However, their utilisation comes at a high cost to the environment. Emissions from heavy-freight trucks (HFTs) have grown more quickly than any other transport mode, at 2.4% annually since the year 2000, according to the International Energy Agency (IEA).

Road freight transport relies primarily on diesel, which accounts for more than 80% of its oil use. Road freight vehicles alone have accounted for about 80% of the global net increase in diesel demand since 2000, and make up about half of global diesel demand today. As a result, road freight currently accounts for more than 35% of transport-related carbon dioxide (CO2) emissions, and about 7% of total energy-related CO2 emissions.

The Kenworth T680 combines hydrogen gas and air to produce electricity.

At the same time, energy consumption has risen by 2.6% a year. At about 17 million barrels per day (b/d), oil demand from road freight vehicles accounts for approximately one-fifth of the global oil demand. Trucks account for more than 90% of the growth in energy consumption, with buses accounting for the rest.

A report published by the IEA, entitled ‘The Future of Trucks: Implications for Energy and the Environment’, indicates that without further policy efforts, oil demand from road freight vehicles is set to rise by five million b/d to 2050.

Three main options are available to modernise road freight transport. The first is to improve vehicle efficiency, the second is to improve road freight operations with intelligent data collection systems, and the third is to adopt alternative fuels and vehicles.

Natural gas, biofuels, electricity, and hydrogen are the main alternatives to oil, but so far they all play only minor roles in supplying energy to road freight vehicles.

The hurdles to electrification are least significant for trucks with lower GVW and shorter annual mileages. Due to the cost implications for large battery requirements, the challenge for the electrification HFTs is to reduce battery needs through the supply of electricity to vehicles while in motion.

Currently, battery-operated and plug-in/catenary electric trucks are in the pilot stage for heavy-duty rigid trucks and tractor-trailers, and are in the early deployment stage for medium-duty trucks in urban operations.

Two major fuel alternatives have emerged for long-haul transportation: natural gas and hydrogen.

A practical option 

Natural gas, which is mainly methane, is a suitable transport fuel either in its compressed form (CNG), or in its liquefied form (LNG), and it has the volumetric energy density that makes it viable for use in trucks. Natural gas fuels are less toxic than gasoline and diesel, and are not carcinogenic. In addition, engines running on natural gas emit less noise than those running on diesel.

The size and application of the truck determines the choice of CNG or LNG. The lower energy density of CNG fuels compared to diesel increases the in-vehicle fuel storage volumes by up to six times. Therefore, light- and medium-duty vehicles with low annual utilisation tend to use CNG.

About double the volume of LNG fuel is required to deliver a comparable travel distance to diesel, depending on engine efficiency. However, an LNG tank can store more than twice the fuel compared to a CNG tank of the same size. This makes LNG more suitable for HFTs. Furthermore, due to the boil-off risk of LNG, the fuel also needs to be used in trucks that drive regularly.

CNG and LNG can be cost competitive in markets where natural gas prices are lower than diesel prices, and with a fuel distribution infrastructure. CNG and LNG can be cost competitive in markets where natural gas prices are lower than diesel prices, and with a fuel distribution infrastructure. 

Refuelling a truck with LNG can be achieved at similar speeds as gasoline or diesel, but LNG refuelling stations require complex and specialised equipment, such as cryogenic storage tanks, cooling systems, and security devices to avoid critical increases in the LNG storage pressure. In addition, drivers must be trained to refuel with CNG or LNG.

China is currently the largest market in the world for LNG in road transport, with more than 200,000 heavy-duty trucks and buses using LNG. In 2017, RedStar, a joint venture of Shell and Shaanxi Yanchang Group Company, opened an LNG retail site in Shaan’Xi, in northwest China.

In 2018, Shell opened its first LNG retail stations for trucks in Germany and Belgium. Shell has developed engine oils for the specific operating conditions of trucks and buses that run on natural gas.

