Scientists discover entirely new wood type that could be highly efficient at carbon storage

Researchers undertaking an evolutionary survey of the microscopic structure of wood from some of the world's most iconic trees and shrubs have discovered an entirely new type of wood. 

This discovery may open new opportunities to improve carbon sequestration in plantation forests by planting a fast-growing tree more commonly seen in ornamental gardens.

The study found that Tulip Trees, which are related to magnolias and can grow well over 100 feet tall, have a unique type of wood that does not fit into either category of hardwood or softwood.

Scientists from Jagiellonian University and the University of Cambridge used a low temperature scanning electron microscope (cryo-SEM) to image the nanoscale architecture of secondary cell walls (wood) in their native hydrated state.

The researchers found the two surviving species of the ancient Liriodendron genus, commonly known as the Tulip Tree (Liriodendron tulipifera) and Chinese Tulip Tree (Liriodendron chinense) have much larger macrofibrils then their hardwood relatives (macrofibrils are long fibres aligned in layers in the secondary cell wall).

Lead author of the research published in New Phytologist, Dr Jan Łyczakowski from Jagiellonian University, said: "We show Liriodendrons have an intermediate macrofibril structure that is significantly different from the structure of either softwood or hardwood. Liriodendrons diverged from Magnolia Trees around 30-50 million years ago, which coincided with a rapid reduction in atmospheric CO2. This might help explain why Tulip Trees are highly effective at carbon storage."

The team suspect it is the larger macrofibrils in this "midwood" or "accumulator-wood" that is behind the Tulip Trees' rapid growth.

Łyczakowski added: "Both Tulip Tree species are known to be exceptionally efficient at locking in carbon, and their enlarged macrofibril structure could be an adaptation to help them more readily capture and store larger quantities of carbon when the availability of atmospheric carbon was being reduced. Tulip Trees may end up being useful for carbon capture plantations. Some east Asian countries are already using Liriodendron plantations to efficiently lock in carbon, and we now think this might be related to its novel wood structure." 

Liriodendron tulipifera are native to northern America and Liriodendron chinense is a native species of central and southern China and Vietnam.

The discovery was part of a survey of 33 tree species from the Cambridge University Botanic Garden's Living Collections exploring how wood ultrastructure evolved across softwoods (gymnosperms such as pines and conifers) and hardwoods (angiosperms including oak, ash, birch, and eucalypts).

Łyczakowski said: "Despite its importance, we know little about how the structure of wood evolves and adapts to the external environment. We made some key new discoveries in this survey -- an entirely novel form of wood ultrastructure never observed before and a family of gymnosperms with angiosperm-like hardwood instead of the typical gymnosperm softwood. 

"The main building blocks of wood are the secondary cell walls, and it is the architecture of these cell walls that give wood its density and strength that we rely on for construction. Secondary cell walls are also the largest repository of carbon in the biosphere, which makes it even more important to understand their diversity to further our carbon capture programmes to help mitigate climate change."

Wood ultrastructure

Wood ultrastructure refers to the detailed microscopic architecture of wood, encompassing the arrangement and organisation of its material components. This survey of wood using a cryo-scanning electron microscope focused on:

•  The Secondary Cell Wall: This is composed of mainly cellulose plus other complex sugars and is impregnated with lignin to make the whole structure rigid. These components make up the macrofibril, forming long aligned fibres that are arranged in distinct layers within the secondary cell wall.
• The Macrofibril: This is currently the smallest structure we can measure using the cryoSEM and is in the order of 10 -- 40 nanometres thick. It is composed of cellulose microfibrils (3-4 nanometres) plus other components.

Studying the wood ultrastructure is crucial for various applications, including wood processing, material science, and understanding the ecological and evolutionary aspects of trees. Understanding the biology behind tree growth and wood deposition is also valuable information when calculating carbon capture.

The Living Collections of the Cambridge University Botanic Garden

The wood samples were collected from trees in the Cambridge University Botanic Garden in coordination with the Garden's Collections Coordinator Margeaux Apple. Fresh samples of wood deposited in the previous spring growing season were collected from a selection of trees to reflect the evolutionary history of gymnosperm and angiosperm populations as they diverged and evolved. 

Microscopy Core Facility Manager at the Sainsbury Laboratory Cambridge University, Dr Raymond Wightman, said: "We analysed some of the world's most iconic trees like the giant sequoia, Wollemi pine and so-called "living fossils" such as Amborella trichopoda, which is the sole surviving species of a family of plants that was the earliest still existing group to evolve separately from all other flowering plants.

