Commercial vehicle operators are under pressure to protect their bottom line while also ensuring they comply with emission regulations. As a result, many are assessing the potential benefits of a switch from traditional diesel to alternate fuel options.

Alternative fuels types

Alternative fuels are expected to be a growing part of the commercial vehicle energy mix. The leading contenders are biofuels, Liquefied Natural Gas (LNG), Compressed Natural Gas (CNG) and electricity. These alternative fuels can be renewable depending on the source of feedstock or energy used.

Biofuels

The two main biofuels for use in diesel vehicles are Hydro Treated Vegetable Oil (HVO) and Fatty Acid Methyl Esters (FAME).

HVO

Has better combustion qualities than diesel,
produces lower particulate matter (PM) and Nitrogen Oxide (NOx) emissions,
can be used as a direct replacement or added to traditional diesel without engine modification¹,
has limited availability.

FAME

Can produce lower PM emissions than diesel,
may require additional processing to remove impurities that can cause filter blocking at lower temperatures,
has a potential to promote microbiological growth,
must be blended with diesel, as engine manufacturers typically specify a maximum concentration of FAME.

Natural gas

LNG and CNG both have very low PM and NOx emissions and can reduce Carbon Dioxide (CO₂) output by 10 – 15% compared with diesel. Some LNG and CNG trucks may meet current European emission requirements with a simpler after-treatment system than diesel trucks, reducing or avoiding the need to use Adblue, etc.

LNG

Requires cryogenic tanks and vehicles are typically more expensive than diesel alternatives,
could prove a compelling choice for larger vehicles with a high annual mileage (100,000 km or more). Newer vehicles have good ranges of up to 1,000 km and once the infrastructure is in place,
is typically available at a lower cost than diesel.

CNG

Has approximately half of the energy density of LNG, making it more suitable for shorter distance/regular return-to-base fleets, such as waste disposal vehicles and buses, due to the trade-off between energy storage and vehicle payload,
has a lower cost of installation than LNG and refueling is performed at lower pressure, so requires less stringent safety measures.

Electricity

Electricity is being used to power automotive vehicles, but a very large battery would be required given the power requirements of large commercial vehicles, potentially impacting the maximum payload. At the moment, the primary applications for electric commercial vehicles are city buses and urban delivery vehicles operating in low emission zones, with short/medium return to base operations.

Total cost of ownership

Before switching to alternative fuels, operators need to consider factors such as:

Vehicle cost
Fuel availability
Total distance
Typical routes
Average mileage

Undertaking a Total Cost of Ownership (TCO) analysis will also help to determine the best fuel and vehicle mix for a fleet.

The future of diesel

Trials of alternative fuels are widely reported, but diesel will remain a significant part of the fuels mix for large commercial vehicles.

Engine manufacturers continue to develop diesel-fuelled vehicles that offer very low PM and NOx emissions, while leading oil companies are investing in research and development to improve diesel performance. For example, ExxonMobil has developed Esso Diesel Efficient™ fuel, which is designed to clean up deposits on fuel injectors, helping to improve engine performance.

Trials at Millbrook, one of the most comprehensive independent vehicle testing facilities in the world, found that Esso Diesel Efficient™ fuel helped to reduce emissions² by 10% for NOx, 22% for PM and 2.8% for CO₂ while also improving fuel consumption on average by 2.8%.

A mixed fuels future

The infrastructure to supply alternative fuels is still in its infancy so diesel will remain the dominant fuel choice in the medium term. However, emission regulations are getting tighter so it’s important for commercial vehicle operators to choose reputable fuel suppliers who they can work with to develop the optimum fuels solution for their business.

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Alternatives to traditional fossil fuels Glossary

What is renewable energy?

Renewable energy is energy that is generated from renewable non-fossil sources. Examples include sunlight, geothermal heat, wind, tides, hydropower, and sustainable forms of biomass.

What is biomass?

Biomass is organic matter derived from living or recently living organisms, such as wood, waste, and animal- or vegetable-based fuels. Biomass must typically meet certain sustainability criteria defined by legislation in order to be considered as a source for renewable energy.

What is Biodiesel?

Biodiesel is fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats. They are typically made from renewable organic raw materials such as soybean or rapeseed oils, animal fats, waste vegetable oils or microalgae oils. An example of biodiesel is FAME.

What is FAME?

FAME is an abbreviation for fatty acid methyl esters, a type of biodiesel which is made by esterifying vegetable oils and fats (ie biomass) with methanol. FAME is typically blended with traditional diesel, up to limits imposed by legislation (e.g. Fuels Quality Directive), fuel specifications, and/or recommended by vehicle manufacturers.

When is a fuel considered a “biofuel”?

A biofuel is a fuel or a component of fuel derived from biomass. Examples are bio-ethanol, biodiesel, hydro-treated vegetable oil (HVO), and biogas. Biofuels may be blended with conventional petroleum-based fuels (for example, “B7” diesel is a blend containing up to 7% biodiesel or FAME).

What is HVO?

HVO is an abbreviation for hydro-treated vegetable oil which is made by hydro-treating vegetable and animal oils and fats. HVO may also be referred to as renewable diesel and may be blended with traditional diesel. Unlike FAME, HVO does not contain oxygen and can be used as a standalone fuel in diesel vehicles if approved by the vehicle manufacturer¹.

What is natural gas?

Natural gas is a complex gaseous mixture of hydrocarbons, primarily methane, but generally includes ethane, propane and higher hydrocarbons, and some non-combustible gases such as nitrogen and carbon dioxide.

What is LNG ?

LNG is natural gas that has been liquefied for storage or transportation purposes. It must be stored in cryogenic (low temperature) tanks below -162°C so the natural gas is maintained as a liquid. LNG can be made from fossil or biomass sources (biomethane).

What is CNG?

CNG is natural gas which is compressed under pressure and stored at ambient temperature. The gas is compressed to ~1% of the volume which would be present at atmospheric pressure. CNG can be made from fossil or biomass sources (biomethane). CNG can be compressed from the standard gas supply network or converted from LNG (liquefied natural gas).

¹Vehicle manufacturer fuel requirements should be checked when considering the use of 100% HVO.

² Independent tests performed at Millbrook Proving Ground Ltd., UK:

Compared the performance in heavy-duty vehicles of Esso™ unadditised diesel with Esso Diesel Efficient™ fuel
Used third-party customer trucks (Euro III and Euro V specifications)
Covered approximately 110,000 miles/177,000 km
Five months of normal daily on-road operations (motorway, rural, and urban environments)
Took trucks out of service periodically for lab testing
Test results range of 2.1% to 3.4% lower fuel consumption

Millbrook has expertise in automotive, test, and propulsion technologies and remain pioneers in low carbon development. (ISO Certification - ISO 17025, ISO 9001 and ISO 14001.)

Esso Diesel Efficient™ fuel claims are based on internal and third-party vehicle engine testing, laboratory testing, and/or industry or other scientific literature. Basis for comparison for all claims is versus Esso™ unadditised diesel. Vehicle type, engine type, driving behaviour, and other factors also impact fuel and vehicle performance, emissions, and fuel economy. Esso Diesel Efficient™ fuel may be used in all heavy-duty and light-duty vehicles, but results may vary. Fuel economy testing was performed in the UK using on-road trucks.

Fueling commercial vehicles of the future