Green Production Processes are Critical
Today’s Hydrogen Needs to Become Clean Hydrogen
Hydrogen is a major component of numerous energy-intensive industrial activities globally. Nearly all hydrogen is produced by a process that burns natural gas, so hydrogen has a significant CO₂ emissions footprint. Decarbonizing hydrogen production is an important step to combat climate change. This article will explain some of the current initiatives to facilitate a transition to “clean” hydrogen in the coming decades.
Hydrogen Characteristics
Hydrogen (H₂) is odorless, tasteless, non-toxic, highly combustible, and colorless. It is the most abundant element in the universe.
Hydrogen only occurs naturally on earth in compounds with other elements. Combine it with oxygen and you’ve got water (H₂O). Hydrogen combined with carbon forms many different compounds called hydrocarbons such as natural gas (its largest component is methane, CH₄), coal, and petroleum.
While many of these hydrocarbons contribute to the climate crisis, when pure hydrogen is burned, the only byproduct is water vapor. No Greenhouse Gasses (GHGs) are produced. GHGs absorb and emit radiant energy within the thermal infrared range, causing the greenhouse effect and associated global warming. The most significant GHGs are carbon dioxide (CO₂) methane (CH₄), nitrous oxide (N₂O) and hydrofluorocarbons (HFCs).
Hydrogen Production
About 95% of hydrogen consumed in the U.S. is produced from natural gas using high-temperature steam in a process called steam methane reforming (SMR). Globally, about 75% of hydrogen is produced via SMR.
Colors are used to designate how hydrogen is produced. There’s actually a rainbow of colors, but for this article we’ll discuss these three:
- Gray — produced via a fossil fuel-burning process (SMR or others)
- Blue — produced via a fossil fuel-burning process equipped with carbon capture and storage (CCS)
- Green — produced via a process based on renewable sources
For 2020, it is estimated that about 120 million metric tons of H₂ were consumed globally.¹ 95% of this is gray hydrogen, so that’s about 114 million metric tons. (A metric ton is 1,000 kg.) About 75% of this total, 86 million metric tons, is produced using SMR. Each kilogram (kg) of hydrogen produced via SMR results in about 9.3 kg of CO₂ emissions.²
Production of 86 million metric tons of hydrogen using SMR results in about 800 million metric tons of CO₂, or 0.8 GtCO₂ each year. (Gt, gigaton, is 1,000 million tons.)
What this means, is that the production of hydrogen contributes to the climate crisis in a way that should not be ignored. Net total energy-related CO₂ emissions for 2020 are estimated at 31.5 Gt by the International Energy Agency (IEA). Therefore, emissions from hydrogen SMR production comprise about 2.5% of this global CO₂ emissions total. That’s significant enough to care about.
Hydrogen Uses, Green Initiatives and Challenges
Nearly all of the hydrogen currently consumed in the U.S. and throughout the world is used by industry for:
- Refining petroleum, including using hydrogen to lower the sulfur content of fuels
- Producing metals such as steel and iron
- Producing fertilizer and other chemicals such as ammonia, resins and polymers
- Processing foods
Clean hydrogen has the potential to decarbonize these and other human activities, such as electricity generation, transportation and heating. There are a variety of ways to obtain clean hydrogen. The most common methods are:
- SMR with CCS — if the CO₂ emitted in the SMR process is captured, the resulting hydrogen is blue, meaning fossil fuels were used in the process, but GHGs were captured, negating their impact on the environment.
- Electrolysis — using green electricity to split water into hydrogen and oxygen yields green hydrogen. (The equipment and processes used to accomplish electrolysis are referred to as electrolyzers.)
The costs for either of these clean production methods are currently high, and both approaches are in the early stages of development. The IEA estimates production costs³ as follows:
- Green H₂ via electrolyzer-based production: $US 3 to 8 per kg
- Blue H₂ via SMR with CCS: $US 1.20 to 2.60 per kg
- Gray H₂ via SMR (the predominant current process): $US 0.50 to 1.70 per kg
In addition to cost hurdles, electrolyzer production facilities require huge amounts of green energy. The magnitude of power consumed by these facilities necessitates careful integration with electrical grids, which impacts physical location and the timing of bringing facilities on line.
