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A Big Year For Rooftop Solar | Earth Wise

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The global capacity of rooftop solar power grew by 49% in 2022.  Overall, the installed amount of rooftop solar grew from 79 gigawatts to 118 gigawatts last year and it is projected to reach 159 gigawatts by the end of this year.  By comparison, a typical nuclear power plant can produce 1 gigawatt; a gas-powered power plant is typically half a gigawatt.

Rooftop solar constitutes a relatively small fraction of the total global installed solar capacity, which is dominated by utility-scale solar arrays.  Total installed solar capacity rose from 950 gigawatts to 1,177 gigawatts last year and is projected to reach 1,518 gigawatts this year.  That is enough power to meet more than half the electricity demand of the European Union.

The rapid growth of solar power can only continue if there is more energy storage put in place to manage the peaks and troughs in solar output.  Countries will also need to upgrade their power grids to be able to transport excess solar power from where it is generated to where it is needed.   Bottlenecks in the grids of most of the leading solar-producing nations are already interfering with further solar development.

The overall potential for rooftop solar is based on the number of rooftops that would be suitable for solar power, which depends on the size, shading, orientation, and location of the roofs.  According to the National Renewable Energy Laboratory, rooftops in the United States have the potential for more than 1,000 gigawatts of solar capacity. Currently, only about 4% of US homes have rooftop solar. 

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Rooftop Solar Grew Nearly 50 Percent Globally Last Year

Photo, posted November 16, 2022, courtesy of Oliver Knight via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Moss And Carbon Storage | Earth Wise

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All plants, including algae and cyanobacteria, carry out photosynthesis. During the process of photosynthesis, plants remove carbon dioxide from the air and release oxygen to the air.  As a result, plants play a crucial role in the fight against climate change. 

According to a new study recently published in the journal Nature Geoscience, mosses – those tiny plants often found on the ground or rocks – might be important antidotes to climate change.  The study, which was led by scientists from the University of New South Wales in Australia and the Institute of Natural Resources and Agrobiology in Spain, uncovered evidence that mosses have the potential to store a massive amount of carbon in the soil beneath them.

The researchers found that mosses sequester around seven billion tons more carbon in the soil than is stored in the bare patches of soil typically found near them.  To put that figure in perspective, that is six times the annual global carbon emissions caused by global land use change, which includes things like deforestation, urbanization, and mining.  The researchers also found that moss-covered soil possessed heightened levels of vital nutrients and fewer instances of soil-borne plant pathogens on average compared to moss-less soil.

Mosses cover an area of more than 3.6 million square miles, which is similar in size to Canada, and can thrive in challenging environments.  The widespread presence and hardiness of mosses is why they can have such a significant impact on soil biodiversity and carbon sequestration. 

The research team hopes future work will focus on understanding the role of all types of vegetation, not just mosses and trees, in capturing carbon.

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Study: Modest moss supports billions of tons of carbon storage

Photo, posted August 23, 2017, courtesy of Peter Handke via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Large Lakes In Decline | Earth Wise

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Globally, freshwater lakes and reservoirs hold 87% of the planet’s liquid freshwater, making them a valuable resource for both people and wildlife.  Despite their value, the long-term trends and changes to water levels of lakes have been largely unknown – until now.

According to a new assessment recently published in the journal Science, more than half of the largest lakes around the world are losing water.  Using satellite observations and climate data, the research team created a technique to measure changes in water levels in nearly 2,000 of the world’s biggest lakes and reservoirs, representing 95% of the total lake water storage on Earth.

The results are staggering.  According to the findings, 53% of Earth’s largest lakes and reservoirs now store significantly less water than they did in 1992.  The total amount of water lost is estimated to be 144.5 cubic miles, which is equivalent to the volume of 17 Lake Meads (the largest reservoir in the U.S.). 

Unsurprisingly, climate warming and human consumption were the main drivers of water loss from lakes, whereas sedimentation — the buildup of debris — was the biggest driver of water loss in reservoirs.  Roughly one-quarter of the world’s population – two billion people – live in the basin of a drying lake, indicating the urgent need for sustainable water resources management.

But the news is not entirely bleak.  According to the research team, the new method of tracking lake water storage trends can give water managers and communities insight into how to better protect this critical resource. 

