Reducing Waste in Centralized and Decentralized Hydrogen Production and Distribution with Sapphire’s FreeSpin® In-line Turboexpander
April 27, 2023
As the energy sector, various end markets, and governments worldwide look to curb greenhouse gas emissions, hydrogen is increasingly emerging as part of the solution.
As the energy sector, various end markets, and governments worldwide look to curb greenhouse gas emissions, hydrogen is increasingly emerging as part of the solution. The major advantages to using hydrogen as a fuel are that it can be produced using renewable energy sources and it does not produce greenhouse gases when combusted. Indeed, the United Nation’s latest climate report cites hydrogen as a sustainable fuel that could reduce CO2 emissions in manufacturing, shipping, aviation, and heavy-duty land transport.[1] In the transportation sector, which accounts for 20% of global emissions, hydrogen and hydrogen-based fuels have the potential to reduce emissions by offsetting existing fuel sources, like diesel. Hydrogen has various industrial use cases that could help reduce the industrial sector’s 26% contribution to global emissions, for example as a replacement for coal in steel production.[2] In fact, with proper infrastructure in place, the Environmental Defense Fund (EDF) projects the adoption of hydrogen fuel could lead to an 80% decrease in warming in the next five years.[3]
While various use cases for hydrogen exist, there is no centralized infrastructure for the production, transportation and storage of hydrogen and decentralized technologies for producing and utilizing hydrogen are still in emerging stages. This blog explores the considerations involved in centralized versus decentralized systems for the production and distribution of hydrogen and suggests ways in which Sapphire’s FreeSpin® In-line Turboexpander (FIT) can be deployed to make various processes in each system more environmentally and economically friendly.
In comparing centralized vs. decentralized hydrogen systems, we must consider different methods of hydrogen production. The table below summarizes key methods for producing hydrogen according to the IEA, and their suitability for each system.[4]
As this table describes, one main challenge for decentralized hydrogen production is that the systems for producing hydrogen at small scale are still largely emerging technologies.
While the relative advantages and disadvantages of centralized versus decentralized hydrogen production and distribution vary depending on the end application, there are generalizations we can make about each system. A centralized system for hydrogen production and distribution is likely to ensure a more secure and stable supply of hydrogen. Centralized hydrogen production and distribution also allows for manufacturers to mitigate demand-side risk by creating supply-side inventory. However, transportation and storage also pose significant costs: a substantial amount of energy is required to liquefy hydrogen for transport via road or tanker. A decentralized system, in contrast, has lower distribution costs than a centralized system but higher per unit production costs. Decentralized electrolysis is more energy efficient because it requires less of the electricity-intensive compression and conversion steps required for transport. Because hydrogen can be produced from a variety of renewable energy resources, decentralized hydrogen production can maximize use of local resources. However, studies have shown that decentralized hydrogen production is only economically viable under specific market conditions depending on the end application. [5]
There are several pressure let down processes in hydrogen distribution and consumption where Sapphire’s FIT can be used to harness wasted energy. In particular, the FIT system can help offset the energy costs and reduce waste involved in the transportation and distribution of hydrogen in a centralized system. In a centralized system, hydrogen is distributed as liquid hydrogen (LH2), compressed gaseous hydrogen (GH2) or as a liquid organic hydrogen carrier. Liquefaction is a well-established process that makes the transportation of hydrogen easier. During the liquefaction process, turboexpanders are used to cool the gas to cryogenic temperatures. Sapphire’s FIT system can be used to recover power during this process and redistribute it to other areas of the liquefaction plant, such as the compressors.
The FreeSpin® In-line Turboexpander can also be used to recover energy that might be lost when dispensing gaseous hydrogen to a storage site in a centralized system. As the high-pressure gas is dispensed at the storage site, FIT can be used to recover the trailer’s stored pressure energy.
As an energy carrier, instead of a fuel source, hydrogen has tremendous potential to aid in the more-flexible use of other renewable energy sources. In these applications, the high storage pressure (~400 bar) of hydrogen is let down to 20 to 50 bar for gas turbines and as low as .1 bar for proton exchange membrane fuel cells. This pressure letdown process is necessary for operation, and Sapphire’s turboexpander system can be integrated into the process to generate incremental power from pressure energy recovery. Turboexpanders have interesting implications for a decentralized hydrogen production system that takes advantage of the existing electric grid and/or local renewables.
Regardless of the sector and end application for hydrogen – as a fuel or carrier – the ability to inject flexibility and reduce wasted energy will be paramount to achieving the economics that make hydrogen a viable long-term energy strategy. The potential applications for Sapphire’s FreeSpin® In-line Turboexpander continue to expand as the hydrogen economy continues to evolve.
Sources
[1] IPCC AR6 Synthesis Report: Climate Change 2023, pgs. 71-72. Available at:
https://report.ipcc.ch/ar6syr/pdf/IPCC_AR6_SYR_LongerReport.pdf
[2] Global Hydrogen Review 2021. Available at:
https://www.iea.org/reports/global-hydrogen-review-2021
[3] Environmental Defense Fund 2022. Available at:
https://www.edf.org/blog/2022/03/07/hydrogen-climate-solution-leaks-must-be-tackled
[4] IEA. Available at:
https://iea.blob.core.windows.net/assets/e19e0c2a-0cef-4de6-a559-59d0342974c3/hydrogen.pdf
[5] The Energy Transition Hub, 2020. Available at:
https://www.energy-transition-hub.org/files/resource/attachment/2005.03464.pdf
