Grown-Up Talk about Blue Hydrogen

January 30, 2024

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by Terry Mazanec (Lee Enterprises Consulting/Biofuels Digest) ... What constitutes the hydrogen economy? According to most analysts, the hydrogen economy is “an economy that relies on hydrogen as the commercial fuel that would deliver a substantial fraction of a nation’s energy and services.”[1] That sounds straightforward, but there are numerous routes by which hydrogen can deliver energy. Some paths involve producing hydrogen and using it directly as fuel in a combustion engine or fuel cell. Other paths make derivatives from hydrogen that are used as fuels. Current hydrogen production would provide only 2.3% of the world’s energy requirements so an 8X increase in production would be needed to reach 20%.

Routes to Hydrogen Economy

Underlying all the paths to a hydrogen economy are processes for producing hydrogen.

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A sophisticated model, called GREET[2], developed at Argonne Labs, is used to calculate CI (carbon intensity). GREET combines numerous measured properties and process features along with user-designated assumptions to provide a CI value for a particular pathway.

The oldest and most widely used hydrogen production methods start with fossil fuels coal or natural gas, and are labeled as black or grey, since they are considered the least environmentally friendly and have high CI values. (CI is scored like golf; low scores are better) At the other end of the hydrogen spectrum are those processes that rely on renewable energy and involve no carbon directly such as electrolysis of water using electricity from wind, solar, or hydroelectric generation, which are considered green. Those processes produce hydrogen with very low CI scores. In between are numerous variations and combinations that include those that use biomass as feed, nuclear energy, biological processes, or integrate any process with carbon capture and storage (“CCS”) to reduce CI. There are even processes that have negative CI scores, i.e. their net effect is to remove CO2 from the environment. So-called blue hydrogen is hydrogen produced from natural gas using conventional steam methane reforming (“SMR”) with the capture of CO2 for storage.

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Burning natural gas emits almost 45 percent less carbon dioxide than does burning coal while producing the same amount of energy.

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Carbon capture technologies were developed to remove CO2 from chemical process streams and power plant flue gas.

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There is no free lunch, however, as the additional CCS processing reduces the overall process efficiency of an integrated combined cycle natural gas-powered plant by about 5 points, from 43% to 38%.[7] A blue hydrogen installation that replaces a conventional coal-fired plant with a gas-fired SMR + CCS plant could reduce the CO2 emissions produced by as much as 86%. Where low emissions electricity is available to produce oxygen, the use of autothermal reforming (ATR) can reduce CO2 emissions even further since the higher concentration of CO2 in the flue gas makes CO2 capture more efficient.

Carbon Capture – Key to Blue Hydrogen

Blue hydrogen relies on carbon capture and storage technology. There are currently 41 operational CCS facilities worldwide, seven of which make blue hydrogen for ammonia used in fertilizer production.

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Considerable controversy exists over the role of blue hydrogen in the drive to reduce CO2 emissions. Since blue hydrogen relies on two inputs that are typically non-renewable, i.e. natural gas and electricity, some consider it ‘only a modest improvement’ on current practices. These critics dismiss blue hydrogen as a ‘half-measure’ and are anxious to go for the complete transition to green, possibly zero emissions, hydrogen.

Electrolysis of water is a very popular competitor in the hydrogen production sphere since it is seen as emitting no CO2. However, even those who are dedicated to seeing the hydrogen economy take shape are becoming more circumspect as more is learned about the technical and economic hurdles. The Hydrogen Council, for example, reports in its November 2023 summary that “Estimates of the levelized cost of hydrogen (LCOH) for renewable hydrogen are between 30 and 65 percent higher than those in the October 2022 report.”[13] Nevertheless, in the December 2023 “Hydrogen Insights 2023” the Hydrogen Council projects a 50% drop in the cost of H2 by electrolysis in the next 7 years, and a further 50% cost reduction by 2050.[14] Technology developers will have a hard time living up to that projection.

