Returning airships to service could help the move to a sustainable hydrogen-based economy

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Reintroducing airships into the world’s transportation-mix could contribute to lowering the transport sector’s carbon emissions and can play a role in establishing a sustainable hydrogen-based economy. According to the authors of an IIASA-led study, these lighter-than-air aircraft could ultimately increase the feasibility of a 100% sustainable world.

Airships were introduced in the first half of the 20th century before conventional aircraft were used for the long-range transport of cargo and passengers. Their use in cargo and passenger transport was however quickly discontinued for a number of reasons, including the risk of a hydrogen explosion – for which the Hindenburg disaster of 1937 served as a stark case in point; their lower speed compared to that of airplanes; and the lack of reliable weather forecasts. Since then, considerable advances in material sciences, our ability to forecast the weather, and the urgent need to reduce energy consumption and CO2 emissions, have steadily been bringing airships back into political, business, and scientific conversations as a possible transportation alternative.

The transport sector is responsible for around 25% of global CO2 emissions caused by humans. Of these emissions, 3% come from cargo ships, but this figure is expected to increase by between 50% and 250% until 2050. These projections necessitate finding new approaches to transporting cargo with a lower demand for energy and lower CO2 emissions. In their study published in the Springer journal Energy Conversion and Management, researchers from IIASA, Brazil, Germany, and Malaysia looked into how an airship-based industry could be developed using the jet stream as the energy medium to transport cargo around the world.

The jet stream is a core of strong winds that flows from west to east, around 8 to 12 kilometers above the Earth’s surface. According to the researchers, airships flying in the jet stream could reduce CO2 emissions and fuel consumption, as the jet stream itself would contribute most of the energy required to move the airship between destinations, resulting in a round trip of 16 days in the northern hemisphere, and 14 days in the southern hemisphere. This is considerably less time compared to current maritime shipping routes, particularly in the southern hemisphere.

The researchers postulate that the reintroduction of airships into the transport sector could also offer an alternative for the transport of hydrogen. Hydrogen is a good energy carrier and a valuable energy storage alternative. Given that renewable electricity, for example, excess wind power, can be transformed into hydrogen, there is optimism that the hydrogen economy will form a fundamental part of a clean and sustainable future. One of the challenges to implementing a hydrogen-based economy is cooling the hydrogen to below -253°C to liquefy it. The process consumes almost 30% of the embodied energy, with further energy of around 3% required to transport the liquefied hydrogen. In their study, the authors however propose that instead of using energy in liquefaction, hydrogen in gaseous form could be carried inside the airship or balloon and transported by the jet stream with a lower fuel requirement. Once the airship or balloon reaches its destination, the cargo can be unloaded removing around 60% or 80% of the hydrogen used for lift, and leaving 40% or 20%, of the hydrogen inside the airship or balloon to provide enough buoyancy for the return trip without cargo. To address the risk of combustion of the hydrogen in the airship, the authors suggest automating the operation, loading, and unloading of hydrogen airships and designing flightpaths that avoid cities to reduce the risk of fatalities in the event of an accident.

According to study lead-author Julian Hunt, an IIASA post-doctoral fellow, a further interesting aspect unveiled in this study is the possibility that airships and balloons can also be used to improve the efficiency of liquefying hydrogen. As the temperature of the stratosphere (where the airships will be flying to utilize the jet stream) varies between -50°C to -80°C, it means that less energy will be required to meet the -253°C mark if the process happens onboard the airship. The energy required for the additional cooling needed can be generated using the hydrogen in the airship.

Hunt says that this process also presents a number of additional possibilities: The process of generating energy from hydrogen produces water – one ton of hydrogen produces nine tons of water. This water could be used to increase the weight of the airship and further save energy in its descending trajectory. Another possible application for the water produced is rainmaking, which involves releasing the water produced from the stratosphere at a height where it will freeze before entering the troposphere where it would then melt again. This reduces the temperature and increases the relative humidity of the troposphere until it saturates and starts raining. The rain will in turn initiate a convection rain pattern, thus feeding even more humidity and rain into the system. This process could be used to alleviate water stress in regions suffering from shortages.

