Fuel Cells (FCs) are electrochemical devices that convert the chemical energy of a fuel source, such as natural gas, and an oxidant, such as air, to electrical energy and by-products including heat. They consist of an electrolyte sandwiched between two electrodes – an anode and a cathode. A fuel specific catalyst at the anode stimulates the fuel molecules or atoms to split up into electrons and ions. The ions migrate through the electrolyte and react with the electrons transferred by external circuit and oxygen (O2) at the cathode, thereby producing heat and water.
There are several variations of this basic process depending on the fuel source or fuel cell type:
Because they are a highly efficient energy technology, fuel cells may help meet the objective of reducing consumption of limited natural resources. Stationary fuel cell systems are already an option for the provision of electric power and heat in decentralised applications and they can compensate for fluctuations in the local energy demand (given that the provision of a convenient fuel is assured). Additionally, fuel cell systems do not involve fuel combustion and may therefore substantially reduce the release of air polluting gases such as sulphur compounds or particulates. This feature is of particular relevance in urban areas with heavy air pollution.
Fuel cells may form part of a low carbon energy system, especially if hydrogen from renewable sources is used. If so, fuel cells are essentially carbon-free in all operational phases. However, holistic assessments also have to consider conflicts related to potential utilisation competition within the entire energy system, especially in the case of limited biomass potentials. This said, widespread market deployment of small-scale fuel cell systems would foster the transformation of energy systems into decentralised and highly flexible energy systems with little transmission losses.
Small-scale fuel cells are able to provide a reliable source of power in stand-alone applications. This feature may allow them to be used to improve the energy provision of poor communities. However, the very high capital costs of the technology remain a barrier to the widespread deployment of fuel cells even in industrialised countries and as a tool against energy poverty.
Fuel cells are currently and primarily fed with natural gas to produce the hydrogen needed to generate electricity and heat. Due to their high efficiencies, fuel cells are nonetheless considered as clean technologies. However, in order to be a very clean energy technology, the fuel base for hydrogen production needs to be shifted to renewable energy sources, such as wind, solar or hydro.
Besides CO2 mitigation, fuel cells potentially reduce the discharge of air pollutants. As fuel cells include no fuel combustion, fewer gases are released into the environment. For example, almost no sulphur oxides (SOX) or nitrogen oxides (NOX) are emitted and emissions do not include any particular matter.
Fuel cells are still neither economically competitive nor commercially mature. Applications of fuel cells are restricted to very specific niche markets. The interaction of individuals or social structures with the technology is still rather marginal. The further development and especially the commercialisation of the technology may represent important employment potential in regions where know-how and expertise is being developed
The development and deployment of fuel cells has so far been limited to developed countries. Regional focal points are North America, Europe and Japan. Since fuel cells are not yet economically viable or technologically mature, they are not suitable as a near-term solution for either sustainable power generation or sustainable transport in developing countries. This is also the case because fuel cells are made from expensive and scarce materials. For example, producing PEMFCs requires platinum group metals, graphite and membranes.
Licences for the different types of fuel cells are concentrated in the hands of companies from industrialised countries or regions, e.g. Europe, Japan or North America. This corresponds with the geographic locations of the major centres of development and where fuel cell demonstration projects are currently taking place. Developing countries do not therefore have access to the ownership rights needed for fuel cell production. This limitation inhibits both the development and deployment of fuel cells and the generation of technology know-how and expertise in developing countries. The mid-term future employment potential of fuel cell production is therefore located in the above-listed regions.
Several thousand FC systems are produced each year. Most of these are for small stationary units, though several hundred are produced respectively for large stationary systems and for car and bus demonstration projects. Total installed power capacity is some 50 MW. There are around 3,000 stationary systems in operation worldwide. A number of small units are being installed for remote applications and for telecommunication power supplies.
The current role of fuel cell types
PEMFCs are the preferred technology for the transportation sector but they also represent 70-80% of the current small-scale stationary FC market. While PAFCs have been pioneering for the large-scale stationary market, MCFCs and SOFCs are now the reference options in this sector. They are expected to become economically competitive in a few years' time and used in niche markets, such as back up or remote power generation. SOFCs represent 15-20% of the stationary market and their share is expected to increase.
Research and development challenges are mainly related to cost reductions. Steps to increase the efficiency of different fuel cell models (e.g. by using new materials) and reduce the costs of hydrogen production need to be investigated, for example.
According to the International Energy Agency (IEA), the costs of prototypes or small-scale units for MCFC and SOFC systems are between USD 12,000/kW and USD 15,000/kW1.
Large-scale production and increased technological know-how could reduce the costs to between USD 1,500/kW and USD 1,600/kW in the long term. The current high costs of fuel cell systems are in part due to the high costs of stack production, i.e. the production and supply of platinum group metals, graphite and membranes for PEMFC technologies.
Gerboni et al. (2008) have developed three cost scenarios ("very optimistic, "optimistic realistic“ and "pessimistic“) for fuel cell technologies up to 20502. The scenarios are based on differing assumptions concerning the global deployment of fuel cell technologies. Based on current costs of EUR 10,000/kW, the investment costs for fuel cells are projected to decrease to EUR 760/kW in the event of rapid capacity expansion of up to 300 GW by 2050 ("very optimistic“). In the more realistic case (200 GW by 2050), costs decline to EUR 2,396/kW by 2050.