The emissions benefits of water electrolysis are being called into question as well.

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Of particular note, is the two-step process being advanced by Raven SR. The Raven process first steam reforms any mixture that contains hydrocarbons – MSW, biomass, food waste, plastics – in a rotating kiln, followed by a higher temperature SMR-type reforming step to produce syngas that is readily shifted to hydrogen. The rotating kiln can accommodate solids and separates the unreactive contaminants like glass, metal, and minerals from the useful hydrocarbons in the process, making it applicable to a wide range of situations and feeds.[17] With green electricity and renewable feeds such as wood waste the process is fully renewable.

With a long history in coal upgrading, gasification holds promise that it can be adapted successfully to waste feeds like MSW or biomass to produce renewable, low-CO2 hydrogen. There are 3 competing gasification schemes.

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In China, it appears that the choice for hydrogen production has been made – coal gasification with CCS.

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Coal now supplies 69% of China’s electricity and is adding a new coal plant almost every week. To date the implementation of CCS has lagged far behind the buildout of coal plants.

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Plasma gasification is another competitor. Electrically heated furnaces, combustion flames, and electric discharges have been considered for high temperature plasma generation. The very high temperatures available in plasma systems (~ 3000 °C) are attractive because they decompose the gas into atoms that recombine to a high H2 content syngas. However, the cost of energy, the requirement for expensive materials, and the difficulty in controlling the gas cooling have severely limited applications to hydrogen production. Tacking on an additional CCS unit would merely drive up costs.

Methane pyrolysis is being advanced as a hydrogen source. The temperatures of methane pyrolysis are typically about 1000-1100°C due to the stability of methane; catalysts reduce the required temperatures to the 500-900 °C range. During the reaction, each mole of methane splits into two molecules of hydrogen and one atom of carbon. When compared to steam methane reforming, pyrolysis of methane produces only half as much hydrogen per CH4.

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CH4 => C + 2 H2

One advantage of methane pyrolysis over other methane or natural gas hydrogen production technologies is the production of solid carbon instead of CO2.The lack of CO2 emissions makes methane pyrolysis a cleaner and more attractive hydrogen production pathway. Solid carbon can be a valuable product in its own right or could be steamed to generate CO and additional H2. The drawback is that in addition to H2, pyrolysis makes a complex byproduct mixture of hydrocarbons including some tars that present operational issues. If pyrolysis uses a renewable methane source such as biogas, it could be one of the ‘greener’ alternatives.

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Methane is about 25x more potent than CO2 as a greenhouse gas (GHG). Despite efforts to reduce gas flaring, it still accounts for about 150 billion cubic meters of CO2 globally each year, just a bit less than that produced by agriculture. If this methane could be recovered and converted to blue hydrogen the impact on CO2 emissions would be enormous. READ MORE

[1] Nehrir, M. H., Wang, C., “Fuel Cells”, in “Electric Renewable Energy Systems”, Academic Press, 2016 92-113, https://www.sciencedirect.com/science/article/pii/B9780128044483000062 .

[2] GREET stands for Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation, https://www.energy.gov/eere/bioenergy/articles/greet-greenhouse-gases-regulated-emissions-and-energy-use-transportation .

[3] https://globalenergyinfrastructure.com/articles/2021/03-march/hydrogen-data-telling-a-story/

[4] EIA; https://www.eia.gov/todayinenergy/detail.php?id=48296

[5] The Hydrogen Council, “Hydrogen decarbonization pathways – A life-cycle assessment,” January 2021, https://hydrogencouncil.com/en/hydrogen-decarbonization-pathways/

[6] Howarth, RW, Jacobson, MZ, “How Green is Blue Hydrogen?” Energy Sci Eng, 2021, 1676-1687.

[7] Hendriks, C.A., Blok, K., Turkenburg, W.C. (1989). “The Recovery of Carbon Dioxide from Power Plants.” In: Okken, P.A., Swart, R.J., Zwerver, S. (eds) Climate and Energy: The Feasibility of Controlling CO2 Emissions. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-0485-9_9 .

