Development of hydrogen technologies is mainly pursued because of the potential to store energy from intermittent energy sources and to provide an alternative fuel for transportation.
Regarding energy storage, the starting point is the realization of the new conditions that will likely prevail in the future energy systems, and specifically in electric power systems. From both the environmental and security of supply viewpoints, energy production from indigenous renewable sources is highly recommended. However, most renewable energy is actually renewable electricity, and most of it is “intermittent”, that is, not available on command but subject to uncontrollable conditions (time-of-day, cloud cover, wind, et caetera). Large-scale economic electricity storage cannot be addressed with present technologies, which poses difficulties for deployment of intermittent renewable electricity in Europe as generation must balance demand at any moment. Use of electrical energy storage facilities is a must if Europe intends to obtain renewable electricity in amounts similar to those of fossil fuels based electricity today, without investing huge amounts of capital in back-up facilities to cover the gaps when renewable generation is not available. Other energy storage technologies that could fill this role also deserve attention.
Hydrogen could also be a substitute of hydrocarbon-based liquid fuels for transportation uses. Arguably, transportation poses the most difficult challenge in the process of de-carbonizing the world economy and freeing Europe from the need of importing most of its primary energy. Other alternatives are biofuels, which could be limited from the availability of land that may be needed for other purposes, and electricity, which appears to have a major potential as plug-in hybrid cars may constitute a new paradigm for future road transportation, especially if improved batteries are developed soon.
A weakness of the hydrogen path in the design of a more sustainable future energy model is the need for further significant technological development along all of the hydrogen chain; namely the processes of production, transportation, distribution and final use of hydrogen.
Hydrogen can be produced from fossil fuels, by water electrolysis or possibly from nuclear power. Presently, the dominant technology is natural gas steam reforming. The procedure, as any other that is based on fossil fuels, results in the emission of carbon dioxide. Therefore, sustainable large scale hydrogen production from fossil fuels will require CCS (Carbon Capture and Sequestration). Besides, if hydrogen were produced from natural gas, European security of supply problems could be seriously amplified.
Water electrolysis is a well-known, commercially available technology for very pure hydrogen production. It would have the additional advantage of allowing decentralized operation, therefore easing the infrastructure building effort as compared to production from fossil fuels, biomass or nuclear energy. However, significant reductions in the costs of electrolysis equipment and improvements in efficiency would be required in order for electrolysis to become commercially viable.
Nuclear energy could provide an electricity source for hydrogen production, if general concerns about security, environmental impact and cost are met in the wider arena of electricity generation by nuclear plants. There are also proposals for direct hydrogen production by high-temperature water thermolysis, although commercial systems are still to be built.
If hydrogen is to become an energy vector with the same footing as electricity today, vast amounts of investment in building infrastructure are to be needed, especially if it is produced in centralized facilities either from fossil fuels or by water thermolisys in nuclear plants. It is worth pointing out that the amount of energy that would have to be carried is expected to be greater than the amount that is presently transported in natural gas pipelines, not being the required technology simpler in any way.
Use of hydrogen in transportation is viewed by many as the real justification of a hydrogen economy. At present, applications are limited to demonstration projects and niche applications, in which cost is a secondary concern. Widespread adoption hinges in technological breakthroughs that allow cheaper fuel cells and, more importantly, improved ways to store hydrogen in vehicles in order for them to boast ranges commensurate with those of present gasoline cars. Use of hydrogen in automobiles highlights the need and difficulties of developing an infrastructure that makes them to the users as attractive as gasoline cars.
Even if some hydrogen technologies have been well-known for a long time, it is widely felt that a significant effort in R&D is still needed, and that plans for deployment in the near future are premature. Therefore, an increased R&D effort is advised, especially when it is taken into account that most hydrogen technologies could play a significant role in the future energy system even if this one were not to be based on hydrogen. For instance, hydrogen from coal technologies are important in connection with cleaner coal, hydrogen fuel-cell cars are nothing else that electric cars in which the batteries have been substituted by a fuel-cell and a hydrogen tank, and nuclear fusion is a worthwhile object even if only used to generate electricity. There is a host of other hydrogen technologies, as direct thermo-solar hydrogen generation or photo-biological hydrogen production that are not only fascinating and potentially relevant, and whose development could provide important breakthroughs in other energy technologies as by-products. However, they are still in an infant stage, and more research is required.
There is also widespread support to the notion that the required research efforts should not detract from other and possibly more urgent energy research areas, but rather complement them. There is a consensus that European research effort in energy is clearly insufficient, and it has been advised to increase it by an order of magnitude.
Julian Barquin and Ignacio Perez-Arriaga, Universidad Pontificia Comillas
P.S. This Policy brief is informed by the work of the CESSA project, especially by the CESSA Conference held at Madrid from April 14 to 15, 2008.