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The role of CCS in hydrogen production

A recent report by Global Witness has cast doubt on the value that carbon capture and storage (CCS) can bring to the mitigation of emissions associated with hydrogen manufacture from natural gas. This is based on an analysis of the Quest CCS project in Canada. However, the report fails to discuss the full context in which this project was developed and therefore draws an incorrect conclusion as to the benefits delivered by the project and the prospect for CCS linked to future hydrogen production.

Just over 20 years ago, I attended my first meeting of the Shell Canada Greenhouse Gas Advisory Panel. Shell Canada had established this panel to recommend and oversee measures to manage the carbon footprint of its operations at that time. Led by the then President/CEO, the panel included Shell Canada staff, representatives from Canadian and international NGOs and First Nations, and me representing the broader Shell group.

We met 2-3 times per year up until the mid-2000s and the Shell Canada team took forward a number of the panel’s recommendations to reduce emissions at Shell’s operations in Alberta. One of the earliest discussion points was around the need to develop CCS at Shell’s Scotford Complex in Alberta. These were the early discussions that led to the Quest CCS project.

Shell opened the Scotford Complex in 1984 with a refinery and chemicals plants, then expanded it in the early 2000s to process heavy oil into refined petroleum products. To do this, Scotford incorporated an ‘upgrader’, a unit that transforms bitumen into a light/sweet synthetic crude oil by fractionation and hydrogenation (improving the hydrogen to carbon ratio of the oil).

At the time, some of the hydrogen at the Scotford Complex originated from a nearby industrial facility where it was a by-product. But as Scotford grew with increasing production, Shell built a steam-methane reformer (SMR) to produce its own hydrogen. This is a process where natural gas is converted to hydrogen, with the remaining carbon being emitted as carbon dioxide from the process. A simplified representation of the process is;

CH4 (natural gas) + 2H2O (water as steam) –> CO2 (carbon dioxide emitted) + 4H2 (hydrogen produced)

In the case of a conventional SMR, which the original unit is, additional CO2 is also emitted from the process when natural gas is burned to provide energy.

Fast forward to today, Quest CCS has been running since 2015 and captures just over one million tonnes of CO2 each year – more reliably and at a lower cost than expected – with the CO2 coming from the reaction outlined above in the steam reformer that produces hydrogen for the upgrader.

Quest was designed as a million-tonne unit to capture one third of the emissions from the Scotford upgrader. Its purpose was to demonstrate not only that CO2 could be captured, but also that it could be stored more than 2 km underground in a geological formation that lies under much of Western Canada called the Basal Cambrian Sands. Quest is part of a knowledge sharing effort with the governments of Alberta and Canada to encourage wider use of CCS technology and bring down future costs. As such, its designs, emissions data and certain intellectual property are publicly available on the Government of Alberta website.

Quest was not, however, designed to capture all of the CO2 emissions associated with steam reforming of methane to make hydrogen. Nor has Shell claimed in its publicity that Quest is capable of capturing all CO2 emissions from the hydrogen plants or the upgrader. Annual performance reports on the Government of Alberta’s website have been audited and reviewed, and reflect an accurate characterization of what Quest has achieved to date: it has successfully captured and then permanently stored underground more than six million tonnes of CO2.

And importantly, Quest was not designed to produce blue hydrogen, and as such, it should not be used as an example of blue hydrogen production. Rather, Quest was designed to demonstrate that capture and storage of CO2 does work; and it has done just that.

Diagrammatic representation of Scotford CCS. Source: Shell Canada

Since Quest began operating, the energy transition has gathered pace and the role of hydrogen as an energy carrier has become a focus of attention. As a result, how hydrogen is produced has also become an important consideration. There are two approaches under consideration for a world that needs to head towards net-zero emissions.

  1. Green hydrogen – this is produced by the electrolysis of water using electricity from renewable energy sources. The basic process dates back over 200 years, but it has remained a relatively small scale process, until very recently. Now electrolysers are growing rapidly in size with Shell amongst a handful of companies installing very large units. In July last year, Europe’s largest PEM hydrogen electrolyser began operations at Shell’s Energy and Chemicals Park Rheinland, producing green hydrogen.
  2. Blue hydrogen – this is produced through the conversion of natural gas to hydrogen, with a very high percentage of the carbon dioxide which would otherwise be emitted by the facility, captured and geologically stored. Although the Quest CCS project captures and stores CO2 from hydrogen production, this is not a blue hydrogen facility. That is because only a portion of the CO2 is captured, as per the design criteria discussed above.

The Global Witness report has drawn on the Quest experience and used it to criticise the carbon footprint of blue hydrogen. The report concludes that future blue hydrogen projects should not be considered based on the observation that the existing hydrogen facility on which Quest is attached continues to emit a good portion of total CO2 produced.

But the analysis fails to contextualize Quest and doesn’t consider that future blue hydrogen projects would be designed very differently to Quest and the associated hydrogen plant, even employing different process technology for the methane conversion itself which in turns makes CO2 capture much more manageable and cost effective. For example, the proposed Polaris CCS project that Shell is planning for Scoford’s refinery and chemicals plants would include what’s called ‘post-combustion capture’ which has the more than 90% CO2 capture rates needed to produce blue hydrogen.

The route towards the current best process for blue hydrogen is described in a white paper produced by Shell Catalysts and Technologies, with its infographic shown below. The paper indicates the possibility of >99% CO2 capture in the Shell gas partial oxidation process (SGP).

Hydrogen processes with CCS. Source: Shell Catalysts and Technologies

As the century unfolds and the energy transition takes hold, hydrogen may become an important part of the new energy system. So society needs to be able to produce it at scale and do this quickly. Hydrogen from renewable sources and from natural gas with CCS will be required to meet demand. Both routes are more than capable of delivering hydrogen with a very low carbon footprint and ultimately cost will decide the winner, including the carbon cost associated with managing any ongoing emissions attributable to either process.

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