Shell’s investment in LNG is aligned with its commitment to BioLNG EuroNet, a consortium comprising Shell, Disa, Scania, Iveco, and CNH Industrial Capital Europe under the trademark of Iveco Capital and Nordsol, and co-funded by the European Union.

The consortium is driving the adoption of LNG as a road transport fuel in Europe, with new infrastructure that should ensure long-term success and wide-scale uptake.

The members of the consortium will each deliver separate activities that will see 2,000 more LNG trucks on the road, 39 LNG fuelling stations, and the construction of a BioLNG production plant in the Netherlands.

The LNG retail stations will form part of a pan-European network and be built in Belgium, France, Germany, the Netherlands, Poland, and Spain. The stations will be located approximately every 400km along core road network corridors running from Spain to eastern Poland.

Scania recently unveiled a long-distance coach fuelled by LNG, the Scania Interlink Medium Decker, which provides a range of up to 1,000km.

The Iveco Stralis NP 460 features an LNG tank.

In October 2018, an Iveco Stralis NP 460 truck from the UK completed a 1,728km road journey from London to Madrid on a single fill of LNG, to demonstrate the suitability of natural gas-powered vehicles for domestic and European road transport.

The Stralis NP 4×2 tractor unit pulled a tri-axle box van trailer and ran at a GVW of 30t. After a short ferry crossing from Dover on England’s south coast to Calais in France, it completed the 1,728km road journey without needing to refuel, exceeding the vehicle’s official range of 1,600km.

According to Iveco, the single-fuel truck with double LNG tanks, 460 horsepower (HP), and an autonomy range of up to 1,600km, delivers up to 15% lower fuel consumption and up to 9% lower total cost of ownership than a diesel truck. Compared to an equivalent Euro VI diesel truck, a Stralis NP running on LNG emits approximately 90% less nitrogen dioxide, 99% less particulate matter, and up to 15% less CO2.

The 12.9-litre Cursor 13 NP displacement engine powering the Stralis NP is engineered by FPT Industrial. The high fuel-flow gas injectors, fuel rail, pistons, and turbo are designed to deliver high power output and torque. This result is achieved by applying spark-ignition stoichiometric combustion to natural gas.

The exhaust after-treatment is based on a compact and light three-way catalyst that requires no regeneration or additives. Stoichiometric combustion runs at a 12:1 compression ratio and is quieter than the the 17:1 ratio of the diesel cycle.

The Stralis NP 460 offers a choice of tank combinations based on short, long, right- or left-mounted, LNG or CNG, to tailor the vehicle to specific customer requirements. On standard articulated trucks, LNG tanks are available in three sizes.

This makes it possible to customise the vehicle by freeing up the space on the chassis that is required for the ancillaries of the customer’s mission. The small-sized tanks can leave one metre of space where components such as compressors for tankers can be mounted, or the vehicle can be specified without the left-side tank, to allow space for installing larger-sized components, or for weight-sensitive missions.

Volvo Trucks has launched Euro 6-compliant, gas-powered trucks that offer fuel efficiency and performance on a par with that of diesel-driven trucks. The Volvo FH LNG and Volvo FM LNG can run on either biogas, which cuts CO2 by up to 100%, or natural gas, which reduces CO2 emissions by 20% compared to diesel.

This relates to emissions from the vehicle during usage, known as tank-to-wheel.

Compared with current gas-powered trucks that are available on the market, Volvo Trucks’ new vehicles use 15%-25% less fuel. In order to give the trucks the greatest possible operating range, they run on LNG.

An operator covering 120,000km a year in heavy transport, who chooses natural gas instead of diesel, could cut CO2 emissions by betweeen 18t and 20t a year.

The Volvo Trucks FH LNG and FM LNG models are Euro 6- compliant.

Director-environment and innovation at Volvo Trucks, Lars Mårtensson, says: “We regard LNG as a long-term, first-choice alternative to diesel, both for regional and long-haul truck operations where fuel efficiency, payload, and productivity are all crucial.