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Satellites reveal widespread decline in global lake water storage

Photo, posted February 10, 2010, courtesy of Ninara via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Better Zinc Batteries | Earth Wise

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The rapid growth of wind and solar power continues to drive a global quest for new battery technologies that can be used to store the energy generated by these sources when the sun isn’t shining, and the wind isn’t blowing.

For the most part, current battery energy storage systems use lithium-ion batteries – the same sort of batteries found in cellphones and electric vehicles.  There are many other battery chemistries, but they mostly have shortcomings in performance, economy, or longevity. 

Batteries store electricity in the form of chemical energy and chemical reactions convert that energy into electrical energy. Every battery has two electrodes:  the anode, from which electrons flow into external circuits, and the cathode, which receives electrons from the external circuit.  The electrolyte is the chemical medium through which the electrons flow.

One technology that has great potential is zinc-based batteries.  Zinc itself is a metal that is safe and abundant.  Batteries based on it are energy dense. However, zinc batteries have faced the challenge of having a short cycle life.  The batteries end up plating zinc on their anodes and battery performance degrades. 

A team of researchers at Oregon State University and three other universities have recently developed a new electrolyte for zinc batteries that raises the efficiency of the zinc metal anode to nearly 100% – actually slightly better than lithium-ion batteries.

Zinc batteries have a number of potential advantages over lithium-ion.  The new hybrid electrolyte developed by the researchers is non-flammable, cost-effective, and has low environmental impact.  Lithium-ion batteries rely on the supplies of relatively rare metals that are often difficult and environmentally harmful to obtain. 

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Researchers develop electrolyte enabling high efficiency of safe, sustainable zinc batteries

Photo, posted May 13, 2017, courtesy of Jeanne Menjoulet via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Storing Carbon Dioxide In The Ocean | Earth Wise

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Reducing the amount of carbon dioxide entering the atmosphere means either shutting down emission sources (primarily curbing the use of fossil fuels) or capturing the CO2 as it is emitted.  Capturing carbon dioxide from smokestacks and other point sources with high concentrations is relatively efficient and can make economic sense.  Removing it from the air, which even at today’s dangerously high levels contains only 400 parts per million, is difficult and energy intensive.  And even when it is removed, it then must be stored somewhere.

Researchers at Lehigh University have developed a novel way to capture carbon dioxide from the air and store it in what is effectively the infinite sink of the ocean.  The approach uses an innovative copper-containing filter that essentially converts CO2 into sodium bicarbonate (better known as baking soda.)  The bicarbonate can be released harmlessly into the ocean.

This technique has produced a 300 percent increase in the amount of carbon dioxide captured compared with existing direct air capture methods.   It does not require any specific level of carbon dioxide to work.  The filter becomes saturated with the gas molecules as air is blown through it.  Once this occurs, seawater is passed through the filter and the CO2 is converted to dissolved bicarbonate.  Dumping it into the ocean has no adverse effect on the ocean.  It doesn’t change the salinity at all, and the stuff is slightly alkaline, which will help reduce ocean acidification.

Reusing the filter requires cleaning it with a sodium hydroxide solution, which can be created from seawater using electricity generated by waves, wind, or sun.

The filter, called DeCarbonHIX, is attracting interest from companies based in countries around the world.

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

Photo, posted March 10, 2007, courtesy of Gail via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Pulling Carbon Dioxide Out Of Seawater | Earth Wise

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The world’s largest sink for carbon dioxide from the atmosphere is the ocean.  The world’s oceans soak up 30-40% of all the gas produced by human activities.  Dissolving carbon dioxide in water produces carbonic acid.   This is the reason that oceans are becoming increasingly acidic, which is causing serious damage to ocean ecosystems.

There are many efforts underway aimed at directly removing carbon dioxide from the air as a way to mitigate the effects of ongoing emissions.  But another possibility is to remove CO2 directly from ocean water.  Existing methods for doing it involve the use of expensive membranes and complex chemicals. The economics of such methods are quite unfavorable.

Recently, a team of researchers at MIT has identified what they claim is a truly efficient and inexpensive removal mechanism. It involves a reversible process based on membrane-free electrochemical cells.  Electrodes in the cells release protons that are introduced to seawater which drive the release of carbon dioxide dissolved in the water. The carbon dioxide can be collected and the processed water ends up being alkaline.