“Airships have been used in the past and provided great services to society. Due to current needs, airships should be reconsidered and returned to the skies. Our paper presents results and arguments in favor of this. The development of an airship industry will reduce the costs of fast delivery cargo shipping, particularly in regions far from the coast. The possibility to transport hydrogen without the need to liquefy it would reduce the costs for the development of a sustainable and hydrogen-based economy, ultimately increasing the feasibility of a 100% renewable world,” concludes Hunt.

Learn more: Making a case for returning airships to the skies

 

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Unlocking the potential for a hydrogen powered vehicle revolution with efficient hydrogen storage

The real advantage this brings is in situations where you anticipate being off grid for long periods of time, such as long haul truck journeys, drones, and robotics. It could also be used to run a house or a remote neighbourhood off a fuel cell.
Professor David Antonelli

Scientists have discovered a new material that could hold the key to unlocking the potential of hydrogen powered vehicles.

As the world looks towards a gradual move away from fossil fuel powered cars and trucks, greener alternative technologies are being explored, such as electric battery powered vehicles.

Another ‘green’ technology with great potential is hydrogen power. However, a major obstacle has been the size, complexity, and expense of the fuel systems – until now.

An international team of researchers, led by Professor David Antonelli of Lancaster University, has discovered a new material made from manganese hydride that offers a solution. The new material would be used to make molecular sieves within fuel tanks – which store the hydrogen and work alongside fuel cells in a hydrogen powered ‘system’.

The material, called KMH-1 (Kubas Manganese Hydride-1), would enable the design of tanks that are far smaller, cheaper, more convenient and energy dense than existing hydrogen fuel technologies, and significantly out-perform battery-powered vehicles.

Professor Antonelli, Chair in Physical Chemistry at Lancaster University and who has been researching this area for more than 15 years, said: “The cost of manufacturing our material is so low, and the energy density it can store is so much higher than a lithium ion battery, that we could see hydrogen fuel cell systems that cost five times less than lithium ion batteries as well as providing a much longer range – potentially enabling journeys up to around four or five times longer between fill-ups.”

The material takes advantage of a chemical process called Kubas binding. This process enables the storage of hydrogen by distancing the hydrogen atoms within a H2 molecule and works at room temperature. This eliminates the need to split, and bind, the bonds between atoms, processes that require high energies and extremes of temperature and need complex equipment to deliver.

The KMH-1 material also absorbs and stores any excess energy so external heat and cooling is not needed. This is crucial because it means cooling and heating equipment does not need to be used in vehicles, resulting in systems with the potential to be far more efficient than existing designs.

The sieve works by absorbing hydrogen under around 120 atmospheres of pressure, which is less than a typical scuba tank. It then releases hydrogen from the tank into the fuel cell when the pressure is released.

The researchers’ experiments show that the material could enable the storage of four times as much hydrogen in the same volume as existing hydrogen fuel technologies. This is great for vehicle manufactures as it provides them with flexibility to design vehicles with increased range of up to four times, or allowing them to reducing the size of the tanks by up to a factor of four.

Although vehicles, including cars and heavy goods vehicles, are the most obvious application, the researchers believe there are many other applications for KMH-1.

“This material can also be used in portable devices such as drones or within mobile chargers so people could go on week-long camping trips without having to recharge their devices,” said Professor Antonelli. “The real advantage this brings is in situations where you anticipate being off grid for long periods of time, such as long haul truck journeys, drones, and robotics. It could also be used to run a house or a remote neighbourhood off a fuel cell.”

Learn more: New material could unlock potential for hydrogen powered vehicle revolution

 

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A cheaper, cleaner and more sustainable way of making hydrogen fuel from water using sunlight moves closer

Perovskite solar cells are cheaper and thinner than silicon-based ones – via University of Bath

Researchers have used a graphite coating that makes perovskite solar cells waterproof.

