How “Green Hydrogen” Ecosystems will Change (Save) our World
Introduction (part one of a two-part article)
The 2022 UN report on climate change declares[1], “harmful carbon emissions from 2010-2019 have never been higher in human history”, confirming that we are on a “fast track to disaster”, with scientists claiming that it is “now or never to limit global warming to 1.5 degrees”.???
As we begin COP 27, our present trajectory is frightening.?It is currently looking like we will reach double the number that 196 countries committed to in the 2015 Paris Agreement (COP 21) and we may reach the irreversible point by 2025.?This means that within this decade coastal cities may face unprecedented flooding from rising ocean levels, while other places will face severe droughts, significantly altering the landscape of our lives for generations to come.?
As of 2022, most of the world’s greenhouse gas (GHG) emissions are still derived from fossil fuels, dominated by coal (42%), followed by oil (34%) and natural gas (22%)[2]. ?From a sector perspective, power generation contributes 40%, followed by transportation at 27% and buildings at 25%.[3]?
Why Green Hydrogen?
While advances in battery technology has been making a minor dent in carbon emissions from consumer transportation (via electric vehicles (EV)), this effort impacts a negligible part of the crisis. ?
Hydrogen (H2) and specifically Green Hydrogen will likely be our key energy solution.?The primary reason being that only Green Hydrogen would be a carbon neutral alternative in the most polluting sectors (e.g. power generation, heavy industry, commercial transport, and agriculture). ?
However, there is a H2 conundrum.?While H2, once in-hand, is an efficient and energy-dense fuel with virtually zero carbon emissions (only water vapor).?The problem is that production of H2 can be a pollution intensive process.?Thus, when referring to H2 use-cases, a full understanding of the production supply chain is critical.?Therefore, only Green Hydrogen will be addressed here.?
As inferred above, “Green Hydrogen” is the only final product where the production process is powered by non-carbon emitting energy resources (e.g., solar and/or wind power generation).?Further, the electrolyzers, the machines producing the H2 by separating the H2 from water (H2O) through electrolysis[4], also need to be made from fully renewable powered factories to ensure the supply chain is truly green.[5] ?
Why is the pervasive use of green hydrogen a key solution in our global endeavor of mitigating our climate crisis???There are three fundamental reasons:
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Sustainable long-term renewable energy storage?
While traditional battery storage options generally offer up to a day of storage, H2 provides essentially infinite duration storage and backup power, allowing for the seasonal load shifting potential that will increase reliability of renewables.?Accordingly, massive hydrogen projects have already been implemented globally, where companies store compressed hydrogen with major capacity.?
H2 fuel can be stored directly or converted to hydrogen-based fuel. The choice of storage medium depends on the accessibility to the geological storage site as well as the duration and scale of storage and transportation needs. ??In small-scale projects, storage tanks are viable. However, for large projects, geological storage sites such as salt caverns are being used to store enormous amounts of hydrogen [6]. Given that H2 is a low-density gas, more storage capacity is required when stored room-temperature.??
That said, H2 is commonly converted into hydrogen-based fuels and resources, such as ammonia, liquid organic hydrogen carriers, synthetic hydrocarbons, or synthetic liquid fuels, which are stored efficiently and transported over long distances. ?This storage enabling tech is quickly advancing the utility of hydrogen, given that H2 has the highest energy per mass of any fuel.[7]?In fact, on a mass basis, hydrogen has about three times the energy capacity of gasoline.?
Hydrogen can be stored physically in high-pressure tanks or as a liquid at cryogenic temperatures on the surfaces of solids (by adsorption) or within solids (by absorption).[8]?Compressed gas storage, is a more cost-effective near-term storage option.?The long-term option uses cryo-compressed hydrogen, where increased hydrogen density and insulated pressure vessels allow materials-based hydrogen storage technologies, with properties having the potential to be far superior for aircraft, shipping, and other industrial grade commercial use where efficiency is needed.[9]?
Stay tuned for Part 2 where current and future use-cases are addressed.
[1] Statement from the UN Secretary General António Guterres
[2] IEA (2021), Greenhouse Gas Emissions from Energy Data Explorer, IEA, Paris https://www.iea.org/data-and-statistics/data-tools/greenhouse-gas-emissions-from-energy-data-explorer
[3] Ibid
[4] The process of using electricity to split H2 & O from water molecules (H2O), the machine is called an electrolyser. Electrolysers consist of anodes and cathodes in water, while some technologies also include electrolytes. Electric current is applied to the cathode and flows through the water, causing the water molecules to split into hydrogen and oxygen. There are three main electrolysis technologies (e.g., alkaline electrolysis, proton exchange membrane electrolysis and solid oxide electrolysis)
[5] There are many other colors of Hydrogen, other than green, the most common are black, brown, grey, pink, blue and turquoise, but each of these produce pollutants, thus the author thinks they should be ignored in this paper as they are not the most viable solutions in mitigating our impending climate crisis.
[6] Ho, A., Mohammadi, K., Memmott, M., Hedengren, J. and Powell, K.M., 2021. Dynamic simulation of a novel nuclear hybrid energy system with large-scale hydrogen storage in an underground salt cavern. International Journal of Hydrogen Energy, 46(61), pp.31143-31157.
[7] US Department of Energy, Hydrogen Program Plan, November 2020, pp 21-24
[8] Ibid
[9] Ibid