Running this process at a site that is already collecting seawater – such as at a desalination plant – would be an effective way to collect carbon dioxide as well as help mitigate ocean acidification.

Once the carbon dioxide is removed from the water, it still needs to be disposed of, just as is the case for other carbon removal processes.  It could be turned into useful chemicals or it could be stored in underground caverns.  But this approach is fairly unique in that the carbon dioxide has already been captured by the ocean.  The issue remains what to do with it.

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How to pull carbon dioxide out of seawater

Photo, posted January 19, 2016, courtesy of Judy Dean via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Cheaper Carbon Capture | Earth Wise

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As the years roll by without sufficient progress in reducing carbon dioxide emissions, the need for technologies that can capture CO2 from its sources or remove it from the air becomes stronger and stronger.  People have developed various ways to capture carbon dioxide, but to date, they generally suffer from some combination of being too costly or not being able to scale up to the necessary magnitude.

Scientists at the Pacific Northwest National Laboratory in Richland, Washington recently announced the creation of a new system that they claim is the least costly to date that captures carbon dioxide and turns it into a widely-used chemical: methanol.

Technologies that simply capture carbon dioxide that then needs to be stored in some secure location are difficult to implement from a cost perspective.  The PNNL researchers believe that turning CO2 into methanol can provide the financial incentive for widespread implementation.   Methanol can be used as a fuel, a solvent, or an important ingredient in plastics, paint, construction materials, and car parts.

The system is designed to be installed in fossil fuel-fired power plants as well as cement and steel plants.  Using a capture solvent developed by PNNL, the system grabs carbon dioxide molecules before they are emitted and converts them into methanol. Creating methanol from CO2 is nothing new, but capturing the carbon dioxide and converting into methanol in one continuously flowing system is new.

More work is needed to optimize and scale the process and it may be several years before it is ready for commercial deployment.

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Scientists Unveil Least Costly Carbon Capture System to Date

Photo, posted November 25, 2022, courtesy of Massachusetts Department of Environmental Conservation via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Turning Carbon Into Stone | Earth Wise

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A start-up company in Oman called 44.01 was recently awarded a $1.2 million Earthshot Prize by Prince William of the U.K.  The company, whose name corresponds to the molecular weight of carbon dioxide, is working on speeding up natural chemical reactions that take carbon from the air and lock it into solid mineral form.

The company’s location in Oman is no random occurrence.  The mountains of northern Oman and along the coast of the United Arab Emirates are the site of a huge block of oceanic crust and upper mantle that was thrust upward some 96 million years ago.  The tilted mass of rock is over 200 miles long and is the largest surface exposure of the Earth’s mantle in the world.

This type of rock, called peridotite, is rich in olivine and pyroxene, which react with water and carbon dioxide to form calcium-based minerals like serpentine and calcite that permanently lock in carbon. Other kinds of rock also are capable of carbon-storing mineralization, but this mantle rock is the most effective for the purpose. It only exists at the Earth’s surface in a few places, including Papua New Guinea and some spots in California and Oregon.

The 44.1 company is planning to use solar-powered direct air capture devices to remove CO2 from the air, use it to produce carbonated water, and inject the water into the reactive rocks.  The company will operate a couple of pilot systems during 2023.  Ultimately, the company believes it can scale up the process to be able to permanently sequester as much as a billion tons of CO2 a year by the year 2040 without needing to inject the gas into deep caverns or find other places to store it.

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With Major Prize, a Project to Turn Carbon Emissions to Stone Gains Momentum

Photo, posted August 10, 2018, courtesy of JM McBeth via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Hybrid Renewable Energy Plants | Earth Wise

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Hybrid renewable energy systems combine multiple renewable energy and/or energy storage technologies into a single plant.  The goal is to reduce costs and increase energy output relative to separate systems taking advantage of common infrastructure and the ability of one renewable energy source having appreciable output while a second one might not at a particular time.

Recently, the largest hybrid renewable power plant in the United States was completed in rural Oregon.  The Wheatridge Renewable Energy Facility combines a wind farm, a solar array, and battery storage.

Plants that include just solar power and energy storage are also called hybrid plants, but the Wheatridge Facility is special because it includes wind power.  The facility comprises a 200-megawatt wind farm, a 50-megawatt solar array, and a 30-megawatt battery system capable of providing power for four hours.  The combined system can provide for the electricity needs of about 100,000 homes.

