Practical Implementation Of Renewable Hydrogen

Practical Implementation of Renewable Hydrogen & Fuel Cell Installations in the Built Environment Paper prepared for Detail Design in Architecture 8 “Translating sustainable design into sustainable construction”, 4th September 2009, Cardiff, UK. University of Wales Institute Cardiff, Cardiff School of Art & Design. Gavin D. J. Harpera* Ross Gazeyb a) The E.S.R.C. Centre for Business Relationships Accountability Sustainability and Society (B.R.A.S.S.), Cardiff University, b) Pure Energy® Centre *-

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Abstract There is significant interest in fuel cells for use in the built environment, as a technology that has the potential to produce localised heat and power, with increased efficiency and reduced carbon emissions which give it an advantage over alternative technologies. Whilst fuel cell technology is easy to understand on paper, there is a paucity of information on practical implementation of fuel cell technology in the built environment for architects. This paper discusses some of the practical aspects of implementing renewable hydrogen installations in the United Kingdom, that is to say installations that produce their own hydrogen onsite from renewable energy sources. Introduction There is a well articulated need to reduce the impact of energy consumption in the built environment, on a local level initiatives such as the London Borough of Merton’s Planning Guidance, which has since become known as “The Merton Rule” (Harper, 2006), provide clear incentives for building developers to reduce the energy use and carbon emissions of their building. On a national level, UK Government consultation such as the Draft Climate Change Bill, and Building a Greener Future: Towards Zero Carbon Development suggest a future trajectory for the UK Built Environment where renewable energy systems and zero-carbon technologies will play a vital role in the energy provision of our buildings. Whilst the biggest challenge is making “better use of the technologies and techniques for energy-efficient building design that are already available” (Pitts, 2008) there is clearly room for innovation, particularly in the field of energy generation and transformation. Increasing penetration of renewables into the grid will doubtless require extra storage capacity in order to help manage fluctuation of supply and balance supply and demand.

According to Pitts (2008) the current UK building stock is characterised by a reliance on grid-based electricity supply used by 99% of consumers and mains gas in areas where it is available. Many energy commentators believe that there will be a move towards more decentralised and embedded electricity generation in the UK network, this will eventually necessitate a change in pricing structure of electricity – ‘dynamic pricing’ of electricity is one option which looks likely under a future “smart grid” scenario. This could make it economically advantageous for ‘flexible’ users of electricity who are able to tailor their demand to the prevailing supply conditions. There is also the issue of land which is not cost-effectively accessible to traditional utilities. If solutions are found to providing heat and electrical power in remote locations at a cost effective price, then the value of this land increases. This makes renewable hydrogen-based solutions particularly attractive to ‘islanded communities’ (Sovacool & Hirsh 2008; Gazey et.al 2006). The Built-Environment has been identified as a fertile early-market for fuel cell technologies as the fuel cell technology types that are well-suited to stationary applications are reaching a level of maturity where for some applications they are economically viable. This is a trend that is likely to increase. In some projections, Hydrogen will be a major final end-use carrier in the Built Environment by the end of the century, with some (Van Ruijven, 2007), predicting it will provide 45% of residential energy by 2100. Financing Hydrogen Projects In the current economic climate, house building and construction has experienced a massive downturn, meanwhile as a result of the international focus on developing clean technologies that has been enthusiastically embraced by politicians there is funding available for development of innovative, state-ofthe-art projects incorporating low-carbon building technologies that push the envelope of design knowledge. From experience gained working on a number of renewable hydrogen projects it has been found that it is the financing of the building that is the biggest barrier, not the technology. For example, in the Hydrogen Homes that the Pure Energy® Centre has been developing in association with the Hjaltland Housing Association, The credit crunch has changed the settlement agreement. Nationally there has been a change in allocations for housing association financing. By contrast the technology can be funded through different routes, although funding for hydrogen and fuel cell projects is relatively small compared to other more “traditional” fields of energy. Competition for the funding available for hydrogen technology is very high. Renewable Hydrogen Installations There are fuel cell installations which take natural gas and reform it on-site to produce hydrogen which in turn is used by a fuel cell to generate heat and

power. Whilst many of the points in this paper will also apply to this type of installation, it is not expressly the subject of this paper. A renewable hydrogen installation commonly contains the following components: •

Renewable Energy Device; this can be any renewable energy conversion device, Solar, Wind, Micro Hydro e.t.c. which produces electricity from the natural resource. Energy from this device may form part of a metering agreement with the National Grid where extra electricity is sold to the grid when there is excess.

