HyGear together with project partners investigated the feasibility to produce hydrogen from biodiesel. The green hydrogen can be used in fuel cells to generate electricity for vehicles and domestic appliances. This route to hydrogen is especially interesting for remote areas difficult to access by road infrastructure. The study showed its feasibility from both technical as economical perspective.

Advantages of hydrogen

Hydrogen is called the energy of the future for several reasons. First reason, and one of the most import reasons for this study, is the fact that combustion engines are less efficient than fuel cells. So, you can drive more kilometres on hydrogen than on the same energetic amount of (bio)diesel, gasoline, (green) gas etcetera. So although it sounds illogic to first convert a fuel into hydrogen instead of directly driving on the fuel, it is very logical indeed.

Second reason, by using hydrogen as energy carrier, the only emission is water. Movie stars Joshua Jackson and Diane Kruger demonstrated the purity of the exhaust water by drinking it during their Mercedes F-cell car road trip through the desert. By driving on hydrogen, cities won’t suffer from harmful emissions.

And third reason to favour hydrogen is that it can store surpluses of electricity. The hydrogen can be converted into electricity or natural gas when and wherever needed.

Hydrogen generation

The most effective way to produce hydrogen is by steam methane reforming (SMR). In this chemical reaction the hydrocarbons are split in hydrogen and carbon-oxides by using heat and steam. Hydrogen is predominantly produced by this method by central production plants on a large-scale. Central hydrogen production will suffer from additional costs associated with the distribution of gaseous-phase hydrogen by trailer over long distances. HyGear has scaled down this process into a small sized chemical plant (the Hy.GEN) with the same efficiency as these large-scale plants. The Hy.GEN can be installed at the end-user’s site, making transportation of hydrogen gas obsolete. On-site hydrogen production is widely seen as a promising alternative in the transition phase towards a fully renewable hydrogen production economy.

Green reforming of biodiesel

Instead of fossil sources, renewable sources like biogas can be used to generate hydrogen. Biodiesel, produced from vegetable oils, is most favourite to use as feedstock for the hydrogen production for fuel cell cars. It is a renewable and non-polluting resource with a high energy density and low sulphur content. Also, biodiesel can easily be integrated in the already existing supply infrastructure of gasoline and diesel.

Technical feasibility

In the past years, several experimental studies have been conducted shedding light on biodiesel steam reforming. Although considerable progress had been made, the low-cost biodiesel reforming is still in an early phase of research and development. Therefore, HyGear and project partners conducted research to improve the performance and decrease the investment and operational costs by maximizing system efficiency.

Conventionally, the maximum efficiency is obtained by requiring a complex and costly heat exchanger network. In this study a novel fuel processor for steam reforming of biodiesel is proposed, based on a fully heat integrated system. By simulating the process streams in a computer model, the optimal set point for reformer performance and PSA yield was calculated by varying the pressure and heat. To be more specific, a higher pressure leads to a higher production yield, but will consume more power. By utilising the combustion of the PSA off-gas, the heat integration of the system was further optimised.

Economical feasibility

It can be concluded that an energy efficient and cost-effective biodiesel reforming system is technically possible due to advanced system integration. The techno-economic evaluation reveals hydrogen production costs ranging from 5.77 €/kg to 11.15 €/kg, depending on the biodiesel market price. With 6-11 eurocents per kilometre, compared to approximately 8 eurocents for gasoline cars, this is a very reasonable price for cleaner and greener road transport.

Acknowledgement

The study (Nemesis 2+) has been conducted by HyGear, the German Aerospace Center, Johnson Mattey, Abengoa, Centre for Research and Technology Hellas and Instituto Superior Technico. The research started in 2013 and was funded by Europe’s Fuel Cell and Hydrogen Joint Undertaking under Grant Agreement No. 278138. The complete scientific article can be read in the International Journal of Hydrogen Energy, volume 41, issue 16 or can be downloaded here.