There are about 140 projects in the United States that combine solar and storage.  There are 14 that combine solar and wind.  There are only four plants – with the completion of Wheatridge – that have wind, solar, and storage.  

Wind and solar energy are generally complementary technologies.  Wind is usually strongest at night while solar, of course, is a daytime source of energy.  Solar and wind plants don’t need to be close together to take advantage of this, but hybrid projects benefit from needing only one grid connection and one lease for land.

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A Clean Energy Trifecta: Wind, Solar and Storage in the Same Project

Photo, posted December 27, 2015, courtesy of Gerry Machen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

California Climate Legislation | Earth Wise

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At the end of its summer session, California’s state legislature passed five climate-related bills including ones that it had been unable to pass in previous sessions.  Taking all of these actions puts California in the position of blazing a trail for the country and the rest of world in taking aggressive action on climate issues.

One bill confirmed California’s goal of reaching net-zero emissions by 2045.  Another bill added interim-term targets to go along with the state’s goal of 100% renewable electricity by 2045.  It sets a target of 90% by 2030 and 95% by 2040.  That bill mandates that California state agencies use 100% clean energy by 2035, which is a decade earlier than the previous requirement.

A third bill requires the California Air Resources Board to determine steps and regulations for carbon-capture and storage projects at pollution hotspots like oil refineries.

A fourth bill requires the state to set goals for removing carbon dioxide from the atmosphere through natural means such as tree planting.

The California state budget includes a record-breaking $54 billion to be spent on climate programs over the next five years, including $6.1 billion toward electric vehicles, $14.8 billion towards public transit projects, more than $8 billion for electric grid stabilization, $2.7 billion towards preventing wildfires, and $2.8 billion towards managing drought.

California has been dealing with ongoing drought and numerous wildfires and is highly motivated to take decisive action in dealing with the climate crisis.  California’s environmental initiatives often result in comparable actions taken by other states.

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California Passes Massive Climate Legislation Package

Photo, posted March 16, 2019, courtesy of Raymond Shobe via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Carbon Storage In Harvested Wood | Earth Wise

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Trees are an exceedingly important carbon sink on our planet.  For this reason, deforestation is a major contributor to climate change.  But when trees are harvested for wood products like lumber, much of the carbon in that wood continues to be stored.  Even when a wood product is discarded at the end of its useful life, it can keep storing carbon.

Over 90% of new single-family homes in the U.S. are built with wood.  Each year, about 400,000 homes, apartment buildings, and other housing units are lost to floods and other natural disasters.  Others fall apart from decay or are torn down to be replaced with newer structures.  Given how much carbon is stored in houses, it is important to understand what the future trajectory of residential structures will be.

A new study by the USDA Forest Service published in the journal PLOS ONE looks at the future of harvested wood products in residential structures.  According to the study, wood products in these structures will continue to increase the country’s carbon storage for the next 50 years. 

Even after residential structures reach the end of their useful life and much of the materials end up in landfills (which is typical in this country), the wood products do not immediately release their carbon.  It may take decades for that to happen.

The study looked at various scenarios for future home construction.  Although housing starts are projected to decline in the future, residential housing and the need to maintain existing structures are projected to continue to increase carbon storage in wood products for the next several decades.

The role of trees as a carbon sink does not end when they are harvested for their wood.

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Carbon Storage in Harvested Wood Products

Photo, posted January 27, 2022, courtesy of Luke McKernan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A Cheap Material For Carbon Capture | Earth Wise

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The recently passed Inflation Reduction Act includes significant support for carbon capture technologies. Eliminating fossil fuel burning is essential for halting climate change, but in the interim, methods for capturing emissions of carbon dioxide and either storing it or turning it into usable products are increasingly necessary.

There are a variety of techniques being developed for carbon capture but at this point, none of them are commercially viable.  The best technique in use today involves piping flue gases through chemicals called liquid amines, which bind CO2.  The process requires large amounts of energy to release the bound carbon dioxide so it can be concentrated and stored.  As a result, it is complicated and expensive.

Researchers at UC Berkeley, Stanford, and Texas A&M University have developed a carbon capture method using melamine, which is an inexpensive polymer used to make Formica, as well as low-cost dinnerware, industrial coatings, and other plastics.  Porous melamine itself adsorbs CO2 to a limited extent.  But the researchers discovered that adsorption could be much improved by adding the chemical DETA (diethylenetriamine) to bind the CO2.  In addition, adding cyanuric acid increased the melamine pore size and radically improved CO2 capture efficiency even more.

