Recent Changes - Search:




edit SideBar

Large Scale Vs Small Scale And Centralized Vs Decentralized Production

At present, most hydrogen is produced on-site in commercial, large-scale SMR units dedicated to the needs of the chemical and petrochemical industries. On-site production means flexible, on-purpose production with low or no transportation cost. In contrast, centralized hydrogen production refers to large-scale systems connected to a hydrogen delivery/distribution network transporting the H2 to the point of use in gaseous or liquid state via pipeline or truck. Centralization allows for a secure and stable supply. Centralized large facilities are usually the result of efforts to decrease specific production cost by increasing the unit size (economy of scale). Also the use of nuclear primary energy as well as large hydro-electric power only makes sense for centralized H2 production on a large scale. . Renewable energy sources with their low-density energy and typically intermittent operation mode will be typically constitue a dispersed system of H2 generation plants. They can also be used to generate electricity and provide it to the grid at any place. The same applies to H2 from biomass plants which will be limited in size simply because of the difficulty to transportbiomass. Natural gas could be used for both centralized and decentralized H2 production.

Advantages of decentralized distributive generation of H2 is the ability to take benefit of the existing and widely available grids for electricity and natural gas. For future applications of hydrogen as part of the energy economy, the installation of a network of small-scale H2 production units appears to be a good short-term approach for the introduction phase. Market prospects for stationary and mobile fuel cell applications have already led to the development of small-scale H2 units on the prototype level to either be part of the required infrastructure for fuel cell vehicles or for feeding local grids for residential stationary fuel cell systems. Small SMR or electrolyzer units, which are competitors at this scale, are attractive for early low-demand stages. They require less absolute capital investment and no transport and delivery infrastructure. On the other hand, there are drawbacks in terms of limited efficiency and high H2 cost, because they are lacking the advantages of the economy-of-scale factor and of the improved storage efficiency of large plants. Furthermore operation and control of many small H2 units require a cost effective process control and high safety standards (HFP:StrategicResearchAgenda:2005). If connected to a pipeline grid, a problem may also be seen in the mixing of H2 streams from different sources unless minimum quality requirements are set for each source. In areas with lack of natural gas, reforming of methanol as easily transportable and storable fuel may represent an economic way of localized H2 production. In other small-scale applications, reforming of methanol may be more cost-effective, so may be electrolysis on a very small scale. The market for small H2 capacities in the range 50-500 Nm3/h is existing, but limited. On-board reforming of methanol has been considered an alternative option to H2 storage in an FCV which could take advantage of the already existing conventional transportation fuel distribution network. With respect to the planned network of H2 refueling stations, a comparative cost analysis study has shown for consumptions lower than 600 Nm3/h, the delivery of LH2 by tank truck represents the most economic option (RankeH:2004).


{European Hydrogen and Fuel Cell Technology Platform. Implementation Panel} (2005) Strategic Research Agenda..(BibTeX)
Ranke H. and Schoedel N. (2004) Hydrogen production technology - Status and new developments. Oil Gas European Magazine, p.78-84.(BibTeX)
---- << Liquid Hydrogen Production in the World | Content | Nuclear Hydrogen Production >>

Edit - History - Print - Recent Changes - Search
Page last modified on December 19, 2008, at 03:07 PM