Genesis Energy says it has successfully completed a biomass burn trial as it looks at alternative fuel options for its coal and gas-burning Huntly Power Station.

The objective of the week-long trial was to prove the technical viability of operating one of Huntly’s Rankine units solely on biomass.

Genesis said that was achieved; a Rankine ran only on biomass for several hours.

It followed work over the past year to identify the most suitable type of biomass to use, securing a supply of it from offshore, understanding the adjustments needed to operate the Rankine and putting in place robust health and safety guidelines.

Interim chief executive Tracey Hickman said the trial was important for Genesis and the country, given Huntly was built to provide vital back-up to New Zealand’s highly renewable electricity generation.

“We see Huntly’s back-up role continuing for some time and it’s important we explore more sustainable and cost-effective alternatives to coal, especially if we’re able to adapt existing plant that can be used to 2035 and extended to 2040,” she said.

“It makes sense for the country in terms of reducing emissions, security of supply and financially,” Hickman said.

“Eventually, new technology or an over-supply of new renewable generation might be able to provide security of supply, but that is some time away and not yet certain.”

Biomass is increasingly being used offshore as an alternative to coal.

Genesis Energy's interim CEO Tracey Hickman. Photo / Supplied

It can deliver a similar amount of energy and can be stored outside.

Genesis will analyse the findings from the trial over the coming months, including the critical issue of exploring the viability of a local and sustainable supply chain.

There is currently no local source of the type of pellets needed for Huntly and Genesis will talk with businesses in a similar position that might provide the scale to support a reliable local supply chain.

“We believe it’s worth some focus by government and business to see if a sustainable local supply chain can be developed. Compared to some other decarbonisation solutions, biomass conversion could be implemented much sooner to the benefit of the country,” Hickman said.

Findings are being shared with government officials and other large commercial businesses also working on decarbonisation.

The trial used black “torrefied” biomass sourced from Canada.

During torrefaction, wood residue is heated slowly without oxygen to between 200 to 300 degrees.

The process creates a solid uniform product with lower moisture and about 30 per cent more energy than raw biomass. Using torrefied biomass generally produces less than 10 per cent of the emissions of coal.

The fuel Genesis has used in the trial has an energy content similar to coal.

The difference in energy on a volume basis for our trial was, however, lower.

Genesis needed in the order of 25 per cent more biomass fuel than coal in order to get the same energy output.

The company, just over half owned by the Government, is not putting a timeline on when biomass could be used at Huntly.

“While we assess the trial findings from an engineering point of view we will also be working with Fonterra, which is in a similar position, to look at whether a local supply chain for the pellets required is feasible,” the company said.

Biomass plants built overseas have typically taken 18 months to construct, however, allowances also need to be made for securing agreements, consenting and commercial arrangements, Genesis said.

As it stands, Genesis said there is sufficient coal to provide back-up support for the country’s system until at least 2024 under normal market conditions.

“We are hopeful that between now and then we will know whether a local supply chain is feasible,” it said.