Tag Archives: electrolysis

How Mars brine could produce breathable air and fuel for a colony

Our understanding of Mars has been a true rollercoaster. Centuries ago, scholars thought Mars could host rivers and oceans like on Earth and maybe teeming with life. When the first observations came in from Galileo Galilei in 1610, astronomers discovered a planet with polar ice caps that was seemingly similar to Earth, so the hypothesis seemed to stand. But as we learned increasingly more, it became apparent that Mars isn’t exactly a lush planet.

Mars is barren nowadays, and while it may have been water-rich at some point in the past, that’s not really the case now. But there’s one more twist to the story: Mars really does have ice caps, and it does have some liquid water. Granted, that water is full of salts and buried beneath the surface, but it’s still liquid water.

According to a new study, this brine can be used to produce breathable air and fuel for Martian colonists — two valuable resources we would absolutely need on the Red Planet.

Some Martian layers are hiding pockets of water beneath the surface. This water may be used by astronomers to produce breathable air and fuel. Image credits: NASA/MRO.

The rovers we’ve sent to Mars don’t really need oxygen. They do just fine in the ultra-thin atmosphere of the planet, wandering around and doing experiments in freezing temperatures. But if we want to establish a colony (or more likely, a research base), we can’t really manage without oxygen.

In 2008, NASA’s Phoenix Mars Lander came with some good news in that regard. It “tasted” the Martian water and upon analyzing it, found out how it manages to stay liquid on the freezing temperatures of Mars.

The key is something called perchlorate, a chemical compound containing chlorine and oxygen. Perchlorate is very stable in water, and its salts are very solluble — up to the point where they absorb and collect water vapor over time. As the perchlorate absorbs more water, it also dissolves into the water, substantially lowering its freezing temperature — this is how the water manages to remain liquid at temperatures way below the normal freezing point of water.

The European Space Agency’s Mars Express has found several such underground ponds of perchlorate brine and now, a new study reports that these pockets of liquid water could be used to produce valuable resources.

Of course, you can’t drink salty water. You also can’t use it for too many things. If you want to apply the electrolysis to break it down into oxygen (for breathing) and hydrogen (for fuel), you’d normally need to remove the salt — a very costly and complicated process in the harsh Martian environment. This is where the research team led by Vijay Ramani from the University of Connecticut comes in.

Typically, electrolysis requires purified water, but Ramani’s research team found a way to apply electrolysis efficiently to extract hydrogen and oxygen out of the brine simultaneously, without needing to also extract the perchlorate.

“Our Martian brine electrolyzer radically changes the logistical calculus of missions to Mars and beyond” said Ramani. “This technology is equally useful on Earth where it opens up the oceans as a viable oxygen and fuel source”

An outcrop of rocks on the surface of Mars. Image credits: NASA.

They built a modular electrolysis system and tested it at -33 Fahrenheit (-36 Celsius), showing that it really does work. The fact that it’s modular means you can start a small operation on Mars (say, a small research base) and then build on it. Ironically, they were also able to use the salt in their favor.

“Paradoxically, the dissolved perchlorate in the water, so-called impurities, actually help in an environment like that of Mars,” said Shrihari Sankarasubramanian, a research scientist in Ramani’s group and joint first author of the paper.

“They prevent the water from freezing,” he said, “and also improve the performance of the electrolyzer system by lowering the electrical resistance.”

The results are so promising, researchers say, that they’re even considering using a similar technology here on Earth. For instance, submarines or deep-sea could make great use of this technology, potentially enabling us to explore uncharted environments in the deep ocean.

“Having demonstrated these electrolyzers under demanding Martian conditions, we intend to also deploy them under much milder conditions on Earth to utilize brackish or salt water feeds to produce hydrogen and oxygen, for example through seawater electrolysis,” said Pralay Gayen, a postdoctoral research associate in Ramani’s group and also a joint first author on this study.

NASA’s Perseverance rover, currently en-route to Mars, is also carrying some instruments that will allow it to produce oxygen from the Martian brine — but no hydrogen. Perseverance’s equipment is also 25 times less efficient than that designed in Ramani’s lab, but it will be a test for the technology and could perhaps offer new insights on how to apply the technology.

While a Martian base is probably pretty distant possibility, a lunar outpost is almost in sight. NASA has concrete plans to send humans back to the moon in this decade, and it wants to lay down infrastructure for a permanent research base. If this is successful, a Martian base might not be that far off.

The study “Fuel and oxygen harvesting from Martian regolithic brine” was published in PNAS

Saltwater electrolysis.

