Feb-2022

Decarbonising the economy: no-regrets pathways to hydrogen

While fuel switching to hydrogen is the long-term solution for many hard-to-abate processes, no-regrets strategies can be the first step to reducing carbon emissions.

Wayne Bridger, BOC UK & Ireland
BOC UK & Ireland

Article Summary

There are high hopes for hydrogen and the role it can play in decarbonising the UK 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. As far as hydrogen goes, it is 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 is 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.

The UK’s 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 under way 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.

Alternative refrigeration
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.

Carbon capture
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.