Germany-based cleantech company Sunfire in April started producing synthetic diesel – which does not contain any sulphur or fossil oil – from air, water and green electrical energy at its power-to-liquids (PTL) demonstration rig in Dresden.
The rig uses Sunfire’s PTL technology to transform water and carbon dioxide (CO2) into high-purity synthetic fuels with the aid of renewable electricity. PTL fuels, which are also known as ‘e-fuels’, can be used in pure form or as an admixture in combination with conventional fuels. They are recognised as an environment-friendly, resource-saving alternative, which contributes to the fulfilment of greenhouse-gas quotas.
Sunfire built the unique demonstration rig for PTL technology, which was inaugurated by German Minister of Education and Research Johanna Wanka in November 2014. Wanka noted at the inauguration of the rig: “The Sunfire process reduces CO2 emissions and reduces our dependence on oil.
“It therefore represents an opportunity to protect our climate, save resources and, at the same time, promote a new technology, which promises to deliver economic growth,” she said.
Wanka also highlighted that the significant benefit of PTL fuels is that existing infrastructure, such as filling stations, pipelines and motors can continue to be used without modification. “This paves the way for sustainable mobility based on renewable energies,” she said.
The PTL plant reached its full operating condition and now produces synthetic diesel fuel. On behalf of Sunfire’s project partner, automotive manufacturer Audi, an independent laboratory confirmed that the outstanding characteristics of the fuel are superior to the properties of fossil fuel.
Audi exposed the synthetic diesel to laboratory tests, resulting in the fuel being approved. The analysis showed that its properties are superior to fossil fuel.
“The engine runs quieter and fewer pollutants are being created,” says Sunfire CTO Christian von Olshausen. The cetane number is high, roughly 70, and ensures a cleaner and better combustion as a blending component for conventional diesel fuel.
The PTL technology reaches system efficiencies of about 70%. The centrepiece of the three-stage procedure is the reversible electrolysis (rSOC) based on the solid oxide power core. The rSOC generates hydrogen with an efficiency of about 90%.
The main advantage is when electricity prices rise to a level that makes hydrogen production unprofitable: after a short turnaround interval, the system can be switched to fuel cell mode and used to convert hydrogen reserves or any another fuel back into power and heat.
Moreover, Sunfire filled an Audi A8, used as the official car by the Minister, with a few litres of the synthetic fuel. The Ministry supported the development of the manufacturing plant in Dresden. The new fuel is a synthetic diesel-distillate based on Blue Crude, or hydrocarbons.
The scalable PTL demonstration rig is able to produce up to 160 ℓ of Blue Crude per day. In future, a bigger plant is envisioned. “If we get the first sales order, we will be ready to commercialise our technology,” Von Olshausen says.
Sunfire, one of the top 100 companies in clean technologies worldwide, is also supported by several corporate venture capital companies and funds, including Bilfinger Venture Capital, Total Ventures, KfW and Electranova Capital, a venture capital fund financed by Allianz and EDF.