GREEN RANKING FOR 2009
Ranking: 8
Worth: £11.5bn
Green investment: Natural fuels

Microsoft co-founder Paul Allen’s Vulcan Capital investment arm sank $250,000 into Seattle’s Imperium Renewables, which plans to supply 40% of the growing American market for diesel fuel made from vegetable oil. Last August Vulcan was part of a consortium investing £20m in a Californian company called Alta Rock Energy, which develops enhanced geothermal systems. This improves on the century-old technology of tapping geothermal energy from geysers, hot springs or volcanoes to generate electricity. Allen’s property investment company is constructing 100m sq ft of housing made from environmentally sensitive materials in Seattle. Allen still has a substantial stake in Microsoft, though this represents only 20% of his wealth today. Forbes valued Allen at £11.5 billion in its 2008 list of the 400 richest Americans.