A cheaper, cleaner and more sustainable way of making hydrogen fuel from water using sunlight is a step closer thanks to new research from the University of Bath’s Centre for Sustainable Chemical Technologies.

With the pressure on global leaders to reduce carbon emissions significantly to solve a climate change emergency, there is an urgent need to develop cleaner energy alternatives to burning fossil fuels. Hydrogen is a zero carbon emission fuel alternative that can be used to power cars, producing only water as a waste product.

It can be made by splitting water into hydrogen and oxygen, however the process requires large amounts of electricity. Most electricity is made by burning methane so researchers at the University of Bath are developing new solar cells that use light energy directly to split water.

Most solar cells currently on the market are made of silicon, however they are expensive to make and require a lot of very pure silicon to manufacture. They are also quite thick and heavy, which limits their applications.

Perovskite solar cells, using materials with the same 3D structure as calcium titanium oxide, are cheaper to make, thinner and can be easily printed onto surfaces. They also work in low light conditions and can produce a higher voltage than silicon cells, meaning they could be used indoors to power devices without the need to plug into the mains.

The downside is they are unstable in water which presents a huge obstacle in their development and also limits their use for the direct generation of clean hydrogen fuels.

The team of scientists and chemical engineers, from the University of Bath’s Centre for Sustainable Chemical Technologies, has solved this problem by using a waterproof coating from graphite, the material used in pencil leads.

They tested the waterproofing by submerging the coated perovskite cells in water and using the harvested solar energy to split water into hydrogen and oxygen. The coated cells worked underwater for 30 hours – ten hours longer than the previous record.

After this period, the glue sandwiching the coat to the cells failed; the scientists anticipate that using a stronger glue could stabilise the cells for even longer.

Previously, alloys containing indium were used to protect the solar cells for water splitting, however indium is a rare metal and is therefore expensive and the mining process to obtain it is not sustainable.

The Bath team instead used commercially available graphite, which is very cheap and much more sustainable than indium.

Dr Petra Cameron, Senior Lecturer in Chemistry, said: “Perovskite solar cell technology could make solar energy much more affordable for people and allow solar cells to be printed onto roof tiles. However at the moment they are really unstable in water – solar cells are not much use if they dissolve in the rain!’

“We’ve developed a coating that could effectively waterproof the cells for a range of applications. The most exciting thing about this is that we used commercially available graphite, which is much cheaper and more sustainable than the materials previously tried.”

Perovskite solar cells produce a higher voltage than silicon based cells, but still not enough needed to split water using solar cells alone. To solve this challenge, the team is adding catalysts to reduce the energy requirement needed to drive the reaction.

Isabella Poli, Marie Curie FIRE Fellow and PhD student from the Centre for Sustainable Chemical Technologies, said: “Currently hydrogen fuel is made by burning methane, which is neither clean nor sustainable.

“But we hope that in the future we can create clean hydrogen and oxygen fuels from solar energy using perovskite cells.”

Learn more: Solar-powered hydrogen fuels a step closer

 

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Reversible liquid organic hydrogen carrier system brings the hydrogen economy closer

Chemical Hydrogen Storage System – Wiley-VCH

Reversible liquid organic hydrogen carrier system made of simple organic chemicals

Hydrogen is a highly attractive, but also highly explosive energy carrier, which requires safe, lightweight and cheap storage as well as transportation systems. Scientists at the Weizmann Institute of Science, Israel, have now developed a chemical storage system based on simple and abundant organic compounds. As reported in the journal Angewandte Chemie, the liquid hydrogen carrier system has a high theoretical capacity and uses the same catalyst for the charging-discharging reaction.

Hydrogen carries a lot of energy, which can be converted into electricity or power, and the only byproduct from combustion is water. However, as hydrogen is a gas, its energy density by volume is low. Therefore, pure hydrogen is handled mostly in its pressurized state or liquid form, but the steel tanks add weight, and its release and usage is hazardous.

