One of the biggest challenges with using hydrogen to power the future is the cost of the infrastructure. An international consortium comprising 39 partners with industry expertise from gas companies, gas research institutes and universities has been participating in the NaturalHy project, a five-year project to study the feasibility of using the existing natural gas pipelines to deliver hydrogen to end users.
“When talk of the so-called hydrogen economy comes up, it is mainly driven by the idea of sustainability,” said Project Director O.O. Florisson. “Of course, the environment is an important issue for the natural gas companies, and they have taken a lot of initiatives to make the transportation and use of natural gas more environmentally friendly. Hydrogen offers an interesting opportunity to ‘green’ or de-carbonize natural gas.
On the other hand, we must do things safely with acceptable consequences for the gas system and with cost-effectiveness high on the agenda. All of these considerations are present as we carry out our work today.” Though hydrogen may prove to be an important energy carrier and an essential element for global sustainable development, there are many significant challenges to face when implementing a complete energy system based on hydrogen. However, global interest in hydrogen as an energy carrier remains strong, as does commercial competition, which is emerging from the European Union (EU), Japan and the United States.
The aim of NaturalHy is to test all critical components of a hydrogen system by adding hydrogen to natural gas in existing networks. This transitional approach will provide further experience with the transmission of mixtures of hydrogen and natural gas, and by means of innovative separation technologies, the hydrogen utilization instationary end-use applications.
“We concluded that through the use of the natural gas system already in place, a smooth, short-term introduction of hydrogen into society at a relatively low cost by using the existing widespread natural gas system might be a good fit,” added Florisson. “Adding hydrogen to natural gas affects the physical and chemical properties of the gas and might have an impact on such things as the safety aspects of transmission, distribution, end use, pipeline durability, pipeline integrity or even the performance of the end user’s appliances. Therefore, the extent to which the existing natural gas system can be used for hydrogen delivery depends strongly on the local situation.”
This is the only realistic solution to large-scale distribution of hydrogen in Europe in the next 30 to 50 years, according to Florisson. The basis of this view is that significant financial and economic benefits can arise from the use of the existing infrastructure with its inherent economic value of several hundred billion Euros. Using the existing gas infrastructure for the change to a more sustainable economy accelerates the transition rate and innovations in all relevant fields.
“The natural gas companies wanted to prepare themselves to participate in transporting hydrogen and hydrogencontaining gases produced from industrial gases or from gasifiers,” said Florisson.
The risk areas investigated relate to the high-pressure transmission, distribution and use of hydrogen/natural gas mixtures. Large-scale safety experiments have been carried out at the Spadeadam test site in northern England, in addition to basic combustion characterization work done at the University of Leeds. Assessments have been made of the combustion properties, focusing particularly on the proper function of appliances.
A variety of membranes that separate the hydrogen from natural gas near the end users, have been developed for the project. One type is based on carbon and another on palladium. The risk aspects of hydrogen versus natural gas remain under consideration. The diffusion of hydrogen into the pipeline material can have a negative effect on the mechanical properties of the material. Consequently, activities have been defined on degradation of pipeline material due to hydrogen. The work, for instance, concerned the acceptability of corrosion defects and sharp defects contained in these brittle zones. In order to update the associated assessment criteria and maintenance procedures, repair techniques and equipment were needed to assess the integrity of steel pipelines in the presence of hydrogen and natural gas mixtures.
But before answering the question of whether using the existing natural gas system for hydrogen delivery is environmentallybeneficial, the life cycle ofthe whole system has had to be assessed and compared to its alternatives. Lifecycle and socio-economic assessment workbooks take this into account and make calculations regarding the whole process, including the production ofhydrogen and all related activities.
“The NaturalHy project is now in its completion phase,” revealed Florisson. “The tests, calculations, analyses and other measures have more or less been completed now, and their outcomes are being implemented in the Decision Support Tool, which is the main technical deliverable of the project.” This is a software program tool that helps gas companies detect points in the system that determine the permitted hydrogen percentage in the gas mixture. This, in turn, can be applied to a certain region or element of the system and it pinpointswhere any difficulties may arise.