New process can make hydrogen fuel out of seawater without destroying the devices

Researchers from Stanford University have developed a process to make hydrogen fuel using only electrodes, solar power, and saltwater from the San Francisco Bay.

Saltwater electrolysis.

A prototype device used solar energy to create hydrogen fuel from seawater.
Image credits Yun Kuang et al., (2019), PNAS.

Hydrogen fuel holds a lot of promise as the energy source of the future. It’s clean, doesn’t emit anything, it’s energy-dense, and it’s beyond abundant — if only we were able to develop a way of retrieving the element from its chemical constraints. A new paper describes a way to do just that, starting from saltwater.

Salt of the water

Why is this news? Well, it simply comes down to quantities — the Earth has a lot of saltwater, but not very much fresh water. Methods of producing hydrogen fuel from the latter have already been developed, but the fact of the matter is that fresh water is valuable. We need it to drink, we need it to wash, we need it to grow our crops and, as our planet’s population increases, we run a very real risk of not having enough water for everyone. So it doesn’t make sense to use it for energy — we need it elsewhere.

“You need so much hydrogen [to power our cities and economies that] it is not conceivable to use purified water,” said Hongjie Dai, J.G. Jackson and C.J. Wood professor in chemistry at Stanford and co-senior author on the paper. “We barely have enough water for our current needs in California.”

Salty water, in contrast, is plentiful — which also means cheap. There’s enough of it that we can turn it into hydrogen without upsetting the natural balance of Earth’s ecosystems too much. Hydrogen fuel also doesn’t emit carbon dioxide as it ‘burns’, only water. Given our current troubles with man-made climate change and habitat destruction, both are very appealing qualities.

Saltwater does, however, come with a major drawback. It’s not that hard to split water into hydrogen and oxygen, and we’ve known how to do it for a long time now. Just take a power source, connect two wires to and place their other end (or some electrodes if you want to be fancy about it) in water. Turn the power on, and you’ll get hydrogen bubbles at the negative end (cathode), and oxygen bubbles at the positive end (anode). This process is called electrolysis.

So far so good. But, if you try the same thing with saltwater, the chloride ions in salt (salt is a mix of chloride and sodium atoms) will corrode the anode and break down the system pretty quickly. Dai and his team wanted to find a way to stop those components from breaking down in the process.

Their approach was to coat the anode in several layers of negatively-charged material, which would repeal chloride, thus prolonging the useable life of the electrolysis rig. They layered nickel-iron hydroxide on top of nickel sulfide, over a nickel foam core. The nickel foam acts as a conductor, carrying electricity from the power source, while the nickel-iron hydroxide performs the electrolysis proper, separating water into oxygen and hydrogen.

As this happens, the nickel sulfide becomes negatively charged, protecting the anode. Just as the negative ends of two magnets push against one another, the negatively charged layer repels chloride and prevents it from reaching the core metal. Without the coating, the anode only works for around 12 hours in seawater, according to Michael Kenney, a graduate student in the Dai lab and co-lead author on the paper.

“The whole electrode falls apart into a crumble,” Kenney said. “But with this layer, it is able to go more than a thousand hours.”

Another bonus this coating brings to the table is that it allows for electrolysis to be performed at much higher currents. Previous efforts to split seawater had to use low current, as higher values promote corrosion. The team was able to conduct up to 10 times more electricity through their multi-layer device, which helps it generate hydrogen faster. Dai says they likely “set a record on the current to split seawater.” By eliminating the corrosive effect of salt, the team was able to use the same currents as those in devices that use purified water.

The team conducted most of their tests in controlled laboratory conditions, where they could regulate the amount of electricity entering the system. But, they also designed a solar-powered demonstration machine that produced hydrogen and oxygen gas from seawater collected from San Francisco Bay. Dai says the team pointed the way forward but will leave it up to manufacturers to scale and mass produce the design.

“One could just use these elements in existing electrolyzer systems and that could be pretty quick,” he adds. “It’s not like starting from zero — it’s more like starting from 80 or 90 percent.”

In the future, the technology could be used to generate breathable oxygen for divers or submarines while also providing power. And, perhaps, it could also be used in space exploration to limit the need for water purification systems — at least as far as power and oxygen are concerned.

