Maxine Perella reports on the development and trial of hydrogen and fuel cell technologies
Scotland has access to some of the richest and most diverse renewable resources in Europe, but harnessing them has always been problematic. Developing the means to manage intermittent electricity generation, especially from wind turbines, has been a key challenge for grid operators, but the country is now making great strides - notably through the use of hydrogen and fuel cell technologies.
The potential of hydrogen has long been recognised by the Scottish government. In its Hydrogen and fuel cell opportunities for Scotland report, published in 2006, the government noted that leveraging both technologies to balance and integrate diverse and intermittent sources of energy could net the economy £500 million a year and sustain 10,000 jobs.
Essential mechanism
The 2020 routemap for renewable energy in Scotland, published in 2011, sets a target for the country's electricity demand to be supplied from renewable sources by the end of the decade. The government considers hydrogen an essential mechanism to help achieve this, while recognising that it can also support the development of community-based renewable energy projects, such as those on the islands. Figures from Decc show that, in 2014, Scotland's renewable power generation was equivalent to almost half (49.8%) of all electricity used in the country. But, as Nigel Holmes, chief executive at the Scottish Hydrogen & Fuel Cell Association (SHFCA), points out, as the amount of intermittent renewable energy rises there can be local constraints in the power distribution and transmission networks.
"This is already affecting areas such as Western Isles and the Orkney Islands, and leads to renewable energy production being curtailed," he says. "During 2014, the Orkney Islands produced more electricity from renewables than the islands consumed and it was a net exporter. This could have been even higher if the Orkney grid connections had sufficient capacity."
To try to resolve this challenge, hydrogen demonstrator projects are now emerging. Hydrogen's gift lies in its flexibility: it can be compressed, stored and converted back to electricity when needed. When electricity generated from intermittent renewables is used to produce hydrogen, it "top slices" the energy that cannot be fed into the grid and stores it for future use. This type of production carries a low-carbon footprint and is known as green hydrogen. When produced from the electrolysis of water, it can be generated with zero-carbon emissions, making it an ideal sustainable transport fuel.
"Fuel cells using hydrogen have essentially zero emissions of carbon dioxide and other forms of air pollution such as fine particulate matter [PM] or nitrogen oxides [NOx]," says Holmes. "This is particularly relevant for cities and urban areas where PM and NOx are currently responsible for regular breaches of air quality limits, along with the associated health concerns."
The granite city
One city exploiting this is Aberdeen, which is home to one of Europe's largest hydrogen projects. H2 Aberdeen is a far-reaching programme that aims to strategically position north-east Scotland as a world-class, low-carbon energy hub by building a hydrogen economy that will eventually cascade down to Edinburgh, Dundee, Glasgow, Stirling, Inverness and Perth.
Attention so far has centred on Aberdeen's £20 million hydrogen fuel cell bus project, under which the council has already deployed a fleet of 10 vehicles in the city. They give a quieter, smoother ride compared with the diesel models, according to Fiona Goodenough, Scottish cities alliance hydrogen project officer at Aberdeen City Council, one of the key H2 facilitators.
"The bus fleet emits only water from the tailpipe and operates with circa 95% reduced noise level," says Goodenough, adding that the public's response has been positive. "Part of the project is to complete public perception surveys before, during and after the project. The surveys carried out before found that more than 80% of people would be happy to use the hydrogen buses. From a health and wellbeing perspective, this is key to our communities."
However, reports of the buses breaking down suggest some teething problems. Goodenough acknowledges this, but emphasises that it is a demonstration project. "We are currently in the six-month testing phase and expect that there will be technology issues," she says. "As issues arise, they are addressed by a team of engineers from the manufacturer. Reliability has improved considerably since their deployment."
A hydrogen production and bus refuelling station and maintenance depot has been installed at one of the council's depots. Goodenough says the council is now trialling other vehicle types, such as hybrid hydrogen diesel vans. "The vans emit 59g/km carbon dioxide under test, which equates to a 70% reduction in CO2 and 40% reduction in nitrogen oxides compared with a diesel equivalent."
Going further
Dundee City Council is keeping a watchful eye on developments. "We want to follow on with the lead Aberdeen has taken," says Neil Gellatly, head of transport. The council considers itself a pioneer in the electrification of transport and claims to operate the largest local authority fleet of electric vehicles in the UK, totalling more than 60 cars and vans.
Gellatly now wants to introduce hydrogen buses into the city. "We've identified through our air quality action plan where our hotspots are and these are where our major public transport corridors are. Because we've got a pedestrianised city with controlled entry, the buses work in the heart of the city all day. They run on clean-diesel engines. But the only way you can go zero emissions is by using something like a hydrogen fuel cell."
On the other side of the River Tay from Dundee, Fife Council is set to become one of the first local authorities to run hydrogen-powered refuse collection vehicles (RCVs). The council recently awarded a contract worth £1.5 million to Dunfermline-based Heil Farid European Company to supply nine RCVs, two of which will be converted to run on dual-fuel hydrogen and diesel.
