SEATTLE - A report ranks Washington fourth in the nation in venture capital going to clean technology. Many startups are headed by former software executives.

They include V2 Green, a Seattle company that makes technology for plug-in vehicles; Bionavita, a Snoqualmie company that makes biofuel out of algae; and Propel Biofuels, a Seattle company that operates biodiesel stations around Puget Sound.

Others include Imperium Renewables, which is building a biodiesel facility at Hoquiam; General Biodiesel of Seattle, which recycles vegetable oil; and EnerG2, which develops nanomaterials for more efficient energy storage.

A report by the National Venture Capital Association says the top states in clean-tech venture investments are California, Massachusetts, Texas and then Washington.