There are high hopes for hydrogen and the role it can play in decarbonising our economy. These hopes are well founded. We have zero-emission vehicles running today, fuelled by green hydrogen.
Demonstration projects have shown that we can use hydrogen to make green steel, decarbonise glassmaking and many other high temperature, direct-firing industries such as ceramics production and minerals processing. As far as hydrogen goes, it’s time to believe the hype.
So, where’s the catch? Despite hydrogen’s potential, the UK’s net-zero ambition raises some important questions. The stated aim is to achieve 5 gigawatts (GW) of low-carbon hydrogen production capacity by 2030. For context, currently, just 1% of the world’s hydrogen is produced by electrolysis using renewable energy. The UK’s electrolysis production capacity is estimated at around 20-30 megawatts (MW). Bridging the gap to 5 GW requires that we increase capacity up to 250x in under 10 years, which will require a hugely focused effort.
Achieving such a scale-up in production requires investment. We need to develop and deploy bigger, more efficient electrolysers. Access to cheaper renewables will help to drive down operational costs while availability of capital will fund infrastructure build. As well as developing the capacity to produce green hydrogen at scale, the aim should be to drive down costs so that it becomes cheaper than fossil-fuel alternatives. We must also invest in education and training to address the hydrogen skills gap.
The challenge of producing green hydrogen at scale may explain the government’s decision to simultaneously back blue hydrogen in its 2021 strategy.
Steam methane reforming (SMR) is the industrial process commonly used to extract hydrogen from natural gas, which is the feedstock for most of the hydrogen produced today. This process, which results in grey hydrogen, emits CO2. When the CO2 is captured, the hydrogen is designated as blue.
The low-carbon credentials of blue hydrogen are being challenged from many sides. Simply put, the effectiveness of the carbon capture process is critical to achieving a truly low-carbon supply of hydrogen. It’s fair to say that carbon capture efficiency varies considerably, but the latest technologies are much more effective in capturing carbon than before.
Blue hydrogen production plants planned for the UK will use Autothermal Reforming (ATR), which captures CO2 as part of the production process rather than as a separate step. ATR is proven and its 97% effectiveness in capturing CO2 is backed up with production data. Just like green hydrogen production using electrolysis, the carbon intensity of the electricity supply used by the ATR system ultimately determines the carbon intensity of the blue hydrogen. Well-engineered solutions using the latest technology can produce hydrogen with emissions of the order of 10-20g CO2/MJ.
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The independent Committee on Climate Change (CCC) has itself recommended that significant volumes of blue hydrogen can help industry cut emissions faster than would be possible if we wait for green hydrogen to become widely available.
Bridging the hydrogen gap
While fuel-switching to hydrogen is the long-term solution for many hard-to-abate processes, there are other proven existing technologies that we can use to reduce energy consumption and, therefore, carbon emissions today.
These are ‘no-regrets/low-regrets’ strategies that use well-understood technologies, which can help businesses take the first steps towards reducing carbon emissions.
Fuel-switching and intensifying processes
When devising a decarbonisation strategy, it makes sense to do the easier things first. Being more efficient with the use of any fuel falls into that category; using less fuel emits less carbon.
Process intensification is the key to doing more with less. One approach is to burn a fuel using pure oxygen, or a mixture of oxygen and recirculated flue gas, instead of air. This approach intensifies the combustion process, which reduces fuel consumption and can deliver better temperature uniformity. Depending on the nature of the process it is possible to reduce fuel consumption by between 10% and 50%, with a consequent reduction in carbon.
In terms of fuel savings, the economic benefits of process intensification vary from case-to-case. A reduction in natural gas costs can be offset by the additional cost of using oxygen in the combustion process. However, adding carbon tax savings into the economic model makes the business case compelling for process intensification.
Industries that can benefit from intensification include those dependent on high temperature furnaces where there is a high proportion of natural gas combustion in their processes. These include industries such as glassmaking, steel and the minerals sector, including cement production.
Other applications that burn natural gas may be candidates for a ‘blending’ approach to fuel switching where hydrogen is mixed with the natural gas before combustion. Trials in the UK are underway to demonstrate that blending up to 20% volume of hydrogen with natural gas is a safe and lower-carbon alternative for home cooking and heating appliances.
