There have been hundreds of green technology start-ups funded by venture capitalists but a new fund with an impressive pedigree is looking to scale up clean energy technologies.

Private equity company Silver Lake today said that it has joined with George Soros' Soros Fund Management to create Lake Kraftwerk, a fund designed for late-stage investments in energy technology companies.

Former Foundation Capital venture capitalist Adam Grosser will head the fund. Cathy Zoi, which recently resigned as acting under secretary of Energy at the Department of Energy and assistant secretary for energy efficiency and renewable energy, is part of the investment team.

Silver Lake Kraftwerk will focus on companies involved in energy efficiency, waste and emissions reduction, renewable energy, and better use of natural resources.

The point is to provide "growth capital" for companies that already have developed technology and a proven business model, Grosser said in an interview today. It will stay away from traditional project finance, the type of investments used to finance building new factories.

Specific areas that Silver Lake Kraftwerk expects to invest in are in the grid, such as sensors or software for more efficient operation, Grosser said. Efficient LED lighting, low-carbon content building materials, and alternative solar technologies are also of interest as well as remediation methods for the coal and oil industries, he said.

There have been billions of dollars of venture capital invested in the clean tech category in the past decade but there have only been a handful of companies which have successfully gone public and remain profitable, in part because energy businesses are typically require lots of capital to get to large scale.

Investors often say there's a funding gap between the money that's needed to develop products and get first customers and capital to expand. Grosser said that Silver Lake Kratwerk aims to be the "last money" in before a company is self sustaining.