26 May 2019
KITT/IASS - Producing CO2 free hydrogen from natural gas for energy usage

 

By Dr. Alexander Gusev, former IASS Employee
Spring 2019


KIT / IASS won the GERMAN GAS INDUSTRY INNOVATION AWARD for innovative technology to help achieve a low-carbon energy future after 2050.

The associations of the German gas industry, under the auspices of the German Federal Minister of Education and Research, Ms Anja Karliczek, awarded the 20th GERMAN GAS INDUSTRY INNOVATION AWARD to honour innovative developments and concepts from industry, skilled crafts, trade, and science. The award in the category “Research and Development” went to the Karlsruhe Institute of Technology (KIT) and the Institute for Advanced Sustainability Studies (IASS) in Potsdam for their joint work on the technological innovation of methane pyrolysis. This innovation was also the subject of a professional workshop in which participants discussed several issues, including how the technology can be used on an industrial scale in the future.

What role can natural gas play in a low-carbon energy future? And how can it contribute to the achievement of the global climate goals? More and more experts from politics, science and the energy industry have come to the realization that a fully electrified energy transition based solely on renewable energies is neither technologically nor economically feasible. The focus will therefore be on technology-open approaches that concentrate on gradual carbon avoidance through energy efficiency, replacement of the particularly carbon-intensive energy sources coal and oil, and the gradual transition to low-carbon energy sources within the existing infrastructure.

Hydrogen production from natural gas to accompany renewable energies
In addition to hydrogen from wind energy, another low-carbon energy carrier is CO2-free hydrogen from methane. Corresponding technologies are currently under development, and the next step will be to build the systems that will make it possible to use them efficiently and economically on an industrial scale. Currently many experts favour methane pyrolysis. Professor Dr Thomas Wetzel from KIT Karlsruhe explained this procedure in a professional workshop. The procedure, which involves splitting natural gas into hydrogen and solid carbon (graphite / black carbon), does not generate any harmful emissions. While hydrogen can be used as a clean energy source in a low-carbon energy system, the by-product of the pyrolysis, solid black elemental carbon (graphite), can be used as an industrial raw material for the production of steel, batteries, carbon fibres as well as numerous carbon-based structures and materials. In that way this process could potentially also contribute to reducing emissions in other sectors.

Two cracking products can be fully utilized
If you compare the entire life cycle of both technologies, methane pyrolysis within a liquid metal reactor releases significantly fewer emissions compared to water electrolysis with renewable electricity, says Dr Alberto Abánades from the Polytechnic University of Madrid.

With regard to the economic viability and market potential of the technology, Dr Abánades states that it is currently possible only to estimate the full costs and revenues to be expected. What is however clear is that in this new clean hydrogen production technology all outputs are valuable commodities (e.g. hydrogen, heat, and solid carbon/graphite). In general, however, hydrogen and carbon can be produced at competitive production costs compared with other procedures if the carbon price is €50 per ton.

Dr Abánades says, though, that a more accurate cost-benefit analysis also depends on how the markets for carbon and hydrogen as raw materials evolve in the future, but that significant market potential exists for both products. With regard to applications for hydrogen, he says the possibilities include use in fuel cells, for power generation, in hydrogen-powered vehicles and as a raw material for the production of ammonia. Carbon could be used in a number of applications, including the production of steel, as a conductor for batteries, carbon fibres and even enhanced building material. Although the market for high-grade elemental carbon is currently still small, there is great potential for the material, especially in Europe, according to Dr Abánades. While 70 per cent of the currently produced carbon comes from China, Europe contributes just one per cent, although it consumes ten per cent of the total produced.

Long-term integration into the energy systems to achieve the climate goals
Gazprom also pointed out possible business models for the future use of CO2-free hydrogen generated from natural gas, saying they could be an important method for reducing carbon emissions. With regard to the national and international climate goals, the company says this energy source could play an important role in minimising carbon emissions if it is integrated more strongly into the energy system.

One of the ways to reduce the carbon footprint will be to blend natural gas with hydrogen, into a new product called "Hythane" and thereby establishing a low-carbon energy product. However, the first step is to transition in the energy and transport sectors from coal and oil to natural gas, for example through power plants based on natural gas, cogeneration of heat and power, and natural gas vehicles.

Taking this step would already cut back between 13 and 18 per cent of total carbon emissions in the European Union compared to 2016 (or 35 to 39 per cent compared to the 1990 reference year), according to Gazprom. If in the next step methane-hydrogen mixtures are used in these sectors, the EU’s 2030 climate targets could be achieved without costly changes in the distribution systems. Overall, a 25 to 35 per cent carbon reduction is possible compared to 2016 (45 to 51 per cent on 1990). And finally, says the company, switching energy systems to hydrogen from methane as the main source of energy could achieve an 80% reduction in carbon emissions in the European Union by 2050.

Gazprom's assessment matches the findings of the "Integrated Energy Transition" lead study published last year by the German Energy Agency (dena). According to this study, demand for hydrogen with the lowest possible carbon content will increase in the coming decades from around 30 terawatt hours (TWh) in 2030 to more than 150 TWh in 2050. In fact, these are conservative assumptions that assume usage primarily in the industrial and mobility sectors. If the use of hydrogen and renewable syngas also progresses in the energy sector, the need could even rise to more than 900 TWh.

The natural gas industry is already making progress in this regard and is using hydrogen-methane mixtures for the operation of compressors in gas transport. As a result, carbon emissions can be reduced by around 30 per cent, according to initial analyses.

Conclusion
Methane pyrolysis is a very promising alternative to minimise the carbon footprint in the energy system. CO2-free hydrogen produced from natural gas is a very relevant opportunity, not only to reduce CO2-emissions of the energy industry as such, but also as a basis to make an important contribution to achieving the 2050 climate objectives of the European Union.


The procedure uses a reactor based on liquid metal technology for the pyrolysis. Small methane bubbles are placed in this reactor from the bottom into a column filled with molten tin. As they rise in the liquid metal, the cracking reaction takes place. The carbon is secreted onto the bubble surface, and when the bubbles disintegrate, the carbon is deposited as a powder at the top of the reactor (solid, black, elementary carbon). In the laboratory set-up, the reactor ran in a continuous operation for two weeks and produced hydrogen at a conversion rate of up to 78 per cent at temperatures of around 1,200 degrees Celsius. The successfully-tested continuous operation is the crucial requirement for future, comparable reactor types on an industrial scale. Modern digital technologies can help to implement the procedure in a particularly economic manner. Falling prices for sensor technology and micro-controller devices lead to substantial cost advantages in this regard. Smart sensor technology and Big Data analysis methods can be used, for example, to enable automated, predictive maintenance.

Alternative methods for breaking down methane include plasma arc technology or iron ore catalysts. Although these methods are already more developed than the procedure with a liquid metal reactor, the latter is superior to the other methods in terms of material use and costs, as well as energy consumption and safety, according to expert opinion. In addition, Gazprom is currently developing further procedures that are suitable for smaller applications and which are characterized by lower specific energy consumption per cubic meter of hydrogen produced.