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Introduction
This report will address the questions to literature previously documented in part 1 and present primary data towards the methodology to be established, and also determine the theoretical body of knowledge to identify critical issues associated with emerging fuel cell technology.
Literature Review
Fuel Cells, A Brief History
“Fuel cells are electrochemical devices that convert the chemical energy of a reaction directly into electrical energy” (USDE 2000, p.16)
Contrary to popular belief fuel cells have been researched for decades and “..despite almost one hundred and fifty years of intermitent research [Solid Oxide Fuel Cells] are only now approaching commercialisation” (Weston & Matcham, 2002 p.5). Obviously in the early stages of fuel cell research technical obstacles would have certainly been a barrier to further research. The solid oxide fuel cell (SOFC) for example has a working temprature of between 700°C and 1000°C (FcFocus 2007). This would have certainly caused difficulties in the early part of the 19th century. It was Francis Bacon who developed the first fuel cell that was successful in 1932, with a hydrogen-oxygen cell using alkaline electrolytes and nickel electrodes. Fig 1 demonatrates how a modern basic fuel cell (Proton Exchange Membrane) produces electricity. Please also see Appendix B for an actual working model.
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Exploded View
Fig 1.
Pressureised Hydrogen is forced through the anode and then to the catalyst, which causes a chemical reaction where the hydrogen oxidises into H+ ions and 2 electrons (e-). The elctrons are then conducted through the anode into a circuit creating a voltage before returning back to the cathode. At the cathode oxygen is forced through, and again, upon reaching the catalyst it forms two oxygen atoms. The H+ ions are atrracted through the catalyst by negatively charged oxgen molecules to then form water (H2O) as a waste product. (Bloman and Mugerwa 1993).
In 1959, Francis Bacon moved on to produce and demostrate a 5Kw fuel cell system along with Harry Karl Ihrig who “...presented his now-famous 20-horsepower fuel cell-powered tractor that same year”. (SAE 2007, p.1). The energy crisis of the mid - 1970s, led to a rush to promote energy efficient and sustainable technologies as well as “..crash programmes in developing renewable sources..” (Turner 1999a, p. 687)
As supply and demand equalised during the 1980s enevitably renewable projects were reduced but as Turner (1999b, p. 687) continues to explain this did leave a legacy that “..spurred work to avoid or remedy environmental damage from fossil fuel extraction, processing and transport..”. It was NASA that then took up the helm, in more serious research of the technology, for the Appollo program to provide the in flight electrical requirement, as nuclear reaction was considered far too dangerous and solar power too bulky to use in space vehicles. “...[This] involvement [by NASA] is one of the primary reasons that the technology is now viable for the private sector...” (Kala & Hicks 2004, p.5)
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Alkaline cells were used until the development of solid polymer cells, which prompted a return to low temprature and efficient PEM type fuel cells (Murphy 2003). Since the continued development of technology there are now numerous different types of fuel cells, each with distinct advantages and disadvantages. Fuel cells are capable of producing both electricity and heat and are generally categorised by their electrolite (Catalyst used for transformation of energy) and operating temprature (Anon 2003a) The most common fuel cells are currently:
· Polymer Eloctrolyte Membrane (PEM)
· Solid Oxide Fuel Cell (SOFC)
· Direct Methanol Fuel Cell (DMFC)
· Metal Air Fuel Cell (MAFC)
· Phosphoric Acid Fuel Cell (PAFC)
· Alkaline Fuel Cell (AFC)
· Molton Carbonate Fuel Cell (MCFC)
· Regenerative Fuel Cell (RFC)
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It is beyond the scope of this report to explain the technical aspects of each type of fuel cell but additional technical information can be obtained by seeing appendix A. The main interest within this literature review is primarily directed at whether fuel cells are a viable alternative when replacing existing plant in the UK construction sector and to help fulfill the aims and objectives identified in part 1.
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To simplify this process and to give a sample for comparison, generally fuel cells that operate at high tempratures are ideal for stationary power and CHP (Combined Heat and Power) where as fuel cells that operate at lower tempratures are ideal for portable and mobile applications (Anon 2003b). It is this practical application that will be reviewed throughout this report.
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Hydrogen Economy
“Hydrogen looks likely to play a key role in future
low-carbon energy systems, as an ‘energy carrier’
through which non-fossil energy can replace fossil fuels”
(DTI 2003, p.71)
Hydrogen , whilst in abundance on earth is not available in a natural state and therfore requires “manufacturing from some other material that includes hydrogen [as a component]” (Murphy 2003,
p.8) This is where one of the myths of fuel cells is revealed Murphy (2003) identifies that the extraction process generates pollutants from fuel burning power plants during the extraction process known as ‘reforming’. It is possible however, to reduce this significantly through Carbon sequestration systems (Graves, 2006) this is the process of capturing the CO2 gas and storing this in the earth for natural dispersal.
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Ultimately, for a truly renewable and CO2 free fuel cell system, hydrogen will be produced from “electrolysis of water” (Crawley & Butler 2007, p.4) powered from a renewable energy source e.g. Wind turbines to produce Hydrogen. Fig 2. helps to give an idea of the rudimentary basics of electrolysis. An electrical current is passed from the direct current battery through the electrolyte (in this example an acid solution) but this can also be water, methanol, alkaline etc. The electrical current enters the electrolyte via 2 electrodes. The positive electrode is called the anode with the negative called the cathode. This creates a chemical reaction, essentially splitting the sum of components of the electrolyte to produce Hydrogen and oxygen gas (McMullan 2002)
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Fig. 2
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Dutton (2002) however, places emphasis on the fact that the convertion of electrcity from renewable sources and then back into electrcity results in energy losses and additional costs. Weston & Matchum (2002, p.40) quantify this stating a “...10–30% loss...” to produce hydrogen with a “...further 50% loss...” to convert back to electrcity. Comparable with a “...5-10% [loss]...” of distributing the same electricity across the UK national grid. Although It should be noted that this is a also a relatively new technology (Raj 2007) and it would simply be unrealistic to compare “...an established infrastructure built on over 100 years of development and process novation...” (Hendry, Harborne, Brown 2004, p.5) with an emerging technology. It does raise the question though, as to the scope that fuel cells currently have as an alternative energy source within the market. Clearly at this present moment in time, in terms of infrastructure change, fuel cells have a long way to go and the “...technology has yet to enter the arena of economic viability alongside already established (and viable) technologies” (Powell et al 2004, p.11)
No doubt that there is difficulty with transportation, distribution and also storage of hydrogen. And without government intervention and further demonstration programmes, the technology is unlikely “to develop as a credible alternative energy technology” (Peters & Powell 2001, p.12).
Market Emergence
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Utterback (2004) explains a process which seems to resemble the current trend of fuel cells, this being that of the fluid phase. This is a period of intense innovative production, eventually this leads to a transitional phase where an industy standard design is achieved and is marketed. DTI (2003) establishes the main applications for fuel cells which are: -
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· Vehicle Propulsion
· Auxillary Power Units
· Distributed Generation/CHP
· Domestic and small commercial CHP
· Small Gensets¹ and Remote Power
· Portable Applications.
Continuation to follow soon...
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