• A number of both emerging and ready-now solutions will be required to support the decarbonisation of on- and off-road transportation
  • Hydrogen offers promise, and could power heavy-duty transport applications through use within fuel cells or combustion engines
  • E-fuels may have a niche role to play for selected applications
  • Renewable liquid fuels will be increasingly crucial as a drop-in solution, and an immediate route to significant carbon reductions

In the first part of this article, we discussed how Electric Vehicles (EVs) are an essential part of reducing greenhouse gas emissions in the transportation sector. However, they are not a one-size-fits-all solution for all types of transportation.

There are various challenges, such as limitations in battery technology for heavy-duty vehicles, issues with charging infrastructure, and the time and cost associated with replacing entire vehicle fleets. To achieve our decarbonisation goals, we need to explore additional solutions alongside electrification.

In this second part, we'll explore some of these alternative solutions, including emerging technologies like green hydrogen and e-fuels, as well as readily available options such as Renewable Diesel HVO.


The role low-carbon hydrogen may play in decarbonising transportation

Hydrogen, the most abundant molecule in the universe, is a colourless, odourless, non-toxic gas. On earth, hydrogen is mostly found combined with oxygen as water, although the two elements can be separated by passing through an electric current. This process is known as electrolysis. When this process uses electricity from renewable sources, the hydrogen produced is known as green hydrogen. .

The UK government's Hydrogen Strategy highlights the crucial role that hydrogen can play in the transition to a low-carbon future. Hydrogen is mostly likely to be used to displace natural gas in industrial processes, either as feedstock or for the generation of process heat. It is also likely to have a role in heavy transport, either directly in fuel cells or indirectly as e-fuels made from it.  Lesser roles could include a fuel for peaking power generation and possibly in decarbonising domestic and commercial heating (by blending low-carbon hydrogen into the gas network).

The hydrogen value chain based on HM Government (2021)

Hydrogen can be used for transportation in three main ways:

1. In hydrogen-powered fuel cell electric vehicles (FCEVs), where hydrogen is stored and converted into electricity through a fuel cell to power the vehicle. This process is more efficient than traditional combustion engines and produces zero tailpipe emissions - only water vapour and air.

2. As a combustion fuel in hydrogen engines, where hydrogen is burned to generate thrust. This process results in no unburned hydrocarbons, carbon monoxide, or CO2 emissions, but it does produce nitrogen oxides, so will rely on exhaust treatment systems, such as AdBlue.

3. As an additive in diesel engines, where hydrogen is injected into the air intake. Typically this results in a 30% reduction in diesel consumption, and a greater than 30% reduction in emissions as the hydrogen increases the efficiency of combustion.

These approaches are in their infancy, although in recent years we’ve seen news of diggers and HGV cabs fuelled by hydrogen combustion engines at various stages of development. FCEV buses and HGVs are increasingly being deployed, particularly in China, North America and Europe, including the UK, while hydrogen fuel cell trains are being trialled in Europe and Canada.

Whichever technology emerges, there are challenges in adopting hydrogen as a mainstream transportation fuel. Hydrogen is far more energy dense when stored as a liquid than as a gas, however the process of liquifying hydrogen means cooling it down to a temperature below -250ºC. That process is energy intensive.

Achieving a 100% reduction in CO2 emissions through a switching to hydrogen also relies on a sufficient supply of hydrogen produced from electrolysis that uses 100% renewable electricity. Green hydrogen is available today, but currently accounts for a small percentage of all hydrogen produced globally, with most produced via much more energy - and carbon-intensive processes.

We’re working to help grow it though. Through our parent company World Kinect, we’ve recently invested in Meld Energy – a UK-based company who is working to deliver green hydrogen for industrial, ground transportation, and marine applications, both for the UK and globally.

Even so, developing a larger hydrogen economy requires tackling the ‘chicken and egg’ problem of growing both supply and demand at the same time: users must have access to hydrogen-using equipment, and a sufficient supply of green hydrogen must be readily available, and at the right price.


e-fuels may have a niche role to play for selected applications

Hydrogen can also provide an alternative to electrification through its use within e-fuels, which are synthetic alcohols, petrols, diesels and ammonia.

e-fuels are created by combining green hydrogen either with carbon from CO2 (to produce a liquid hydrocarbon fuel) or nitrogen (to produce green ammonia). These fuels can be used as replacements for fossil fuels in in internal combustion engines. Where no engine modifications are required (i.e with e-petrol and e-diesel), the fuels are known as drop-in fuels. In the case of e-methanol and green ammonia, engine modifications are required.

  • However, the production process for e-fuels is energy-intensive, and even when made using renewable power, a significant amount of energy is consumed in the production process.
  • This makes e-fuels unlikely to become a scalable solution for mass-market vehicles in the road transportation sector. They may find niche applications in collector cars or specific high-performance vehicles.
  • E-methanol and green ammonia are likely to find considerable application in the maritime sector, particularly for long-distance shipping, where their energy density greatly exceeds the alternatives. Even so, their lower energy density than bunker oil means that ships’ bunkers will have to be 230% larger to achieve the same range as a ship fuels by oil.


Renewable liquid fuels offer a ready-now, drop in solution

Unlike hydrogen and e-fuels, renewable liquid fuels like Renewable Diesel HVO offer an immediate solution to reduce carbon emissions without requiring major infrastructure changes or upfront investments.

HVO, short for Hydrotreated Vegetable Oil, is a liquid fuel synthesised from vegetable oils or animal fats. It is a second-generation biofuel with a different chemical composition than first-generation biofuels like Fatty Acid Methyl Ester biodiesel.

