Hydrogen carries a well deserved reputation for being the clean fuel, and offering a route away from the continuous polluting cycle associated with mainstream fuels such as petrol and diesel. There is, however, a challenge for both commercial and private users of fuel to gain an understanding of hydrogen, the readiness of the associated technology, and the economics. This is a challenge that ITM Power has sought to address head on.
The HFuel system
The hydrogen refuelling platform developed by ITM Power is called HFuel®. It is modular, based around water electrolysis, and successfully integrates all of the equipment necessary to turn electricity and tap water into 350 bar (5000 psi) hydrogen and dispense it rapidly into vehicles.
As an integrated package, it contains input water purification, AC/DC power conversion, hydrogen generation using PEM electrolysis, compression, storage and dispensing, together with an overarching control system and backup power provision. The systems are packaged in standard ISO shipping containers for ease of transport.
The hydrogen is generated in electrolyser stacks, which operate at 15 bar (218 psi), and is accumulated in a buffer store. An electrically driven compressor draws from the buffer store and progressively fills higher-pressure storage vessels to 250, 350 and 410 bar (3600, 5000 and 5950 psi). These pressures have been determined by analysis and optimisation of the cascade refuelling process, which uses the differential pressure to deliver hydrogen into the vehicle as quickly as possible.
The use of hydrogen, unlike batteries, enables energy to be transferred into a vehicle in minutes rather than hours. Crucially, the electrolyser technology is able to start and stop rapidly, and as such can accept an undulating input power profile – typical of renewable energy generation.
The ‘triple zero’ fuel
Hydrogen is well known for being clean at the point of use – when it is burned, it does not release any carbon or greenhouse gases. However, it is also important to consider the supply chain when assessing its green credentials. The vast majority of hydrogen is derived from natural gas via steam reformation, and then transported by tanker to where it is needed by sea and road.
But hydrogen generated by electrolysis is very different! In addition to being clean at the point of use, its generation is clean, as the input electricity can be sourced from a renewable resource such as wind or solar. Furthermore, there is no carbon footprint associated with the logistics of moving the hydrogen, as it can easily be generated onsite.
Engaging with the industry
ITM Power has devised and is operating a scheme called HOST (Hydrogen On Site Trials), which allows commercial companies to use hydrogen refuelling together with Ford Transit vans with internal combustion engines converted to run on hydrogen, and judge for themselves the value proposition to their businesses.
The HOST programme has 21 partners spread across seven industrial sectors – a deliberate move to gain exposure to as many different usage profiles as possible – which makes it the largest hydrogen refuelling trial in the UK.
Participating companies utilise an HFuel system (capable of generating 15 kg of hydrogen per day) and two hydrogen/petrol bi-fuel Ford Transit vans, to be used as part of an existing return-to-base fleet for one week for free. At the end of each partner’s trial, a comprehensive report is generated, summarising the operation of the system and highlighting key metrics which enable a commercial assessment of the system to be made.
HOST was launched in March 2011 at London Stansted Airport, and 13 of the 21 trials had been successfully completed by the end of January 2012.
Performance in the field
The HOST trials have generated a rich data set. Key among the observations is 100% availability – no one has ever tried to refuel their vehicle and found that HFuel was not able to respond. Using data from the trial which took place with logistics operator DHL, 45 kg of hydrogen was generated over the five days, at an average efficiency of 56 kWh/kg. This translates to an average efficiency of 65%, with peaks of 69.5% for the whole system.
Considering the cost of the input electricity, hydrogen achieves price parity with petrol per mile when electricity can be sourced for 6.5p/kWh – a tariff which is easily accessible to the commercial user.
This brief analysis includes the use of hydrogen in an internal combustion engine – the stepping stone to fuel cell vehicles.
Roughly speaking, 1 kg of hydrogen contains the same energy content as a gallon (US) of petrol. Therefore an internal combustion engine vehicle which achieves 35 miles per gallon (8 liters per 100 km) of petrol would be expected to complete 35 miles per kg of hydrogen.
However, a fuel cell vehicle would achieve close to double that range for the same quantity of hydrogen, owing to the more efficient electrochemical conversion process. The Honda FCX Clarity car, for example, claims over 61 miles per kg of hydrogen.
The rollout of hydrogen infrastructure
There is no question that Germany is leading the way in Europe. The German H2 Mobility programme will see the investment of €2.6 billion (US$3.4 billion) towards the deployment of hydrogen refuelling infrastructure across the country. A key date in this scheme is 2015; a date shared by most automotive OEM manufacturers, and coinciding with production quantities of hydrogen powered fuel cell cars hitting the streets.
The Clean Energy Partnership – the organisation with the responsibility for installing the hydrogen refuelling stations – is seeking ‘green hydrogen’ to be dispensed by 50% of the infrastructure put down in Germany. Hydrogen derived by electrolysis is the way to satisfy this.
The UK government is following this lead. On 18 January Business Minister Mark Prisk officially announced the launch of UKH2Mobility. This programme brings together three government departments and 13 industrial participants from the utility, gas, infrastructure, and global car manufacturing sectors.
The group will evaluate the potential for hydrogen as a fuel for Ultra Low Carbon Vehicles in the UK before developing an action plan for an anticipated rollout to consumers in 2014–2015.
This is an important commitment, signalling that the UK recognises hydrogen as the future of fuel, and intends to ensure that the UK is well positioned for the rollout of hydrogen fuel cell vehicles.
ITM Power is one of the 13 industry signatories of the memorandum of understanding that establishes UKH2Mobility.
An integrated solution
A hydrogen system incorporates multiple components and subsystems. Crucial to their effective and efficient operation is careful integration. Taking on this job and achieving product compliance is not for the faint hearted!
As traction for hydrogen fuel builds, there is a need to offer flexibility in order to tailor the infrastructure to specific applications and usage profiles. This is something that ITM Power has taken to heart. The HFuel platform is fully modular, offering the user the flexibility to specify generation capacity and storage capacity separately. A wide range of schemes have been analysed, ranging from 5 kg/day to 100 kg/day of hydrogen generation, and up to 260 kg (circa 8.8 MWh) of energy storage capacity.
About ITM Power
ITM Power designs and manufactures hydrogen energy systems for energy storage and clean fuel production. The company has grown from its original platform of novel polymeric electrolytes (for water electrolysis and hydrogen fuel cells) to that of a technology provider. It now has both a strong base of intellectual property and engineering expertise for providing complete hydrogen solutions and CE-marked products for sale.
Part 2 will look at the challenge of integration with renewable energy, including ITM Power’s HOST programme and the company’s participation in the broader EcoIsland initiative in the Isle of Wight.
About the author: Dr Simon Bourne is Chief Technology Officer of ITM Power, based in Sheffield, UK.
This article was originally published in the Fuel Cells Bulletin – check out the sample Digital Edition, which includes the full original version of this article.