The result is a material that is more efficient even than exotic carbon capture materials like metalorganic frameworks and is much cheaper and easier to make. The researchers aim to design equipment that can used in industrial facilities, attached to buildings and other structures, or even to the tailpipes of gas-powered vehicles.

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A simple, cheap material for carbon capture, perhaps from tailpipes

Photo, posted June 10, 2006, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Lithium-Sulfur Batteries | Earth Wise

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The growing use of electric vehicles as well as energy storage systems has created a major focus on the batteries for these applications.  Lithium-ion batteries dominate these applications and the demand for the materials needed to manufacture them continues to grow.

The raw materials for these batteries include not only lithium, but also can include nickel, manganese, and cobalt. 

Sulfur has been a desirable alternative for use in lithium-based batteries for quite a while because it is an abundant element and can be extracted in ways that are safe and environmentally friendly.  However, previous attempts to create lithium batteries that combine sulfur cathodes and the standard carbonate electrolytes used in lithium-ion batteries have not been successful because of irreversible chemical reactions between intermediate sulfur products and the electrolytes.

A group of chemical engineers at Drexel University has now found a way to introduce sulfur into lithium-ion batteries that solves the stability problem and also has major performance advantages.  The new batteries have three times the capacity of conventional lithium-ion batteries, and last more than 4,000 recharges, which is also a substantial improvement.

The new battery technology involves creating a stable form of sulfur called monoclinic gamma sulfur by depositing the sulfur on carbon nanofibers.   Previously, this sulfur phase was only observed at high temperatures and was only stable for 20 or 30 minutes.  This chemical phase of sulfur does not react with carbonate electrolytes and therefore produces a battery that is chemically stable over time.

 Incorporating this sulfur into battery cathodes results in a better battery that doesn’t need any cobalt, nickel, or manganese.  It could be the next big thing in electric vehicle batteries.

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Breakthrough in Cathode Chemistry Clears Path for Lithium-Sulfur Batteries’ Commercial Viability

Photo, posted April 5, 2022, courtesy of Oregon Department of Transportation via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Carbon Capture: Solution Or Band-Aid? | Earth Wise

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The idea of capturing the CO2 emissions from industry and locking them up is nothing new.  It’s been going on for decades in some places.  Norway’s state-owned oil company Equinor has been holing away a million tons of CO2 a year for a long time.  But overall, CCS – carbon capture and storage – has had very limited use.  As of last year, there were only about 30 large-scale projects in operation around the world, capturing only 0.1% of global emissions.

There is now growing interest in CCS and many new projects are underway.  A combination of rising carbon prices in Europe, tax breaks for CCS in the US, national net-zero targets, and the increasing need to ramp down global emissions are all driving rising CCS activities. 

While recent reports from the Intergovernmental Panel on Climate change still claim that it is possible to remain below 2 degrees Celsius of warming without using carbon capture, there is growing belief that it may be necessary given the present pace of the transition away from fossil fuels.

Two industries that together produce about 14% of global CO2 emissions are cement and steel.  These are both industries for which it is difficult to eliminate emissions regardless of the energy sources used. CCS may be the best approach to reducing their emissions.

But there is considerable pushback against CCS.  The concern is that CCS is primarily a way to delay decarbonization.  It encourages various industries to continue to use fossil fuels instead of shifting away from them.  Nonetheless, CCS no doubt has its place as part of the solution to climate change.

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Solution or Band-Aid? Carbon Capture Projects Are Moving Ahead

Photo, posted June 5, 2022, courtesy of Mark Dixon via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Storing Sunshine To Make Electricity On Demand | Earth Wise

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Researchers at Chalmers University in Sweden have developed an entirely new way of capturing and storing energy from sunlight.  The system is called the Molecular Thermal Energy Storage System or MOST.  It is based on a specially designed molecule that changes shape when it is exposed to sunshine.

The molecule is composed of carbon, hydrogen, and nitrogen.  When sunlight hits it, it changes into an energy-rich isomer – a molecule made up of the same atoms but arranged together in a different way.  That isomer is stable and can be stored for many years.  When a specially designed catalyst is applied, the stored energy is released in the form of heat and the molecule returns to its original form and can be reused. 

