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Fuel From Lignin | Earth Wise

November 26, 2020 By EarthWise Leave a Comment

Lignin is an organic polymer that provides the rigid structure of plants and is what gives wood and bark their characteristic properties. Lignin typically comprises between 20 and 35% of the mass of wood. The two major substances extracted from trees, grasses, and other biomass materials are cellulose and lignin. Cellulose is used to make paper, bioethanol, and other products, but lignin is largely unused because it is difficult to break down into useful substances such as feedstocks for fuels. As a result, lignin is largely wasted. Worldwide, some 50 million tons of lignin are produced from paper and bioethanol manufacturing each year and almost all of that is simply burned to generate heat.

Lignin can be broken down using pyrolysis techniques at high temperatures to create bio-oils, but those oils lack sufficient hydrogen and contain too much oxygen to be useful as fuels. There is a process called hydrodeoxygenation that adds hydrogen and removes oxygen, but it requires high temperatures and very high pressures as well as producing char and tar that reduces the efficiency of the process.

Researchers at Georgia Tech recently published work describing a new process for turning lignin into useful products. They developed a dual catalyst system of super-acid and platinum particles that adds hydrogen and removes oxygen from lignin bio-oil and makes it useful as a fuel and source of chemical feedstocks.

The new process could help meet the growing demand for bio-based oils as well as helping the forest product, paper, and bioethanol industries by providing an additional revenue stream from what previously was a waste product.

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New Process Boosts Lignin Bio-oil as a Next-Generation Fuel

Photo, posted August 16, 2017, courtesy of evcabartakova via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Generating Hydrogen From Poor-Quality Water | Earth Wise

September 8, 2020 By EarthWise Leave a Comment

Hydrogen could be the basis of a complete energy system. It could be stored and transported and could be used to power vehicles and to generate electricity in power plants. Proponents of the so-called hydrogen economy contend that hydrogen is the best solution to the global energy challenge. But among the challenges faced by a hydrogen economy is the development of an efficient and green method to produce hydrogen.

The primary carbon-free method of producing hydrogen is to break down water into its constituent elements – hydrogen and oxygen. This can be done in a number of ways, notably by using electricity in a process called electrolysis. A method that seems particularly attractive is to use sunlight as the energy source that breaks down the water molecule.

While there is an abundance of water on our planet, only some of it is suitable for people to drink and consume in other ways. Much of the accessible water on earth is salty or polluted. So, a technique to obtain hydrogen from water ideally should work with water that is otherwise of little use to people.

Researchers in Russia and the Czech Republic have recently developed a new material that efficiently generates hydrogen molecules by exposing water – even saltwater or polluted water – to sunlight.

The new material is a three-layer structure composed of a thin film of gold, an ultra-thin layer of platinum, and a metal-organic framework or MOF of chromium compounds and organic molecules. The MOF layer acts as a filter that gets rid of impurities.

Experiments have demonstrated that 100 square centimeters of the material can generate half a liter of hydrogen in an hour. The researchers continue to improve the material and increase its efficiency over a broad range of the solar spectrum.

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New Material Can Generate Hydrogen from Salt and Polluted Water

Photo courtesy of Tomsk Polytechnic University.

Earth Wise is a production of WAMC Northeast Public Radio.

Hydrogen From The Ocean

November 15, 2019 By EarthWise Leave a Comment

Hydrogen is frequently touted as an excellent source of clean energy that could be used as a fuel in vehicles, or as a storage medium for energy generated by wind and solar power. The challenge is that hydrogen is rather difficult and expensive to attain, and the most economical methods are not clean and green.

Most industrial hydrogen is produced by reforming natural gas, which has the drawback that carbon dioxide is generated in the process. The environmentally friendly way to produce hydrogen is via electrolysis, in which a chemical reaction is triggered by a catalyst enabling electricity to split water into its constituent elements of oxygen and hydrogen.

The best performing catalyst for electrolysis is platinum, but its high price is a big drawback for the economics of making hydrogen. Researchers at the Pacific Northwest National Laboratory have found a pairing of minerals that may solve the problem. Testing a molybdenum-phosphide catalyst with wastewater in a small reactor called a microbial electrolysis cell revealed that the new catalyst actually worked better than platinum.

Even better, the molybdenum-phosphide catalyst worked well with seawater. If hydrogen can be produced using seawater, there would be a pretty much unlimited resource for making it. By eliminating the use of platinum catalysts, it may be possible to reduce the cost of hydrogen made by electrolysis to a competitive level.

