Green Energy

In 2007, 22-year-old P. Ramesh’s groundnut farm was losing money. As was the norm in most of India (and still is), Ramesh was using a cocktail of pesticides and fertilizers across his 2.4 hectares in the Anantapur district of southern India. In this desert-like area, which gets less than 600 millimeters of rainfall most years, farming is a challenge.

“I lost a lot of money growing groundnuts through chemical farming methods,” says Ramesh, who goes by the first letter of his father’s name followed by his first name, as is common in many parts of southern India. The chemicals were expensive and his yields low.

Then in 2017, he dropped the chemicals. “Ever since I took up regenerative agricultural practices like agroforestry and natural farming, both my yield and income have increased,” he says.

Agroforestry involves planting woody perennials (trees, shrubs, palms, bamboos, etc.) alongside agricultural crops (SN: 7/3/21 & 7/17/21, p. 30). One natural farming method calls for replacing all chemical fertilizers and pesticides with organic matter such as cow dung, cow urine and jaggery, a type of solid dark sugar made from sugarcane, to boost soil nutrient levels. Ramesh also expanded his crops, originally groundnuts and some tomatoes, by adding papaya, millets, okra, eggplant (called brinjal locally) and other crops.

With help from the nonprofit Accion Fraterna Ecology Centre in Anantapur, which works with farmers who want to try sustainable farming, Ramesh increased his profits enough to buy more land, expanding his parcel to about four hectares. Like the thousands of other farmers practicing regenerative farming across India, Ramesh has managed to nourish his depleted soil, while his new trees help keep carbon out of the atmosphere, thus playing a small but important role in reducing India’s carbon footprint. Recent studies have shown that the carbon sequestration potential of agroforestry is as much as 34 percent higher than standard forms of agriculture.

In western India, more than 1,000 kilometers from Anantapur, in Dhundi village in Gujarat, 36-year-old Pravinbhai Parmar is using his rice farm for climate change mitigation. By installing solar panels, he no longer uses diesel to power his groundwater pumps. And he has an incentive to pump only the water he needs because he can sell the electricity he doesn’t use.

If all farmers like Parmar shifted to solar, India’s carbon emissions, which are 2.88 billion metric tons per year, could drop by between 45 million and 62 million tons annually, according to a 2020 report in Carbon Management. So far, the country has about 250,000 solar irrigation pumps out of an estimated 20 million to 25 million total groundwater pumps.

For a nation that has to provide for what will soon be the world’s largest population, growing food while trying to bring down already high greenhouse gas emissions from agricultural practices is difficult. Today, agriculture and livestock account for 14 percent of India’s gross national greenhouse gas emissions. Adding in the electricity used by the agriculture sector brings this figure up to 22 percent.

Ramesh and Parmar are part of a small but growing group of farmers getting assistance from government and nongovernmental programs to change how they farm. There’s still a ways to go to reach the estimated 146 million others who cultivate 160 million hectares of arable land in India. But these farmers’ success stories are testimony that one of India’s largest emitting sectors can change.

Feeding the soil, sustaining farmers

India’s farmers are already deeply feeling the effects of climate change, coping with dry spells, erratic rainfall and increasingly frequent heat waves and tropical cyclones. “When we talk about climate-smart agriculture, we are largely talking about how it has reduced emissions,” says Indu Murthy, sector head for climate, environment and sustainability at the Center for Study of Science, Technology and Policy, a think tank in Bengaluru. But such a system should also help farmers “cope with unexpected changes and weather patterns,” she says.

This, in many ways, is the philosophy driving a variety of sustainable and regenerative agricultural practices under the agroecology umbrella. Natural farming and agroforestry are two components of this system that are finding more and more takers across India’s varied landscapes, says Y.V. Malla Reddy, director of Accion Fraterna Ecology Centre.

“For me, the important change is the change in attitude of people towards trees and vegetation in the last few decades,” Reddy says. “In the ’70s and ’80s, people were not really conscious of the value of the trees, but now they consider trees, especially fruit and utilitarian trees, as also a source of income.” Reddy has advocated for sustainable farming in India for close to 50 years. Certain types of trees, such as pongamia, subabul and avisa, have economic benefits apart from their fruits; they provide fodder for livestock and biomass for fuel.