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Electrolyser; the electrolyser takes electricity and water, and uses the former to disassociate the latter into Hydrogen and Oxygen. It produces hydrogen “on site”.

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Compressor; this is an optional stage. It is used to compress hydrogen to a level whereby it can be used to refuel hydrogen vehicles (which tend to require hydrogen gas in the region 350-700 bar pressure). By pressurising the hydrogen gas, more gas can be stored in a smaller volume reducing the space requirements for hydrogen storage. In the Pure Energy® Centre HyPod® system a compressor is eliminated by using a specially developed high-pressure electrolyser. It should be noted that the inclusion of a compressor stage, whilst affording amenity in the hydrogen installation, will also consume energy reducing the overall energy balance of the system.

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Storage; storage is used onsite to store hydrogen which has been produced for later use. This stored hydrogen can be used for heat and power in the building, using a Combined Heat and Power fuel cell, or for refuelling external devices such as hydrogen vehicles.

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Fuel Cell; the fuel cell itself takes Hydrogen from the storage and converts this into electrical and thermal energy.

Figure 1: Block Diagram of the Hydrogen System at the Energy & Environment Technology Centre, Yorkshire At the moment, the fuel cell in this installation has been optimised for electrical generation and the waste heat has not been used at the present time, this exists as an upgrade path in the future.

Electrolyser Technology Electrolysers take an input of electricity and water to produce renewable hydrogen, and oxygen which can be vented to atmosphere or used for other processes. Electrolyser technology has the potential to take surplus renewable electricity from stand-alone installations and turn it into hydrogen which can be stored for later use. For grid-connected installations, in a future scenario where energy is priced dynamically based on a “real-time” commodity price, buildings that integrate electrolyser technology would have the potential to generate their own hydrogen overnight or in periods where electricity was plentiful and the spot-price was cheap – this stored energy could then be used by the building during periods when the cost of grid electricity increased beyond a set-point. Fuel Cell Technology Experience from a range of installations has tended to lean toward Solid Oxide Fuel Cell technology being selected as the technology of choice for stand-alone installations. Proton Exchange Membrane fuel cells have been used with varying degrees of success, however, the membrane assemblies are particularly fragile and have been prone to cracking. Experience with Solid Oxide Technology has also encountered issues of durability and robustness with the ceramics used in the cell stack. Whilst SOFC technology works well if run up to a steady state it performs less favourably with cyclical operation as ceramic materials deteriorate when heated and cooled in cycle. This is due to the cell technology and issues with thermal cycling deteriorating the cell stack. The lifetime of a continuously run SOFC should in theory run (in excess of 10,000 hours). This is to say for a year and a half. The life of the cell will be far exceeded by the balance of plant and support equipment, therefore it is necessarily to periodically rebuild the system and stack. For this reason, building design should anticipate easy access for service and repair to the fuel cell stack. Solid Oxide Fuel Cells are a high temperature fuel cell technology and rely on a high temperature for their electrochemical conversion process. However, from cold-starting the temperature is not there to start the chemical reaction, as a result, the cell must be slowly heated at a rate that is compatible with the ceramic materials co-efficient of expansion. Heating beyond this rate will cause degradation of the ceramic material – and ultimately if it is too fast, the stack will fail. Systems Integration Whilst the individual components of Hydrogen and Fuel Cell installations are reaching the point where they are shown to have acceptable reliability and service life, this is usually measured under optimum conditions. The challenge remains to integrate the components of renewable fuel cell installations to ensure that all components within the installation work at their optimum in order to ensure long service life and the longevity of the installation.

