(515b) Alternative Transport Fuels and Their Production Using Surplus Renewable Electricity, Water and CO2

Electrical power generated from wind energy fluctuates strongly. As put forward by the EU Commission, in 2050 80 % of the electricity demand should be covered by renewables. Therefore, the integration of fluctuating electricity generation from renewables plays a fundamental role in Europeâ??s and especially Germanyâ??s future energy system. Additionally for 2050, the EU Commission postulates a reduction of anthropogenic CO₂ emissions of about 80-95 %, compared to 1990. In Germany, the transport sector was accountable for approximately 20 % of the domestic CO₂ emissions in 2014, while contributing 30 % to the domestic energy demand. One reason for this high share is that 90 % of the transport sector is run on fossil fuels. Hence, to achieve the goals for 2050, non-fossil alternative fuels need to be found. A popular option is the further integration of fuel cell cars. However, especially for heavy duty vehicles and planes, there is long term need for liquid fuels such as diesel and kerosene. Another promising option is the idea of Power-to-Fuel (PTF): the synthesis of fuels based on sustainably produced hydrogen and usage of CO₂ as a feedstock. The energy required to run those processes can be provided by surplus electricity from renewable sources. This is energy which cannot be fed into the grid when there is no demand on the consumer side.

If an alternative renewable fuel is able to penetrate the market, two main requirements need to be met: its potential for an implementation strategy into an existing market as well as a technically feasible and economic production. Put differently, a renewable fuel should not require a significant alteration of the fuel infrastructure, thereby allowing a gradual integration in the existing infrastructure. Additionally, a range of different fuels for different usages need to be offered. Just as the fossil fuel market, the renewable fuel market needs diversification.

At the Institute of Energy and Climate Research (IEK-3) of Forschungszentrum Jülich, intensive research is being carried out on a comparable overview of the several products and process routes of PTF. In this contribution, investigations on two different routes from synthesis gas to an alternative renewable fuel will be outlined. The respective products of the two outlined processes are Fischer-Tropsch (FT)-diesel and polyoxymethylene dimethylene (POMDME). Both products can be blended with conventional diesel and with each other because they have appropriate compatibility. Therefore, an implementation strategy into the existing fuel market is practicable.

Despite an equal product application, the comparison of both technologies is widely diversified. At the molecular level, FT-diesel is closely related to conventional diesel; this applies less to POMDME. POMDME also has a considerably lower heating value; however, it has great potential as a fuel due to its beneficial combustion properties.

Although nowadays FT is not used for PTF in large scale, state-of-the-art FT-processes have been used industrially for many decades. In contrast to FT, owing to low product demand, processes for POMDME have not yet been developed on an industrial scale. Both processes have various options for the interconnection of system components and for complete process control. The systemâ??s interconnections as well as the process parameters have influence on raw material and energy demand and also product quality, co- and byproducts. Just as the product specifications, the process analysis results will play an important role in the fuel implementation strategy.