Another hurdle involves whether blue hydrogen is truly clean when the energy input to drive the CCS process is considered. A recent analysis⁴ indicates that if electricity derived from natural gas is used to drive CCS, the overall GHG emissions (including methane) for the process lifecycle are only 9 to 12% less than gray hydrogen. That’s not a very clean version of a blue classification.
Both private industry and government agencies understand the importance of decarbonizing hydrogen production. Hydrogen also is being used to displace other fossil-fuel based energy sources. Various initiatives are underway to pursue these objectives.
The U.S. Department of Energy’s (DOE) Energy Earthshots Initiative aims to “accelerate breakthroughs of more abundant, affordable, and reliable clean energy solutions within the decade.” This initiative has a goal of reducing the cost of clean hydrogen from its current level of $5/kg to $1/kg within 10 years. The DOE has requested $US 400 million in the 2022 budget, and spent about $US 285 million on this initiative in 2021.
Here are a some private industry examples of hydrogen initiatives :
- Cummins, Inc., a manufacturer of diesel engines and power generation equipment, understands that medium and heavy-duty trucks are a major source of CO₂ emissions. Potential solutions include fuel cell electric vehicles (FCEVs) and hydrogen burning internal combustion engines (ICEs). Cummins has examples of hydrogen application in their products.
- A fuel cell company, Plug Power, Inc., is building North America’s largest green hydrogen production facility utilizing hydropower as the green energy source for its electrolyzers.
- Long Ridge Energy’s natural gas fired electricity plant in Ohio is now burning hydrogen mixed with natural gas, with a design that will facilitate a transition to all hydrogen operation in the future.
- List of US electrolyzer locations
Summary
The scope of government and industry initiatives suggests that the hydrogen industry will decarbonize over time. However, there is still a long way to go: current green hydrogen production via electrolysis accounts for only 1% of total production.
Since hydrogen production is a significant source of CO₂ emissions, it is worthwhile to keep an eye on how hydrogen initiatives progress. A few key trends to watch:
- The amount of clean hydrogen produced globally compared to the demand for both existing and new hydrogen applications
- Improvements and cost-cutting efforts in electrolyzer processes, hydrogen fuel cells and the adaptation of CCS to SMR
- Further analysis of whether blue hydrogen is actually an effective path to net lower GHG emissions
- Adoption of hydrogen by the transportation industry, particularly in trucking and heavy-duty commercial vehicles
- The level of research and development investments by industries and governments
Hydrogen can be a key component in combating climate change if substantially lower production cost for green hydrogen is achieved. Hydrogen’s role will be further expanded if SMR with CCS is proven to be cost effective and clean at scale, and it’s worth keeping tabs on.
¹ Global hydrogen use 2020, by country, Published by N. Sönnichsen, Feb 24, 2022, Statista, https://www.statista.com/statistics/1292403/global-hydrogen-consumption-by-country/
² Estimating The Carbon Footprint Of Hydrogen Production, Robert Rapier, Jun 15, 2020, https://oilprice.com/Latest-Energy-News/World-News/Estimating-The-Carbon-Footprint-Of-Hydrogen-Production.html
³ IEA report on hydrogen, https://www.iea.org/reports/hydrogen
⁴ How green is blue hydrogen? by Robert W. Howarth and Mark Z. Jacobson, August 12, 2021, Energy Science & Engineering published by Society of Chemical Industry and John Wiley & Sons Ltd. https://onlinelibrary.wiley.com/doi/full/10.1002/ese3.956
For further reading: (Updated 03/17/23)
AUSTRALIA GOES ALL-IN ON GREEN HYDROGEN, Juggernaut or boondoggle—it’s too soon to tell, by Peter Fairley, December 26, 2022, https://spectrum.ieee.org/green-hydrogen
Hydrogen Insights 2022, the Hydrogen Council, September 20, 2022, https://hydrogencouncil.com/en/hydrogen-insights-2022/