Debunking The Myth: Hydrogen’s High Energy Density By Mass Is Trumped By Low Density By Volume

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Hydrogen is commonly cited for its excessive power density by mass — roughly 120 MJ/kg — making it look like a really perfect power provider. Nevertheless, this determine is steadily misunderstood or introduced out of context, resulting in deceptive conclusions about hydrogen’s suitability for real-world power storage and transportation. The difficulty lies not in its theoretical mass-based power content material however within the sensible challenges related to its volumetric power density, storage necessities, and general system effectivity.

It is a companion article to the Cranky Stepdad vs Hydrogen for Energy materials. In the same method to John Cook dinner’s Skeptical Sciencethe intent is a speedy and catchy debunk, a second degree of element within the Companion to Cranky Stepdad vs Hydrogen for Energyafter which a fuller article because the third degree of element.

Hydrogen might weigh much less, however storing it’s like making an attempt to squeeze a watermelon right into a soda can.

Underneath customary atmospheric circumstances, hydrogen is a really gentle gasoline with extraordinarily low power density by quantity — about 0.01 MJ/L in comparison with gasoline’s 34.2 MJ/L. To be saved in usable portions, hydrogen have to be both compressed to extraordinarily excessive pressures (usually 350 to 700 bar), liquefied at cryogenic temperatures (−253°C), or chemically sure in carriers equivalent to ammonia or metallic hydrides. Every of those choices introduces vital power penalties and complexity.

Compression to 700 bar — the strain utilized in most hydrogen gasoline cell automobile tanks — requires about 10–15% of the power content material of the hydrogen itself only for the compression course of (U.S. Division of Vitality, 2023). Liquefaction is much more energy-intensive, consuming between 30–40% of hydrogen’s power content material (Worldwide Vitality Company (IEA), 2021). Chemical carriers introduce conversion and reconversion steps, additional decreasing general effectivity.

These storage and transport challenges lead to a considerably decrease system-level power effectivity for hydrogen than is commonly acknowledged. Bertuccioli et al. (2014) emphasize that whereas hydrogen can theoretically retailer power effectively by mass, real-world purposes contain infrastructure that considerably erodes these good points. Lifecycle assessments present hydrogen’s round-trip effectivity — factoring in manufacturing through electrolysis, compression or liquefaction, transport, and remaining conversion again to electrical energy — could be as little as 25–35% (Qiu et al., 2021).

In distinction, lithium-ion batteries, whereas heavier, obtain round-trip efficiencies of 85–95% and don’t require high-pressure or cryogenic infrastructure. Electrical automobile (EV) drivetrains utilizing batteries are usually over twice as power environment friendly as these counting on hydrogen gasoline cells when measured from supply to wheel (European Fee, 2022).

This concern is compounded when evaluating infrastructure prices and complexity. Hydrogen requires pipelines designed to deal with excessive diffusivity and embrittlement, or alternatively, costly overland transport through cryogenic vans or pressurized containers. These distribution challenges additional cut back hydrogen’s competitiveness relative to direct electrification.

The widespread use of gravimetric power density as a headline determine for hydrogen’s capabilities is subsequently deceptive — a textbook case of the deceptive statistics fallacy. Whereas technically right, this single metric is divorced from the realities of how hydrogen have to be saved, transported, and utilized. Bossel (2006) was among the many first to comprehensively spotlight this concern, arguing that hydrogen is “not an energy source, but a synthetic energy carrier with fundamental disadvantages.”

Hydrogen is important as an industrial feedstock, for instance within the manufacturing of ammonia fertilizers. Nevertheless, for transportation, warmth and power storage purposes, its low volumetric power density and excessive infrastructure calls for current main limitations to widespread deployment.

The power content material of a gasoline by mass is just one piece of the puzzle. When quantity, effectivity, infrastructure necessities, and lifecycle prices are included within the evaluation, hydrogen isn’t viable as an power provider.

References:

Bertuccioli, L., Chan, A., Hart, D., Lehner, F., Madden, B., & Standen, E. (2014). The restrictions of hydrogen as an power storage medium. Worldwide Journal of Hydrogen Vitality, 39(36), 21647–21662.

Bossel, U. (2006). Does a hydrogen financial system make sense? Proceedings of the IEEE, 94(10), 1826–1837.

European Fee. (2022). Hydrogen Storage and Transport: Technical and Financial Obstacles. Brussels: European Union.

Worldwide Vitality Company. (2021). The Way forward for Hydrogen: Storage and Transport Challenges. Paris: IEA.

Qiu, Y., Wang, L., Zhang, X., & Ding, Y. (2021). Evaluating hydrogen storage with various power carriers: A lifecycle effectivity evaluation. Vitality Reviews, 73950–3962.

U.S. Division of Vitality. (2023). Hydrogen Storage and Distribution: Assessing Effectivity and Prices. Washington, DC: DOE.

Hume, N. (2021, October 4). Hydrogen’s power density downside: Why storage and transport stay key obstacles. Monetary Occasions.