Hydrogen as a vehicle fuel currently costs about twice as much as gasoline on an energy-equivalent basis. Given that running cars from batteries is considerably cheaper than using gas, the cost of hydrogen needs to come down considerably for it to be a viable vehicle fuel.

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Ditching Platinum for the Ocean Could Make Hydrogen Cheap

Photo, posted July 19, 2011, courtesy of Heather Paul via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Hydrogen From Water And Sun

March 7, 2019 By EarthWise 1 Comment

There are research efforts around the world seeking ways to produce hydrogen starting from water and using clean energy. Finding an economical and scalable way to do this is a key to the so-called hydrogen economy.

A recent study at Argonne National Laboratory makes use of a chemical reaction pathway central to plant biology to create a process that converts water into hydrogen using energy from the sun.

The process combines two membrane-bound protein complexes to perform the conversion of water molecules into hydrogen and oxygen.

The first protein complex, which the researchers call Photosystem I, is a membrane protein that uses energy from light to feed electrons to an inorganic catalyst that makes hydrogen. But this represents only half of the overall process.

A second protein complex that they call Photosystem II uses energy from light to split water and take electrons from it. The electrons are then fed to Photosystem I.

The two protein complexes are embedded in thylakoid membranes, which are like those found inside the oxygen-creating chloroplasts in plants. This membrane is an essential part of pairing the two photosystems. It supports both of the photosystems and provides a pathway for transferring electrons between the proteins.

The researchers also make use of a synthetic catalyst made from nickel or cobalt that replaces expensive platinum catalysts used in conventional water-splitting schemes. Combining the light-triggered transport of electrons with the synthetic catalyst results in what the researchers call the “Z-scheme”, an adaptation of photosynthesis to produce hydrogen.

The next step is to incorporate the scheme into a living system which the researchers hope will lead to a practical system for hydrogen production.

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Discovery adapts natural membrane to make hydrogen fuel from water

Photo, posted December 25, 2017, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A New Way to Make Hydrogen

January 31, 2019 By EarthWise Leave a Comment

Many people consider hydrogen to be the fuel of the future, both for powering vehicles and for storing energy generated by renewable sources. Hydrogen itself is a clean and green fuel. Generating energy from it using fuel cells results in only water as a byproduct.

The biggest problem with hydrogen is that the most economical way to produce it and therefore the way most hydrogen is produced today, is by reforming natural gas, which is a process that generates carbon emissions.

The desirable way to make hydrogen is to produce it by breaking apart water into its hydrogen and oxygen components, a process known as electrolysis. There are many ways to do it, but none of them to date measures up in terms of efficiency, cost, and longevity.

Researchers at the University of Toronto have recently developed a new catalyst that uses abundant, low-cost elements to split water molecules into hydrogen and oxygen. The catalyst is made from copper, nickel, and chromium, all of which are more abundant and less costly than platinum, which is the usual electrolysis catalyst.

The new catalyst performs well under pH-neutral conditions, which means it could even work on seawater without incurring the expense of desalination. The Toronto researchers also believe their catalyst could be used as part of a process to make hydrocarbon fuels from hydrogen and CO2₂. Their group is among the five finalists in the Carbon XPrize competition, which has a grand prize of $7.5 million for finding a way to convert waste CO2 into fuel.

Finding a low-cost, energy-efficient, and reliable way to make hydrogen out of water will be a big deal if it can be done on an industrial scale.

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U of T researchers discover low-cost way to produce hydrogen from water

Photo, posted July 23, 2015, courtesy of Magnus Johansson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A New Catalyst For Splitting Water

August 13, 2018 By EarthWise Leave a Comment

Hydrogen is widely considered to be a desirable source of clean energy. It can be used in fuel cells to power electric motors in cars or can be burned directly in internal combustion engines. If it is compressed or converted to liquid, it can be efficiently stored and transported. Most of all, when it is used as an energy source, the only emission it produces is water.

Better Zinc-Air Batteries

September 26, 2017 By EarthWise Leave a Comment

Zinc-air batteries are metal-air batteries powered by oxidizing zinc with the oxygen from the air. They have high energy densities (as much as five times more energy than lithium-ion batteries) and are more environmentally friendly. Since they are based on abundant zinc, they are potentially much cheaper to produce than the lithium-ion batteries that are used in so many current applications. But because it is difficult and expensive to produce rechargeable versions of these batteries, they have only found limited use in hearing aids, in some film cameras, and in large form to power navigation instruments, oceanographic experiments and railway signals.