The paper ” Solar-driven, highly sustained splitting of seawater into hydrogen and oxygen fuels” has been published in the journal Proceedings of the National Academy of Sciences.

cobalt catalyst

This cheap catalyst might finally make the hydrogen economy work

Hydrogen is a great medium for storing energy. It can be used as an alternative to batteries to store the excess energy from renewable energy systems like solar panels or wind turbines, and can be released from a tank to power a vehicle equipped with fuel cells. More than a decade ago, these prospects hyped the so called “hydrogen economy”. Governments and funding agencies drew up ambitious plans to develop cheaper fuel cells and to enable cars to store practicable quantities of hydrogen. In 2003, President George Bush committed $720 million to the research effort. But eventually… it all turned out to be a pipeline dream mostly because of two shortcomings: hydrogen is very expensive to store and make; from renewable sources at least.

cobalt catalyst

Bathed in simulated sunlight, this photoelectrolysis cell in the lab of Song Jin, a professor of chemistry at the University of Wisconsin-Madison, splits water into hydrogen and oxygen using a catalyst made of the abundant elements cobalt, phosphorus and sulfur. Image: David Tenenbaum/University of Wisconsin-Madison

 

A novel research attempts to solve this latter issue underlying the hydrogen economy. Prof Song Jin of Most of University of Wisconsin-Madison says his team found an exiting new catalyst that can split water into hydrogen almost as well as platinum, the highly expensive noble metal used both in electrolysis devices and fuel cells.

Man-made hydrogen is made through methane reforming, a process in which hot tubes heat the methane gas and steam in the presence of a catalyst to create pure hydrogen. This is the cheapest way to make hydrogen available today because you can make lots of it at a time. The disadvantage is that you have to burn a lot of energy and it’s all fossil fuel based. The other alternative is to split water molecules using electrolysis, with electricity sourced from renewable energy. To problem is that both fuel cells and electrolysis machines require expensive catalysts based on noble metals like palladium or platinum.

“In the hydrogen evolution reaction, the whole game is coming up with inexpensive alternatives to platinum and the other noble metals,” says Song Jin, a professor of chemistry at the University of Wisconsin-Madison.

Jin’s team was experimenting with iron pyrite and other inexpensive, abundant materials for energy transformation for quite a while. They struck gold when they eventually replaced the iron with cobalt. To the cobalt pyrite they added phosphorus resulting in a new material that’s been found to be highly effective as a catalyst. According to Jin, it’s the best non-noble metal catalyst and almost on par with platinum, but while platinum is traded with almost $1000 per ounce the cobalt catalyst is dirt cheap. What’s more, the catalyst also works as a photocatalyst, meaning it can kick start a reaction using energy provided by the sun directly, as reported in Nature Materials.

Of course, platinum electrolyzers are still the most efficient. For the same money, however, you could build more stacks based on the cobalt catalyst and effectively generate more hydrogen or energy for the same unit price. “One needs to consider the cost of the catalyst compared to the whole system. There’s always a tradeoff: If you want to build the best electrolyzer, you still want to use platinum. If you are able to sacrifice a bit of performance and are more concerned about the cost and scalability, you may use this new cobalt catalyst,” Jin says.

The UWM researchers have already filed for a patent and if the findings can be transferred from the lab into the real world, it could prove quite exciting.

A scheme that shows two methods of hydrogen generation: electrolysis and methane reforming. Image: jaea.go.jp

New electrolysis system produces hydrogen 30 times faster

A scheme that shows two methods of hydrogen generation: electrolysis and methane reforming. Image: jaea.go.jp

A scheme that shows two methods of hydrogen generation: electrolysis and methane reforming. Image: jaea.go.jp

A new method of producing hydrogen has been reported by researchers at University of Glasgow that’s 30 times faster than current state-of-the-art methods, providing yet another advance that might one day lead to a sustainable hydrogen based economy.

There’s only so much that renewable energy can grow with today’s infrastructure due to base load considerations. If the intermittency can be compensated with a storage medium, then solar and wind power can be extended in safely plugged into the grid. Hydrogen is fantastic for energy storage and these latest developments definitely help us reach a point where the hydrogen economy is feasible and make renewable energy the prime mean of generating energy.

[ALSO READ] Researchers split water using device that runs on AAA battery

Hydrogen economy: pipe dream or way of the future?

The cleanest way to produce hydrogen is through electrolysis – an electrochemical method which uses electricity to break the bonds between water’s constituent elements, hydrogen and oxygen, and releases them as gas. There aren’t any environmentally harmful byproducts and the hydrogen can then be stored for later use in fuel cells, for instance, which work like electrolysis in reverse.

[RELATED] US navy synthesizes jet fuel solely from seawater

At an industrial level, the most popular method for generating hydrogen out of renewable power is by using proton exchange membrane electrolysers (PEMEs). These devices, however, require precious metal catalysts (platinum, palladium), and need to be subjected to high pressure and high densities of current. The new method allows larger-than-ever quantities of hydrogen to be produced at atmospheric pressure using lower power loads, typical of those generated by renewable power sources.

