Positioned at the Australian pavilion among exhibits from Santos, the country's second-largest oil and gas producer, and Fortescue, the fourth-largest iron ore producer in the world, Ms Hamblin Wang estimates she gave her clean energy pitch for Mineral Carbonation International around 6000 times.

Interest spiked after the 33 year-old Canberran beat 2700 worldwide competitors in a best business pitch competition on day three of the summit.

"So, that was a crazy day for me," she said.

After a breakfast with Prime Minister Scott Morrison, Minister for Emissions Reduction Angus Taylor and chief executives of many of the biggest companies in Australia, where "we were the only startup in clean tech represented", Ms Hamblin Wang gave her winning pitch.

"There was then a reception for the pitch battle where we met all the investors who wanted to start initial discussions that day," she said.

Following another meeting with Mr Taylor and Australia's high commissioner to the United Kingdom George Brandis, together with about 150 influential Australians, Ms Hamblin Wang gave an online keynote address into Sydney at 11.30pm.

"And because we won the pitch battle it just caused this tidal wave of interest," she said.

While the worldwide recognition might be recent, MCI has been around since 2013. It was founded by Canberra entrepreneurs John Beever and Ms Hamblin Wang's stepbrother Marcus Dawe.

With a pilot plant at the Newcastle Institute for Energy and Resources, the company operates a low-energy chemical engineering process that transforms CO2 emissions from industrial sources into solid materials.

The technology takes CO2 from industrial operations and mixes it with feedstock such as mining tailings. By speeding up the Earth's natural carbonation process, products such as calcium and magnesium carbonates and silicas are created.

The products can be turned into building materials, including glass, concrete and fibreglass.

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Its mission is to remove 1 billion tonnes of CO2 by 2040, by focusing on the hard-to-abate sectors.

"We've been really focusing on helping to decarbonise those industries that don't have clear pathways to do so otherwise," Ms Hamblin Wang said.

"So the steel industry. A lot of people don't know that you need metallurgical coal in order to get to the 1600 degrees to create steel, there's no alternative.

"They're developing hydrogen pathways but that's still decades away. And then also cement; when cement is actually created, it releases CO2, it's part of the chemical process.

"So that's those two fundamental parts of our infrastructure future that don't have pathways."

Mr Dawe said new manufacturing processes were at least 10 years away, so MCI was focusing on the transition.

"Every tonne of CO2 going into our atmosphere right now is causing climate change, so we've got to stop it," he said.

"You don't just get to 2050 and suddenly say, 'Right, now we've turned it off'. It's about, 'How do you get there'?"

With the business pitch win leading to lines of people queuing to find out about the company at COP26, including Andrew 'Twiggy' Forrest who had to be rushed along, Ms Hamblin Wang said returning to Canberra this week felt like they were on the cusp of something huge.

"We've been absolutely catapulted onto the world stage," she said.

"We're experiencing a moment of exponential growth."

In two weeks the company's Linkedin has experienced a 17,000 per cent increase. Each post receives around 10,000 views, Mr Dawe said.

Having received a $14.6 million grant recently to build a plant in Newcastle, the company will build a modular facility which can be picked up and taken to steel, cement or nickel mines.

"We're looking at three key places next - Gladstone, Illawarra, and Kalgoorlie - but that's not exhaustive," she said.

"We're scoping our next project right now and it's likely to be in one of five places - Japan, the EU, the US, Canada or maybe Singapore."