The majority of commercial fuels are manufactured from oil and gas based petrochemical feedstocks. However, following the announcement that the UK intends to ban the sale of new cars powered solely by either petrol or diesel fuel by 2040 (and with similar bans announced, to date, by France and China), the race is on to make alternative fuel technologies more efficient and affordable.

All may not be lost, though, for petrol and diesel powered engines. A new, future niche could have been found if a recent report by Bosch on environmentally friendly synthetic fuel is embraced by the automotive and petrochemical industries. In this regard, Audi, for one, announced in November 2017 the construction of a large scale manufacturing plant in Laufenburg, Switzerland for ‘sustainable’ diesel (see further below).

History of synthetic fuel

Synthetic fuel is not a new idea and its origins can be traced back to the early 1900s. In 1914, Friedrich Bergius built a synthetic fuel manufacturing plant to carry out his patented process (US1059818 A) that produced liquid hydrocarbons via the hydrogenation of coal at high temperature and pressure. Unfortunately, the First World War delayed production until 1919, after which demand decreased and the fuel became less commercially attractive. Bergius sold his patent to BASF where the technology was further developed. In 1931, Bergius went on to win the Nobel Prize in Chemistry alongside Carl Bosch (nephew of Robert Bosch) for contributions to the invention and development of chemical high pressure methods.

Bergius was not the only chemist to develop a synthetic route to hydrocarbonaceous fuel. The more widely known Fischer-Tropsch process was developed in 1925 and converts a mixture of carbon monoxide and hydrogen, also known as ‘syngas’, into liquid hydrocarbons. The Fischer-Tropsch process continues to be used in some commercial operations today as the syngas feedstock is commonly used in the production routes for ammonia and hydrogen, amongst other chemicals.

So what’s new?

The original Bergius and Fischer-Tropsch processes were not particularly environmentally friendly due to their high energy consumption and reliance upon coal or oil derived feedstocks. However, advances in the viability of renewable energy combined with developments in carbon capture technology have led experts to reconsider the potential of such processes.

In August of 2017, Bosch published the findings of a new report into the future of synthetic fuels. The Bosch experts determined that a process built upon the Fischer-Tropsch framework using only renewable energy to convert water to hydrogen, combined with a carbon feedstock based upon captured or waste CO2, could lead to a carbon neutral fuel. In theory, if the energy used is itself carbon neutral, the process should capture and consume the same quantity of carbon as is released during combustion of the fuel. Bosch believe that conversion of the existing European car fleet to this type of synthetic fuel in combination with the current trend towards vehicular electrification could save up to 2.8 gigatons of CO2 annually by 2050. For context, Germany’s CO2 emissions in 2016 are estimated at around 0.8 gigatons.

Dr. Volkmar Denner, chairman of the board of management of Robert Bosch GmbH said “Synthetic fuels can make gasoline- and diesel-powered cars carbon neutral, and thus make a significant contribution to limiting global warming”.

Bosch have been clear that they do not intend to manufacture synthetic fuels at this time. However, other organisations have already begun trials that could see Bosch’s vision become a reality. As early as 2015 Audi revealed details of their own research into environmentally friendly synthetic diesel production using the process shown below.

Audi’s trials appear to have been successful as a November 2017 press release announced the construction of a large scale manufacturing plant in Laufenburg, Switzerland.

The future of synthetic fuels

Cost has always posed the greatest hurdle to the commercial viability of synthetic fuels. Advances in renewable energy in conjunction with developments in carbon capture and processing will make such processes increasingly attractive. Innovation in the sector continues and, according to the World Intellectual Property Office (WIPO) PATENTSCOPE system, over 50 patent applications relating to synthetic fuel or syngas processes were published in the past two years.

The automotive industry is eager to retain the applicability of the decades of knowledge, innovation and development in the field of combustion engine technology. Among other benefits, acceptance of carbon neutral hydrocarbonaceous fuels would allow continued use of existing fuel infrastructure. Unfortunately, hydrocarbon fuels may struggle to recover political favourability following the global backlash against petrol and diesel vehicles. However, alternative systems such as hydrogen or electrical power are currently unsuitable for powering large scale aircraft or shipping vessels and it is in these areas of long distance transportation that synthetic fuels are expected to provide the largest economic and environmental impact.