“The process uses a liquid that allows the hydrogen to be locked up in a liquid-based inorganic fuel. By using a liquid sponge known as a redox mediator that can soak up electrons and acid we’ve been able to create a system where hydrogen can be produced in a separate chamber without any additional energy input after the electrolysis of water takes place,” according to Professor Lee Cronin of the University of Glasgow’s School of Chemistry.

“The link between the rate of water oxidation and hydrogen production has been overcome, allowing hydrogen to be released from the water 30 times faster than the leading PEME process on a per-milligram-of-catalyst basis,” he added.

There’s a great demand for hydrogen in the world right now, especially for agriculture where the gas is an indispensable component of ammonia fertilizer production. Essentially hydrogen helps feed half the world, at least. But it could also power it. The main problem right now with hydrogen is that it’s far from being sustainable – the way it’s being produced that is. More than 95% of the hydrogen available today is  made via steam-methane reforming, a mature production process in which high-temperature steam (700°C–1,000°C) is used to produce hydrogen from a methane source, such as natural gas. In steam-methane reforming, methane reacts with steam under 3–25 bar pressure (1 bar = 14.5 psi) in the presence of a catalyst to produce hydrogen, carbon monoxide, and a relatively small amount of carbon dioxide. So, what we’re seeing is a fossil fuel being subjected to a highly energy intensive treatment, whose energy most likely comes from fossil fuel combustion in the first place.

Developments such as these can only makes us happy and hope for a time where electrolysis systems can produce hydrogen cheaply and fast. Findings appeared in the journal Science.

 

Stanford scientists split water with device that runs on an ordinary AAA battery

Researchers from Stanford have found a way to split water into oxygen and hydrogen using very little energy; the hydrogen they obtain could be used to power fuel cells in zero-emissions vehicles.

I’m quite excited for cars that run on hydrogen, which are set to hit the market in 2015; but while they are always presented as “zero emission cars”, many of the hydrogen cars will actually use hydrogen obtained with natural gas – which is still a fossil fuel and still has considerable emissions. Hopefully, that will only be a temporary stage, and pretty soon, manufacturers will move on to greener, more sustainable solutions – like this project from Stanford University.

A team working there found a way to separate hydrogen from water cheaply and efficiently, producing water electrolysis only powered by a battery. The battery sends an electric current through two electrodes that split liquid water into hydrogen and oxygen gas. Unlike other water splitters that use precious-metal catalysts, the electrodes in the Stanford device are made of inexpensive and abundant nickel and iron.

“Using nickel and iron, which are cheap materials, we were able to make the electrocatalysts active enough to split water at room temperature with a single 1.5-volt battery,” said Hongjie Dai, a professor of chemistry at Stanford. “This is the first time anyone has used non-precious metal catalysts to split water at a voltage that low. It’s quite remarkable, because normally you need expensive metals, like platinum or iridium, to achieve that voltage.”

In addition to producing hydrogen, the same technique could be used to obtain chlorine gas and sodium hydroxide, an important industrial chemical.

Hydrogen cars and carbon emissions

Stanford scientists have developed a low-cost device that uses an ordinary AAA battery to split water into oxygen and hydrogen gas. Gas bubbles are produced by electrodes made of inexpensive nickel and iron.

The auto industry has considered developing hydrogen fuel cell as a promising alternative to the gasoline engine for decades, using fuel cell technology. Fuel cell technology is basically water splitting in reverse – it’s like creating water, and getting energy in the process. Basically, the fuel cell stores hydrogen which reacts with the oxygen from the air to create electricity which powers the car. The only by-product is water – no emissions whatsoever.

Earlier this year, Hyundai began leasing fuel cell vehicles in Southern California, but it’s still a local thing. In 2015, Toyota and Honda will hit the market, selling fuel cell cars. The only problem with this technology is a cheap way of obtaining hydrogen – something for which the Stanford team proposes a simple yet surprising solution.

“It’s been a constant pursuit for decades to make low-cost electrocatalysts with high activity and long durability,” Dai said. “When we found out that a nickel-based catalyst is as effective as platinum, it came as a complete surprise.”

This could save time and a lot of money, potentially taking gas guzzling cars out of the streets in the long run. The discovery wouldn’t have been possible without Stanford graduate student Ming Gong, co-lead author of the study.

