Thinking outside the NOx

Charlotte Morton, Chief Executive of the Anaerobic Digestion & Bioresources Association, discusses how biomethane-fuelled vehicles can help improve air quality and reduce the UK’s carbon emissions.

Readers of Air Quality News will need no introduction to the problem of air quality in UK towns and cities, but there is often a disproportionate focus on private vehicles as the primary source of this.

Charlotte Morton, chief executive, ADBA

Over half of roadside emissions come from buses, taxis, light goods vehicles (LGVs), and heavy goods vehicles (HGVs), all of which have high levels of nitrogen-oxide (NOx) emissions. With emissions from HGVs in particular having risen over the past five years, significant improvements in air quality can be achieved by focusing on LGVs, buses, and HGVs.

The benefits of biomethane

This is where biomethane comes in. Biomethane is a low-carbon, methane-based transport fuel produced by anaerobic digestion (AD), a natural process that breaks down organic wastes and purpose-grown crops to create a biogas that can then be upgraded to biomethane.

Use of biomethane as a vehicle fuel provides numerous benefits compared to other fuels, particularly for heavy vehicles such as buses and HGVs that are proving difficult to electrify. In terms of air quality, biomethane-fuelled vehicles have dramatically reduced NOx emissions and fewer ozone promoters, aldehydes and non-methane hydrocarbons than Euro V diesel vehicles, as well as particulate-matter-free combustion.

But with new Euro VI diesel vehicles achieving similar air-quality outcomes to gas options, biomethane’s unique selling point is its well-to-wheel carbon savings, whether feedstocks of waste, residue, or crop are used. A recent study by NGVA Europe confirmed that natural gas reduces greenhouse gas emissions from heavy-duty vehicles by 16% for compressed natural gas and 15% for liquefied natural gas; continued uptake of biomethane will therefore help the UK achieve its Carbon Budgets under the 2008 Climate Change Act, with the potential to deliver £2.1 bn in CO₂e savings per year (assuming a carbon price of £100/tCO₂e).

The potential of biomethane

Given how far hydrogen is from being a reliable option for transport and the difficulties in using electric batteries to power heavy vehicles, over the short to mid term biomethane is a technology-ready, cost-effective means of slashing emissions and particulate matter and improving air quality, and is the only practical means of decarbonising HGVs, buses, and other large vehicles.

The UK has close to 100 AD plants already producing biomethane with dozens more being built, and the whole UK AD industry has sufficient capacity today to produce enough biomethane to power 80% of the UK’s entire bus fleet and the potential to produce enough biomethane to power 75% of all HGVs in the UK.

Indeed, lots of bus companies across the UK are increasingly looking at gas buses to improve local air quality, reduce their carbon emissions, and save money, with uptake having been stimulated by government policies such as the Bus Service Operators Grant and the Green Bus Fund. Managers of HGV fleets are doing likewise, with six major UK fleet operators currently trialling 81 gas-fuelled HGVs in what has been described as the UK’s largest biomethane fuel trial to date.

Looking to the future

Importantly, the UK government sees biomethane as a clean fuel and is encouraging its use through the Renewable Transport Fuel Obligation. It’s critical, however, that there is also support from central government for the generation of biogas and its upgrading to biomethane — without this, the AD industry will be unable to generate biomethane for transport and the many benefits of this clean fuel mentioned above will not be realised.

We’ll be discussing how to stimulate the UK biomethane-for-transport market and examining case studies of biomethane vehicle fleets from around the world at UK AD & World Biogas Expo 2018, taking place on 11^th-12^th July at the NEC in Birmingham. The expo is free to attend and will bring together fleet managers looking for green solutions with AD plant operators looking for a market for their biomethane.

We hope to see you there to help push forward the market for this vital fuel, which can make a huge difference to air quality and carbon emissions in the UK and beyond.