LAGUNA NIGUEL, Calif.--An "energy resource management" software company co-founded by Tom Siebel called C3 is growing rapidly in a market that's larger than the one his namesake CRM software company entered 16 years ago.

Siebel, who co-founded customer relationship management software company Siebel Systems and was one of the first employees at Oracle, today provided some details on C3, which boasts some high-profile board members, including former Secretary of State Condeleeza Rice. He was interviewed here at the Fortune Brainstorm Green green business conference.

C3, which was founded a few years ago, is working with a small number of very large corporate customers, including Dow Chemical and utilities PG&E and Constellation Energy, which are using C3's software to improve the energy efficiency of their businesses.

Software as a service lets corporations monitor energy usage in real-time and then manage projects for reducing energy spending and carbon emissions. It can gather data from thousand of points, generate reports, and let businesses take advantage of government incentives around efficiency or pollution reduction, he said. C3 is also working with banks to offer corporate customers a way to finance the purchase cost of the software, said Siebel who is chairman of C3.

Customers have been able to reduce energy spending on the order of 20 percent through different projects, such as on-site combined heat and power or solar photovoltaics, he said.

The area of energy and carbon management software catering to businesses has become crowded with several companies offering applications. Siebel said that he's bullish on the sector because there is so much money is spent on energy and efficiency projects typically have a relatively fast payback.

"At early stages this is growing faster rate than Siebel Systems did. What Siebel was about was applying state of the art in information and communications technology to the problem of sales, marketing and customer service. C3 is basically the same game. It's just a much bigger problem," he said.

He projects that the company will spend $150 million over 10 years building out the software. "This looks more like the vision of an SAP than a start-up," he said.