Reddy’s organization has provided assistance to more than 60,000 Indian farming families to practice natural farming and agroforestry on almost 165,000 hectares. Calculation of the soil carbon sequestration potential of their work is ongoing. But a 2020 report by India’s Ministry of Environment, Forest and Climate Change notes that these farming practices can help India reach its goal of having 33 percent forest and tree cover to meet its carbon sequestration commitments under the Paris climate agreement by 2030.

Regenerative agriculture is a relatively inexpensive way to reduce carbon dioxide in the atmosphere, as compared with other solutions. Regenerative farming costs $10 to $100 per ton of carbon dioxide removed from the atmosphere, compared with $100 to $1,000 per ton of carbon dioxide for technologies that mechanically remove carbon from the air, according to a 2020 analysis in Nature Sustainability. Such farming not only makes sense for the environment, but chances are the farmers’ earnings will also increase as they shift to regenerative agriculture, Reddy says.

Growing solar

Establishing agroecology practices to see an effect on carbon sequestration can take years or decades. But using renewable energy in farming can quickly reduce emissions. For this reason, the nonprofit International Water Management Institute, IWMI, launched the program Solar Power as Remunerative Crop in Dhundi village in 2016.

“The biggest threat climate change presents, specifically to farmers, is the uncertainty that it brings,” says Shilp Verma, an IWMI researcher of water, energy and food policies based in Anand. “Any agricultural practice that will help farmers cope with uncertainty will improve resilience to climate change.” Farmers have more funds to deal with insecure conditions when they can pump groundwater in a climate-friendly way that also provides incentives for keeping some water in the ground. “If you pump less, then you can sell the surplus energy to the grid,” he says. Solar power becomes an income source.

Growing rice, especially lowland rice, which is grown on flooded land, requires a lot of water. On average it takes about 1,432 liters of water to produce one kilogram of rice, according to the International Rice Research Institute. The organization says that irrigated rice receives an estimated 34 to 43 percent of the world’s total irrigation water. India is the largest extractor of groundwater in the world, accounting for 25 percent of global extraction. When diesel pumps do the extracting, carbon is emitted into the atmosphere. Parmar and his fellow farmers used to have to buy that fuel to keep their pumps going.

Scientists from Nanyang Technological University, Singapore (NTU Singapore) have found a way to create biocement from waste, making the alternative to regular cement even greener and more sustainable.

Biocement is a renewable form of cement that typically uses bacteria to form a hardening reaction that binds soil into a solid block.

The NTU scientists have now managed to use two common waste materials, industrial carbide sludge and urea—from the urine of mammals—to create biocement.

They developed a process in which the reaction of urea with calcium ions in industrial carbide sludge forms a hard solid, or precipitate. When this reaction takes place in soil, the precipitate bonds soil particles together and fills the gaps between them, creating a compact mass of soil. This results in a strong, sturdy and less permeable block of biocement.

The research team, led by Professor Chu Jian, Chair of the School of Civil and Environmental Engineering, showed in a proof-of-concept research paper published in February 2022 in the Journal of Environmental Chemical Engineering that their biocement could potentially become a sustainable and cost-effective method for soil improvement, such as strengthening the ground for use in construction or excavation, controlling beach erosion, reducing dust or wind erosion in the desert, or building freshwater reservoirs on beaches or in the desert.

It can also be used as biogrout to seal cracks in rock for seepage control and even to touch up and repair monuments like rock carvings and statues.

“Biocement is a sustainable and renewable alternative to traditional cement and has great potential to be used for construction projects that require the ground to be treated,” said Prof Chu, who is also the Director of NTU’s Center for Urban Solutions. “Our research makes biocement even more sustainable by using two types of waste material as its raw materials. In the long run, it will not only make it cheaper to manufacture biocement, but also reduce the cost involved for waste disposal.”

The NTU scientists’ research supports the NTU 2025 strategic plan which aims to address some of humanity’s grand challenges, including in mitigating human impact on the environment through advancing research and development in sustainability.

Urine, bacteria, and calcium: A simple recipe for biocement

The biocement-making process requires less energy and generates fewer carbon emissions compared to traditional cement production methods.