As an example, Gammon (2006) discusses the limitations of an electrolyser unit, whose performance would degrade appreciably after 2500 on/off cycles, this was mitigated by including a battery back-up to reduce the degree to which on/off switching was necessary. As more modern electrolysis techniques are developed, electrolyser technology will become more resilient and the balance of plant can be reduced. Through developing specialist electrode coatings and optimising the electrode technology – a combination of advanced control and materials science techniques, this phenomenon can be reduced to a negligible level. By way of contrast, the electrolyser at the Pure Energy® Centre site in Baltasound, has recorded in excess of 19000 on/off cycles without noticeable degradation of stack performance. To some extent, this can be solved with “packaged” hydrogen systems. Off-site prefabrication is now extensively used within the construction industry in order to concentrate skilled labour and maintain high levels of quality. The Pure Energy® Centre produces a “HyPod®”, in the first generation HyPod® the fuel cell is external to the container (pictured in Figures 2 & 3) however, depending on the type and certification constraints there is potential for integrating a fuel cell installation within a trans-modal shipping container, to allow simple shipping of the solution to site. Experience within other domains in the construction industry has shown that offsite fabrication reduces the need for a skilled workforce on site – allows for increased quality control as components are assembled in a central factory location by a skilled workforce. Modular renewable hydrogen systems fabricated off-site and moved to the site of installation as a complete unit could present one blueprint for the development of renewable hydrogen in the built environment.

Figure 2 (Left): PURE Energy Centre’s HyPod™ System Showing red Hydrogen Storage Cylinders and Stationary P.E.M. Fuel Cell. Figure 3 (Right): PURE Energy Centre’s HyPod™ weather monitoring equipment is clearly visible. Integration of Renewable Hydrogen Technologies with Existing Building Systems

Integrating hydrogen and fuel cells into building systems should present no more of a challenge than any other building services, if space requirements are taken into consideration. As hydrogen services are still under development, they may take up more space and require more generous room for access and service than well-established technologies. A consideration for the architect is that hydrogen, as a gas that is lighter than air rises, to provide passive-safety designers should ensure that in service areas the highest point of the building envelope is ventilated, and that the envelope of the service area is designed in such a way that any hydrogen that is accidentally vented can rise upwards to this point. Good passive ventilation of the area will ensure that any hydrogen leaks can be safely dispersed. Sizing Fuel Cell Installations Where the installation is a grid-connected installation in common with other CHP technologies, it is wise to size the fuel cell in accordance with the maximum heat demand, as electrical power can easily be imported and exported to and from the grid. At the moment as this technology is still expensive and used in a limited number of installations, it is common practice to use fuel cell technology in concert with other more conventional technologies, with the fuel cell providing a portion of demand. This has the advantage that there is a back-up system in place to provide heat and power during fuel cell service intervals e.t.c. Using Fuel Cells with other Low Carbon Technologies Fuel Cells with GSHP In the installation at the “Hydrogen Office” in Methil, for which the Pure Energy® Centre provided the hydrogen installation, the Fuel cell is used in concert with a ground source heat pump to meet the buildings heating needs. The heat pump takes thermal energy from the surrounding ground area and concentrates it into the building envelope. For every unit of electrical energy used to drive the heating system it is anticipated that up to 3 units of equivalent thermal energy are recovered from the ground. This is known as the Coefficient of Performance (CoP)

Fuel Cells for Cooling It is possible to use fuel cells in concert with absorption chillers to provide building cooling. Where additional cooling is required, however, for good lowenergy design, passive cooling techniques should be adopted first where possible to reduce building energy demand. Safety in Hydrogen Installations

