Airbus just announced its intention to produce hydrogen-fuelled planes by 2035. If you hadn’t heard of hydrogen energy yet, it is a light, storable, energy-dense fuel whose usage creates only water as a by-product.
Is hydrogen really the zero-emission holy grail the world has been looking for or is there a catch?
Earth.Org takes a closer look.
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Hydrogen energy has gained momentum and is hailed by many as a key component in the future of energy production. Demand has grown threefold since 1975 and continues to rise thanks to a large number of governmental targets, mandates and policies incentivizing its development.The Hydrogen Council, formed by BP, Shell and other oil and gas majors, even called for heating all homes with hydrogen in the future. As of now, it remains more expensive than fossil fuels and thus is used only in certain industries.
Production comes in three forms, but ~95% is generated from steam methane reforming (SMR) of natural gas. The fossil fuel-powered process uses heat and pressure to convert the methane in natural gas into hydrogen and CO2 at a ratio of 1 to 9.3. That is 9.3kg of CO2 for every 1kg of the so-called “grey hydrogen” this method produces.
Grey hydrogen’s output and energy density.
Brown hydrogen is made identically but with gasified coal instead of natural gas, which releases quite a bit more CO2. Blue hydrogen is the same as grey hydrogen, but with integrated carbon capture and storage (CCS), thus considered to be a low-emission alternative. Finally, green hydrogen is obtained by splitting water atoms with electricity from renewable sources only, making it very expensive, though very “clean”.
Blue hydrogen is considered more viable thanks to its lower cost and acceptably low emissions, and plans for its development have proliferated across North America, Europe and the Middle East. Carbon pricing has also made the classical grey hydrogen more expensive, while blue hydrogen’s CCS has made it more competitive.
We can expect hydrogen to be commonplace in the global energy mix by the end of the decade, but many scientists have warned that it is far from a silver bullet. In fact, a study in August took a closer look, and the results were shocking. Robert Howarth from Cornell University and Mark Jacobson from Stanford University produced the first peer-reviewed look at the life-cycle emissions of blue hydrogen, accounting for both the CO2 produced by the reaction, and importantly, the fugitive, unburned methane.
They found that fugitive methane, seemingly a detail in the equation, actually ends up making blue hydrogen anything but a low emission process. In the study’s base set of assumptions, blue hydrogen’s emissions are only 9% – 12% less than grey hydrogen over a 20 year-period of activity.
In fact, the greenhouse gas footprint of blue hydrogen is more than 20% greater than simply burning natural gas or coal for heat.
Source: Howarth and Jackson (2021).
How did this slip past our nets? There are a few reasons, but first and foremost, how we estimate methane’s warming potential. Methane (CH4) is considered to have 28-34 times the warming potential of CO2, though this is over a 100-year period. This is a strange frame of reference considering CH4’s half-life in the atmosphere is only around 12 years! Half of it at least is completely inactive for 88 of the 100 years, naturally decreasing its warming potential over the time-period. When adjusted to a 20 year period, CH4 traps 84-86 times more heat than CO2.
This skews institutional assessments of CH4’s contribution to global warming, making it seem like blue hydrogen’s fugitive emissions aren’t as bad as they seem.
What does it say about the fossil fuel industry’s call to heat all houses with hydrogen? Just this: blue hydrogen’s heavy reliance on natural gas makes this little of a transition. The current gas infrastructure will continue to flourish, while we commit to an expensive, time-consuming non-solution.
The Problem With Carbon Capture
Blue hydrogen’s most redeeming feature, carbon capture, also comes with an asterisk. According to IHS Markit, 88% of reused CO2 is dedicated to “gaseous” use, or the extraction of more fossil fuels in a process called enhanced oil recovery (EOR). For the sustainably-minded, this simply defeats the purpose.
Unfortunately, carbon credits aren’t enough to incentivize simple carbon capture and storage. EOR creates the vast majority of the demand that keeps carbon capture existent, an absolute necessity considering it is an essential feature of climate adaptation plans.
Still, in the near-term (~10 to 20 years), blue hydrogen’s system will only result in a net increase in CO2 emissions per unit of energy produced. Research into green hydrogen, the truly sustainable option, is being put on hold to allow for the blue counterpart’s development, and this is a terrible mistake.
This article was written by Owen Muhern. Cover photo by Federico Beccari on Unsplash.
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