?A farce?: experts dismiss government claims a controversial and unproven technology will cut emissions by 15%

Experts have questioned how a controversial energy technology that doesn't currently exist in Australia could be earmarked as a major source of cuts to greenhouse gas emissions in the Morrison government's plan to reach net zero by 2050.

According to the government's modelling report of its "technology not taxes" plan, a technique known as BECCS - bioenergy with carbon capture and storage - would be removing about 15% from the nation's gross greenhouse gas emissions by 2050.

But the approach, which involves burning vegetation or waste for power and then capturing the carbon dioxide and injecting it underground, is not one of the priority technologies the government has picked to support.

The government's modelling report has already come under fire from experts for questionable assumptions and an approach which leaves the gas industry to grow while relying on international offsets.

Experts said it was not clear how the government had arrived at the BECCS figure, with some saying the technique itself was unproven, problematic and ecologically risky.

BECCS theoretically requires three key elements - the availability of biomass such as trees, vegetation or waste and land and water to grow it; a power plant to burn the biomass and capture the CO2; and then a geological formation underground close by where the CO2 could be injected.

There was no mention of BECCS in the government's latest progress report on its low emissions technology plans, published earlier this month.