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BRHS /
StationaryThe previous chapter was dealing with mobile applications for a hydrogen economy including the necessary stationary applications to build an infrastructure to make these mobile applications feasible like hydrogen refueling facilities. The application of hydrogen driven fuel cells are also thought to be valuable in other stationary applications e.g. in households. Field tests are being performed in several countries e.g. in Germany and Norway to show the feasibility of a combined electrical power and heat supply for households utilizing e.g. PEM or SOFC fuel cells. While in mobile systems PEM cells working at low temperatures -e.g. giving fast start up times - are the most suitable solution presently, stationary systems may benefit from high temperature type fuel cells as e.g. the SOFC (solid-oxide fuel cell) systems. These are working at about 700 to 900O C and have the advantage of being less sensitive on impurities in the supplied hydrogen and being able to internally convert natural gas and other fuels. (see figure 1 and 2) (PalssonJ:2003). The higher operating temperature is in the stationary application considered as an advantage as it makes the utilization of the waste heat easier. Fuel cell (e.g. SOFC) cannot only provide electrical power, but also can work in an inversed mode as electrolysers producing hydrogen, see also chapter 1.3.2.2. This potential flexibility would be important for a future strategy of decentralized electrical power supply, as this flexibility will help stabilizing the demand of electrical power. The role would be to act as a “power station” for periods with large demands of electricity and as a “consumer of electricity” for periods of excess production of electricity, e.g. in wind power systems. In such future systems the natural gas supply grid would be connected with the electrical power grid. It also would make it possible to establishing private hydrogen refilling stations e.g. for overnight refilling of the family car. For economic reasons, a wide hydrogen supply infrastructure for industrial or residential applications is not expected to be in place in the foreseeable future. Until a suitable hydrogen supply infrastructure is developed, fuel cells for industrial and residential use will typically be fuelled through conversion to hydrogen of natural gas, LPG or methanol. According to the Hynet report this technology has an expected market entry of between 2006 and 2008. Stationary applications can be divided in
and the general design of a fuel cell power system as described in the (IEC:TC105:2005) draft standard on stationary fuel cell systems (working group 3) shall form an assembly of integrated systems, as necessary, intended to perform designated functions, as follows:
coverts, typically, hydrogen rich gas and air reactants to dc power, heat, water and other by-products.
Most of the technologies (electrolysers, fuel cells, instrumentation, storage, compressors) are currently available or developed for commercialisation for operation with i.e. natural gas. Although several hydrogen specific end-use technologies such as gas turbines, internal combustion engines and also Stirling engines exist, fuel cells are believed to have the best chance for widespread commercialisation in stationary hydrogen energy systems as they provide highest efficiencies and a number of other structural advantages. For specific tasks such as compression for pipeline transport, gas turbines or during the transition phase towards a wide hydrogen use, gas internal combustion engines can become viable options.  Figure 2: Principal of NG reforming utilizing PEMFC (see ([[http://www.hysafe.net/wiki/BRHS/Stationary?action=bibentry&bibfile=DB&bibref=PalssonJ:2003 | PalssonJ:2003 Δ))]] However, the future use of hydrogen entering the stationary market as a viable fuel will be dictated by infrastructure. It is expected that in the longer term, i.e. after 2020, a hydrogen infrastructure for stationary applications could develop. The success of this will depend on a number of factors including the degree of decentralization in stationary energy markets, energy demand reduction, the need for load leveling capabilities for renewable energy and the success of competing technologies such as combining a hydrogen admixture to the natural gas in the existing grid. Additionally carbon capture schemes for large-scale centralized power generation could be based in the future on natural gas reforming or fossil fuel gasification technologies, with large scale production of hydrogen and its consumption in efficient combined cycle gas turbine (CCGT) schemes. These different options will have to be tested, with lighthouse demonstration projects being a viable way of achieving this. A current limiting step in these demonstration projects is the lack of small reformers for fuel cells in the 1 - 10 kWel class. A possible means of bridging this technology gap could be to use local hydrogen distribution grids fed with hydrogen from either commercially available central reformers, electrolysers or from by-product hydrogen. In this way, a hydrogen infrastructure for stationary supply would evolve from local clusters. It is not expected that the direct use of hydrogen to provide power for industrial or residential use will play an important role in the short-medium term. However, longer term, an increasing amount of hydrogen for use as an energy buffer may be required. The development of the necessary infrastructure will have to be adapted to the changing needs of the evolving decentralized energy markets. It will likely start with local and virtual hydrogen supply islands. References IEC-TC-105 (2005) Fuel Cell Technologies - Part 3-3: Stationary Fuel Cell Power Plants - Installation..(BibTeX) |