"Our survey data has given us new insights into the evolutionary relationships between wood nanostructure and the cell wall composition, which differs across the lineages of angiosperm and gymnosperm plants. Angiosperm cell walls possess characteristic narrower elementary units, called macrofibrils, compared to gymnosperms and this small macrofibril emerged after divergence from the Amborella trichopodaancestor." 

Lyczakowski and Wightman also analysed the cell wall macrofibrils of two gymnosperm plants in the Gnetophytes family -- Gnetum gnemon and Gnetum edule -- and confirmed both have a secondary cell wall ultrastructure synonymous with the hardwood cell wall structures of angiosperms.

This is an example of convergent evolution where the Gnetophytes have independently evolved a hardwood-type structure normally only seen in angiosperms.

The survey was undertaken while the UK was sweltering under the UK's 4th hottest ever recorded summer in 2022. 

"We think this could be the largest survey, using a cryo-electron microscope, of woody plants ever done," Wightman said. "It was only possible to do such a large survey of fresh hydrated wood because the Sainsbury Lab is located within the grounds of the Cambridge University Botanic Garden. We collected all the samples during the summer of 2022 -- collecting in the early morning, freezing the samples in ultra-cold slush nitrogen and then imaging the samples through to midnight.

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Path to net-zero carbon capture and storage may lead to ocean

Lehigh Engineering researcher Arup SenGupta has developed a novel way to capture carbon dioxide from the air and store it in the "infinite sink" of the ocean.

The approach uses an innovative copper-containing polymeric filter and essentially converts CO2 into sodium bicarbonate (aka baking soda) that can be released harmlessly into the ocean. This new hybrid material, or filter, is called DeCarbonHIX (i.e., decarbonization through hybrid ion exchange material), and is described in a paper recently published in the journal Science Advances.

The research, which demonstrated a 300 percent increase in the amount of carbon captured compared with existing direct air capture methods, has garnered international attention from media outlets like the BBC, CNN, Fast Company, and The Daily Beast, and professional organizations like the American Chemical Society. SenGupta himself has been fielding interest in the technology from companies based in Brazil, Ireland, and the Middle East.

"The climate crisis is an international problem," says SenGupta, who is a professor of chemical and biomolecular engineering and civil and environmental engineering in Lehigh's P.C. Rossin College of Engineering and Applied Science. "And I believe we have a responsibility to build direct air capture technology in a way that it can be implemented by people and countries around the world. Anyone who can operate a cell phone should be able to operate this process. This is not technology for making money. It's for saving the world."

The work is yet another extension of SenGupta's personal and professional commitment to developing technologies that benefit humanity, and in particular, marginalized communities around the world. His research on water science and technology has included drinking water treatment methodologies, desalination, municipal wastewater reuse, and resource recovery. He invented the first reusable, arsenic-selective hybrid anion exchanger nanomaterial (HAIX-Nano), and as a result, more than two million people around the world now drink arsenic-safe water. Two of his patents have been recognized as "Patents for Humanity" by the US patent and Trademark Office.

His invention of DeCarbonHIX was the outcome of an ongoing CO2-driven wastewater desalination project funded by the Bureau of Reclamation under the jurisdiction of the U.S. Department of the Interior. SenGupta and his students were on the lookout for a reliable supply of CO2 even in remote places. That quest led the way to the field of direct air capture, or DAC, and the creation of DeCarbonHIX. This subject was the dissertation topic for environmental engineering student Hao Chen '23 PhD, who successfully defended his PhD in March and will receive his doctorate in May.

Capturing carbon at lower concentrations

The most abundant of the greenhouse gasses contributing to global warming is carbon dioxide. In 2021, global emissions of CO2 rose by 6 percent from the previous year -- to 36.3 gigatons, according to the International Energy Agency. Just one gigaton (equal to 1 billion tons) is the equivalent of the mass of all land mammals on earth.

Emissions from greenhouse gasses have increased global temperatures by approximately 1.1 degrees Celsius above pre-industrial levels, according to the Intergovernmental Panel on Climate Change. In its 2021 working group report, the IPCC estimates the average yearly temperature over the next 20 years is expected to rise by at least 1.5 degrees Celsius. The warmer the earth gets, the greater the fallout in terms of rising sea levels, extreme storm events, and ecological disruption, all of which have repercussions on global health, security, and stability.

