Kiwi cleantech company CarbonScape hopes to win €500,000 (NZ$790,000) from a global enviro-business challenge that would help get it into commercial production for its first supply of substitute coal "green coke" in May.

Blenheim-based CarbonScape has patented a way to use microwave technology to turn wood and other biowaste into graphite and "green coke", which can replace coking coal to reduce carbon emissions. It is one of three finalists vying for an international Dutch Postcode Lottery Green Challenge grant co-sponsored by the Clinton Global Initiative.

The initiative was founded in 2005 by former United States president Bill Clinton to solve the world's pressing challenges by bringing together leading statespeople, scientists and business leaders.

It has made 2100 "commitments to action", pledging a total of US$69 billion.

After making the cut in several shortlists, the three green companies are headed to the challenge's final showdown for the €500,000, which will be held at the Clinton Global Initiative's annual meeting in New York on Sunday. The two runners-up will get €100,000 each.

CarbonScape founder and director Tim Langley said as far as he knew it was the first time a Kiwi company had entered the challenge.

"The main prize to us is not the cash, but the intros to who's who."

Investors and potential partners were interested in the company after its performance in the challenge, Langley said.

About 7.8 per cent of all greenhouse-gas emissions were from the steel industry, and using a more green replacement for coal could significantly lower emissions, he said.

The potential scale of carbon emission reduction meant the company had a good chance of winning the challenge, the prizemoney, and the industry credit, Langley said.

The company had a deal with a large New Zealand steel manufacturer to supply 9000 tonnes of "green coke" for the year from May. To meet the order the company's pilot plant at Riverlands, south of Blenheim, needed to be expanded to commercial production, he said.

The money and connections made through the challenge would help get the company over the line - he was confident it would be ready by May. CarbonScape director Nick Gerritsen represented the company in the Netherlands this week.

He said making the final three had already given the company massive exposure to potential customers and investors.

"These awards have a big following internationally and the dinner in New York is very much a top-drawer affair.

"This is a real breakthrough for CarbonScape," Gerritsen said.

The company was courting international investment fund managers since it started being shortlisted in the competition, he said.

- © Fairfax NZ News