Renewable Liquid
Gases – Three To
Watch

Liquid gas is an important transition fuel, given its lower carbon emissions relative to other fossil fuels. Renewable liquid gases could be the next step towards cleaner energy – here’s how.

Liquid gas, often referred to as LPG (Liquefied Petroleum Gas), is made from butane or propane molecules. It plays a critical role as a clean-burning hydrocarbon for customers who don’t have the option of on-grid natural gas for cooking, heating or industrial processes. ‘Liquid gas’ may seem a contradiction in terms since all things in nature are either a liquid, solid or a gas. Yet, liquidity is the unique character of liquid gas that makes it such a popular and widely used fuel. At normal temperature and pressure, liquid gas is gaseous, but it changes to a liquid when subjected to modest pressure or cooling, which allows for efficient storage and transportation.

Liquid gas is extremely useful for the here and now, and we’re committed to building credible pathways for our customers to transition to even lower-carbon alternatives. So, what’s next, and why does this look so promising?

What is biopropane and how is it made?

Biopropane is chemically identical to fossil propane – and it’s sometimes referred to as bioLPG or rLPG. Today, the main source of biopropane is the refining process for Hydrotreated Vegetable Oil (HVO or renewable diesel) and Sustainable Aviation Fuel (SAF). When biopropane is captured as a by-product in this way, it typically represents 5-10 per cent of HVO or SAF output.

Why it’s so good

Biopropane is a drop-in alternative to liquid gas: switching is simple – you don’t have to change your infrastructure or appliances and there’s no disruption. Depending on the vegetable oils used as input, HVO biopropane has 70-80 per cent¹ less CO₂ emissions than fossil propane on a lifecycle basis.

What’s biopropane’s place in the cleaner-energy mix?

Biopropane production is already commonplace and projected to grow. In Europe, the need for SAF to meet aviation decarbonisation targets is driving investment in biorefineries which will vastly increase biopropane production. Given other uses for biopropane (particularly in petrochemicals) and the limitations on available feedstock, we anticipate biopropane could substitute up to 15 per cent² of non-petrochemical liquid gas demand by 2030 in Europe.

What is rDME and how is it made?

rDME is the renewable version of dimethyl ether (DME). The majority of DME today is produced with methanol from fossil fuels and is used in various chemical products and as an aerosol. Renewable DME was developed as a substitute for liquid gas and diesel. In the past few years, there’s been a scale-up in methods of producing renewable methanol and rDME. Farmyard manure, household rubbish, black liquor (produced during chemical paper and pulp manufacturing), energy crops and forest products can all be turned into rDME. Another option is to produce methanol and rDME from green hydrogen and captured carbon.

Why it’s so good

Depending on the feedstock and production process, rDME produces up to 85 per cent^1,3 fewer CO₂ emissions than fossil fuels. Unlike the majority of biopropane produced, rDME isn’t a by-product of other processes, so production is more easily scalable. Blended up to 12 per cent with liquid gas, rDME can be dropped in to existing liquid gas infrastructure; above that, some modifications to seals, piping and tanks may be necessary.

What’s rDME’s place in the cleaner-energy mix?

We expect this gas to be a major contributor to the renewable liquid gas transition, with dedicated rDME production units on the drawing board in the US and Europe. Separately, the way it gets over the challenges of transporting hydrogen has piqued interest in it as a low-cost hydrogen carrier.

What is green ammonia and how is it made?

Ammonia contains no carbon – it’s a low-cost, zero-emissions fuel. One way of making ammonia is to fuse the hydrogen in water with nitrogen from the air using water electrolysis. Ammonia becomes ‘green’ ammonia when the electricity for that process comes from renewables like solar or wind power.

Why it’s so good

Ammonia has a higher energy density than any form of hydrogen. It makes a good hydrogen carrier and it’s easy to transport using existing infrastructure. With new ammonia import and storage terminals on the way in Europe, green ammonia will likely become more widely available by 2030.

What is green ammonia’s place in the cleaner-energy mix?

Cargo ships that spend weeks at sea without refuelling are likely to be first users, along with high-temperature industries. Flogas Britain, a DCC Energy business, and Cardiff University have formed a consortium, with government funding, to develop the world’s first ammonia steam boiler. This avoids the cost of having to crack the ammonia back to hydrogen before it’s burned as a fuel. Any downsides? Ammonia is toxic, so training in handling it is crucial.