Although everyone knows that coal-based energy is a thing of the past, declarations about nuclear power plants somehow do not want to enter into force.
No other power-generating device raises as much concern as the nuclear reactor. Because of this, until recently the future of the entire energy sector has been determined by its past.
On the eve of the pandemic, the European energy sector found itself at a crossroads, somewhere between Great Britain, Germany and Poland. Five years ago, across the English Channel, the then Prime Minister David Cameron announced an ambitious program to build 12 new nuclear power plants with a total capacity of 16 GW. While developing renewable energy resources, they would allow the United Kingdom to reduce carbon dioxide emissions from the energy sector to almost zero. Soon after, Cameron came up with the idea of a referendum on leaving the EU – and Brexit reset all long-term British plans. However, the British are already producing electricity in a very sustainable way. Almost 38% comes from renewable sources, about 20% from nuclear power plants, while the remainder is provided by gas-powered plants, the only ones that emit CO2.
Meanwhile in Germany, the aversion towards nuclear energy has been growing for years. Finally, following the Fukushima disaster in March 2011, chancellor Angela Merkel announced that all nuclear power plants would be shut down by 2022. For the first few years, the great Energiewende (energy transformation) plan seemed to be going well. Thanks to subsidies and increased electricity prices for individual customers, the intensive development of wind farms and solar power plants continued. However, no technological solution has been found to overcome the main weakness of renewable energy sources: plants running on renewable sources work on average for 20-30% of the day and remain completely dependent on whether the wind blows or the sun shines. Because of this, they are not able to handle energy peaks. In turn, when a gale comes, suddenly there is a network overload due to excess power. In both these extreme cases, the entire country is at risk of blackout, and the risk of collapsing energy supplies increases significantly when more than 30% is obtained from renewable sources. Safety requires the maintenance of traditional power plants, which due to their flexibility, stabilize the entire system.
In Germany, as subsequent nuclear reactors began to shut down, lignite-fired power plants started to play a key role. Unlike nuclear plants, they devastate the natural environment not only due to CO2 emissions, but also the need to expand opencast mines. A huge wave of criticism from environmentalists and Berlin's goal to lead by example in the fight against global warming have brought an adjustment in strategy. Today, coal-fired power plants are being replaced by gas-fired ones that emit one-third less carbon dioxide. Russia will provide fuel for them via the Nord Stream and Nord Stream 2 gas pipelines. However, withdrawal from the decommissioning of nuclear power plants is now out of the question.
In turn, the development of renewable energy in Poland is suffering, despite the construction of one or more nuclear power plants having been announced two decades ago. Before the pandemic, the government envoy for strategic energy infrastructure Piotr Naimski claimed that by the end of 2045 as many as six nuclear reactors with a total capacity of 6 GW would be built. Although everyone knows that coal-based energy is a thing of the past, declarations about nuclear power plants somehow do not want to enter into force. And this is a very complicated undertaking, during which any disregard of security standards can awaken demons from the past.
A pile of trouble
"In fifteen years, nuclear power will provide electricity too cheap to measure its consumption," the head of the American Atomic Energy Commission, Lewis Strauss, prophesied in 1954. By the end of that decade, energy corporations had overcome technological barriers. "Westinghouse has perfected the PWR reactor, the water-pressure reactor, and GE [General Electric] the BWR reactor, boiling water reactor," explains Daniel Yergin in the The Quest: In Search of Energy. These two types of first generation reactors have spread throughout the world. By 1970, 15 nuclear power plants had launched in 62 countries and the construction of a further 89 had begun. Most of them were located in the US, USSR, UK, France, Japan and West Germany. Three years later, the first oil crisis erupted and it seemed certain that highly developed countries would base their future on nuclear power plants. However, the first problems began to emerge.