[8] Global CCS Institute, “Global Status of CCS 2023,” https://status23.globalccsinstitute.com/ .

[9] IEA Tech Report 2017-02, “Techno – Economic Evaluation of SMR Based Standalone (Merchant) Hydrogen Plant with CCS,” https://ieaghg.org/component/content/article/49-publications/technical-reports/784-2017-02-smr-based-h2-plant-with-ccs

[10] Ibid.

[11] IPCC Chapter 3,”IPCC Special Report on Carbon dioxide Capture and Storage,” https://www.ipcc.ch/report/carbon-dioxide-capture-and-storage/capture-of-co2/

[12] George, J. F., “Is blue hydrogen a bridging technology?,” Energy Policy 167 (2022), 113072.

[13] The Hydrogen Council, “Global Hydrogen Flows – 2023 Update – Considerations for evolving global hydrogen trade,” November 2023, https://hydrogencouncil.com/en/global-hydrogen-flows-2023-update/

[14] The Hydrogen Council, “Hydrogen Insights 2023 December Update,” https://hydrogencouncil.com/en/hydrogen-insights-2023-december-update/

[15] Delft, CE Delft, “Feasibility study into blue hydrogen – Technical, economic & sustainability analysis,” https://cedelft.eu/publications/feasibility-study-into-blue-hydrogen/

[16] George, J. F., et al,. op cit.

[17] https://ravensr.com/

[18] Li, et al, “The carbon footprint and cost of coal-based hydrogen production with and without carbon capture and storage technology in China,” J Cleaner Production, 362, 2022, 132514; https://doi.org/10.1016/j.jclepro.2022.132514 .

[19] Fan et al, “A levelized cost of hydrogen (LCOH) comparison of coal-to-hydrogen with CCS and water electrolysis powered by renewable energy in China,” Energy 242, 2022, 123003; . https://doi.org/10.1016/j.energy.2021.123003 .

[20] Korányi, Tamás I., et al. “Recent Advances in Methane Pyrolysis: Turquoise Hydrogen with Solid Carbon Production.” Energies 15.17 (2022): 6342.

[21] Exxon website, 30-Jan-2023, “Low-carbon hydrogen: Fueling our Baytown facilities and our net-zero ambition,” https://corporate.exxonmobil.com/news/viewpoints/low-carbon-hydrogen

[22] Shell website, “Shell to start building Europe’s largest renewable hydrogen plant”, 7-Jul-2022, https://www.shell.com/media/news-and-media-releases/2022/shell-to-start-building-europes-largest-renewable-hydrogen-plant.html

[23] MHA Nation Partnering with Bakken Energy and Mitsubishi Power on Great Plains Hydrogen Hub, February 9, 2022, https://www.bakkenenergy.com/mha-nation-partnering-with-bakken-energy-and-mitsubishi-power-on-great-plains-hydrogen-hub/ .

[24] https://www.cbc.ca/news/canada/edmonton/calgary-energy-firm-backs-away-from-proposed-4b-northern-alberta-methanol-plant-1.6739176

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woody biomass water syngas (synthesis gas) recycled plastics pyrolysis plastic Netherlands natural gas MSW (Municipal Solid Waste) methane/biomethane Hydrogen/Renewable Hydrogen GREET Greenhouse Gases Regulated Emissions and Energy Use in Transportation Model GHG (Greenhouse Gas Emissions) gasification food waste flue gas fertilizer electrolysis coal China catalysis carbon/CO2 sequestration Carbon Intensity (CI)/Carbon Footprint Carbon Dioxide (CO2) carbon capture and storage (CCS) carbon BioRefineries/Renewable Fuel Production biomass biohydrogen Biogas BioChemicals/Renewable Chemicals ammonia Investing Sustainability

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