"The worst part of this crisis is that people who are marginalized, who are poor, will suffer 10 times more than those who contributed to this situation," says SenGupta.

There are three ways to reduce CO2, he says. The first -- government action -- can reduce emissions, but that won't address what's already in the air.

"The second way is removing it from point sources, places like chimneys and stacks where carbon dioxide is being emitted in huge amounts," he says. "The good thing about that is you can remove it at very high concentrations, but it only targets emissions from specific sources."

The newest method is called direct air capture, which, he says, "allows you to remove CO2 from anywhere, even your own backyard."

With DAC, chemical processes remove CO2 from the atmosphere, after which it's typically stored underground. However, says SenGupta, the technology is limited by its capacity. It can't capture enough CO2 to overcome the energy cost of running the process.

"If you're capturing carbon dioxide from a chimney at a plant, the amount of CO2 in the air can be upwards of 100,000 parts per million," he says. "At that concentration, it's easy to remove. But generally speaking, the CO2 level in the air is around 400 parts per million. That's very high from a climate change point of view, but for removal purposes, we consider that ultra-dilute. Current filter materials just can't collect enough of it."

Another challenge with DAC involves storage. After the CO2 is captured, it's dissolved, put under pressure, liquified, and typically stored miles underground. A DAC operation must then be located in an area with enough geological storage -- and stability. A country like Japan, for instance, can't pump CO2 underground because the area is prone to earthquakes.

Seeing a solution in seawater

SenGupta has developed a DAC method that overcomes both the capture problem and the issue of storage.

For the capture problem, he developed DeCarbonHIX -- a mechanically strong, chemically stable sorbent (a material used to absorb liquids or gasses) -- that contains copper.

"The copper changes an intrinsic property of the parent polymer material and enhances the capturing capacity by 300 percent," he says. "We showed that for direct air capture from air with 400 parts per million of CO2, we achieve capacity, meaning capacity is no longer a function of how much carbon dioxide is in the air. The filter will get saturated completely at any concentration, which means you can perform DAC in your backyard, in the middle of the desert, or in the middle of the ocean."

The ocean is actually SenGupta's solution to the storage problem. His DAC process starts with air blowing through the filter to capture CO2. Once the filter is saturated with gas molecules (determined by measuring the amount of gas going into the filter versus coming out of it), seawater is passed through the filter. The seawater converts the carbon dioxide to sodium bicarbonate (you likely know it as baking soda, but lose the visual as we're talking about a dissolved solution here). The dissolved sodium bicarbonate is then released directly into the ocean, what Sengupta calls "an infinite sink."

"And it has no adverse impact on the ocean whatsoever," says SenGupta. "It doesn't change the salinity at all."

In fact, he says, the sodium bicarbonate, which is slightly alkaline, may improve the health of the ocean. That's because elevated levels of CO2 in the atmosphere have gradually reduced the pH of the ocean, causing acidification. More acidic waters harm the growth and reproduction of marine life like corals and plankton and can create catastrophic collapses in the food chain.

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Climate 'spiral' threatens land carbon stores

The world's forests are losing their ability to absorb carbon due to increasingly 'unstable' conditions caused by humans, a landmark study has found.

Dramatic changes to forests, and other habitats that store carbon in plants and soils, are becoming more likely in some regions across Earth, with less carbon consistently absorbed by the 'land carbon sink' provided by trees, soil and plants, according to scientists writing in Nature.

The short-term impacts of rising temperatures, deforestation and farming on many vulnerable landscapes means carbon stores on land are less likely to recover in the longer term, the scientists say. This reduces the overall storage capacity of the land to absorb carbon and undermines global efforts to curb or reduce levels of greenhouse gases in the atmosphere.

Dr Patrick McGuire, a climate scientist working jointly in the Department of Meteorology and the National Centre for Atmospheric Science branch, both at the University of Reading, UK, was a co-author of the new study, which was led by colleagues at CREAF, Barcelona, and Antwerp University.

Dr McGuire said: "We found that large regions of the world are vulnerable to sudden and dramatic changes to their landscape, because the ability of their ecosystems to absorb carbon starts to destabilise.

"For example, forest fires in California are more likely because of extremely dry and hot conditions caused by a hotter atmosphere. More fires means forest turns to scrubland, sometimes permanently. This reduces the land's overall ability to suck carbon out of the atmosphere as it did before.