The NTU team’s biocement is created from two types of waste material: industrial carbide sludge—the waste material from the production of acetylene gas, sourced from Singapore factories—and urea found in urine.

Firstly, the team treats carbide sludge with an acid to produce soluble calcium. Urea is then added to the soluble calcium to form a cementation solution. The team then adds a bacterial culture to this cementation solution. The bacteria from the culture then break down the urea in the solution to form carbonate ions.

These ions react with the soluble calcium ions in a process called microbially induced calcite precipitation (MICP). This reaction forms calcium carbonate—a hard, solid material that is naturally found in chalk, limestone and marble.

When this reaction occurs in soil or sand, the resulting calcium carbonate generated bonds soil or sand particles together to increase their strength and fills the pores between them to reduce water seepage through the material. The same process can also be used on rock joints, which allows for the repair of rock carvings and statues.

The soil reinforced with biocement has an unconfined compression strength of up to 1.7 megapascals (MPa), which is higher than that of the same soil treated using an equivalent amount of cement.

This makes the team’s biocement suitable for use in soil improvement projects such as strengthening the ground or reducing water seepage for use in construction or excavation or controlling beach erosion along coastlines.

Paper first author Dr. Yang Yang, a former NTU Ph.D. student and research associate at the Center for Urban Solutions who is currently a postdoctorate fellow at Chongqing University, China, said: “The calcium carbonate precipitation at various cementation levels strengthens the soil or sand by gradually filling out the pores among the particles. The biocement could also be used to seal cracks in soil or rock to reduce water seepage.”

A sustainable alternative to cement

Biocement production is greener and more sustainable than the methods used to produce traditional cement.

“One part of the cement-making process is the burning of raw materials at very high temperatures over 1,000 degrees Celsius to form clinkers—the binding agent for cement. This process produces a lot of carbon dioxide,” said Prof Chu. “However, our biocement is produced at room temperature without burning anything, and thus it is a greener, less energy demanding, and carbon-neutral process.”

Dr. Yang Yang said: “In Singapore, carbide sludge is seen as waste material. However, it is a good raw material for the production of biocement. By extracting calcium from carbide sludge, we make the production more sustainable as we do not need to use materials like limestone which has to be mined from a mountain.”

Prof Chu added: “Limestone is a finite resource—once it’s gone, it’s gone. The mining of limestone affects our natural environment and ecosystem too.”

The research team says that if biocement production could be scaled to the levels of traditional cement-making, the overall cost of its production compared to that of conventional cement would be lower, which would make biocement both a greener and cheaper alternative to cement.

Restoring monuments and strengthening shorelines

Another advantage of the NTU team’s method in formulating biocement is that both the bacterial culture and cementation solution are colorless. When applied to soil, sand or rock, their original color is preserved.

This makes it useful for restoring old rock monuments and artifacts. For example, Dr. Yang Yang has used the biocement to repair old Buddha monuments in China. The biocement can be used to seal gaps in cracked monuments and has been used to restore broken-off pieces, such as the fingers of a Buddha’s hands. As the solution is colorless, the monuments retain their original color, keeping the restoration work true to history.

In collaboration with relevant national agencies in Singapore, the team is currently trialing their new biocement at East Coast Park, where it is being used to strengthen the sand on the beach. By spraying the biocement solutions on top of the sand, a hard crust is formed, preventing sand from being washed out to sea.

The team is also exploring further large-scale applications of their biocement in Singapore, such as road repair by sealing cracks on roads, sealing gaps in underground tunnels to prevent water seepage, or even as cultivation grounds for coral reefs as carol larvae like to grow on calcium carbonate.

The paper, “Utilization of carbide sludge and urine for sustainable biocement production,” is published in the Journal of Environmental Chemical Engineering.

Transportation is the single biggest source of greenhouse gas emissions in the United States, accounting for about a third of all emissions. We could quickly lower those emissions by electrifying vehicles, but there’s just one hitch: we don’t currently generate enough power.

“If all transportation goes electric, we are effectively doubling demand,” said Matthias Preindl, an EV expert at Columbia Engineering. “And the grid isn’t built to withstand that.”