The hydrogen vehicles, which are expected to be on the streets in early 2016, will be fitted with an ECOpto drive system so that a much larger hydraulic pump can be used. This means that, when the vehicle is operating the packer and bin lifts, the engine does not need to rev so high, resulting in less fuel consumption.
"Due to the innovative nature of the refuse vehicle design, it is not possible to quantify the expected carbon savings until the design is completed," says Tom Henderson, the council's service manager for fleet operations. "But the saving is expected to be significant, and will apply to both the motive and the compactive energy used on the vehicle."
Significantly, the RCVs form part of a wider hydrogen drive in the region. The council is a member of the Levenmouth Community Energy Project (LCEP), which houses the Hydrogen Office in Methil - a leading demonstrator site of hydrogen applications. The LCEP is led by Bright Green Hydrogen and involves a consortium of partners including Toshiba, the SHFCA, BOC and Community Energy Scotland.
According to Bright Green Hydrogen's technical manager, David Hogg, Levenmouth will eventually become home to one of Europe's largest fleets of hydrogen dual-fuel vehicles - up to 25. "Hydrogen refuelling has been installed in London, Swindon and Aberdeen, but the Levenmouth project involves developing one of the largest concentration of vehicles in the UK," he says. "As a result, it is pivotal to putting the region on the global clean-energy map."
The office is also helping to broaden Levenmouth's ambition. The building's energy system includes a 750kW wind turbine, 30kw electrolyser, 10kW hydrogen fuel cell and a geothermal source heat pump. It also houses a 5kW hydrogen boiler, which provides space heating in the nearby Fife Renewables Innovation Centre.
Hogg says this will improve the business park's capacity to be energy self-sufficient. "Such an approach will also demonstrate how more renewable energy can be connected to the grid nationally by alleviating the network export constraints that are becoming all too common in areas such as Scotland in times of peak renewable generation. This ability to guarantee an energy supply enables renewably generated hydrogen to be used for higher value applications."
LCEP started in earnest in March, when it was awarded a £4 million grant from the Scottish government. It has plans to lease out dual-fuel powered vans next year to local businesses in Fife. These will include 10 electric-powered Renault Kangoo vans with hydrogen fuel cell range extenders, enabling each to travel up to 200 miles between recharging. Businesses will be able to refuel at the Hydrogen Office and the council's Bankhead depot in Glenrothes.
Hogg says: "The vans will be leased to the public and private sectors. The leases will very flexible - based on periods of months or years - so that businesses can try them out. The project also includes five Transit dual-fuel, diesel-hydrogen vehicles which are to be owned and operated by Fife Council."
On the islands
Meanwhile, several Scottish islands are exploring hydrogen energy conversion. The Orkney Surf 'n' Turf project recently received £1.35 million from the Scottish government's local energy challenge fund to combine electricity from two tidal turbines and a wind turbine on the island of Eday. These small islands often produce more power than they need so excess electricity will be used to produce compressed hydrogen, which will be exported to the main town, Kirkwall, and converted into electrical power for buildings and berthed ferries at the harbour. This will reduce harbour costs and create jobs for the local community.
Ian Garman, innovation development officer at Community Energy Scotland, which is leading the project, believes energy generation for the area is being reshaped. "It is first a clear demonstration of how we can get around local restrictions and provide a workable alternative to the current model - grid export only - for local electricity generation. It also lays the foundations for a more ambitious indigenous alternative to brought-in fossil fuels for marine transport and other onshore power requirements," he says.
Garman points out that there are some technical challenges to overcome before hydrogen can become a mainstream transport fuel. "Our main focus is on the crew training and installation approvals needed before any seagoing public passenger vessel can rely on hydrogen power," he says. "This is a major block to any use of hydrogen on vessels. This project aims to provide both the training facilities and approved courses and certification necessary as an integral part of its operation."
Garman says overcoming these hurdles will open the door for Orkney's next generation of inter-island ferries to consider hydrogen as a viable energy source: "The amount of energy needed to run an inter-island ferry for an operational day is broadly equivalent to the energy harnessed in 24 hours by a 900kW wind turbine, such as the type that many of the local communities served by the ferries host."
Holmes believes this type of project has the potential to be "disrupt" the status quo through its "bottom up" approach to energy production and local use. "Remote and island communities where conventional fuel access is limited will be an early opportunity area for hydrogen," he says. "These same remote areas often have the best renewable energy resources, in the form of wind, hydropower and even solar." Despite such progress, commercial viability remains key if there is to be greater uptake of such technologies. "The main challenges at this stage are the embedded nature of the existing incumbent energy and transport technologies," says Holmes.
"Early stage deployment of innovative technologies will struggle to compete with the incumbent technologies on cost, and the commercial benefits to businesses from carbon and pollution reduction are not yet compelling. For this reason, public sector support for early stage deployments will be essential if we are to scale up and bring down costs."
