Could trucks be a better way to transport (and even store) hydrogen than pipelines? Yes, says a research team led by the MIT Energy Initiative (MITEI), mainly because of the flexibility they offer particularly in the early stages of the hydrogen roll-out. Kathryn O’Neill at MIT explains the findings. A pipeline can take 10 years to build, during which time the locations where the supply and demand must be met are likely to have moved, given the hydrogen economy is only now taking shape. Existing gas pipelines can be re-purposed for hydrogen, but they were never mapped out to be in the right places for the production of green hydrogen from clean energy (think wind and solar locations). Trucks can be deployed immediately, travel anywhere, and even sit idle to provide storage. But is it cost effective, and can it cope with the volumes required? The researchers have created a whole-supply-chain model to show a 9% cost reduction in the hydrogen supply chain, by bringing down the need for other storage solutions. They used the U.S. Northeast as a case study. The modelling tools are being developed to allow others to apply them to their own circumstances. Parameters include hydrogen demand, policy frameworks, carbon prices, cost of electrolysers, and more.
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MITEI researchers build a supply chain model to support the hydrogen economy. Study: Using trucks as both storage and means of energy transmission reduces hydrogen supply chain costs and encourages green hydrogen production from variable renewable energy. By Kathryn O’Neill, MIT News.
Over the past decades, the need for carbon-free energy has driven increasing interest in hydrogen as an environmentally clean fuel. But shifting the economy away from fossils fuels to clean-burning hydrogen will require significant adjustments in current supply chains. To facilitate this transition, an MIT-led team of researchers has developed a new hydrogen supply chain planning model.
“We propose flexible scheduling for trucks and pipelines, allowing them to serve as both storage and transmission,” says Guannan He, a postdoc at the MIT Energy Initiative (MITEI) and lead author of a recent paper published by IEEE Transactions on Sustainable Energy. “This is very important to green hydrogen produced from intermittent renewables, because this can provide extra flexibility to meet variability in supply and demand.”
Hydrogen has been widely recognised as a promising path to decarbonising many sectors of the economy because it packs in more energy by weight than even gasoline or natural gas, yet generates zero emissions when used as an energy source.
The challenge: producing clean hydrogen, transmission, storage
Producing hydrogen, however, can generate significant emissions. According to the U.S. Office of Energy Efficiency and Renewable Energy, 95 percent of the hydrogen produced today is generated through steam methane reforming (SMR), an energy-intensive process in which methane reacts with water to produce hydrogen and carbon monoxide. A secondary part of this process adds steam to the cooled gas to convert carbon monoxide to carbon dioxide (CO2) and produce more hydrogen.
Ultimately, hydrogen production today accounts for about 4 percent of CO2 emissions globally, says He, and that number will rise significantly if hydrogen becomes popular as a fuel for electric vehicles and such industrial processes as steel refining and ammonia production. Realising the vision of creating an entirely decarbonised hydrogen economy therefore depends on using renewable energy to produce hydrogen, a task often accomplished through electrolysis, a process that extracts hydrogen from water electrochemically.
However, using renewable energy requires storage to move energy from times and places with peak generation to those with peak demand. And, storage is expensive.
Trucks for hydrogen transmission and storage
The researchers expanded their thinking about storage to address this key concern: They used trucks in their model both as a means of fuel transmission and of storage — since hydrogen can be readily stored in idled trucks.
This tactic reduces costs in the hydrogen supply chain by about 9 percent by bringing down the need for other storage solutions, says He. “We found it very important to use the trucks in this way,” says He. “It can reduce the cost of the system and encourage renewable-based hydrogen production, instead of gas-based production.”
Developing a whole-supply-chain model
Previous studies have attempted to assess the potential benefit of hydrogen storage in power systems, but they have not considered infrastructure investment needs from the perspective of a whole hydrogen supply chain, He says. And such work is critical to enabling a hydrogen economy.
For the new model, the research team — He; MITEI research scientists Emre Gençer and Dharik Mallapragada; Abhishek Bose, an MIT master’s student in technology and policy; and Clara F. Heuberger, a researcher at Shell Global Solutions International B.V. — adopted the perspective of a central planner interested in minimising system costs and maximising societal benefit.
The researchers looked at costs associated with the four main steps in the hydrogen supply chain: production, storage, compression, and transmission. “Unless we take a holistic approach to analysing the entire supply chain, it is hard to determine the prospects for hydrogen. This work fills that gap in the literature,” Gençer says.
Multiple solutions
To ensure their model was as comprehensive as possible, the researchers included a wide range of hydrogen-related technologies, including SMR with and without carbon capture and storage, hydrogen transport as a gas or liquid, and transmission via pipeline and trucks. “We have developed a scalable modelling and decision-making tool for a hydrogen supply chain that fully captures the flexibility of various resources as well as components,” Gençer says.
While considering all options, in the end the researchers found that pipelines were a less flexible option than trucks for transmission (although retrofitting gas pipelines could make hydrogen pipelines cost-effective for some uses), and trucking hydrogen gas was less expensive than trucking hydrogen in liquid form, since liquefaction has much higher energy consumption and capital costs than gas compression.
