers, used to generate CO2 by burning natural gas. By tripling the concentration of the gas inside the greenhouse they allow the plants to photosynthesise more quickly. This boosts productivity by up to 25% and cuts growing time, but the CO2 ended up in the atmosphere.

"We came to the conclusion that they used a lot of natural gas to provide CO2. Of course, thats not a very good situation for the environment," said Jacob Limbeek, who with the late Hans Tiemeijer came up with the idea for the scheme called Organic CO2 for Assimilation of Plants.

According to the journal Nature the €100m (£65m) scheme supplies greenhouses with CO2 at between €40 and €70 a tonne - just over half the price of generating the CO2. Once the 100 greenhouses are plumbed in by the end of the year, the distribution network will be delivering up to 130 tonnes an hour.

"Of course, there is a reduction in the use of natural gas at the greenhouse," Mr Limbeek said. "But under European emissions trading rules it is Shell who benefits because CO2 that would have been emitted by them now goes somewhere else." Shell will share some of the profit from selling carbon credits with the greenhouses after 2008, but Mr Limbeek was not prepared to reveal details of the deal.
(James Randerson, The Guardian, 12/08/2006)
http://www.guardian.co.uk/science/story/0,,1843094,00.html?gusrc=rss&feed=18