Despite some investment and expansion since the 1950s, the U.S. grid has a mostly aging fleet of generators, and maxed out transmission loads due to congested lines. Making matters worse, extreme weather events like heatwaves and wildfires have repeatedly melted power cables.

The U.S. would have to invest $125 billion by 2030 just to keep up with EVs’ growing demands for power, according to a 2020 study. But what if the EVs themselves could be part of the solution, adding power to the grid? Columbia News spoke with Preindl, a professor of electrical engineering, and Daniel Bienstock, a professor of applied physics and applied mathematics, as well as industrial engineering and operations research.

Vehicle-to-grid (V2G) technology

By 2030, some 145 million electric cars, buses, trucks, and vans will be on the road. Sort of. On average, drivers park their vehicles 95% of the time. With close to $5 billion in federal money recently allocated to build a nationwide network of EV charging stations along interstate highways, all those idle EVs could be put to work via vehicle-to-grid (V2G) technology—an idea experts say could transform the already overwhelmed electrical grid.

V2G technology involves using bidirectional chargers to carry unused power from an EV’s batteries into the smart grid. As an EV gets charged, the grid’s AC (alternating current) electricity is converted to the batteries’ DC (direct current)—which is then used to run the vehicle. A bidirectional charger can convert DC to AC and transfer it to the grid from the EV’s lithium-ion cells. It can also simultaneously control how much power enters or leaves the battery.

“Potentially, EVs could become the largest, distributed energy storage facility deployed,” Preindl said. “Together, they could supply more electric power than all conventional power plants combined.”

The extra electricity that V2G technology feeds back to the grid could power homes and businesses in states like California that heavily rely on renewables for 24-7 access to electricity. Often, green energy efforts have primarily focused on using large wind or solar farms located in remote areas. These farms require new and expensive transmission lines to provide electricity to areas with high-energy demands.

And wind and solar energy can experience large real-time variability, said Bienstock, who is also an expert on power-grid dynamics at Columbia Engineering.

“Today, without large renewable penetration, variability is addressed in real-time using conventional generation,” he said. “Large, real-time swings in power flows can be challenging and require proper set up of rapid generation and adequate transmission resources.” Upgrading equipment to that extent is no small feat, which means that variability due to renewables will continue to be a concern. “V2G, coupled with more fully distributed generation, is one of the most viable solutions moving forward,” said Bienstock.

Cars that have V2G

So far, only four commercially available electric cars are V2G compatible—Nissan e-NV200, Nissan LEAF, Mitsubishi Outlander PHEV, and Mitsubishi Eclipse Cross PHEV. This year, Volkswagen, Ford, and General Motors are also gradually launching EVs compatible with bidirectional charging. Industry experts project that the V2G market will grow by 48% by 2027.

But building bidirectional power into the system is more than a numbers game; technical hurdles also stand in the way of widespread V2G adoption. For instance, routinely using V2G for recharging and discharging EVs’ lithium-ion batteries can reduce their lifespan.

Does V2G reduce battery life

“From a grid perspective, it’s most useful when many EVs are connected over long periods and when they use low to medium charging powers,” said Preindl. “That’s actually better for the EV as well. From a technical standpoint, there are a lot of things V2G can do to minimize battery degradation.”

Other than the risk of lithium-ion batteries getting damaged, conventional designs of bidirectional or V2G chargers are also expensive. There are two types of V2G chargers: onboard and offboard. Most cars use unidirectional onboard chargers. The few V2G chargers to hit the market have only come online in the past few months; these early designs are typically offboard, mounted to a wall and also lack standardization, while the industry catches up to the technology.

But researchers are getting better at designing cost-effective V2G on-board chargers. Preindl’s lab is developing systems that can achieve 99% efficiency for as little as one cent per kilowatt. “That’s two to five times cheaper, with two to five times lower energy losses, than current designs,” he said.

The possibility of V2G

While car companies are attempting to scale V2G technology, there is still a long way to go before it can help in decarbonizing the grid. Last month, around 15 utilities in 14 states announced that they will launch pilot electric school bus V2G programs, according to the World Resources Institute.

But despite utility companies’ small initiatives in 2021 that proved how effective V2G technology is in reducing emissions, policy experts say more investments are required to make the technology accessible.