Apart from tanks, hydrogen can also be masked and stored in a chemical reaction system. This is in principle the way nature stores and uses hydrogen: In biological cells, finely adjusted chemical compounds bind and release hydrogen to build up the chemical compounds needed by the cells. All these biological processes are catalyzed by enzymes.

Powerful catalysts mediating hydrogen conversion have also been developed in chemical laboratories. One example is the ruthenium pincer catalyst, a soluble complex of ruthenium with an organic ligand, developed by David Milstein and his colleagues. With the help of this catalyst, they explored the ability of a reaction system of simple organic chemicals to store and release hydrogen.

“Finding a suitable hydrogen storage method is an important challenge toward the ‘hydrogen economy,’” is how the authors of the publication explained their motivation. Among the conditions that have to be fulfilled are safe chemicals, easy loading and unloading schemes, and as low a volume as possible.

Such a system, consisting of the chemical compounds ethylenediamine and methanol, was identified by Milstein and his colleagues. When the two molecules react, pure hydrogen is released. The other reaction product is a compound called ethylene urea. The theoretical capacity of this “liquid organic hydrogen carrier system” (LOHC) is 6.52 percent by weight, which is a very high value for a LOHC.

The scientists first set up the hydrogenation reaction. In this reaction, liquid hydrogen carriers ethylenediamine and methanol were formed from ethylene urea and hydrogen gas with hundred percent conversion when the ruthenium pincer catalyst was used.

Then they examined the hydrogen release reaction, which is the reaction of ethylenediamine with methanol. Here, the yield of hydrogen was close to 100 percent, but the reaction seemed to proceed over intermediate stages and ended with an equilibrium of products. Nevertheless, full re-hydrogenation was possible, which led the authors to conclude that they had indeed developed a fully rechargeable system for hydrogen storage. This system was made of liquid organic compounds that are abundant, cheap, easily handled, and not very hazardous.

Its advantage is the simple nature of the compounds and the high theoretical capacity. However, to be more efficient and greener, like setup in nature, reaction times must still be shorter and temperatures lower. For this, even “greener” catalysts should be examined.

Learn more: Chemical Hydrogen Storage System

 

 

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A breakthrough that could change the economics of a hydrogen economy

Electron microscope image depicts the water splitting alloy

Researchers at KTH Royal Institute of Technology have successfully tested a new material that can be used for cheap and large-scale production of hydrogen – a promising alternative to fossil fuel.

Precious metals are the standard catalyst material used for extracting hydrogen from water. The problem is these materials – such as platinum, ruthenium and iridium – are too costly. A team from KTH Royal Institute of Technology recently announced a breakthrough that could change the economics of a hydrogen economy.

Led by Licheng Sun, professor of molecular electronics at KTH, the researchers concluded that precious metals can be replaced by a much cheaper combination of nickel, iron and copper (NiFeCu).

“The new alloy can be used to split water into hydrogen,” says researcher Peili Zhang. “This catalyst becomes more efficient than the technologies available today, and significantly cheaper.

“This technology could enable a large-scale hydrogen production economy,” he says. Hydrogen can be used for example to reduce carbon dioxide from steel production or to produce diesel and aircraft fuel.

It’s not the first time a cheaper material has been proposed for water splitting, but the researchers argue that their solution is more effective than others. They published their results recently in the scientific journal Nature Communication.

“The high catalytic performance of core-shell NiFeCu for water oxidation is attributed to the synergistic effect of Ni, Fe and Cu,” Zhang says.

Zhang says that copper plays an interesting role in the preparation of the electrode. In an aqueous solution, surface copper dissolves and leave a very porous structure to enhance the electrochemically active surface area. “The porous oxide shell with its high electrochemically active surface area is responsible for the catalytic activity, while the metallic cores work as facile electron transport highways,” Zhang says.

Learn more: Hydrogen extraction breakthrough could be game-changer

 

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