The High Court looked at coal climate emissions overseas. But what about emissions at home?
Debate about climate pollution from Australian coal mines is focused overseas. But emissions released at home matter, too.
The High Court recently delved into the climate emissions of overseas coal mines. However, they need to focus on the emissions produced domestically as well. While the Court found the state planners had only considered a small portion of the emissions released by the Mount Pleasant mine overseas, the emissions produced in Australia are still a significant concern.
These emissions count towards Australia's climate targets and are directly the responsibility of the country. The planning commission approved the Hunter Valley Operations mine expansion based on federal rules meant to control these domestic emissions. Yet, these rules have two major flaws. First, they likely underestimate the methane emissions from open-cut mines.
Second, every coal mine faces the same emissions target, regardless of the fact that underground mines release significantly more total emissions per tonne of coal. The rules for measuring and setting emissions targets for coal mines, including the methane issue, are currently under review. This is the opportune time to rectify these problems.
Most of the emissions from coal mines are methane, a potent greenhouse gas. Underground mines typically emit nearly six times more total emissions per tonne of coal than open-cut mines. The federal government manages these emissions via the Safeguard Mechanism, which gives each big emitter an annual emissions limit that decreases over time.
Facilities that exceed this limit must buy carbon credits, while those that reduce their emissions can sell the credits they earn. The way methane is measured in underground versus open-cut mines varies. Underground mines measure methane by testing the air pumped out of the mine, while many open-cut mines estimate their methane using a state-wide average.
Large mines must now test rock samples from their own site instead. However, this change has led to significant fluctuations in reported emissions, but it only alters the estimate, not the actual methane escaping. For instance, Mount Pleasant's emissions fell by three-quarters in 2023-24 despite mining more coal. Similarly, Glencore's Hail Creek mine in Queensland reported a 159% rise in methane emissions.
These discrepancies highlight concerns over the accuracy of the estimates. In 2023, scientists flew aircraft over 17 Queensland coal mines to measure their methane. They found that above the open-cut mines, the readings were about 3.6 times higher than reported. Satellite data from NSW, home to both Hunter Valley mines, show a similar trend, with mines producing two-thirds of the state's coal releasing nearly twice the methane officially reported for the whole state.
The federal government's own expert panel on methane measurement suggested last month that the estimation method warrants review. This means the reported emissions could significantly underestimate the actual methane emissions. To address this, the federal government should ensure open-cut mines improve their methane estimation methods, so their reported figures match their actual emissions.
The government is currently reviewing these methods. Mine estimates should also be regularly checked against aircraft measurements. Over time, open-cut mines should have to measure their methane, just like underground mines do. Additionally, the Safeguard Mechanism should set separate limits for open-cut and underground mines based on these improved estimates, and apply a new limit only where it is stricter than the current one.
This would reduce open-cut mines' limits by about 1.3 million tonnes a year. The High Court's focus on overseas coal emissions should also extend to the methane leaking from Australian mines.
Written by urgent.news from The Conversation AU's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
