|Fossil fuels are incredibly valuable resources. How efficiently we use these resources will determine how long they last. Fuel Cells Make Fuels Last Longer.|
|Benefits of Fuel Cell and Hydrogen Technologies|
Fuel Cell Technologies
Fuel cells provide a range of critical benefits that no other single power technology can match.
Fuelled by pure "clean" hydrogen, fuel cells produce only pure water as exhaust. Even when powered by fossil fuels, they produce far less pollution than conventional technologies. Releasing the energy in a fuel through high-temperature combustion (as in an internal combustion engine) results in the creation of polluting nitrogenous and sulphurous oxides.
Fuel cells extract more energy from a fuel due to the increase in efficiency of electrochemical conversion over combustion. There are no moving parts in a fuel cell stack itself so there are no mechanical inefficiencies (compared with the Carnot Efficiency that limits normal engine efficiency). However, it should be well noted that the balance of plant introduces a large parasitic load. Furthermore, the heat produced in a fuel cell stack can often be used rather than wasted - a process known as Combined Heat & Power (CHP) generation or Combined Heat, Cooling and Power (Tri-generation). Generation of electrical power close to the electrical load (this is called Distributed Generation) allows the more efficient use of electrons and heat energy. Fuel cells also provide high efficiencies at partial loadings and at small sizes - both are important advantages over traditional energy converters. Many of these efficiency benefits are due to the modular nature of fuel cell design.
Silent / Vibration-free
With no moving parts, fuel cell stacks themselves are silent and vibration-free. A fuel cell system needs pumps, compressors and other moving parts that do produce vibration and sound, but these are on a different order of magnitude than the sound and vibration produced by traditional combustion engine technologies.
The absence of combustion and moving parts means that fuel cell technologies are expected to provide much improved reliability over traditional combustion engines. Research has demonstrated this potential, and in certain applications, fuel cell technologies have demonstrated reliabilities of 99.999999% - more than for any alternative technology.
Fuel cells can be responsive to changing electrical loads: more fuel is simply fed into the fuel cell stack. The speed of such a response is fast enough for many applications. Where faster response times are required, complementary technologies can be used.
High Quality Power
Fuel cells provide high quality DC power, perfect for modern electrical applications such as sensitive electronics or hospital equipment. National electrical grids typically suffer from power fluctuations, black outs and brown outs (where the electricity doesn't fail completely, but does fall below critical parameters), which can be avoided or mitigated by using a fuel cells-powered distributed generation energy network.
Batteries share many of the same properties as fuel cells, but have the disadvantage that they need to be recharged, and this is often a time-consuming process. Similar to internal combustion engines, fuel cells can produce electricity and heat as long as fuel is available.
Independence from traditional infrastructure
Fuel cell systems, with their ability to convert fuel to electricity and heat and unlimited runtime, enable independence from traditional, centralised energy infrastructures. With these technologies, national grids are no-longer the only way to enjoy the luxury of power and heat on-demand. Provided there is enough available fuel, independence from traditional large-scale infrastructure can be achieved. The environmentally-friendly nature of fuel cells, coupled with considerable scalability allows systems to be placed in a very wide variety of locations / sites. Fuel cells can operate on both existing widely available fuels (such as natural gas) and future fuels (such as hydrogen).
Use a variety of fuels
Pure hydrogen is the perfect fuel for fuel cells. Unfortunately, hydrogen is a very reactive element and is very rarely found in a pure form on earth. It is possible to produce hydrogen fuel from both renewable and traditional energy sources. In addition to hydrogen, it is also possible to run fuel cells on numerous other fuels, including fossil fuels and bio-fuels. Some fuel cell types, like Solid Oxide and Molten Carbonate fuel cells (SOFCs & MCFCs) can run directly on hydrocarbon fuels as their operating temperature allows internal reforming. Other fuel cells like Polymer Electrolyte Membrane fuel cells (PEMFCs) require pure hydrogen and therefore need an auxiliary fuel processor to convert hydrocarbon fuels into pure hydrogen before being fed into the fuel cell. Internal combustion engines can also run on a wide variety of fuels, but lose out to fuel cells in terms of efficiency (fuel cells make fuels last longer). The electrochemical conversion process in fuel cells is very different to the combustion process in internal combustion engines, and in certain instances can have additional advantages. For example, using biogas (which often has a high carbon dioxide content) as a fuel can impair the performance of internal combustion engines, but is an advantage for MCFCs as it can actually increase overall efficiency.
Fuel cells can achieve total efficiencies of more than 90% by using by-product heat in conjunction with high electrical efficiency. Centralised energy infrastructures cannot make use of the majority of heat produced by electrical generation because of the considerable distances between where the heat is produced and where it is needed. Despite inherent distribution losses, transferring electricity over such distances is worthwhile. It is not worthwhile (or possible) to distribute the heat from such a power station effectively. Fuel cells allow electrical generation on-site, and with that generation heat becomes available on-site too. This heat can be used for industrial processes, central heating or hot water production. CHP fuel cell systems are showing promising progress towards mass-commercialisation.
High Power Density
The power density of a generating system defines how much power can be produced per unit volume. With fuel cells, this value is usually given in kWh / l, which are high values. It can very reasonably be expected that the typical power density of fuel cells will rise substantially as technologies are refined.
