Hydrogen can already be a profitable and competitive alternative to petrol and diesel fuels, at least in world energy capital Houston, researchers claim.
In their just-published white paper “Competitive Pricing of Hydrogen as an Economic Alternative to Gasoline and Diesel for the Houston Transportation Sector”, a team of University of Houston academics figure that the city has “more than sufficient” water and commercial filtering systems to support hydrogen generation.
“Add to that the existing natural gas pipeline infrastructure, which makes hydrogen production and supply more cost-effective and makes Houston ideal for transitioning from traditional vehicles to hydrogen-powered ones,” they claim in their paper.
Houston has grown up around the automobile. It has the highest per capita ownership of any US city with 5.5 million registered vehicles recorded in fiscal 2022.
This offers excellent potential for transitioning to the large-scale use of hydrogen-powered fuel cell electric vehicles (FCEVs) as a way of slashing greenhouse gas emissions in and around the gas-guzzling capital.
There is a growing urgency for change as more than 230 million metric tons of carbon dioxide gas are released each year by transportation in Texas.
A key advantage of fuel cell electric vehicles is zero emissions and they can now be refuelled with hydrogen in five minutes, it is claimed.
It happens that Houston is a major US locus of large-scale hydrogen production capability because of the concentration of manufacturing, petrochemicals, aerospace, general engineering and so-forth.
Expansion of H2’s use in transportation is considered straightforward.
The team compared three hydrogen generation processes: steam methane reforming (SMR), SMR with carbon capture (SMRCC), and electrolysis using grid electricity and water.
They acknowledge that, while other known processes for hydrogen generation from natural gas include partial oxidation (POX), autothermal reaction (ATR), and methane pyrolysis, their study considers only SMR.
They utilised the US National Renewable Energy Laboratory (NREL)’s H2A tools to provide cost estimates for these pathways, and the Hydrogen Delivery Scenario Analysis Model (HDSAM) developed by Argonne National Laboratory to generate the delivery model and costs.
Additionally, the team compared the cost of grid hydrogen with the SMRCC product.
A key outcome is that, even without a tax credit incentive, SMRCC hydrogen can be supplied at a lower cost of $6.10 per kg of hydrogen at the pump, which “makes it competitive”.
“This research underscores the transformative potential of hydrogen in the transportation sector,” team member Ehlig-Economides said.
“Our findings indicate that hydrogen can be a cost-competitive and environmentally responsible choice for consumers, businesses, and policymakers in the greater Houston area.”
But whether or not the university’s proposition lands in fertile ground depends on the pace at which Houston’s transportation sector can transition safely at scale, assuming that it is minded to and the pace at which a dedicated hydrogen to fuelling stations pipeline network can be built.
Whilst the researchers highlight the extensive industrial hydrogen transportation infrastructure in the Houston area, they admit that, right now, there are no H2 specific pipelines within the city limits and that is a major challenge in itself.
Meanwhile, the very idea of building such a network in Houston or any other major city around the globe could be scuppered by the growing realisation that there is an alternative that might present a better alternative for fuelling future transportation, road and rail.
Earlier this year, just before the Houston University white paper was published, Norwegian analyst Rystad Energy ran a commentary about the importance of ammonia as a suitable way of exporting produced hydrogen, regardless of whether it is green, blue or whatever.
Rystad said: “As hydrogen gains prominence amid the global pursuit of decarbonisation and energy security, many major infrastructure projects are considering transportation in the form of ammonia, a safer and more cost-effective method for exporting hydrogen supplies in large volumes.“
Moreover, its projections indicate that 174 export terminals worldwide will evolve to primarily convert hydrogen into ammonia by 2035.
“In support of the broader energy transition, a substantial upsurge in clean ammonia transportation and trade is anticipated, with traded volumes of ammonia projected to reach 76 million tonnes by 2035, four times the volume transported and traded in 2020,” said Rystad.