“The utilities need to not only upgrade the electrical grid in terms of new transmission lines and physical transformers but also invest in smart grid technology to assess at what times electricity needs to be discharged or absorbed,” said Steven Cohen, an expert in environmental science and policy at Columbia’s School of International and Public Affairs. “The policy hurdle V2G technology is facing is basically a lack of money.”

“The key requirement would be a financing scheme in which the federal government could fund the initial outlay,” he continued. “Then, local ratepayers pay for the operation and maintenance once the technology is in place. My prediction: New York State and California will be first to invest.”

Researchers have used a widespread species of blue-green algae to power a microprocessor continuously for a year—and counting—using nothing but ambient light and water. Their system has potential as a reliable and renewable way to power small devices.

The system, comparable in size to an AA battery, contains a type of non-toxic algae called Synechocystis that naturally harvests energy from the sun through photosynthesis. The tiny electrical current this generates then interacts with an aluminum electrode and is used to power a microprocessor.

The system is made of common, inexpensive and largely recyclable materials. This means it could easily be replicated hundreds of thousands of times to power large numbers of small devices as part of the Internet of Things. The researchers say it is likely to be most useful in off-grid situations or remote locations, where small amounts of power can be very beneficial.

“The growing Internet of Things needs an increasing amount of power, and we think this will have to come from systems that can generate energy, rather than simply store it like batteries,” said Professor Christopher Howe in the University of Cambridge’s Department of Biochemistry, joint senior author of the paper.

He added: “Our photosynthetic device doesn’t run down the way a battery does because it’s continually using light as the energy source.”

In the experiment, the device was used to power an Arm Cortex M0+, which is a microprocessor used widely in Internet of Things devices. It operated in a domestic environment and semi-outdoor conditions under natural light and associated temperature fluctuations, and after six months of continuous power production the results were submitted for publication.

The study is published today in the journal Energy & Environmental Science.

“We were impressed by how consistently the system worked over a long period of time—we thought it might stop after a few weeks but it just kept going,” said Dr. Paolo Bombelli in the University of Cambridge’s Department of Biochemistry, first author of the paper.

The algae does not need feeding, because it creates its own food as it photosynthesises. And despite the fact that photosynthesis requires light, the device can even continue producing power during periods of darkness. The researchers think this is because the algae processes some of its food when there’s no light, and this continues to generate an electrical current.

The Internet of Things is a vast and growing network of electronic devices—each using only a small amount of power—that collect and share real-time data via the internet. Using low-cost computer chips and wireless networks, many billions of devices are part of this network—from smartwatches to temperature sensors in power stations. This figure is expected to grow to one trillion devices by 2035, requiring a vast number of portable energy sources.

The researchers say that powering trillions of Internet of Things devices using lithium-ion batteries would be impractical: it would need three times more lithium than is produced across the world annually. And traditional photovoltaic devices are made using hazardous materials that have adverse environmental effects.

The work was a collaboration between the University of Cambridge and Arm, a company leading the design of microprocessors. Arm Research developed the ultra-efficient Arm Cortex M0+ testchip, built the board, and set up the data-collection cloud interface presented in the experiments.

As the world’s need for large amounts of portable energy grows at an ever-increasing pace, many innovators have sought to replace current battery technology with something better.

Italian physicist Alessandro Volta tapped into fundamental electrochemical principles when he invented the first battery in 1800. Essentially, the physical joining of two different materials, usually metals, generates a chemical reaction that results in the flow of electrons from one material to the other. That stream of electrons represents portable energy that can be harnessed to generate power.

The first materials people employed to make batteries were copper and zinc. Today’s best batteries—those that produce the highest electrical output in the smallest possible size—pair the metal lithium with one of several different metallic compounds. There have been steady improvements over the centuries, but modern batteries rely on the same strategy as that of Volta: pair together materials that can generate an electrochemical reaction and snatch the electrons that are produced.

But as I describe in my book “Spark: The Life of Electricity and the Electricity of Life,” even before humanmade batteries started generating electric current, electric fishes, such as the saltwater torpedo fish (Torpedo torpedo) of the Mediterranean and especially the various freshwater electric eel species of South America (order Gymnotiformes) were well known to produce electrical outputs of stunning proportions. In fact, electric fishes inspired Volta to conduct the original research that ultimately led to his battery, and today’s battery scientists still look to these electrifying animals for ideas.

