Decarbonising transport: the biomethane solution


Bio-LNG/CNG is rapidly gaining traction as a greener fuel for larger vehicles, as it reduces CO2 emissions by over 85 per cent, NOx emissions by 50-70 per cent, and has almost zero particulate matter. Charlotte Morton, chief executive of the UK Anaerobic Digestion and Bioresources Association (ADBA) explains further

Decarbonising transport is a major challenge for the global economy, not only from a climate change perspective, but also as a public health imperative. Air pollution now kills more people than tobacco and three times as many as Aids, tuberculosis and malaria combined, and transport carries a heavy burden.

In the last year, the transport industry has been the biggest emitter of greenhouse gas (GHG) emissions in the UK, contributing 27 per cent of the total volume, whilst overall GHG emissions in Britain have declined by 44 per cent from 1990 (39 per cent for CO2 alone). The trend is similar in the EU, where the greening of electricity generation taking place alongside the lack of progress in cleaning up transport is increasing the latter's share of total emissions.  

The sector is notoriously difficult to decarbonise. In its 2018 "Road to Zero Strategy" setting out its plans to develop an ultra low-carbon economy, the UK Government calls for an end to the sale of any new conventional petrol and diesel cars and vans by 2040, but the ban does not cover heavy goods vehicles, lorries or buses, which account for 17 per cent of total transport emissions. With the stakes having been upped even higher by the UK's subsequent pledge to achieve Net-Zero emissions by 2050, this category of vehicles, ban or no ban, also needs to get greener.

RTFO - the driving policy mechanism

A staggering 99 per cent of vehicles in the UK are either run on petrol or diesel. The challenge is therefore immense. To encourage the switch away from these highly polluting fuels, back in 2008, the Government established the Renewable Transport Fuel Obligation (RTFO), which imposes the obligation to suppliers to provide a percentage of renewable fuels or pay and opt-out prices to achieve the targets.

As a result of RTFO, alternative renewable fuels available commercially such as biodiesel, electricity and natural gas, have experienced exponential growth over the past few years. The scheme also supports the development of technologies that are not as mature, such as hydrogen. The RTFO volume target for these biofuels has recently been increased from the current 4.75 per cent to 9.75 per cent in 2020, and 12.4 per cent in 2032.

Biomethane is the most supplied fuel under the RTFO scheme after biodiesel and bioethanol. It has the same composition as natural gas from the continental shelf but is produced from organic materials through the process of anaerobic digestion (AD). AD treats organic feedstock such as food and agricultural waste and turns it into biogas on one hand and a bio-fertiliser, called digestate, on the other hand.  The biogas is upgraded to remove impurities and CO2  to become biomethane, which is then transformed into two types of natural gas: Compressed Natural Gas (CNG), for direct use as a green fuel, and Liquefied Natural Gas (LNG), which allows the gas to be easily distributed far and wide through a network of pipelines or by road and sea tankers.

There are over 20m LNG/CNG cars in the global fleet and, for HGVs, Bio-LNG/CNG is rapidly gaining traction as fuel – as it reduces CO2 emissions by over 85 per cent, NOx emissions by 50-70 per cent, and has almost zero particulate matter. It has been found that fleet operators who switch to biomethane more than exceed what is required under the benchmark minimum standard for emissions.

Biomethane vs electrification

Despite the recent success of electric vehicles in the car sales market, and the infrastructure breakthrough of making more electric charging points available in the UK than there are petrol stations (9,300 against 8,400), some major challenges remain for full electrification to become a reality.

Firstly, to achieve carbon neutrality, switching to electricity requires the its generation to be carbon-free. At the time of writing, the average emission factors from producing electricity from the grid was 159g CO2/kWh - still too high to meet the net-zero target. By contrast, the AD process drastically reduces GHG emissions in the production phase as well as in its outputs by removing methane emissions from food and agricultural waste as well as facilitating carbon sinks in the land used for energy crops. Depending on the feedstock used, the European Union has estimated the savings on GHG emissions from biomethane production to range from 60 to 90% compared to average fossil fuel. Biomethane can therefore offer a closer alternative to achieve carbon neutrality, and this was recognised by the Committee on Climate Change in its Biomass in a low carbon economy report.

