Parliament is this afternoon to hear whether fracking is a viable option for New Zealand's energy future.
Fracking opens up previously uneconomic oil shale for energy use and is seen by several of New Zealand's largest energy companies – both state and privately owned – as an big opportunity.
Also known as hydraulic fracturing, fracking extracts gas from shale rock by blasting it with water, sand and chemicals.
The practice has become increasingly popular in the United States in recent years and was touted earlier this month by the International Energy Agency as likely to make the US energy self-sufficient for the first time in nearly 50 years.
Several unused reserves of shale oil and gas resources in New Zealand would be opened up if fracking is allowed, with large reserves in Southland and Canturbury being explored by L&M Energy.
The company says the Southland reserves are potentially as big as any in the US.
Todd Energy is also using the technique in its fields in Taranaki and state-owned Solid Energy has trialled it in Waikato.
Fracking has been bitterly opposed by environmental groups, some of which have invested more than a decade's rhetoric over what they claim is the imminent demise of fossil fuels.
This afternoon Commissioner for the Environment Jan Wright will table an interim report on fracking in parliament.
It is expected to endorse the process but advocate stronger safeguards.
There are legitimate concerns about waste water from fracking contaminating other water sources, and also that it might cause higher methane emissions.
Many of these concerns can be dealt with by a resource consent process under existing Resource Management Act rules and it is not clear whether the law needs amending.
The lengthy IEA report earlier this month calculated any concerns can be managed and will add about 7% to the cost of the average fracking project.
Politically, the report will trigger political drama, with both left-wing parties – Labour and the Greens – competing for air time to oppose fracking.