Transitioning to natural gas to fuel the freight and shipping industries will not be enough to meet emissions targets, and in some cases, the benefits may be eliminated, according to researchers from Imperial College London.
A new white paper from academics at Imperial’s Sustainable Gas Institute, examines the potential benefits of using natural gas for ship and truck fuel and found that some natural gases, like methane, leak as they move through the supply chain, which significantly reduces the benefit of switching fuel.
They also found that natural gas was not as energy efficient as diesel.
Long distance ships and trucks currently use heavy fuel oil and diesel, which emit greenhouse gases like carbon dioxide (CO2) that contributes to global warming. They also emit air pollutants like nitrogen oxides (NOx), sulphur oxides (SOx), and particulates which contribute to air pollution and harm human health.
In 2015 road freight contributed 7% of global CO2 emissions, and ships contributed up to 2.5%. However, reducing or eliminating carbon emissions from long haul vehicles and ships has proven difficult, with advanced battery electric or hydrogen fuel cell systems more expensive and potentially limited in the range they can deliver.
The International Maritime Organisation (IMO) – the United Nations’ organisation for shipping – wants to halve greenhouse gas emissions from ships by 2050 and last week the Department for Transport published its ‘Maritime 2050 strategy‘ which details their vision of a zero-emission shipping industry by 2050 and included noises about promoting the uptake of carbon-neutral fuels for the industry.
The report also questions the value of using natural gas in trucks. In recent years, regulations for trucks has improved their energy efficiency to an extent that switching to natural gas for fuel might not reduce the relative benefit of a switch to natural gas.
Lead author Dr Jamie Speirs, from Imperial’s Department of Earth Science & Engineering, said: ‘The greenhouse gas benefits of natural gas as a transport fuel are useful in the immediate term, but must be coupled with additional energy efficiency measures and longer-term plans that include much lower carbon truck and ship technologies.’
Co-author Dr Marc Stettler, of Imperial’s Department of Civil and Environmental Engineering, said: ‘To get the full picture on greenhouse gas emissions we looked at the whole lifecycle and the fuel supply chain as well as tailpipe emissions.
‘Our review shows that small amounts of methane leakage across the supply chain of natural gas can eliminate the benefit of substituting diesel for natural gas. We also found that natural gas engines tend not to be as energy efficient as diesel engines and that this also reduces the carbon benefits of trucks.’
‘To achieve deeper emissions reductions, we will require a mix of technologies including electric vehicles for short urban routes, electrification of long-haul operations and more efficient logistics processes.’
Read the report here.