Variable Operating Temperature
Fuel cell operating temperatures vary from around 80°C for low-temperature PEMFCs to around 1000°C for MCFCs. Temperatures inside combustion engines may reach over 2000°C.
An important advantage of choosing fuel cell technologies is their excellent suitability for hybridisation with other technologies. Batteries and super-capacitors are commonly used to complement fuel cells, often to help the system cope better with peak loads and very fast-changing loads.
Currently fuel cells are not cheap. However it is predicted that fuel cells will offer significant cost advantages over traditional energy solutions in the not-too-distant future. Not only is total system efficiency far higher, (i.e. fuel cells make fuels last longer) but the additional benefits and advantages conferred by fuel cell technologies enable further savings to be made across a very wide spectrum such as healthcare, homeland security, international socio-economics, environmental stewardship and sustainable development.
Design constraints imposed by conventional energy converters like combustion engines can be alleviated by switching to fuel cell systems. The specific effects of this change in design constraints are dependent on the particular application and requirement. In the case of Fuel Cell Vehicles for example, the removal of one central power plant can allow for more sophisticated and powerful electronic drive systems and new schools of design.
Hydrogen is one of the most promising fuels in the future energy mix. There is no alternative fuel option available with the same advantages.
When produced from renewable energy sources, hydrogen is the cleanest fuel we have at our disposal. When used in a combustion engine, hydrogen burns to produce only water vapour. The heat generated in this reaction is sufficient to produce levels of nitrogenous emissions that can be kept extremely low. In fact, the levels of these emissions produced are sufficiently low that hydrogen internal combustion engines can still pass SULEV vehicle emissions standards (the strictest in the US). When used in a fuel cell, hydrogen combines with oxygen to form water vapour. This reaction takes place at lower temperatures and so the only waste product from a hydrogen-fuelled fuel cell is water vapour. It is pure H20, safe enough to drink!
Hydrogen is a fuel, and like any fuel it has a high energy content. Its inherent safety is neither much greater nor much less than that of natural gas, gasoline or LPG for example. As long as appropriate safety procedures are followed, as they should with any fuel, hydrogen is indeed a safe fuel. Remember that hydrogen has been produced, transported and used in industry for over 100 years. The codes and standards developed for this industrial use to ensure the safety of all involved are being adapted for public or commercial adoption, and new codes are being developed where required.
One of hydrogen's greatest advantages as a fuel is that there are many ways to produce it, using both renewable and traditional energy sources. By far the most common method of hydrogen production is by reforming fossil fuels, particularly natural gas, but also oil and coal. Electrolysis is another method of hydrogen production that uses electricity to split water into hydrogen and oxygen gases. One advantage of electrolysis is that one can perform electrolysis using renewably-sourced electricity so that the hydrogen produced is a renewable fuel.
Although other methods of hydrogen production are under development, steam reformation of natural gas is likely to cater for a majority of hydrogen production in the near future. Nuclear power can produce massive amounts of hydrogen whilst drastically cutting carbon emissions and is being strongly promoted as a solution. Renewable hydrogen production techniques involving locally available resources including; wind, solar, biomass and biological energy sources are all under development and in combination with energy education and an overall shift towards more efficient distributed generation provide the best hope for a sustainable energy paradigm for our planet's people.
The relevance of hydrogen to energy security is that it can offer energy independence. Using hydrogen in conjunction with fuel cells empowers countries to invest in a sustainable energy infrastructure that is matched with their energy production capabilities and demands. In association with distributed generation, hydrogen fuel enables individual homes and communities to manage their own energy supply. This reduces dependence on energy infrastructures such as large-scale power stations, national grids, and long-distance pipelines. This large-scale infrastructure can be costly to secure, and expensive to maintain.
The long-term environmental benefits of using hydrogen as a fuel are enormous. Hydrogen fuel produces few pollutants when burnt, and none at all when used in a fuel cell. Hydrogen is a carbon-free fuel, and when produced using renewable energy, the whole energy system can become carbon-neutral, or even carbon-free. So, hydrogen fuel can contribute to reducing Green House Gas emissions and can reduce the production of many toxic pollutants.
Hydrogen has been produced and used by industry for over a hundred years. The technology required to deploy wide-scale availability of hydrogen fuel is available today. The speed to which these technologies are deployed will depend on the availability of vehicles that use hydrogen fuel. These vehicles are presently only produced in small numbers and as a result are inherently costly to manufacture. To aid with the transition to hydrogen and fuel cell vehicles, these technologies need to be able to integrate and compete with existing technologies which have had the benefit of many years of mass-manufacturing and distribution. Proactive investment by central and regional governments in conjunction with the requirements of the private sector is required to overcome this 'chicken and egg dilemma', and achieve high volume low cost manufacturing and distribution. To aid this transition, measures include: # Financial Incentives # Positive Regulatory Frameworks # Effective Codes & Standards # Creating Demand # Reducing Costs # Improving availability
Security of Fossil Fuel Resources
Fossil fuels are incredibly valuable resources. How efficiently we use these resources will determine how long they last. Fuel Cells Make Fuels Last Longer.
Transitioning to a fuel cell hydrogen economy can ensure the availability of crude oil and its products upon which so many industries depend, for longer.