RDME benefits begin to overshadow challenges

The fuel can exploit readily available feedstocks and is ahead of competitors in terms of production readiness, writes Matt Scotland

Scaling up production of renewable dimethyl ether (rDME) and blending it into LPG is the best way to rapidly decarbonise the LPG industry now, delegates heard at the International DME Association's DME 9 conference in Zurich on 15-17 June.

The LPG sector can develop rDME production "right now", whereas bio-LPG opportunities abound but are quite far back in terms of commercial deployment, global LPG distributor SHV Energy's sustainable fuels director, Rebecca Groen, said at the event. RDME represents the most promising solution for a circular, community-scale fuel that can exploit readily available feedstocks — whether that is agricultural residues, municipal solid waste or sewage sludge — in areas that do not have many alternatives for their energy needs, she said.

SHV and peer UGI International recently formed the Dimeta joint venture to develop six rDME production plants with a combined capacity of 300,000 t/yr across Europe and the US. The first of these 50,000 t/yr facilities will be built in the Teesworks freeport in northeast England by 2024. RDME is "multi-source and multi-process", Dimeta chief executive Soren Jacobsen told delegates. It can be blended up to 20pc with LPG and be sold as a drop-in replacement in most applications, he said. Its similar chemical properties and the fact it can be safely blended mean it can benefit from LPG's well-developed infrastructure and global supply chain networks, delegates heard. "We have a drop-in replacement fuel, which allows all of the investment in pipelines, trucks, camp stoves… to be leveraged," said US firm Suburban Propane's renewable energy vice-president, Douglas Dagan.

This contrasts with other renewable fuels that do not have the necessary infrastructure and supply chains in place, such as hydrogen. "There is some fine-tuning needed… but the infrastructure barrier is a significant advantage for DME over products like hydrogen," the Methanol Institute's chief executive Greg Dolan said.

Investors will need to secure the right feedstock to rapidly scale up rDME production. Only small amounts are produced in California by local firm Oberon Fuels, and sold in a propane blend by Suburban, while the 300,000 t/yr from Dimeta is a leap but not enough to decarbonise an industry that consumes over 300mn t/yr. But the burgeoning biomethanol market offers hope — DME is produced from methanol. Global methanol output is around 100mn t/yr but expected to rise to 500mn t/yr by 2050, 400mn t/yr of which will be renewable, Dolan said. In some cases, biomethanol is already cost competitive with methanol, with prices in a $325-800/t range. The industry also has the support of shipping firm Maersk, which is investing $1.4bn in 12 containerships that will run on biomethanol, and is seeking 750,000 t/yr of supply by 2025, and eventually as much as 6mn t/yr, he said.

Setting standards

The lack of supportive policies and regulatory frameworks is another barrier for rDME. But Oberon and Suburban are overcoming these in California, while Trinidad's Caribbean Gas Chemical and NGC Petrochemicals are helping to establish standards for their new LPG-DME blend. The absence of regulations, tax exemptions or even clear definitions of what is renewable in the EU is "really frustrating", LPG distributor Flogas Scandinavia's managing director, Thomas Edvardsen, said. But these issues are surmountable, and the LPG industry has an important role to play by providing already established demand for rDME, he said.

Flogas Scandinavia intends to develop a new rDME blending facility for its large industrial customers. "Our goal is to attract large-scale rDME production in Sweden and Norway," Edvardsen said. The product will be more expensive than LPG but cost competitive with other renewable fuels. "If our customers want to replace their fossil fuels, they have to accept it will be expensive," he said. "They need to commit to volumes, then we can activate large-scale production."