Renewable Diesel HVO is produced through a process known as hydrotreating, which results in a pure, clear, odourless liquid hydrocarbon fuel with minimal sulphur content. This fuel has a long shelf life and is stable in storage. It can significantly reduce local tailpipe emissions in diesel engines and offers improved burning efficiency.

Since it's not fossil-based and is produced from low-carbon sources, it has a significantly lower carbon impact compared to fossil diesel.

Renewable Diesel HVO is not the same as FAME biodiesel

As one of a number of paraffinic fuels, Renewable Diesel HVO is governed by a different fuel standard than regular diesel – the EN 15940 Paraffinic Fuel Standard. However, it is also so close in composition to its fossil fuel counterpart that it meets or exceeds the EN590 road diesel fuel standard in all properties, except for density.

In fact, the cetane number of Renewable Diesel HVO – a measurement of the quality or performance of the fuel – is much higher (>70) than that of regular diesel (>50), which means it burns more effectively.

Most engine and vehicle manufacturers approve HVO for use in their diesel engines. That means that renewable diesel enjoys another major advantage: they can make use of existing infrastructure, and can be used in existing diesel-powered cars and trucks as a drop in diesel replacement. Transitioning off-road and heavy-duty fleets to renewable diesel can therefore significantly contribute to decarbonising the transportation sector.

Awareness of Renewable Diesel HVO is growing. Recent research from Watson Fuels / YouGov showed that over a third of commercial fuel users are familiar with Renewable Diesel, while over 40% expect it to be important in helping the UK’s transition to Net Zero in the coming years*. Demand is also increasing, particularly within certain commercial and industrial sectors – businesses within manufacturing, construction and road transportation, for instance, are increasingly turning to Renewable Diesel to reduce emissions in order to meet supply-chain demands.

Supply and availability of Renewable Diesel is also increasing across the UK. Recent changes regarding antidumping legislation have served to open up the upstream supply market for HVO, and enable product to be imported from the US and Canada. That has served to increase the number of available suppliers and supply points for Renewable Diesel. And at Watson Fuels, we’re accelerating the rollout of regional Renewable Diesel storage across our UK depot network, in order to enable deliveries in more parts of the UK.

Renewable Diesel is also starting to become available at selected retail forecourts across the country. Esso recently confirmed it was piloting a Renewable Diesel blend, which is available for purchase at 20 Esso retail stations in South East England, while Phillips 66 has had Renewable Diesel at the pump at selected retail sites under its JET fuels brand since 2022.

The one drawback of Renewable Diesel remains its high cost versus regular fossil diesel. In the UK, on a per litre basis at time of writing it’s currently around 30% more expensive than fossil diesel. That differential may reduce over time with increasing economies of scale, but switching to Renewable Diesel today still requires additional investment from businesses looking to reduce their emissions.


A diversified, multi-solutions approach is needed to help decarbonise transport

The world is moving steadily toward lower-emissions mobility, and electric vehicles will be an increasingly important solution in driving that change. But electrification alone won’t be enough. Even when assuming greater uptake of EVs, a substantial part of the UK’s vehicle fleet will still be powered by internal combustion engines in 2030 and beyond.

Solutions other than EVs will be required to decarbonise key forms of land transportation. Hydrogen and e-fuels are likely to play future roles, in varying degrees. But renewable liquid fuels such as Renewable Diesel HVO, offer an immediate, drop-in solution for significantly reducing carbon emissions from existing ICE vehicles, and can be used in existing vehicles and without the need for significant modifications or infrastructure development.


Key Definitions:

Decarbonising Transportation: The process of reducing or eliminating carbon emissions and greenhouse gases from the transportation sector to address climate change and achieve a more sustainable and eco-friendly future.

Infrastructure: The physical and organisational structures and facilities required to support the operation of a system, in this context, the charging stations, refuelling stations, and distribution networks necessary for the operation of electric vehicles and other alternative fuels.

Renewable Diesel (HVO): A type of diesel fuel derived from renewable sources such as vegetable oils and animal fats. It can be used as a direct replacement for traditional diesel fuel, providing a more environmentally friendly alternative with lower carbon emissions.

Hydrogen Fuel Cell Vehicles: Vehicles that use hydrogen gas to generate electricity through fuel cells, emitting only water vapour as a byproduct. Hydrogen fuel cell vehicles offer the potential for zero-emission transportation, particularly suited for specific sectors such as heavy-duty trucks and long-haul transportation.

Carbon Intensity: The amount of carbon dioxide emissions produced per unit of energy generated or consumed. Lower carbon intensity indicates a cleaner and more environmentally friendly fuel or energy source.

LCVs (Light Commercial Vehicles): Vehicles designed for commercial use, such as delivery vans and small trucks, with a relatively light load-carrying capacity.

HGVs (Heavy-Goods Vehicles): Large vehicles designed to carry substantial loads, including trucks and buses. Sometimes also referred to as Heavy Duty Vehicles, or HDVs.

ICE (Internal Combustion Engine): a machine that burns fuel, like petrol, to create power for vehicles and machinery. It works by igniting fuel within a confined space to produce a controlled explosion, which drives a piston and generates mechanical energy.


* Watson Fuels commissioned YouGov to conduct a survey among business leaders who purchase or use liquid fuel in their operations to understand their views on becoming carbon neutral. This study was conducted among 500 businesses in Construction, Manufacturing, Transportation, Agriculture, Commercial Services and Airline industries , between 17th-24th January 2023.

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