Renewable gas, also known as biomethane, is produced by the fermentation of organic matter, such as agriculture and food waste. It can be burnt for energy, much like natural gas, and can be a lower carbon option than this fossil fuel alternative.
However, just because a fuel is ‘renewable’, it does not mean that it is clean or emission-free. Renewable gas is highly processed and contains at least 90 per cent methane. This climate-heating greenhouse gas (GHG) is far more damaging to the climate than carbon dioxide (CO2) and is responsible for 30 per cent of global temperature increases since pre-industrial times.
Uses of renewable gas
Renewable gas can play a unique but marginal role in complementing other decarbonisation efforts. This includes capturing stray methane from landfills or agriculture, or reducing emissions in hard-to-abate sectors, such as the refining of some metals. When used in appropriate industries, it can avoid more GHG emissions than it generates and result in a net-negative carbon intensity.
However, fossil fuel companies are promoting renewable gas to replace the use of fossil natural gas, such as home heating and cooking. However, this is far more polluting than the genuinely clean alternatives already available. These include emission-free renewable energy generation, such as wind and solar, and electrification solutions, such as heat pumps and induction cookers. Therefore, where renewable gas displaces or delays the uptake of these cleaner alternatives, this represents a relative net increase in polluting GHG emissions, which in turn can hinder climate progress.
The difference between renewable gas and fossil natural gas
Renewable gas is chemically identical to fossil natural gas, in that it is primarily methane gas. Renewable gas is labelled as such since it is produced by organic fuels – like food and agricultural waste and landfill emissions – that human activity will generate in perpetuity. Conversely, natural gas is a fossil fuel that originates from decayed organic matter from millions of years ago and is therefore not renewable.
While the lifecycle of renewable gas has an overall lower carbon intensity than fossil natural gas, both gases are methane gas. Therefore, when burned, they emit the same climate and health-damaging emissions. These include the below.
Carbon dioxide
Burning renewable gas emits CO2 – the GHG most responsible for driving dangerous climate change. Ultimately, this is highly problematic for the urgent goal of reaching net zero emissions. Moreover, methane itself is a powerful GHG, over 80 times more potent than carbon dioxide over a 20-year timeframe. Therefore, methane leaks along the supply chain before combustion risks undermining any potential climate benefits.
Nitrous oxide
When burned, renewable gas also releases nitrous oxide, a pollutant that produces smog and poor air quality. This pollution can cause or worsen respiratory illnesses, such as asthma. Moreover, studies have shown that gas stoves emit toxic and carcinogenic pollutants into homes, even when turned off. “Rather than simply replace one bad gas product with another, we would all be better off if we moved away from gas entirely”, writes Annika Hellwig in Conservation Law Foundation.
The renewable gas industry
Industry bodies such as Energy Networks Australia and Australian Gas Networks claim that renewable gas is a carbon-neutral equivalent to natural gas, which can therefore contribute to a decarbonised gas system in Australia. This claim is based on the assumption that if left to decompose, organic waste products release GHGs that heat the climate. Capturing, processing and burning these gases stops them from escaping into the atmosphere, claims the industry. However, in practice, this simplistic model masks the true extent of the climate, environmental and health costs associated with the industry.
Renewable gas and greenwashing
Some criticism of the hype around renewable gas goes even further, accusing the industry of intentional greenwashing. “The gas industry is using RNG [renewable natural gas] to greenwash its image while obscuring its real objective: growth at climate’s expense”, write energy policy experts from Sightline Institute. By creating the illusion that we can decarbonise our gas system by introducing a new fuel, the industry is extending its social licence to pollute. “If the public buys the pitch, it will enable gas companies to invest millions more dollars into new infrastructure that would lock in decades of profits. The result would be consumers paying higher prices for a façade of greenhouse gas reductions.”
Ultimately, renewable gas is too expensive and polluting to advance climate in the way the industry claims it can. “The tall tales about RNG don’t stand up to scrutiny. Although there may be some modest climate benefit for a few niche applications like heavy industry, RNG cannot be a replacement for the way we use natural gas now”, they continue. “Worse yet, it lets the industry get away with spinning yarns that will benefit gas company’s bottom lines at everyone’s expense”.
The renewable energy solutions with zero carbon emissions
While renewable gas presents some opportunities for decarbonisation, it is no substitute for wide-scale electrification and efficiency advancements, says the Climate Council. Zero-emission energy generation, such as wind, water and solar, plus storage, are already proven to provide clean energy around the world – and costs are falling rapidly. Moreover, replacing gas boilers and cookers with electric heat pumps and electric or induction hobs are the cleanest and safest options for households.
Importantly, electrified household utilities also remove the deadly health risks of toxic indoor air pollution from gas cookers in homes. As well as the proven best option for the climate and health, they are far more efficient and affordable over their lifetime. This results in lower power demand and could save households hundreds – even thousands – of dollars each year on energy bills.
Ultimately, the misapplication of renewable gas could result in climate-heating emissions and toxic air pollution, which inhibits progress to net zero emissions. The hype for this fuel must not distract from the cheaper, cleaner and safer transition towards a fully green, sustainable economy.