Secondly, powering the electric vehicles fleet would increase the pressure on the grid, requiring more investment in infrastructure and additional capacity. In its Future Energy Scenarios, National Grid estimates that the additional annual demand from electric vehicles will represent about 11 per cent of 2050 national demand. By contrast, biomethane, which is easier to store than electricity, is currently injected into the existing gas grid and extracted further down the line without creating significant additional cost for the network.  

Finally, the main obstacle yet to the electrification of all vehicles is the range, which is particularly critical for heavy duty vehicles. Biomethane-powered vehicles can cover many more miles on equivalent refuel than electric vehicles - a critical aspect in a commercial and industrial context. Even with a larger electric charge network in place, the risk is too great, especially when operating large fleets of vehicles.

Whilst there are a number of technologies and combinations available to decarbonise private cars alongside electricity, biomethane has proven to be the only viable option for larger vehicles.

Not only environmentally friendly, but also economical

As a result, biomethane is increasingly the preferred option for powering heavy good vehicles as well as buses and tractors. And it offers huge benefits, not only in terms of its environmental and health credentials, but also economically.  Waitrose and John Lewis, for example, are now running 58 biomethane-powered delivery trucks which, in addition to massive savings on CO2 emissions compared to diesel, are also 30-40 per cent cheaper to run.

At the 2019 UK AD and World Biogas Expo, organised by the UK Anaerobic Digestion and Bioresources Association (ADBA) and the World Biogas Association (WBA), the makers of IVECO trucks CNHi introduced the first natural gas lorry specifically designed for long distance haulage,  delivering the same performance as its diesel equivalent (but on ultra-low emissions) with a 33 per cent to 50 per cent cost saving on fuel.  At the show, CNHI's agricultural branch, New Holland, also showcased their prototype biomethane-powered tractor as a precursor to all off-road vehicles running on renewable natural gas.

The Post Office is also trialling biogas trucks on its long-haul routes, and bus services are following suit. Nottingham City Transport leads the way with a fleet of over 50 double decker buses already on the road – and a target of 120 operating by November. The well-to-wheel emissions from their new buses are 84 per cent lower than an equivalent new diesel double decker - a massive improvement for the city's air quality and the well-being of its residents.  Meanwhile, Bristol City Council has just opened a new biomethane refuelling station to service a 77-strong fleet of biomethane buses. With the introduction across the UK of Low Emissions or Clean Air Zones charging buses and HGVs that fail to meet minimum standards £200/day to enter, the transition for cities, local authorities and haulage companies makes total economic sense. It also means that the filling-station infrastructure is emerging too as demand grows.

Ensuring AD capacity to supply biomethane

ADBA, as the trade association for the AD sector, has been lobbying British policy makers to ensure it supports the sector's ability to meet the increasing demand for biogas and biomethane. In particular it is calling for more incentives towards, and investment into, the effective collection of feedstock from household and commercial food waste, agriculture and industry. A recent report by WBA, the Global Potential of Biogas, shows that only two per cent of the global feedstock available is actually being collected and treated through AD.  The scope for growth is therefore immense. The report also states that biogas could reduce global emissions by 10-13 per cent, placing the industry as a major contributor to achieving Climate Change mitigation targets.

More biomethane on the market means that the transport industry will have the tools to stem the negative trend it has set in contributing to GHG emissions, both in the UK and globally. The technology is there, it is mature and it is proven not only to help protect the environment and human health, but also to be an economically-worthwhile option for fleet operators.  

Biomethane is fast becoming an invaluable asset in these challenging environmental and economic times.