The Chalmers researchers sent some of the energy-laden isomer to researchers in China who used it to operate a micron-thin thermoelectric generator, which used the heat released by the isomer material to generate electricity.  The generator is an ultra-thin chip that could be integrated into electronics such as headphones, smart watches, and telephones.  It is currently only at the proof-of-concept stage, but the results are quite promising.  The integration with the MOST technology provides a way that solar energy can generate electricity regardless of weather, time of day, season, or geographical location.  The results of the study were recently published in the journal Cell Reports Physical Science.

In effect, for this demonstration, Swedish sunshine was sent to the other side of the world and converted into electricity in China. The ultimate goal of this research is to create self-charging electronics that uses stored solar energy on demand.

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Converting solar energy to electricity on demand

Photo, posted March 11, 2013, courtesy of Steve Slater via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Record Renewable Use In California | Earth Wise

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California, the most populous state, is the second largest electricity user.  Only Texas, the second most populous state, uses more energy, in part because it consumes large amounts in refining fossil fuels. Overall, California uses about 8% of the electricity generated in the U.S.

Thus, it was a significant milestone when briefly, on April 3, a record 97.6% of the energy on California’s statewide grid came from renewable energy resources.  (The previous record of 96.4% was set just a few days earlier).

Renewable energy’s share of the power typically peaks in the spring when mild temperatures keep demand relatively low and higher sun angles drive greater solar energy production.

On April 8, a record peak solar power production was set at 13,628 megawatts just after noon.  On March 4, the state set an all-time wind generation record of 6,265 megawatts. 

California now has over 15,000 MW of grid-connected solar power and 8,000 MW of wind.  Another 600 MW of solar and 200 MW of wind are coming online by June.  The state also has about 2,700 MW of energy storage online and that will climb to 4,000 MW by June.

In 2020, 34.5% of the state’s retail electricity sales came from wind and solar sources.  Adding in hydropower and nuclear power, nearly 60% of the state’s electricity came from non-fossil fuel.  Despite the effects of drought on hydropower generation and the impact of the pandemic on the pace of renewable energy projects, California continues its dramatic transition to sustainable energy.

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Solar and wind notched records as renewables met California’s energy demand

Photo, posted September 20, 2016, courtesy of Tom Brewster Photography / BLM via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Safely Storing Carbon | Earth Wise

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As carbon dioxide levels continue to increase in the atmosphere and emissions reductions aren’t happening as fast as needed, there is growing interest in carbon capture and storage technologies.

The idea is to capture the CO2 emitted from industrial processes or from the burning of fossil fuels in power generation, and then permanently store it out of harm’s way.  There are several different types of sites where the CO2 might be stored.  Deep saline aquifers are particularly desirable for the purpose, but depleted hydrocarbon reservoirs are commonplace and relatively simple to use.  These are oil and gas wells that have been drained of their resources.

In many cases, CO2 has already been injected into these depleted wells as a means of enhanced oil recovery.  Therefore, such wells provide a unique opportunity to study what happens to carbon dioxide when it’s stored in these places.

Researchers from Oxford University recently published a paper in the journal Nature that compared the state of depleted wells with injected carbon dioxide to that of wells without the injected gas.  They found that nearly 3/4 of the CO2 was dissolved in the groundwater.  Unexpectedly, they also found that 13-19% of the carbon dioxide was converted into methane by methanogenic bacteria.  Methane is less soluble, less compressible, and less reactive than carbon dioxide.

Producing methane in these wells is therefore undesirable.  Deeper sites that have temperatures too high for the bacteria to thrive are much more suitable.  This research is important for identifying future carbon capture and storage sites and for designing long-term monitoring programs that are essential for low-risk, long-term carbon storage.

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Safer carbon capture and storage

Photo, posted November 6, 2015, courtesy of CL Baker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Avoiding Blackouts With Renewable Energy | Earth Wise

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There are some people who worry that an electric grid heavily dependent upon intermittent sources like solar and wind power may be more susceptible to blackouts.  According to a new study by Stanford University, these fears are misplaced.

The study, published in the journal Renewable Energy, found that an energy system running on wind, water, and solar, when combined with energy storage, avoids blackouts, and lowers energy requirements and consumer costs.  In addition, implementing such a system would create millions of jobs, improve people’s health, and reduce land requirements.

