Blue/Green H2 Production
E. MEYER, Yokogawa, Sugar Land, Texas
For a long-term sustainability strategy, hydrogen (H2) offers substantial promise as a zero-emissions energy source. Almost every synthetic chemical begins with H2. Although it is the most abundant element in the universe, on earth it occurs almost exclusively in chemical compounds and must be separated from other elements. Traditional H2 manufacturing is energy-intensive and produces carbon byproducts.
The World Economic Forum (WEF) describes the “many colors of H2”—each referring to how it is produced. The ultimate clean form is green H2. As the WEF states, green H2 is the only variety produced in a climate-neutral manner. Production processes use carbon-zero power sources (e.g., solar photovoltaic, wind). Traditional methods using coal gasification produce the highest emissions. The black H2 production process uses bituminous coal while brown H2 production uses lignite coal. Both produce carbon monoxide (CO) and carbon dioxide (CO2) emissions.
Today, the vast majority of the produced H2 is gray H2. Most often, methane is the key feedstock, but some gray H2 production processes use ethane, propane or naphtha. According to the U.S. Department of Energy (DOE), 95% of the H2 produced in the U.S. is made using natural gas in steam methane reforming (SMR) processes. As the U.S. DOE states, this is an important technological pathway for near-term H2 production. However, emissions are only modestly below those resulting from the production of black or brown H2.
Blue H2 is distinguished from gray H2 because its production processes use carbon capture and storage for the produced greenhouse gases (GHGs). Although blue H2 is sometimes referred to as “carbon neutral,” the amount of CO2 that is actually captured is somewhat below 100%—of the blue H2 being produced across all industries [through SMR with carbon capture and storage (SMR-CCS) or autothermal reforming (ATR) with CCS (ATR-CCS)], 80%–95% is captured and not released.
Green H2 is produced most commonly by a water electrolysis process. Producing long-duration H2 energy storage requires a great deal of energy. While that energy is generated using renewable sources, such as solar or wind, products derived from this H2, such as green ammonia, cost up to four times as much to produce compared with traditional methods. The H2 fuel industry is in the very early stages of development.
According to the U.S. DOE Alternative Fuels Data Center, the availability of fueling stations providing reasonably priced H2 in locations where vehicles will be deployed remains a key challenge to the adoption of this technology. In mid-2021, there were 48 operating retail H2 stations in the U.S. In addition, at least 60 stations were in various stages of planning or construction. There is also work to do in terms of safety and regulations. As the Alternative Fuels Data Center states, “The DOE is coordinating the efforts of codes and standards organizations to develop more robust codes and standards that ensure the safe use of H2 for transportation and stationary applications.” The U.S. DOE is also coordinating demonstration projects to prove the technology in real world applications.
The technologies involved in the manufacturing and deployment of electric vehicles (EVs) or battery electric vehicles (BEVs) are far more developed. While EV technology continues to evolve, operation is feasible today. The U.S. DOE states that there were 43,800 EV charging stations in the U.S. as of August 2021. The Bipartisan Infrastructure Law provides $7.5 B to develop the country’s EV-charging infrastructure with a goal to deploy 500,000 charging units available to the public by 2030.
According to McKinsey, there are potentially four zero-emissions vehicle engine technologies: BEVs, H2 fuel-cell electric vehicles (FCEVs), H2 internal combustion engines (H2-ICEs), and biofuel or synfuel ICEs. The sustainability of the biofuel and synfuel technologies depends heavily on the carbon emissions and carbon capture technologies in both their production and use in vehicles.
The McKinsey report continues, “The CO2 emissions generated in the process of producing electricity, H2 or synfuel can vary significantly. Although BEVs are carbon neutral if charged solely with renewable power, their use currently leads to high carbon emissions when charged with grid electricity in most regions (given the high carbon intensity of the global grid mix).”
Sustainability as a long-term strategy. Given the feasibility of BEVs—but considering the high carbon intensity on today’s grid and the fact that H2 deployment is in its very early stages—can other technologies provide significant progress on the path to sustainability?
As an interim solution, other economical, renewable sources use the same infrastructure as traditional black, brown and gray H2. For example, H2 generation from biomass could have a much lower carbon intensity. Such production using biogas produced from landfills, cattle feedlot waste and dairy waste can reduce the reliance on traditional sources of methane.
For larger chain hydrocarbons, used cooking oils and animal fat can be used to produce renewable diesel and naphtha. Lignin produced in the Kraft paper process has traditionally been used as a fuel in black liquor boilers to produce steam for the process and to generate electricity. Today, paper mills are more often opting to sell the lignin to be further refined into bio-based construction materials, bioplastics and bio-asphalt. The lignin could also be a feedstock for renewable diesel and gasoline.
Many renewable energy facilities are coming online in the near future. ArcelorMittal, one of the world’s leading integrated steel and mining companies, has begun construction of a groundbreaking bioethanol facility. Via the Steelanol plant, the company will transform part of the carbon-containing exhaust gases from blast furnaces into advanced bioethanol that can be used as a sustainable fuel for transportation or as raw material for the production of synthetic materials and chemicals.
The Steelanol plant will be the first industrial installation of its kind in Europe and the largest facility built to date utilizing this technology globally. The plant aims to demonstrate the possibility of producing bioproducts at an industrial scale through an innovative gas fermentation process using bacteria to capture the carbon-rich gases emitted by the steelmaking activities and converting them to bioethanol.
In the U.S., Fidelis New Energy LLC is a unique decarbonization enterprise developing and operating multiple synergistic infrastructure “GigaSystems,” a term the company has trademarked. Fidelis states that these systems generate climate-positive, stable and predictable earnings before interest, taxes, depreciation and amortization (EBITDA). The company is pursuing the production of carbon-negative sustainable aviation fuel, renewable diesel, renewable naphtha and green H2. Fidelis is also developing and operating carbon capture infrastructure and landfill-diverted biomass power generation.
As a McKinsey report states, “The carbon intensity for biofuel and synfuel depends on the sourcing of biomass and carbon, respectively. Hybrid and gas engines represent bridging technologies to reduce emissions in the medium term but cannot achieve zero emissions on their own.” However, when combined with carbon management techniques such as carbon capture, these technologies are very promising.
Takeaway. As the energy transition unfolds, competing in an emerging market with a mixture of new and traditional commodities requires innovation. Process efficiency is crucial. Renewable energy companies pursuing sustainable development goals are finding common ground with companies in the automation and information technology industries. Together, they are working on digital transformations, which will lead to sustainable, autonomous operations with the highest efficiency.
Best-in-class digital transformation strategies result in fully automated assets that do not require human operator action during startup, shutdown and online operation. Autonomous operations thrive with a reduced workforce and improve overall personnel safety. They will enable the step changes that will be required to transition from today’s fossil fuel-based power generation through hybrid technologies to ultimately achieve a sustainable, net-zero world.H2T
About the author
ERIC MEYER is a Systems Consultant and the CombustionONE™ technical lead in North America. Meyer has more than 20 yr of experience in the areas of combustion equipment design and optimization, combustion safety, fired equipment design, project management and business development.