The first generation, 1000 MW water-pressure reactor generated as much as 20 tons of radioactive waste annually. Initially, the Americans placed it into metal containers and buried it in the ocean. The Soviets did the same. Protests by environmental organizations led to containers with a guarantee of durability of a thousand years starting to be buried in the Nevada desert – ignoring the fact that the half-life of plutonium-239 is about 24,400 years. In other countries, old mines were used as waste dumps. The French coped with this problem exemplarily by building a plant at La Hague specializing in the recovery of radioactive uranium and plutonium from waste. Later, these elements are enriched and sold to energy companies. During the 1980s, many countries – including Japan, West Germany, Belgium and Switzerland – began to use the services of the French.
In addition to waste, investment costs have become an equally large problem. "Emerging ecological movements, especially anti-nuclear ones, forced additional reviews and changes. It was necessary to thicken the concrete walls, and remove pipeline installations and rework them. Power plants had to be redesigned, even several times during construction," emphasizes Yergin. He writes: "Power plants also became more expensive because of inflation and later, the high interest rates on loans. Instead of six years, construction took ten; it also cost money. The power plants, which were to cost $200million, ultimately cost $2billion." Later, they produced the cheapest electricity on the market, but gigantic expenses had to be included in its price. While the French model handles waste well, investment costs remain the Achilles' heel of nuclear energy to this day, even if they are less important than the media and public fear.
Awaiting the apocalypse
"There is nothing in the laws of nature that stops us from building better nuclear power plants. We are stopped by a deep justified public distrust. The public distrusts the experts because they claimed to be infallible," writes Freeman Dyson, a physicist who participated in the construction of the first reactors, in the book Imagined Worlds. The distrust of nuclear energy emerged gradually. In the 1960s, everyone remembered the fate of Hiroshima and Nagasaki, but the fear of radioactive radiation had not yet paralysed ordinary people. Experts managed to convince Western societies that the nuclear power plant hardly differed from the coal-fired power plant. All it needs is access to a lot more coolant for the reactor, preferably a huge water tank.
The sense of security began to fade not because of a failure, but catastrophic scenarios loved by the press, especially in West Germany. In October 1975, Der Spiegel very vividly presented to readers what would happen if the reactor at a power plant built near Ludwigshafen overheated. "The molten reactor core will penetrate the surrounding protective structures. It will sink into the ground at a speed of two to four meters per hour. The amount of radiation emitted would correspond to the radiation of a thousand bombs such as the one dropped on Hiroshima," the newspaper forecasted, estimating the number of victims at 100,000 killed immediately and about 1.6 million "dying slowly" due to radiation sickness. Such apocalyptic visions interested Hollywood, resulting in the neo-thriller entitled The China Syndrome. In specialist jargon, this name means the severe meltdown of the core components of the reactor.
Lo and behold, two weeks after the film's release, on 28th March 1979, there was a failure at the Three Mile Island nuclear power plant located on an artificial island. Pipes supplying coolant to the reactor burst when the back-up cooling system was disconnected for inspection. The reactor had warmed up, but the safety measures worked. Each reactor is managed using control rods. They are made of alloys that absorb neutrons. Sliding the control rods in between the fuel rods slows down the chain reaction. Pulling them out has the opposite effect. When the reactor overheats, all control rods fall into the core, quenching the reaction.
This happened at Three Mile Island. However, due to the pipes bursting, water poured out onto the reactor jacket and immediately evaporated, forming a mixture of oxygen and hydrogen under the dome of the power block. One spark could have blown up the power plant. The following day, technicians pumped off hazardous, radioactive gases outside. The residents of nearby Harrisburg panicked. About 80,000 people attempted to escape the city in cars. The US energy minister James Schlesinger's assurances that the radiation only increased by around 0.03 rem and would not hurt anyone fell on deaf ears. Those who have seen The China Syndrome knew better. It wasn't until five days later, when President Jimmy Carter personally visited Three Mile Island and in the presence of TV cameras toured the area, that the panic was subjugated. However, the misfortunes of nuclear power plants were only just beginning.
