Hydrogen is well known for being clean at the point of use as when it is burned it does not release any carbon or greenhouse gases. It is important to also consider the supply chain when assessing its green credentials. The vast majority of today’s hydrogen is derived from natural gas via steam reformation before being transported by road and/or sea to where it is needed.
Thankfully, there are other routes to produce hydrogen. The best understood is electrolysis – using electricity to split water into hydrogen and oxygen gases. The attraction of electrolytic hydrogen is owed to the fact that the electricity used to power the process can be derived from renewable sources (such as wind and solar). In addition, the hydrogen can be generated on site where the fuel is needed, avoiding complex and costly supply logistics and the associated carbon footprint. This is the cleanest and greenest form of hydrogen production available.
The HFuel system
ITM Power has developed a hydrogen generation and refuelling platform called HFuel, which offers a sustainable supply of hydrogen for transport vehicles. It is modular, based around water electrolysis, and integrates all of the equipment necessary to turn electricity and tap water into 350 bar hydrogen and dispense it rapidly into vehicles. As an integrated package, it contains input water purification, AC to DC power conversion, hydrogen generation using PEM (proton exchange membrane) 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 and to minimise civil works associated with refuelling station construction.
The hydrogen is generated in electrolyser stacks at up to 80 bar (see figure 2) and is accumulated in a buffer store. An electrically driven compressor draws from the buffer store and progressively fills higher pressure storage vessels to levels appropriate for either 350 or 700 bar refuelling. 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 economic case
While there can be no argument over the environmental benefits of ‘green hydrogen’ or the independence of a locally produced fuel, the economics are clearly of vital importance. Hydrogen costs are best expressed in GBP per kg and reflect both capital cost amortisation and electricity cost.
Based on a hydrogen generation module capable of producing 100 kg of hydrogen per day, with a one-off price of GBP 713,242 today, an amortisation period of 10 years, efficiency of 60 kWh per kg, and an indicative annual service cost of GBP 35,662, the hydrogen cost is projected at GBP 6.23 per kg within a 10-year capital amortisation period and GBP 3.49 per kg after capital amortisation assuming 70% utilisation factor.
Increasing the utilisation factor to 100% reduces the hydrogen cost to GBP 5 per kg during a 10-year capital amortisation period and GBP 3 per kg thereafter.
The European cost targets for hydrogen generation are EUR 9.90 per kg (GBP 7.92) in 2015 and EUR 5.50 per kg (GBP 4.40) in 2025 (Source: McKinsey, A portfolio of powertrains for Europe: A fact-based analysis). Owing to the ability of HFuel to turn on and off rapidly, and to be demand side managed as a smart load, electricity prices of GBP 0.035 kWh have been assumed, but they may be lower or even negative.
Analysis of this case has revealed that a utilisation factor of 50% or higher will enable hydrogen to be generated for a cost matching, or even beating, the EU target for 2015 (when most automotive OEMs intend to release their fuel cell electric vehicles) as well as being significantly cheaper than diesel (on a cost per mile basis) bought on the high street in the UK today.
There is no question that in Europe, Germany is leading the way. The German H2Mobility programme will see the investment of EUR 2.6 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 OEMs (original equipment manufacturers) as 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 suit. January 2012 saw the official announcement of UK H2 Mobility by the then Business Minister Mark Prisk – a programme which brings together three government departments (the Department of Energy and Climate Change, the Department for Business Information and Skills, and the Department for Transport) and 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 roll-out to consumers in 2014/2015. This is an important commitment, signalling that the UK recognises hydrogen as a fuel of the future and the intent to ensure the UK is well positioned for the roll-out of hydrogen fuel cell vehicles. ITM Power is one of 13 industry signatories of the UK H2 Mobility Memorandum of Understanding.
Author: Rebecca Markillie (ITM POWER)