"This creates a vicious cycle as areas such as these become more vulnerable to the effects of climate change in the future."

Unstable carbon storage

Researchers found that from 1981-2018, ecosystems across the world moved through different phases, ranging from high productivity, when plants were able to take in more carbon, to low productivity, when plants were less able to absorb carbon.

The scale of these fluctuations creates a greater risk of destabilisation, increasing the risk of abrupt landscape changes as ecosystems cannot acclimate to climate change, deforestation, and changes to biodiversity, among other factors.

The study, published today (Wednesday, 22 February 2023) in Nature, found the regions most at risk typically have less forest cover and more cropland, are warmer, and have experienced greater rises in temperature, which could be related to an increase in extreme weather events, such as heatwaves and cold snaps. The areas identified as most at risk include the Mediterranean Basin, Southeast Asia and the west coasts of North and Central America.

The researchers said these vulnerable areas have developed a 'memory' -- described as a 'temporal autocorrelation' -- meaning that years where carbon uptake is lower are more likely to be followed by years where carbon uptake diminishes further. Researchers say that as less carbon is absorbed in areas where forestland dominates, the likelihood of scrubland becoming the permanent landscape increases and forests could be lost forever.

Global variation

While several regions are at risk of abrupt changes in their landscapes, there are parts of the world where carbon absorption levels are consistent and ecosystem collapse is less likely as a result of carbon fluctuations. This includes the tropical forests of the Amazon, and parts of central and northern Europe, where carbon absorption capacity has increased. However, the researchers warn that regions such as the Amazon face other climate threats, such as future shifts in regular patterns of rainfall.

The scientists say these global variations could make it harder to predict the global impact of schemes to absorb carbon, such as planting trees, in helping the world reach carbon net zero.

Read more at Science Daily

Safer carbon capture and storage

Atmospheric carbon dioxide (CO2) levels have increased significantly over the last 50 years, resulting in higher global temperatures and abrupt changes to Earth's climate. Carbon capture and storage (CCS) is one of the new technologies that scientists hope will play an important role in tackling the climate crisis. It involves the capture of CO2 from emissions from industrial processes, or from the burning of fossil fuels in power generation, which is then stored underground in geological formations. CCS will also be key if we want to produce "clean-burning" hydrogen from hydrocarbon systems.

The UK government recently selected four sites to develop multi-billion-pound CCS projects as part of its scheme to cut 20-30m tonnes of CO2 per year by 2030 from heavy industry. Other countries have made similar carbon reduction commitments.

Depleted hydrocarbon reservoirs have a smaller (10%) storage potential compared to deep saline aquifers but are seen as a critical early opportunity in developing geological CO2 storage technologies. Fortuitously, CO2 has historically been injected into numerous depleted hydrocarbon reservoirs as a means of enhanced oil recovery (CO2-EOR). This provides a unique chance to evaluate the (bio)geochemical behaviour of injected carbon over engineering timescales.

'CCS will be a key tool in our battle to avert climate change. Understanding how CCS works in practice, in addition tocomputer modelling and lab-based experiments, is essential to provide confidence in safe and secure CO2 geologicalsequestration.' Said Dr. Rebecca Tyne, Dept Earth Science, The University of Oxford

In a paper published, today in Nature, Dr. Rebecca Tyne and Prof. Chris Ballentine from Oxford University, lead a team of international collaborators to investigate the behaviour of CO2 within a CO2-EOR flooded oil field in Louisiana, USA. They compared (bio)geochemical composition of the CO2-EOR flooded field with that of an adjacent field, which was never subjected to CO2-EOR. Data suggest that up to 74% of CO2 left behind by CO2-EOR was dissolved in the groundwater. Unexpectedly, it also revealed, that microbial methanogenesis converted as much as 13-19% of the injected CO2 to methane, which is a stronger greenhouse gas than CO2.

This study is the first to integrate state of the art isotopic tracers (noble gas, clumped and stable isotope data) with microbiological data to investigate the fate of the injected CO2.

'Methane is less soluble, less compressible and less reactive than CO2, so, if produced, the reduces the amount of CO2 we can safely inject into these sites. However, now this process has been identified, we can take it into account in future CCS site selection.' Said Prof. Chris Ballentine, Dept. Earth Sciences, The University of Oxford.

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