“Ming discovered a nickel-metal/nickel-oxide structure that turns out to be more active than pure nickel metal or pure nickel oxide alone,” Dai said.  “This novel structure favors hydrogen electrocatalysis, but we still don’t fully understand the science behind it.”

Water electrolysis was, of course is not a new thing. The novely comes with the nickel/nickel-oxide catalyst, which significantly reduces the voltage necessary for electrolysis.

“The electrodes are fairly stable, but they do slowly decay over time,” he said. “The current device would probably run for days, but weeks or months would be preferable. That goal is achievable based on my most recent results”

The next step in their research is to make the entire process fully sustainable – that is, obtain the energy for the batteries through solar panels – and there’s no reason why they shouldn’t be successful in their attempts.

“Hydrogen is an ideal fuel for powering vehicles, buildings and storing renewable energy on the grid,” said Dai. “We’re very glad that we were able to make a catalyst that’s very active and low cost. This shows that through nanoscale engineering of materials we can really make a difference in how we make fuels and consume energy.”

Journal Reference: Ming Gong,Wu Zhou,Mon-Che Tsai,Jigang Zhou,Mingyun Guan,Meng-Chang Lin,Bo Zhang,Yongfeng Hu,Di-Yan Wang,Jiang Yang,Stephen J. Pennycook,Bing-Joe Hwang& Hongjie Dai. Nanoscale ​nickel oxide/​nickel heterostructures for active ​hydrogen evolution electrocatalysis. Nature Communications 5, Article number: 4695 doi:10.1038/ncomms5695

New Device Harnesses Sun and Sewage to Produce Hydrogen Fuel

It almost seems too good to be true – a novel device that uses only sunlight and wastewater to produce hydrogen gas could provide a sustainable energy source, while also improving the efficiency of the waste water system.

A sustainable, self-driven system

deviceIn a paper published in the American Chemical Society journal ACS Nano, a team led by Yat Li, associate professor of chemistry at the University of California, Santa Cruz described how they developed the hybrid solar-microbial device which combines a microbial fuel cell (MFC) and a type of solar cell called a photoelectrochemical cell (PEC).

In the Microbial (MFC) component, bacteria generate electricity by degrading the organic material in the waste water. The biologically generated energy is then delivered to the PEC to assist the solar-powered splitting of water (electrolysis) that generates hydrogen and oxygen.

Strictly speaking, both MFC and PEC could be used individually to generate hydrogen gas; the problem however, is that both require a small additional voltage (an “external bias”) to overcome the thermodynamic energy barrier for proton reduction into hydrogen gas. When used together, the two elements are sustainable and self driven, because the combined energy from the organic matter (harvested by the MFC) and sunlight (captured by the PEC) is sufficient to drive the electrolysis of water.

“The only energy sources are wastewater and sunlight,” Li said. “The successful demonstration of such a self-biased, sustainable microbial device for hydrogen generation could provide a new solution that can simultaneously address the need for wastewater treatment and the increasing demand for clean energy.”

Unusual bacteria, scaling, and commercial use

The microbial cells feature some rather unusual bacteria, which are able to generate electricity by transferring metabolically-generated electrons across their cell membranes to an external electrode. In order to develop this component, Li teamed up with researchers at Lawrence Livermore National Laboratory (LLNL) who have been studying electrogenic bacteria and working to enhance MFC performance. As it turns out, waste water is a perfect environment, as it contains both rich organic nutrients and a diverse mix of microbes that feed on those nutrients, including naturally occurring strains of electrogenic bacteria.

When fed with wastewater and illuminated in a solar simulator, the PEC-MFC device showed continuous production of hydrogen gas at an average rate of 0.05 cubic meters per day. Of course, in order to become actually useful, this invention has to be scaled, and considering that researchers also reported a drop in hydrogen as bacteria used up the organic matter in the wastewater, cuold this become commercially viable?

Scientists are optimistic. They are already in the process of scaling up the small laboratory device to make a larger 40-liter prototype continuously fed with municipal wastewater. This is the intermediary step, and if everything works out fine with that, then they can finally take their results to the municipality.

“The MFC will be integrated with the existing pipelines of the plant for continuous wastewater feeding, and the PEC will be set up outdoors to receive natural solar illumination,” Qian said.

“Fortunately, the Golden State is blessed with abundant sunlight that can be used for the field test,” Li added.

Journal Reference: Hanyu Wang, Fang Qian, Gongming Wang, Yongqin Jiao, Zhen He, Yat Li. Self-Biased Solar-Microbial Device for Sustainable Hydrogen Generation. ACS Nano, 2013; 130916123121001 DOI: 10.1021/nn403082m