The weakest link
The owners of the plant, the Westinghouse group, largely caused the Three Mile Island disaster. The power plant was built in a rush to make it operational before 30th December 1978, in order for the company to gain a $40 million tax break. After launching the reactor, it turned out that the coolant supply pipes were leaking. At that point, the management ordered temporary sealing of leaks, after which the test of the emergency cooling system was performed, starting with its shutdown. This was done on the assumption that the main pipes would still last a little longer. "The accident was caused by a series of relatively small equipment failures followed by operator error," the head of the commission investigating the causes of the disaster, Admiral Hyman G. Rickover, wrote in his report. Fortunately, none of the Westinghouse executives were so thoughtless as to deactivate the other safeguards. Seven years later, it turned out that even such recklessness is possible.
On the night of 26th April 1986, the management of the Chernobyl power plant began to experiment with manual control of the reactor in block 4. For complete freedom, all automatic security systems were turned off. During the experiments, the stack heated up rapidly, and the control rods blocked by the staff did not automatically quench the chain reaction. Then the pipes supplying water to the cooling system burst. As in Three Mile Island, the water evaporated by the hot reactor turned into hydrogen and oxygen. The explosion of this mixture tore the dome and threw a 500-ton piece of concrete into the air, which a moment later fell into the reactor, breaking it completely. 50 tons of fuel escaped outside and the core melted. Vast areas of northern Ukraine and Belarus became contaminated due to the radioactive cloud. 50,000 residents of the nearby town of Pripyat and surrounding villages were evacuated.
As a result of the disaster, 31 people lost their lives (mainly irradiated firefighters). UNSCEAR (UN Scientific Committee on Effects of Atomic Radiation) found that there were many more casualties: a 2000 report found that of about 600 employees of the power plant and firefighters, 237 were diagnosed with radiation sickness symptoms. Of these, 28 people died. According to the report, epidemiologists have not observed an increase in the incidence of cancer in the most contaminated areas, except for higher than average rates of thyroid cancer. No genetic defects were found in the offspring of irradiated persons.
A quarter of a century later, the 'Chinese syndrome' became Japanese. Two oil crises in the 1970s encouraged the government of Japan to finance the construction of 50 nuclear reactors. They guaranteed energy security for the state. However, haste made them forget about their side effects in a country where earthquakes happen regularly. The Fukushima reactor was built right on the seafront. When massive shocks (9 on the Richter scale) came on 11th March 2011, the security systems functioned properly. The reactors were automatically quenched and the cooling system switched to the emergency power supply. Nothing bad would have happened if it weren't for the sea. Tectonic shocks caused a tsunami wave of 15-metre heights, and the breakwater was only six-metres high. Huge amounts of water flooded the power plant. The power generators went down and the reactor core suddenly stopped being cooled. Then the water evaporated and the hydroxide mixture exploded.
About 10 times less radioactive substance escaped outside than in Chernobyl, and no-one was killed during the event. The first person irradiated as a result of the disaster's aftermath did not die until September 2018. Yet again, however, a wave of fear swept through the entire world.
The sum of fears
The disaster in Fukushima was a strong blow to the nuclear energy sector – which even without it, suffered bad press – and led to public trepidation, even though by the mid-1980s the number of reactors operating worldwide had reached 430 and stopped growing. New ones were still being built in France, Japan, the USSR (later, Russia), South Korea and China, but elsewhere they were gradually dismantled. The only country that had based their entire energy system on nuclear power plants was France, where they produce over 80% of electricity. Finland is also focusing on the development of nuclear energy. Two nuclear power plants currently generate around 30% of the country's energy, and once the third one is built, this will reach 60% (the rest is to come from renewable sources).
Most countries, however, still recognize the nuclear industry as a dead end. The emergence of much better third generation reactors that use less uranium, while reducing the amount of waste, did not change that. Developed by two companies – the French Framatome and the German Siemens – the EPR (European Pressurized Reactor) has a quadruple safety system and reinforcement that can withstand even the impact of an aircraft crash. In turn, the ESBWR (Economic Simplified Boiling Water Reactor) by GE Hitachi, apart from showing similar resistance, requires minimal amounts of coolant and discharges excess heat directly into the atmosphere.
