Photo: RNZ / Robin Martin
Todd Energy says it has identified the root cause of safety problems which has shut its Kapuni gas plant for nearly a month.
The plant is the country's only domestic producer of food-grade CO2 since the Marsden Point closure last year.
Todd Energy said the problem had been identified as a safety valve releasing ammonia.
It expected liquid CO2 production to restart early next month but the company does not expect to reach full capacity until later this year, and will have to do another three-week shutdown in March.
The closure has sent gas prices skyrocketing close to 600 percent, under some distributors.
BOC has had to ration the gas, and that has left businesses without the products they need - like Garage Project, one of New Zealand's largest breweries, that ran out of carbon dioxide at one site - leaving more than 60,000 litres of unfinished beer.
In a statement this afternoon, Todd Energy chief executive Mark Macfarlane said the plant would start off at 30 percent capacity on reopening.
A staged production ramp-up is planned, which will see the plant built back to full capacity over the next few months.
So far, the plant is expected to be at 30 percent capacity by the start of February, then there is a three-week statutory shutdown needed from the end of February to mid-March.
Todd Energy then expects to bring production back up to 50 percent by the end of April, and full production by the end of this year.
Macfarlane said determining the cause of the issue, and therefore engineering solutions to rectify it, was not a straightforward process.
"Just before Christmas, our normal operating surveillance detected a risk relating to the release of ammonia from a pressure safety valve at our liquid CO2 plant. At the time all plant safety and evacuation systems were activated with no harm caused to people or the environment," Macfarlane said.
"To enable the CO2 plant to resume operation, we needed to understand the root cause of the problem and be satisfied that the right engineering solution can be installed to allow the plant to operate safely, without risk to people or the environment," he said.
"The age of the plant and lack of instrumentation means that it has taken some time to identify the issue, but now that we understand the cause, we can begin implementing solutions to bring the plant back online."