How NZ could become a world leader in decarbonisation using forestry and geothermal technology

ByThomas L. Elston

May 20, 2022 , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,


Energy is the double-edged sword at the root of the weather disaster. Inexpensive power has improved life and underpinned huge financial growth. But simply because most of it comes from burning hydrocarbon fuels, we’re now left with a legacy of significant atmospheric carbon dioxide (CO2) and an emissions-intensive overall economy.

But what if we could flip the electrical power-emissions connection on its head? We would will need a technology that both generates electric power and removes CO2 from the atmosphere.

The superior information is this technological innovation previously exists. What is additional, New Zealand is flawlessly positioned to do this “decarbonisation” less expensive than anyplace else on the planet.

And the timing couldn’t be superior, with the government’s very first Emissions Reduction Program (unveiled yesterday) contacting for daring jobs and innovative alternatives.

We investigation how to burn forestry waste for electrical power although simultaneously capturing the emissions and trapping them in geothermal fields. Considering that forests take away CO2 from the atmosphere as they expand, this system is emissions damaging.

This also suggests a carbon “tax” can be turned into a profits. With New Zealand’s CO2 price tag at an all-time high of NZ$80 per tonne, and abroad businesses saying billion-dollar money to invest in offsets, now is time for cross-field collaboration to make New Zealand a environment chief in decarbonisation.

Wairakei geothermal electrical power station with its present pipelines, wells and steam turbines.

Bioenergy with carbon seize and storage

Synthetic carbon sinks are engineered devices that completely get rid of CO2 from the environment.

Bioenergy with carbon seize and storage (BECCS) achieves this by trapping the CO2 from burned natural and organic make a difference – trees, biowaste – deep underground. An added bonus is that the energy released during combustion can be made use of as a substitute for hydrocarbon-primarily based vitality.

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The Intergovernmental Panel on Climate Modify (IPCC) has explained climate mitigation pathways need to contain significant amounts of BECCS to restrict world-wide warming to 1.5℃. Nevertheless, the technological innovation is however new, with only a several plants about the earth presently working at scale.

Value is a important barrier. New tasks want pricey pipelines to go the CO2, and deep injection wells to retail store it underground. Mainly because CO2 is extra buoyant than h2o, there are also problems that any gasoline stored underground may possibly leak out around time.

This is where geothermal fields can help.

Geothermal methods for BECCS

Geothermal is a dependable resource of electricity in New Zealand, supplying practically 20% of our electric power. We use deep wells to faucet into underground reservoirs of sizzling water, which then passes via a community of pipes to a steam turbine that generates electrical power.

Later on, the drinking water is pumped back again underground, which prevents the reservoir from “drying out”. New Zealand providers are planet leaders at running geothermal sources, and some are even experimenting with reinjecting the small amounts of CO2 that arrive up with the geothermal drinking water.

A geothermal BECCS procedure demonstrating how wooden and h2o can be transformed into electrical energy and destructive CO2 emissions. Besides for (3), all the infrastructure now exists.

Herein lies the chance. Geothermal systems by now have the infrastructure wanted for a profitable BECCS challenge: pipelines, injection wells and turbines. We just have to have to determine out how to marry these two renewable technologies.

We propose that by burning forestry squander we can supercharge the geothermal h2o to greater temperatures, producing even a lot more renewable electrical power. Then, CO2 from the biomass combustion can be dissolved into the geothermal h2o – like a soda stream – just before it is injected back underground.

Read through extra:
IPCC report: how New Zealand could minimize emissions a lot quicker and depend significantly less on offsets to achieve net zero

Tasks in Iceland and France have revealed that dissolving CO2 in geothermal water is greater than injecting it directly. It cuts the expense of new infrastructure (liquid CO2 compression is expensive) and signifies reinjection wells crafted for standard geothermal operation can carry on to be employed.

Not like pure CO2 that is less dense than drinking water and tends to rise, the reinjected carbonated water is about 2% heavier and will sink. As very long as equal amounts of geothermal water are made and reinjected, the CO2 will remain safely and securely dissolved, where by it can slowly but surely convert into rocks and be forever trapped.

How do the figures stack up?

Our initial modelling exhibits that geothermal BECCS could have destructive emissions in the get of -200 to -700 grams of CO2 for every kilowatt hour of electrical power (gCO2/kWh). When compared to about 400 gCO₂/kWh of constructive emissions from a pure fuel electricity plant, this is a spectacular reversal of the energy-emissions trade-off.

Used to a geothermal technique the dimensions of Wairakei (160 megawatts), a solitary geothermal BECCS procedure could lock away 1 million tonnes of CO2 each year. This is equal to getting two hundred thousand cars and trucks off the street and, at present charges, would web tens of hundreds of thousands of dollars in carbon offsets.

These could be traded via the Emissions Trading Scheme to acquire worthwhile time for industries that have been slow to decarbonise, these types of as agriculture or cement, to get down to net zero.

Gasoline for the future: forestry squander is an untapped and valuable source.

Even improved, most of New Zealand’s geothermal fields are found near massive forests with expansive forestry functions. Estimates place our forestry squander technology at all over 3 million cubic meters each individual yr. Alternatively than leaving it to rot, this could be turned into a important resource for geothermal BECCS and a decarbonising New Zealand.

We can start undertaking this now

According to the IPCC it is “now or under no circumstances” for countries to significantly decarbonise their economies. Geothermal BECCS is a promising software but, as with all new systems, there is a learning curve.

Teething problems have to be labored via as charges are brought down and production is scaled. New Zealand has a probability to get on that curve now. And the whole environment will reward if we do.

Study more:
IPCC report: this ten years is critical for adapting to inescapable weather transform impacts and soaring charges

The achievement of geothermal BECCS will transform on new partnerships in between New Zealand’s geothermal generators, companies and the forestry sector. Forestry entrepreneurs can aid transition wooden squander into a precious useful resource and push down gate costs.

Most importantly, geothermal operators can leverage their extensive injection nicely inventories and comprehensive being familiar with of the underground to forever lock up atmospheric carbon.

With the governing administration tightening emissions budgets and investing billions in a Local climate Emergency Reaction Fund, now is the fantastic time to make geothermal BECCS do the job for Aotearoa New Zealand.


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