Solid Energy said it believed it was the first in the world to access energy from a single coal field using four different technologies: underground mining, opencast mining, coal seam gas and underground coal gasification.

While UCG has been established for more than 50

years, only three location world-wide are currently producing synthetic gas, also known as syngas, from UCG.

Solid Energy chief executive officer Don Elder said the pilot plant was designed to ensure all necessary data was yielded to create a commercial UCG plant design.

“The immediate focus of the pilot is to stabilise initial syngas output, before increasing production to planned levels,” Elder said.

While Solid Energy has access to around 2 billion tonnes of coal in the Huntly Coal field, a majority of the resource is too deep to be economic using conventional mining.

“UCG can potentially allow us to access most of this, which represents 10 times the energy of the Maui gas field,” Elder said.

“That amount of gas would help provide energy security on the doorstep of New Zealand's largest population centre, and could also be used to produce affordable, environmentally acceptable, high-value products.”

Solid Energy is considering future options for commercial UCG plants, in both New Zealand and overseas.