Rotokawa Geothermal Power Station. Photo: Mercury
With geothermal energy exploration underway and torrefied wood pellets already in use, New Zealand could look to turn away from fossil fuels
It's already used to rear fish, grow flowers and to lure tourists, but a site near Taupō is the world-leading next step in geothermal energy that could truly deal to our reliance on gas.
Two hours' drive away in Kawerau, work is underway on another cutting edge energy project that could deal to our reliance on coal.
Today The Detail looks at both projects in response to feedback on our podcast about the government's planned $1 billion Liquified Natural Gas plant, when listeners urged us to look at alternative, fossil-free energy under development.
Deep Heat is the name given to the supercritical geothermal energy project where an international group of scientists is working on a plan to drill between four and six kilometres into the earth's crust to reach superhot fluids.
It's a first for New Zealand, it's got $60 million in public money through the Regional Investment Fund, and the first hole at Rotokawa Geothermal Reservoir is expected to be drilled by late next year.
It won't replace the $1b Liquified Natural Gas plant planned to open in Taranaki as early as winter next year, and it could be decades away from being a commercial prospect. But Tim Groser, chair of the Supercritical Geothermal Project board, says New Zealand has the best chance "to try to be the first country to actually crack the engineering problem".
"It will actually be as close to what I'd call a silver bullet in terms of what is really required on climate change," says Groser, a former climate change minister.
He describes supercritical geothermal energy as the heat that can be extracted from fluids when they exceed 370 degrees Celcius and can be brought to the surface and still maintain the pressure at 220 bars.
"What this does is convert the form of the fluids into more like a gas which has greater density and produces approximately three to four times as much energy as conventional lower heat, lower pressure geothermal steam does. It's a massive gain of bang for the buck," says Groser.
He says his expert advisers tell him New Zealand is probably as big as any resource in the world in terms of supercritical geothermal energy. It lies at very shallow depths compared with most other geothermal countries and the rock is "highly permeable" enabling the geothermal fluids to flow more easily through the rocks.
A graphic from MBIE and Earth Sciences NZ shows the difference in depth between traditional geothermal and supercritical geothermal. Photo: Image: Supplied
In Iceland, a geothermal energy leader, work on a third supercritical energy extraction project is underway, after the previous two efforts failed. Groser says New Zealand is working closely with Iceland on the engineering challenges. The work is potentially dangerous but the biggest risk is the failure to be able to bring supercritical fluids to the surface because of the lack of technology to deal with the extreme aspects of the fluid, such as its highly corrosive nature.
"Will New Zealand ever be able to access this renewable energy? Absolutely dead certain. The question is when. Is it in our generation or will we have to wait another generation or maybe a half generation for the technologies that are being developed now," Groser says.
Something that already is on track as a commercially viable renewable energy is just a couple of hours' drive away in Kawerau, where Australian company Foresta is building a $300m factory to make torrefied wood pellets made from forestry waste.
The small black pellets are already in use, and being lined up to replace coal at Genesis Energy's Huntly Power station, says Bioenergy Association head Brian Cox.
A number of high power users like Christchurch hospital, Canterbury University and food processors already have biomass-fuelled boilers but the Foresta plant would be the first in the country to commercially produce the torrefied pellets, he says.
"Additional to the domestic market is the export market, because in Asia - South Korea, Japan - there are power stations of a similar design to Huntly Power Station and so they would be potential customers.
"We get a number of calls from South East Asia from people who are looking to purchase wood fuel and the one they would really like would be the black pellets."
As a biofuel they formed part of a plan called the Integrated Bioenergy Programme that the association submitted as an alternative to the proposed LNG plant, says Cox.
It proposed ways to free up constrained and expensive supplies of gas and electricity by speeding up biomass use.
"We haven't had any response at all from the government because they're focussing on the LNG option," he says. "We're saying, look, why can't we repurpose the infrastructure we already have by smart thinking of converting from using that existing boiler on particular fuel.
"Some of it would be black pellets, some of it would be white pellets, we can use the cheaper chip."
Cox says there's enough forestry waste to meet higher demand for biomass. A small amount of carbon emissions comes from transporting and harvesting the wood but the fuel itself is carbon neutral.
"So, we need to look as a country at the holistic aspect. It is not just a forest contractor or a grower that needs to be dealt with, it's all of us.
"It's a fuel which is under our control."
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