“This surge, primarily originating from Africa and North America, will lead to a five-fold increase in ammonia exports by 2050 to 121 million tonnes.”
Notable among countries that have already adapted their energy strategies to take account of hydrogen’s ascendancy in the quest for Net Zero are Japan and Germany.
“Investors are increasingly raising their confidence in the ammonia market and making significant near-term investments,” said Rystad’s hydrogen research head, Minh Khoi Le.
“Hydrogen penetration is moving quickly and globally, entering new geographies and outpacing market expectations.
“With the ammonia trade booming, there is an urgent need to leverage existing assets to their fullest potential. Converting LNG terminals could be a good solution, not only optimising current infrastructure but also spurring a re-evaluation of strategies that can cope with the scale of the expected market expansion.”
Given such a prediction, it would seem highly appropriate as a part of terrestrial transportation transition that ammonia be more deeply considered as a fuel in its own right than is currently the case.
Moreover, it can be used directly in ICE engines. In compression-ignition engines, for example ammonia can be successfully used in dual-fuel mode with diesel. Petrol engines require some modification.
Ammonia is more energy dense than hydrogen and is considered easy, safe and cheap to transport and store. H2 is not.
But life is never simple; there are downsides to NH3, that researchers at Princeton and Rice Universities in the US are currently trying to crack.
However, last month they warned that, while it may not be a source of carbon pollution, ammonia’s widespread use in the energy sector could pose a grave risk to the nitrogen cycle and climate without proper engineering precautions.
The interdisciplinary team of 12 researchers have found that a well-engineered ammonia economy could help the world achieve its decarbonisation goals and secure a sustainable energy future.
But a mismanaged ammonia economy, on the other hand, could ramp up emissions of nitrous oxide (N2O), a long-lived greenhouse gas around 300 times more potent than CO2 and a major contributor to the thinning of the stratospheric ozone layer.
It could lead to substantial emissions of nitrogen oxides (NOX), a class of pollutants that contribute to the formation of smog and acid rain. And it could directly leak fugitive ammonia emissions into the environment, also forming air pollutants, impacting water quality, and stressing ecosystems by disturbing the global nitrogen cycle.
Fortunately, the team have also found that the potential negative impacts of an ammonia economy can be minimised with good engineering.
They argue that now is the time to start seriously preparing for an ammonia economy, tackling the potential sticking points of NH3 as a fuel before widespread deployment.
“We know an ammonia economy of some scale is likely coming,” said research leader Amilcare Porporato.
“And if we are proactive and future-facing in our approach, an ammonia economy could be a great thing. But we cannot afford to take the risks of ammonia lightly. We cannot afford to be sloppy.”
A lot is known about ammonia and the backbone process for converting hydrogen into ammonia that has existed since the early 20th century.
The Haber-Bosch process combines atmospheric nitrogen with hydrogen to form ammonia.
While it was originally developed as a way to turn atmospheric nitrogen into ammonia for use in fertilizers, cleaning products, and even explosives, the energy sector is considering using Haber Bosch as a way to store and transport hydrogen fuel in the form of ammonia, despite its energy intensity.
Fossil fuels without CO2 capture are currently used to meet almost all of its feedstock and energy demands. However, the hope is that new electricity-driven processes currently under development will revolutionise the production of ammonia.
“At first glance, ammonia seems like an ideal cure for the problem of decarbonization,” Porporato said. “But almost every medicine comes with a set of potential side effects.”
Most N2O emissions from ammonia combustion are the result of disruptions to the combustion process and it has so far been hard to eliminate them.
Princeton colleague Robert Socolow has warned that the widespread use of ammonia in the energy sector will add to all the other impacts that fertilizers have already had on the global nitrogen cycle.
Intriguingly, 20 years ago, Socolow warned: “Ammonia fuel can be done, but it cannot be done in any way we wish. It’s important that we look before we leap.”
One wonders what 2024 will bring.