Fossil gas could increase GHG emissions by up to 9% or decrease them by a maximum of 12% across all transport modes, the research shows, taking into account the effects of leakage of methane – a very potent greenhouse gas.
In cars, burning compressed natural gas (CNG) has a similar climate impact to diesel, while in trucks it emits greenhouse gases in the same range as best-in-class diesel lorries. Burning liquified natural gas (LNG) in ships achieves little or no GHG improvement over using marine gas oil, but these figures are highly dependent on engine methane slip and upstream leakages. When an engine burns LNG, unburned methane escapes through the exhaust and leakages may occur during storage. Methane is also released ‘upstream’ during the production and transportation of fossil gas.
Fossil gas for transport is currently taxed in the EU, on average, at rates 76% lower than diesel. Countries that have high sales of CNG and LNG vehicles tax fossil gas at even lower rates. For example, in Italy, which consumes 60% of the methane used in European transport and accounts for 68% of CNG car sales, fossil gas at the pump is about half the price of diesel. This is due to a CNG tax rate of 0.5% of the diesel tax rate. Similarly for trucks, the business case for LNG depends entirely on gas’ low tax treatment.
T&E’s clean fuels officer, Jori Sihvonen, said: ‘Gas cars, trucks and ships have no real benefits for the climate and they’re a distraction from our real objective, zero-emission transport. Governments should resist the gas lobby’s offensive and stop wasting precious public money on gas infrastructure and tax breaks for fossil gas.’
Gas is also not a solution to the air pollution crisis driven by diesel cars. Gas cars – including those burning renewable gas – belch out as much air pollution as petrol ones and marginally less than new diesels that comply with new real-world limits, the report finds. In trucks, LNG can increase or decrease NOx, depending on the engine type, and can have higher particulate number emissions than diesel.
For ships, LNG has a clear benefit compared to heavy fuel oil although NOx after-treatment systems and further desulphurisation of existing marine fuels can achieve similar results. T&E said the car, truck and shipping industries should use the shift to low-carbon technology to also move to low air pollution technology.
Biomethane (upgraded biogas) from waste also does not offer a comprehensive solution as it could only supply, at maximum, 9.5% of transport’s needs, the research shows. This would also mean no biomethane would be left to decarbonise the other sectors already using gas – residential, heating and power – where the infrastructure already exists. Renewable gas based on electricity (power-to-gas) is very energy intensive and costly to produce, the report finds.
Jori Sihvonen concluded: ‘The idea that we can decarbonise transport with renewable gas is a pipedream. What little biomethane and electro-methane we’ll have will be needed to decarbonise the heating and power sectors, which currently rely on fossil gas. Pushing biomethane in transport actually makes the climate battle harder by depriving industry and domestic heating of this limited renewable resource.’