Safety is imperative in hydrogen installations, both for the imperative of protecting people and property; ensuring duty of care to members of the public who may use and come into contact with such installations, but also to protect “nascent technologies at a critical time in their emergence into the wider consciousness” (Gammon, 2004) “ …we don’t know much about it at all, other than we used to make bombs out of this stuff.” -Local Hornchurch resident, Mike Dyer Romford Recorder May 2003. “My feelings are rather strong on this, I think it must be dangerous.” -Local Hornchurch resident, Stephen Kelly, Romford Recorder May 2003. Quotes excepted from Garrity (2004) There is a lack of understanding about the genuine safety implications of using hydrogen. Urban myths persist about the “dangerous nature of hydrogen”, largely founded on a mistaken understanding of the Hindenberg Disaster (1937) and the Hydrogen bomb. When polled (Garrity, 2004) 17% of all respondents associated “the hydrogen bomb” with the word hydrogen, whilst 2% of all respondents associated the word Hindenburg with hydrogen (These results could be possibly explained by the fact this survey was conducted in Australia, it is believed that a poll in Europe would most likely show a greater awareness of the Hindenburg disaster.) There is a body of best-practise information that can be learned from industry, indeed companies such as BOC have a long experience of safely working with industrial gases, and much of the best-practise they have learned from industry In particular HAZOP Analysis – Hazard and operability studies; are a useful tool in refining process and procedure to ensure safe-working practise. In addition to the safety concerns surrounding the use of hydrogen itself, consideration should also be given to the strong alkali which is used in electrolyser systems, its storage and use should be done in accordance with the COSHH regulations. Contemporary developments in electrolysis and fuel cell technology take account of ATEX, COSHH and PED to fully design in and automate all material handling internally. This removes the need for user intervention in order to create services with a lighter maintenance requirement. Repair and maintenance would be conducted by trained service engineers, much the same way as how a mains gas boiler is used, operated and maintained at this present time. With this in mind, modern products will be more akin to ‘plug and play’ to the user and the risks and dangers associated with the fuel and internal process are fully controlled and automated under a “fail to safe” design methodology. By way of example, modern flat screen plasma televisions contain within them lethal voltages within, tens of thousands of volts, but the technology is packaged in such a way that the user is protected – and if there is a problem or a fault, trained personnel are able to effect a repair. Relevant Legislation

One of the frustrations in developing this innovative building technology is that there is lack of clarity as far as legislation and safety codes. As there are only a limited number of hydrogen installations in settings other than industrial installation, there are limited examples of best-practice to learn from. There is not yet a standard for hydrogen installations in the same way that there is the GasSafe (Formerly CORGI) quality mark for domestic and commercial gas installations. The United Kingdom Hydrogen Association is working to address this. As there is a lack of guidance for domestic / commercial small scale hydrogen standards, at present guidance is taken from the statutory industrial regulations listed below, and projects are assessed on a case-by-case basis, this adds significant expense to hydrogen installations due to the extra work of performing due-diligence and is an area where the cost of a hydrogen installation can be reduced as proper standards are developed. Ideally, the hydrogen community will work towards a standard that can be signed off by a competent person. Pressure Equipment Directive EU standard The pressure equipment directive covers vessels, piping, valves and associated accessories for safety and managing pressure, where the installation contains pressure running at greater than 0.5bar, this is the case for renewable hydrogen installations, with the Pure Energy® Centre’s HyPod® running at 38-42bar as an example, whilst next-generation hydrogen vehicles will require refuelling at between 300-750bar. •

Pressure Equipment Directive 97/23/EC

ATEX directive The ATEX directive in fact consists of two directives, from the European Union, one which applies to the manufacture of equipment and their associated protective systems for use in explosive environments, and the other which applies to the operation and use of equipment in explosive environment. They are: • •

ATEX 95 equipment directive 94/9/EC, Equipment and protective systems intended for use in potentially explosive atmospheres; ATEX 137 workplace directive 99/92/EC, Minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres.

