practical implementation of renewable hydrogen

8/14/2019 Practical Implementation of Renewable Hydrogen

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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. Universityof 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

*- Corresponding Author

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 on-

site 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

Mertons 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, UKGovernment consultation such as the Draft Climate Change Bill, and Building a

Greener Future: Towards Zero Carbon Developmentsuggest 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 managefluctuation of supply and balance supply and demand.


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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-of-

the-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 EnergyCentre 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 toproduce hydrogen which in turn is used by a fuel cell to generate heat and


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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 conversiondevice, 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.

Electrolyser; the electrolyser takes electricity and water, and uses the

former to disassociate the latter into Hydrogen and Oxygen. It produces

hydrogen on site.

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 torequire 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.

Storage; storage is used onsite to store hydrogen which has beenproduced 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.

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 electricalgeneration and the waste heat has not been used at the present time, this existsas an upgrade path in the future.


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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 bestored 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 OxideFuel 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 thecell 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.


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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 fuelcell 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 off-

site 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 Centres HyPod System Showing red Hydrogen

Storage Cylinders and Stationary P.E.M. Fuel Cell.

Figure 3 (Right): PURE Energy Centres HyPod weather monitoring equipment is

clearly visible.

Integration of Renewable Hydrogen Technologies with Existing BuildingSystems


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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 heatdemand, 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 low-

energy design, passive cooling techniques should be adopted first where possible

to reduce building energy demand.

Safety in Hydrogen Installations


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Safety is imperative in hydrogen installations, both for the imperative ofprotecting people and property; ensuring duty of care to members of the publicwho may use and come into contact with such installations, but also to protectnascent technologies at a critical time in their emergence into the widerconsciousness(Gammon, 2004)

we dont know much about it at all, other than we used to make bombs outof 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 inelectrolyser systems, its storage and use should be done in accordance with theCOSHH regulations.

Contemporary developments in electrolysis and fuel cell technology take accountof 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 serviceswith a lighter maintenance requirement.

Repair and maintenance would be conducted by trained service engineers, muchthe same way as how a mains gas boiler is used, operated and maintained at thispresent time. With this in mind, modern products will be more akin to plug andplay to the user and the risks and dangers associated with the fuel and internalprocess are fully controlled and automated under a fail to safe designmethodology. By way of example, modern flat screen plasma televisions containwithin them lethal voltages within, tens of thousands of volts, but the technologyis packaged in such a way that the user is protected and if there is a problem ora fault, trained personnel are able to effect a repair.

Relevant Legislation


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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 thereis 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 Centres 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 riskfrom 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 installationshas given the experience that equipment supplied may often be at variance from


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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

Code of Practice CP25 Revalidation of bulk liquid oxygen, nitrogen,

argon and hydrogen cryogenic storage tanks.

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.

15/96 Gaseous Hydrogen Stations

Whilst the U.S. Compressed Gas Association provide the following guidance

notes;

G-5 Hydrogen

G5-4 Standard for Hydrogen Piping at Consumer Locations

G5-5 Hydrogen vent systems

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

guidance:

50A Gaseous hydrogen systems at consumer sites

50B Liquefied hydrogen systems at consumer sites

Planning Process


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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

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.

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.

Many of the requirements of existing plant rooms are still applicable for

the larger systems, but consideration should be given to the properties ofthe fuel gas used e.g. H2 is very buoyant compared to air.

As a minimum many fuel cells require clearance at the front and the rear

for easy maintenance, this is manufacturer dependent.

Consideration will need to be given to the siting of:

o Electrical cables flowing to and from the fuel cell.

o Hydrogen supply pipework supplying power to the fuel cell.

o An exhaust pipe which will be large diameter and take a similar

form to a gas boiler flue.

o 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 isnot considered healthy to drink too much such pure water as it is thought


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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, inthe 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.

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.

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.

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.

Many fuel cells are of a box within a box design, which means anyhydrogen 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


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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, concertvenues 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.


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Butera, F., (2008) Towards the Renewable Built Environment, In: Droge, P., Urban

Energy Transition: From Fossil Fuels to Renewable Power, Elsevier Science

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H2FC buses in Perth, Hydrogen and Fuel cell futures Conference 12th-15th

September 2004,

Gazey, R., Salman, S.K., & Aklil-DHalluin, 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

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UK

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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

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practical implementation of renewable hydrogen

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