Copying the eel’s electric organ

Prior to Volta’s battery, the only way for people to generate electricity was to rub various materials together, typically silk on glass, and to capture the resulting static electricity. This was neither an easy nor practical way to generate useful electrical power.

Volta knew electric fishes had an internal organ specifically devoted to generating electricity. He reasoned that if he could mimic its workings, he might be able to find a novel way to generate electricity.

The electric organ of a fish is composed of long stacks of cells that look very much like a roll of coins. So Volta cut out coinlike disks from sheets of various materials and started stacking them, in different sequences, to see if he could find any combination that would produce electricity. These stacking experiments kept yielding negative results until he tried pairing copper disks with zinc ones, while separating the stacked pairs with paper disks wetted with saltwater.

This sequence of copper-zinc-paper fortuitously produced electricity, and the electrical output was proportionate to the height of the stack. Volta thought he had uncovered the secret of how eels generate their electricity and that he had actually produced an artificial version of the electric organ of fish, so he initially called his discovery an “artificial electric organ.” But it was not.

What really makes eels electrifying

Scientists now know the electrochemical reactions between dissimilar materials that Volta discovered have nothing to do with the way an electric eel generates its electricity. Rather, the eel uses an approach similar to the way our nerve cells generate their electrical signals, but on a much grander scale.

Specialized cells within the eel’s electric organ pump ions across a semipermeable membrane barrier to produce an electrical charge difference between the inside versus the outside of the membrane. When microscopic gates in the membrane open, the rapid flow of ions from one side of the membrane to the other generates an electrical current. The eel is able to simultaneously open all of its membrane gates at will to generate a huge jolt of electricity, which it unleashes in a targeted fashion upon its prey.

Electric eels don’t shock their prey to death; they just electrically stun it before attacking. An eel can generate hundreds of volts of electricity (American household outlets are 110 volts), but the eel’s voltage does not push enough current (amperage), for a long enough time, to kill. Each electric pulse from an eel lasts only a couple thousandths of a second and delivers less than 1 amp. That’s just 5% of household amperage.

This is similar to how electric fences work, delivering very short pulses of high-voltage electricity, but with very low amperage. They thus shock but do not kill bears or other animal intruders that try to get through them. It is also similar to a modern Taser electroshock weapon, which works by quickly delivering an extremely high-voltage pulse (about 50,000 volts) carrying very low amperage (just a few milliamps).

Modern attempts to mimic the eel

Like Volta, some modern electrical scientists searching to transform battery technology find their inspiration in electric eels.

A team of scientists from the United States and Switzerland is currently working on a new type of battery inspired by eels. They envision that their soft and flexible battery might someday be useful for internally powering medical implants and soft robots. But the team admits they have a long way to go. “The electric organs in eels are incredibly sophisticated; they’re far better at generating power than we are,” lamented Michael Mayer, a team member from the University of Fribourg. So, the eel research continues.

In 2019, the Nobel Prize in Chemistry was awarded to the three scientists who developed the lithium-ion battery. In conferring the award, the Royal Swedish Academy of Sciences asserted that the awardees’ work had “laid the foundation of a wireless, fossil fuel-free society.”

The “wireless” part is definitely true, since lithium-ion batteries now power virtually all handheld wireless devices. We’ll have to wait and see about the “fossil fuel-free society” claim, because today’s lithium-ion batteries are recharged with electricity often generated by burning fossil fuels. No mention was made of the contributions of electric eels.

Later that same year, though, scientists from the Smithsonian Institution announced their discovery of a new South American species of electric eel; this one is notably the strongest known bioelectricity generator on Earth. Researchers recorded the electrical discharge of a single eel at 860 volts, well above that of the previous record-holding eel species, Electrophorus electricus, that clocked in at 650 volts, and 200-fold higher that the top voltage of a single lithium-ion battery (4.2 volts).

Just as we humans try to congratulate ourselves on the greatness of our latest portable energy source, the electric eels continue to humble us with theirs.