Manufacturers Standards Significant reference needs to be made to manufacturers equipment standards during the execution of a renewable hydrogen installation. As with many evolving technologies, the first groups of consumers are often those that have to complete the last phase of product testing. Experience on a range of installations has given the experience that equipment supplied may often be at variance from

the manufacturers published specification; and this can lead to challenges when integrating systems. Guidance from Professional Associations BCGA British Compressed Gas Association, Codes of Practice provide guidance on best practise for the use of compressed gases in the UK. Whilst the regulations pertaining to hydrogen in its gaseous state are the most relevant to current UK Renewable Hydrogen installations, legislation pertaining to liquid and cryogenically stored hydrogen may become relevant as hydrogen installations evolve and more advanced storage technologies are used. The BCGA provide guidance on the use of industrial compressed gases, which provide •

Code of Practice CP8 Safe Storage of gaseous hydrogen in seamless cylinders and similar containers

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Code of Practice CP25 Revalidation of bulk liquid oxygen, nitrogen, argon and hydrogen cryogenic storage tanks.

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Code of Practice CP33 The bulk storage of gaseous hydrogen at user premises 2005.

In addition to the UK professional associations, there are also some international organisations who produce publications relating to safety and best practise that are of note. In addition, the IGC provide the following guidance notes: •

6/93 Code of Practice: Safety in storage, handling and distribution of liquid hydrogen.

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15/96 Gaseous Hydrogen Stations

Whilst the U.S. Compressed Gas Association provide the following guidance notes; •

G-5 Hydrogen

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G5-4 Standard for Hydrogen Piping at Consumer Locations

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G5-5 Hydrogen vent systems

Furthermore, the U.S. National Fire Protection Association provide the following guidance: •

50A Gaseous hydrogen systems at consumer sites

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50B Liquefied hydrogen systems at consumer sites

Planning Process

We can assume that if you are looking at producing a hydrogen installation, you already have a client who is receptive to innovative building technologies. Due to the level of the technology development, this is really a pre-requisite for a renewable hydrogen installation. There are challenges with educating those involved with the planning process about the risks and benefits associated with hydrogen and experience from real-world installations shows that there is a clear need for knowledge transfer between members of the planning community to transfer information about successful installations in one locality to those responsible for decision making in others. Notes on Hydrogen Integration for Architects & Service Engineers

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Fuel cells in the sub-100kw range typically occupy the same space as a 19” rack, commonly used for housing I.T. equipment; this is for their application and deployment in data centre applications. By way of illustration, 10kW “HyPM” modules fit in a standard 19” rack, with a 10kW module occupying a 5U space in the rack. Power conditioning equipment may also occupy a rack-mount installation, sharing common space.

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High temperature systems up to 200kW are approximately the size of a 20” container once all the auxiliary devices, safety systems and conditioning electronics are included.

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Many of the requirements of existing plant rooms are still applicable for the larger systems, but consideration should be given to the properties of the fuel gas used – e.g. H2 is very buoyant compared to air.

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As a minimum many fuel cells require clearance at the front and the rear for easy maintenance, this is manufacturer dependent.

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Consideration will need to be given to the siting of:

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Electrical cables flowing to and from the fuel cell.

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Hydrogen supply pipework supplying power to the fuel cell.

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An exhaust pipe which will be large diameter and take a similar form to a gas boiler flue.

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A waste water drain for the exhaust water from the fuel cell.

Consideration should be given to how to treat the water from the fuel cell. The water is of exceptionally high, pure quality. Some local authorities are happy for this water to go to soakaway rather than enter the drainage system. A green building project may repurpose this water, by using it as part of a greywater recycling system. Waste water from the exhaust of a fuel cell system is pure demineralised, and de-ionised H20. in its self it is not considered healthy to drink too much such pure water as it is thought

to remove nutrients from the body. If mixed with other drinking water this effect would in theory be removed. A common trick I have seen is for the manufacturers of fuel cells to mix the exhaust water with Whisky to add the necessary minerals and charged particles! •

The output flow of water is dependent on the size of the fuel cell stack, in the example of a 5kW plug power unit as used in the PURE project, the output water flow was 2L/h at 5kW (full power) although the stack power will be a little higher than this to accommodate BOP loading.

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Careful consideration should be given to siting the exhaust vent for fuel cell installations. It should be ensured that this vent does not create an “ATEX zone”. All potential sources of ignition should be isolated from the area where the exhaust emerges. Whilst highly manufacturer specific, some fuel cells vent directly, others vent indirectly.

