Venture capitalists expect investment in clean technology to significantly increase next year and are not worried about a potential investment bubble in the clean, or “green,” technology sector, according to a survey by KPMG LLP.

According to research firm Cleantech Group, North America and European investments in clean technology, a large category that includes biofuel for transportation, renewable-energy generation, water and materials, rose to $5.2 billion, up from $1.8 billion in 2004.