The study focused on the stability in all U.S. grid regions as well as individual states based on the requirement that all electricity is provided by clean and renewable sources. No fossil fuel use, bioenergy, blue hydrogen, or even nuclear power were included in the modeling.  Critics of such a shift in the energy system point to grid blackouts during extreme weather events in California in 2020 and Texas in 2021 as evidence that renewable sources can’t be trusted.  But in both cases, renewable energy was not found to be any more vulnerable than other sources.

The study looked at the costs of the transition – which would be substantial – but found that it would pay for itself fairly quickly based on energy cost savings alone.

A significant finding of the study was that long-duration batteries were neither necessary nor helpful for grid stability.  That stability could be obtained by linking together currently available short-duration batteries.  Interconnecting larger and larger geographic regions would make the power system smoother and more reliable.  Overall, intelligent management of the electric grid can result in a reliable and clean power system.

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Stanford researchers point the way to avoiding blackouts with clean, renewable energy

Photo, posted October 17, 2016, courtesy of B Sarangi via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Liquid Fuels From Carbon Dioxide | Earth Wise

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Most of the world’s energy demands are still being met by burning fossil fuels, thereby releasing carbon dioxide into the atmosphere.  The energy system is in the midst of a transition to renewable sources such as solar and wind power, but it will be quite some time before fossil fuels are only a minor part of energy production.  To reduce global warming, it will be necessary to prevent the carbon dioxide from fossil fuels from entering the atmosphere by capturing it and either locking it away or making use of it.

Recent research at several Chinese universities has developed a novel electrocatalyst that efficiently converts CO2 to liquid fuels containing multiple carbon atoms.  The main products of the high-efficiency reaction are ethanol, acetone, and n-butanol.  Previous electrocatalystic methods have mostly produced simpler hydrocarbons – namely, ones with only a single carbon atom.  The fuels the new catalyst produces are much more useful.

The catalyst is made from thin ribbons of a copper/titanium alloy that are etched with hydrofluoric acid to remove the titanium from the surface.  The process results in a material with a porous copper surface on an amorphous CuTi alloy.  The substance exhibits remarkably high activity, selectivity, and stability for catalyzing the reactions leading to the production of the hydrocarbon fuels.

Converting carbon dioxide into liquid fuels would be advantageous because they have high energy density and are safe to store and transport.  Apart from preventing carbon dioxide from entering the atmosphere, the process could also be a way to make use of excess energy produced by solar and wind generation by essentially storing that energy in the form of liquid fuels.

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Liquid Fuels from Carbon Dioxide

Photo courtesy of Angewandte Chemie via Wiley-VCH.

Earth Wise is a production of WAMC Northeast Public Radio.

Reducing Emissions From Cement Manufacturing | Earth Wise

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Cement is the basic ingredient of concrete, which is the most widely used construction material in the world.  About 8% of global carbon dioxide emissions are associated with cement production.

More than half of these emissions come from making clinker, which is a major component of cement produced by heating ground limestone and clay to a temperature of over 2500 degrees Fahrenheit.  Some of the emissions come from burning fossil fuels to heat the materials, but much of them come from the chemical reaction that creates the clinker.

The Portland Cement Association, which represents 92% of US cement manufacturing capacity, has recently released its “Roadmap to Carbon Neutrality”, which lays out a plan to reach carbon net zero across the cement and concrete value chain by 2050.

The plan includes the greater use of alternative fuels to reduce emissions from energy use.  It also involves the adoption of newer versions of cement such as Portland limestone cement, which reduces CO2 levels.  The industry has already reduced emissions by some shifting to Portland limestone cement, but it still only represents a small fraction of cement production.

The most significant strategy would be the adoption of carbon capture, utilization, and storage (or CCUS) technologies.  The idea is to capture the CO2 generated in the production of clinker and inject it into the fresh concrete.  It would actually be permanently sequestered in the concrete and would not be released even if a structure is demolished in the future.

It will take a combination of technologies and initiatives for the cement industry to reduce its emissions.  Fortunately, the industry appears to be committed to that goal.

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US cement manufacturers release their road map to carbon neutrality by 2050

Photo, posted March 26, 2014, courtesy of Michael Coghlan via Flickr.

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