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Dry hydrogen flowing through metal pipes has the potential to build up static charge. All metal pipework needs to be equipotentially bonded to prevent the build up of charge. This should be done in accordance with the 17th Edition Wiring Regulation.

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It should be noted that the output power from a fuel cell is direct current and may be regulated or unregulated. This D.C. can either be used directly with appliances and devices designed for D.C. operation, or an inverter can be used to convert the D.C. to 230v 50Hz mains supply.

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Many fuel cells are of a “box within a box” design, which means any hydrogen leaks can be contained. Equipment that is not of this design may lead to a hydrogen leak turning the room into an ATEX zone. Additional ventilation at high level should be provided to allow hydrogen to ventilate freely to the atmosphere, and the architectural detailing should be such as to permit hydrogen to rise to the highest point of the room for ventilation.

Figure 4 Allowing hydrogen to ventilate naturally provides for passive safety

Conclusions The adoption of renewable hydrogen installations in the built environment is likely to look increasingly inevitable in a world which is rapidly moving towards the adoption of low carbon building technologies. Current installations are by ‘early adopters’ and ‘innovators’ who are willing to tolerate the steep learning curve associated with hydrogen technology at its present state of development. This learning curve is partly offset by available grant funding for developing innovative projects. Buildings that are considered very good candidates for FC technology are data centres, this is due to the existence or planned installation of some form of UPS system to ensure data throughput is not lost in the event of any power outage. On the larger scale manufacturers of high temperature fuel cells such as MTU install them into large public or municipal buildings such as hospitals, concert venues office blocks etc, to provide heat and power from a natural gas source. The emissions are much lower in Co2 and Nox etc than a combustion engine or gas turbine using the same fuel stock, and the electrical efficiency is much higher. Installations will become more cost-effective as codes of best practise, regulation from the industry and standard configurations are developed. There is a need for knowledge sharing within the building, planning and safety communities to ensure that best practise about the practical aspects of hydrogen implementation is effectively disseminated.

References: Butera, F., (2008) Towards the Renewable Built Environment, In: Droge, P., Urban Energy Transition: From Fossil Fuels to Renewable Power, Elsevier Science Garrity, L., (2004) Public Perception and Economic Preferences towards the use of H2FC buses in Perth, Hydrogen and Fuel cell futures Conference 12th-15th September 2004, Gazey, R., Salman, S.K., & Aklil-D’Halluin, D.D. (2006) A field application experience of integrating hydrogen technology with wind power in a remote island location, Journal of Power Sources, 157 (2) pp. 841-847 Gammon, R., Roy, A., Barton, J., & Little, M., (2006) Hydrogen and Renewables Integration (HARI), Report to the International Energy Agency HIA Task 18, CREST (Centre for Renewable Energy Systems Technology), Loughborough University, UK Harper G.D.J., (2006) "The Merton Rule" In: Hall, K.D ed., (2006) "Green Building Bible - Volume 1.: Essential Information to Help You Make Your Home and Buildings Less Harmful to the Environment, the Community and Your Family" 3rd Ed. Llandysul, Wales: Green Building Press pp.56-59 ISBN:978-1898130062 Harper, G.D.J., (2008) Hydrogen integration at West Beacon Farm, Green Building Magazine p.64-65 Harper, G.D.J., (2008) Working towards a hydrogen future: an interview with Allan Jones, p.66-68 Harper, G.D.J., (2008) Hydrogen homes for Scotland, p.69 Pitts, A., (2008) Future-proof construction – Future building and systems design for energy and fuel flexibility, Energy Policy, 36 pp.4539-4543 Sovacool, B.K., & Hirsh, R.F., (2008) Island wind-hydrogen energy: A significant potential US resource, Renewable Energy, 33, 8, pp.1928-1935 Van Ruijven, B., Van Vuuren, D.P., De Vries, B., (2007) The potential role of hydrogen in energy systems with and without climate policy, International Journal of Hydrogen Energy, 32, pp.1655-1672