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By Kate Cranney 26 March 2023 5 min read

Northern Territory's Beetaloo Sub-basin.

Can greenhouse gas emissions from the proposed development of the Northern Territory's Beetaloo Sub-basin be mitigated and offset? That’s the question CSIRO scientists addressed in new research [PDF · 4.6MB]conducted through the organisation's Gas Industry Social and Environmental Research Alliance.

The report will inform discussions around potential onshore gas development in the region. But before exploring the research, let’s take a step back to understand offsets.

Greenhouse gas targets in Australia

Around Australia, corporations and governments have set goals to become net zero greenhouse gas (GHG) emitters. For example, in 2020 the Northern Territory Government confirmed its goal to achieve net zero emissions by 2050, and in 2022 the Australian Government legislated its own net zero goals.

But some emissions cannot be avoided or mitigated. So how do hard-to-abate industries balance the scales to remain net zero emitters? Offsets provide one solution.

An emissions offset is a reduction in emissions made in order to compensate for (or offset) an emission made elsewhere. For example offsets are a measurable way of compensating for the production of GHG emissions. Companies and governments do this by investing in activities that reduce, remove or capture (store or sequester) emissions. Offsets include engineered solutions like direct air capture, and nature-based solutions like savanna fire management.

And it’s these kinds of solutions that CSIRO scientists assessed in their study of onshore gas in the Northern Territory.

Onshore gas in the Beetaloo Sub-basin

The Beetaloo Sub-basin is located southeast of Katherine in the NT. The area spans approximately 30,000 square kilometres and has been identified as a potential area for onshore gas production.

Onshore gas development has been debated in the NT. So, in 2018, an independent scientific inquiry produced a number of recommendations for future development. One recommendation was that ‘the NT and Australian governments seek to ensure that there is no net increase in the life cycle GHG emissions emitted in Australia from any onshore shale gas produced in the NT’.

Dr Damian Barrett is the Director of GISERA. He explained there has also been community confusion around emissions from the proposed development, how those emissions may be mitigated or minimised and the potential role of offsets.

“The community was asking: ‘What should we believe? We’re hearing various things and we’re concerned. We want independent and trustworthy information’,” he said.

This is where CSIRO scientists came in.

An experimental Velkerri vertical well pad in the Beetaloo Sub-basin.

Scoping out gas emissions and offsets

CSIRO scientists assessed the life-cycle GHG emissions of potential NT onshore shale gas development over 25 years: from 2025 to 2050. The report assumed the source of onshore shale gas would be the Beetaloo Sub-basin.

“This is the first attempt to look and address the question of mitigation and offsets with the best available information we have at the moment,” said Dr Barrett.

The questions scientists asked included:

Step 1 – what are the emissions based on current technological understanding?

Step 2 – can some of those emissions be mitigated through technological choices?

Step 3 – can some emissions be captured and stored using Carbon Capture and Storage (CCS)?

Step 4 – for the remaining hard-to-abate emissions, can they be offset?

The report explored the physical and technical viability of different mitigation and offsetting options. It did not consider other social, environmental and policy factors.

“The report explores if there are enough potential offsets within the region, and more broadly in Australia, to offset the predicted emissions for different scenarios of gas production?” said Dr Barrett.

Scientists first created a set of five onshore gas production scenarios for the NT. (Scientists had to create plausible scenarios, as there is currently no gas production in the Beetaloo Sub-basin.) Four scenarios were low impact (365 PJ/year production) and one scenario was high impact (1,130 PJ/ year).

“The researchers tried to push the study to its limit by considering a very high impact scenario. The 1,130 PJ/year production rate is highly unlikely to occur in the future, due to market demand, price, and several other factors,” explained Dr Barrett.

Next, scientists calculated the estimated annual and lifetime emissions from each of the scenarios.

Then looked at mitigation - in field emissions reduction.

Then looked at CCS, some uses of gas allow for more of this than others.

Finally, researchers assessed the options available to offset the emissions from the scenarios.

Breaking new territory for the Northern Territory

The report provides interesting insights into mitigation and offset options in the NT.

The total lifetime emissions (25 years) to be abated under the five production scenarios ranged from 164 Mt to 826 Mt CO2e, with an emissions intensity of gas delivered to Darwin estimated at 8.85 kilograms of CO2e per gigajoule (GJ) of raw gas.

Notably, under all production scenarios, even the least likely (that is, the high impact scenario), there would be enough offsets to counteract the proposed onshore gas development.

The high impact scenario (1,130 PJ/year) — would require international offsets in addition to mitigation and offsets within Australia. But, from an engineering perspective, the majority of GHG emissions from the other four scenarios could be mitigated or physically abated with options available within Australia. This includes options such as:

  • NT based mitigation activities during production
  • Potential carbon capture and storage based out of Darwin
  • NT based offsets including savannah fire management and other land-based offsets.

Estimates of abatement/offset potential are based on previous CSIRO research which was also used by CSIRO in Assessing Australia’s Carbon Sequestration Potential.

“Potential offsets were based on work by CSIRO experts. They did a thorough, independently-reviewed, study on potential offsets in the NT — it’s the best science in this area,” said Dr Barrett.

Vegetation between the Velkerri experimental wells in the Betaloo Sub-Basin, Northern Territory.

Providing independent advice on offsetting emissions

“It is worth saying that CSIRO is agnostic in relation to onshore gas. We provide independent advice, and we are not involved in the approvals or the regulation of the industry,” said Dr Barrett.

The main message from this type of work is that when it comes to offsetting emissions from development, be that a development associate with onshore natural gas or any other emitter, a number of options in offsetting those emissions in space and time is critical to be able to meet the obligations of net zero emissions, but at the same time allowing economic development to occur.”

This study forms part of a suite of other research activities conducted through CSIRO’s GISERA work in the NT. You can find the full report [PDF · 4.6MB] and the fact sheet [PDF · 8.26MB] online. You can also read about the funding of this research, and all of GISERA results, reports, minutes and factsheets on the GISERA website.

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