Is Geothermal really renewable?
Geothermal emissions are now higher than coal in the electricity sector
New Zealand Geothermal Electricity now emits 724,000,000 kilograms CO2e per anum ….
….. that’s 89,000,000 kilograms more than electricity generated by coal from Huntly.
First the bad news
We’ve had geothermal in New Zealand for over 60 years and over that time we’ve been told as a nation that it’s clean and renewable.
But, Geothermal emissions are now higher than coal in the electricity sector. In fact emissions from Geothermal electricity have increased 180% over the last 10 years and is now emitting 724,000,000 kilograms of greenhouse gas per year.
That’s the equivalent to 220,000 car emissions.
In the 2016 Ministry for the Environment Emissions Report it states:
“Emissions from geothermal have increased greatly in recent years. These increases are driven by an increase in geothermal emissions related to electricity generation….”
Now the good news
Wind, Hydro and Solar have much lower emissions
As you would expect, Wind, Hydro and Solar have no direct emissions from operation, so the only emissions to consider are from their construction or installation.
Take Wind Farming for example, if you include all lifetime emissions, wind emits around 7 grams / CO2e / kWh (grams CO2e) over its lifetime. This takes into account the concrete, steel and shipping required to get a wind farm established plus ongoing maintenance.
Remember that figure, 7 grams.
So how does Wind compare with Geothermal?
Geothermal emissions vary greatly between sites, from 30 grams (closed cycle) up to over 597 grams (open cycle), that’s more than a gas plant.
On average throughout New Zealand Geothermal emits 99 grams CO2e, 14 times more emissions than Wind, and 3 times more than Solar.
That means if the average Kiwi household electricity was sourced purely from Geothermal generated electricity, they would be emitting 790 kilograms of CO2e per annum. That’s a lot of CO2e and doesn’t sound very renewable.
Has Geothermal lowered emissions from Coal and Gas?
Geothermal plants are designed to operate for 30 – 40 years. So at the current rate of NZ Geothermal emissions that means we’ve locked in 21,000,000,000 kilograms of geothermal CO2e over the next 30 -50 years. That’s the equivalent emissions of driving a Holden Commodore around the globe 2.7 million times, not flash.
When you consider Wind Farming, Hydro and Solar generation offer much cleaner alternatives to Geothermal, over time, one would expect open cycle geothermal will eventually be priced out of the market due to carbon tax making it too expensive.
Further, Wind is now already one of the cheapest forms of electricity generation to operate, so over the long term will lower energy costs for Kiwis ….. and is not exposed to carbon tax.
Solar is also becoming more competitive and over time most houses in New Zealand will be blessed with their own solar panels.
Simply put, replacing Coal and Gas with Geothermal is replacing one thermal source with another.
Combined with our abundance of Hydro and a rapidly rising fleet of electric vehicles that can store massive amounts of energy, NZ is in a great position to be a truly 100% renewable Nation.
So, the next time someone tries telling you our electricity is 80% renewable, tell them it’s actually 65% from Wind, Hydro and Solar, the rest is still dirty thermal.
Al Yates is a Director of Ecotricity
Ecotricity is NZ’s only 100% carboNZero Certified Electricity sourced from Wind, Hydro and Solar