It is not only high-temperature processes that can benefit from the use of alternative gases to help decarbonise; refrigeration and cooling can benefit too. While freezer units are typically powered using electricity, it is also possible to use liquid nitrogen to facilitate cooling.
By enabling fuel flexibility, businesses have a mechanism to avoid volatile electricity prices. A stored tank of nitrogen, which has been produced using green electricity at a known cost, offers a means of fuel switching from the grid supply at times when the cost of wholesale electricity is high. The nitrogen gas effectively acts as an energy store for a wide range of refrigeration and cooling across industrial applications and food production.
As well as being integral to the process of producing blue hydrogen, there are other industrial processes where carbon capture, utilisation and storage (CCUS) is currently the only option available for decarbonisation. CCUS involves the capture of CO2 from the industrial process, its transport and subsequent use or sequestration.
While the oil majors were early adopters of the technology, CCUS is gaining more traction as a decarbonisation technology for industry and power generation. For large volumes the carbon dioxide will need to be sequestered but there is also the potential to store carbon in, for example, aggregates. This approach offers the potential for additional revenue streams and reduced exposure to future carbon prices.
There are several technology choices available for carbon capture, broadly categorised as either pre-combustion, oxy-fuel and post-combustion. BOC has experience of all three approaches and can best assess and determine the most cost-effective approach for a particular carbon emitting process.
Transport accounts for over a quarter of the UK’s emissions so it remains a prime target for urgent decarbonisation. The automotive industry is building momentum around delivery of a growing range of battery electric vehicles (BEV), primarily targeting private motorists. The key driver for the growth of BEVs is the UK’s 2030 ban on the sale of new petrol and diesel cars.
However, there is a much less clear case for the use of battery electric powertrains with large and heavy vehicles such as buses, HGVs and trains; heavier vehicles require large capacity, heavy batteries, which penalise range. By contrast, hydrogen is proven as a fuel for buses, trains and trucks without incurring a weight penalty. It has a high energy density and refuelling can be carried out from a dispensing pump in minutes to provide a range of hundreds of miles. Many UK councils and local authorities are planning to develop hydrogen refuelling stations (HRS) to provide back-to-base refuelling for bus fleets and maintenance vehicles, including gritter and refuse trucks.
Extending hydrogen hub access to business fleets, such as delivery vehicles and taxis, as well as private motorists, helps to bring economies of scale to refuelling stations.
The commercial vehicle industry is calling for clarity over decarbonisation plans before it commits to an end-sale-date for conventionally fuelled trucks. To accelerate decarbonisation, introducing policies that prioritise the use of green hydrogen for transport and mobility over other industrial applications – at least until we have green hydrogen capacity at scale – might find support from the transport sector.
Planning for action
While clean hydrogen will play a major part in decarbonising many industries, it should be clear by now that today there is no one-size-fits-all panacea. The examples cited above illustrate the varied challenges – and potential solutions, which can bridge the hydrogen gap for a range of applications. In working with businesses across multiple sectors we have learned that different users almost always require tailored solutions.
The first step on your journey towards net zero is to understand what your carbon emissions are, and in which sites and systems these are highest. There may be a range of solutions available to help decarbonise your plant and processes. Assessing the optimum solution for industrial applications requires engineering and operational expertise – as well as experience in applying real-world strategies for reducing emissions.
BOC is currently undertaking its own decarbonisation journey. We have a clear understanding of where our emissions come from and how we will tackle them. We are one of the largest purchasers of electricity in the country and we have already reduced our carbon footprint substantially by opting to use renewable power. We are planning to deploy CCUS at our hydrogen plants. We have taken the decision to retire some older plant because it is more economic and effective to invest in new infrastructure that has a much lower carbon footprint.
The decarbonisation measures that we are applying ourselves reflect the range of recommendations that we are using with customers. As well as specific projects that address large emitters of CO2, we are continuously looking to reduce our own energy consumption by improving energy efficiency; the simple rule of thumb is that energy use has financial, reputational and emissions costs. Generally, good cost management results in good green credentials.
About the author
Wayne Bridger is responsible for Decarbonisation & Hydrogen Applications at BOC UK & Ireland.