“With a higher proportion of biogas, climate impact can be reduced far more. For transport operations in urban environments, where range is not as critical, electrified vehicles will play a greater role in the future,” he continues.

“Our vision is that trucks from Volvo will eventually have zero emissions, although the way of achieving that is not by one single solution, but through several solutions in parallel. LNG is one of them.”

Abundance of hydrogen 

Hydrogen is the most abundant element in the universe and has the highest specific energy density of any non-nuclear power source. It can be created using many sources, stored indefinitely, and can be shipped relatively easily.

According to the US Department of Energy, the interest in hydrogen as an alternative transportation fuel stems from its ability to power fuel cells in zero-emission fuel cell electric vehicles (FCEVs), its potential for domestic production, its fast filling time, and the fuel cell’s high efficiency.

In fact, a fuel cell coupled with an electric motor is two to three times more efficient than an internal combustion engine running on gasoline.In fact, a fuel cell coupled with an electric motor is two to three times more efficient than an internal combustion engine running on gasoline.

Hydrogen can also serve as fuel for internal combustion engines. The energy in 1kg of hydrogen gas is about the same as the energy in 2.8kg of gasoline.

Although in its infancy, fuel cells offer the greatest future potential, according to Toyota, a leading proponent of hydrogen fuel cell technology.

Toyota has found success in hydrogen fuel cell vehicles with the Toyota Mirai saloon, which can be driven for approximately 480km with a full 5kg tank of hydrogen. That quantity of fuel is produced from 50 litres of water, and in the course of driving that distance, the car’s only emission is 50 litres of water.

The growing confidence in hydrogen-powered transport has enabled Toyota to plan an increase in its annual production of fuel cell vehicles from 3,000 units in 2017 to 30,000 units by the early 2020s.

Toyota Motor North America and Kenworth Truck Company are collaborating to develop 10 zero-emission Kenworth T680s powered by Toyota hydrogen fuel cell electric powertrains.

This collaboration is part of a $41m Zero and Near-Zero Emissions Freight Facilities grant that was preliminarily awarded by the California Air Resources Board, with the Port of Los Angeles as the prime applicant. The initiative will help to reduce emissions by 465 metric tons of greenhouse gases and 0.72 weighted tons of oxides of nitrogen, reactive organic gas, and particulate matter.

Some of the world’s largest commercial truck manufacturers are adopting alternative fuels.

The Kenworth T680s with the Toyota hydrogen fuel cell electric powertrains combine hydrogen gas and air to produce electricity. The electricity powers electric motors to move the trucks, while also charging the lithium-ion batteries to optimise performance as needed.

Sophisticated power management systems will apportion the electrical power from the fuel cells to the motors, batteries, and other components, such as electrified power steering and brake air compressors.

The hydrogen fuel cell electric powered Kenworth T680s will have a range of more than 482km under normal drayage operating conditions.

The programme will also fund foundational hydrogen fuel infrastructure, including two new fueling stations that, subject to a final investment decision by Equilon Enterprises (doing business as Shell Oil Products US), will be developed through Shell Oil Products US, to support the operation of the fuel cell electric trucks in Southern California.

Nikola Motor Company has created a hydrogen-electric truck named the Nikola Tre for European markets. The Nikola Tre has 500-1,000 HP, 6×4 or 6×2 configurations, and a range of 500km- 1,200km, depending on options. The Tre will fit within the current size and length restrictions for Europe.

European testing is projected to begin in Norway in 2020. Nikola is also in the preliminary planning stages of identifying a suitable location for its European manufacturing facility.

The Nikola Tre hydrogen powered electric truck.

Nikola is working with Nel Hydrogen of Oslo to set up a hydrogen station infrastructure in the US. By 2028, Nikola plans to have more than 700 hydrogen stations in the US and Canada, capable of between 2,000kg and 8,000kg in daily hydrogen production.

Nikola’s European stations are expected to come online in around 2022 and are projected to cover most of the European market by 2030.