They then proposed a flexible scheduling and routing model for hydrogen trucks that would enable the vehicles to be used as both transmission and storage, as needed. Computationally, this was a particularly challenging step, according to He. “This is a very complex optimisation model,” he says. “We propose some techniques to reduce the complexity of the model.”
The team chose to use judicious approximations for the number of trucks in the system and the needed commitment of SMR units, applying clustering and integer relaxation techniques. This enabled them to greatly improve the computational performance of their program without significantly impacting results in terms of cost and investment outcomes.
Case study: the U.S. Northeast
Once the model was built, the researchers tested it by exploring the future hydrogen infrastructure needs of the U.S. Northeast under various carbon policy and hydrogen demand scenarios. Using 20 representative weeks from seven years of data, they simulated annual operations and determined the optimal mix of hydrogen infrastructure types given different carbon prices and the capital costs of electrolysers.
“We showed that steam methane reforming of natural gas with carbon capture will constitute a significant fraction of hydrogen production and production capacity even under very high carbon price scenarios,” Gençer says.
However, He says the results also suggest there is real synergy between the use of electrolysis for hydrogen generation and the use of compressed-gas trucks for transmission and storage. This finding is important, he explains, because “once we invest in these assets, we cannot easily switch to others.”
Trucks are more flexible than pipelines
He adds that trucks are a significantly more flexible investment than stationary infrastructure, such as pipes and transmission lines; trucks can easily be rerouted to serve new energy-generation facilities and new areas of demand, or even be left sitting to provide storage until more transmission capacity is needed. By comparison, building new electricity transmission lines or pipelines takes time — and they cannot be quickly adapted to changing needs.
“You have more renewables integrated into the system every day. People are installing rooftop solar panels, so you need more assets to transmit energy to other parts of the system,” He says, explaining that a flexible supply chain can make the most of renewable generation. “A transmission line can take 10 years to build, during which time those renewables cannot be used as well. Using smaller-scale, distributed, portable storage or mobile storage can solve this problem in a timely manner.”
Indeed, He and other colleagues recently conducted related research into the potential application of utility-scale portable energy storage in California. In a paper published in Joule in February, they showed that mobilising energy storage can significantly increase revenues from storage in many regions and improve renewable energy integration. “It’s more flexible” than such stationary solutions as additional grid capacity, He says. “When you don’t need mobile storage anymore, you can convert it into stationary storage.”
Now that He and his colleagues have created their hydrogen supply chain planning model, the next step, according to He, is to provide planners with broad access to the tool. “We are developing open-source code so people can use it to develop optimal assets for different sectors,” He says. “We are trying to make the model better.”
This research was supported by Shell New Energies Research and Technology and the MIT Energy Initiative Low-Carbon Energy Centers for Electric Power Systems and Carbon Capture, Utilization, and Storage. The research reported in Joule was supported by the National Natural and Science Foundation of China and a grant from the U.S. Department of Energy.
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Kathryn O’Neill is the Managing Editor for Spectrum at MIT Office of Resource Development
Reprinted with permission of MIT News
Ronald P. Marriott says
Excellent information on the zoom call this morning! I’m working on a new energy discovery Antihydrogen fusion that creates atmospheric sprites. In the Antihydrogen fusion process antihelium and liquid oxygen is produced that traps and regulates the fusion plasma. The fusion coverts the antihelium ring to light or electromagnetic radiation until it is consumed exposing the paramagnetic liquid oxygen which searches for a greater magnetic field Earth. The energy is released from the plasma tubes surrounding the planet creating atmospheric sprites. The liquid oxygen converting to atomic hydrogen while some of the LOx remains as atmospheric oxygen in the ionosphere. The energy is reproducible! We can place the device at organic farms selling hydrogen fuel to the upcoming hydrogen fuel industry and making water for the farm . The electromagnetic radiation can be added to the power grids to support the farms making food free and pure removing poverty and welfare globally while cleaning up the planet. We can develop hydrogen fuel station/organic farms based minigrids removing the need for hydrogen transportation and fossil fuels completely removed.
Roger Arnold says
A couple of points in this article seem deliberately misleading. For starters, the hydrogen truck pictured is a liquid hydrogen delivery truck. The big tank is cryogenically insulated and very heavy, but boil-off of hydrogen is still pretty rapid. This sort of truck is normally only used for quick runs from a hydrogen production facility to a customer facility in the same or adjoining city. It’s not suitable for storage over periods of time exceeding a few hours. The energy cost of liquefying hydrogen is 30% of the energy content of the hydrogen delivered. All of that energy is wasted when the hydrogen is re-gasified.
The reference to hydrogen packing in “more energy by weight than even gasoline or natural gas” is spurious. It’s referring to the mass of the hydrogen gas itself, ignoring the very much larger mass of the tankage or whatever is used to contain the hydrogen. The very expensive graphite composite high pressure tanks used in FCEVs are able to hold 5% of their weight in hydrogen. The less expensive steel tubes used for storage in transportable tube racks do more like 3%.
If infrastructure for a green hydrogen economy has to rely on “solutions” like this, then the whole concept is bankrupt. It will be milked for subsidies for as long as governments can be bribed into into giving them out. Then it will quietly wither away.