There are more innovative constructions, but they have started to generate interest only recently, thanks to the rapid development of Asian countries, and thus an increase in demand for cheap electricity. A nuclear power plant uses roughly 30-50 tons of uranium per year. At a market price of around $55 per kilogram, a cost of fuel of around $2.5 million a year is very cheap – 100 times cheaper than the cost of fuel for a coal-fired power plant fuel. It is estimated that known uranium deposits will last for about 300 years. At the same time, as with crude oil, this deadline may prove to be much more distant, since no new ones have been sought for years. Therefore, it should not come as a surprise that in April 2019 China presented a plan for the vast expansion of its nuclear energy sector. While today the total capacity of Chinese nuclear power plants is about 42 GW, it will exceed 100 GW in 100 years. Then, the People's Republic of China will overtake the US in this field. South Korea has presented slightly less ambitious goals, announcing an increase in nuclear power by one-third.
And what path will the European Union take? The fight against CO2 emissions determines the direction of its energy policy, and renewable energy sources are a priority. However, to fully base their economy on them, efficient energy storage is necessary – methods capable of accumulating electricity at times of overproduction and releasing it in the absence of sun and wind. Even lithium-ion cells cannot fully cope with this task. Attempts are being made at avoiding the lack of this element by designing self-sufficient buildings that draw energy from solar batteries and heat pumps. However, in the scale of cities and entire countries, large power plants cannot be replaced, and the only ones that do not emit carbon dioxide are nuclear power plants. This fact means that even in Europe, their slow renaissance continues. For now, countries on the outskirts of the EU (Finland, Hungary, Lithuania, the Czech Republic and Slovakia) are modernizing old plants or building new ones. In just one year, the construction of over 60 new reactors began.
Despite public resentment, more investments will begin soon. Right now, fear of the 'China syndrome' is weaker than fear of the effects of global warming and sudden energy shortages and blackouts.
Translated from the Polish by Joanna FigielReprinted with permission of Przekrój. Read the original article.
Utilizing nuclear waste converted to diamonds, this company's batteries will reportedly last thousands of years in some cases.
- Nuclear reactor parts converted to radioactive carbon-14 diamonds produce energy.
- To keep them safe, the carbon-14 diamonds are encased in a second protective diamond layer.
- The company predicts batteries for personal devices could last about nine years.
We have an insatiable need for energy. When we need to operate something that cannot be simply plugged in, power is going to have to come from a battery, and the battle for a better battery is being fought in labs all over the world. Hold that thought for a moment.
Nuclear waste — it's the radioactive detritus from nuclear power plants that no one wants stored near their homes or even transported through their towns. The nasty stuff is toxic, dangerous, it takes thousands of years to fully degrade, and we keep making more of it.
Now a company from California, NDB, believes it can solve both of these problems. They say they've developed a self-powered battery made from nuclear waste that can last 28,000 years, perfect for your future electric vehicle or iPhone 1.6 x 104. Producing its own charge—rather than storing energy created elsewhere—the battery is made from two types of nano-diamonds, rendering it essentially crash-proof if used in cars or other moving objects. The company also says its battery is safe, emitting less radiation than the human body.
NDB has already completed a proof of concept and plans to build its first commercial prototype once its labs have resumed operations post-COVID.
NDB's battery as it might look as a circuit-board component
Image source: NDB
The nuclear waste from which NDB plans to make it batteries are reactor parts that have become radioactive due to exposure to nuclear-plant fuel rods. While not considered high-grade nuclear waste—that would be spent fuel—it's still very toxic, and there's a lot of it in a nuclear generator. According to the International Atomic Energy Agency, the "core of a typical graphite moderated reactor may contain 2000 tonnes of graphite." (A tonne is one metric ton, or about 2,205 lbs.)
The graphite contains the carbon-14 radioisotope, the same radioisotope used by archaeologists for carbon dating. It has a half-life of 5,730 years, eventually transmuting into nitrogen 14, an anti-neutrino, and a beta decay electron, whose charge piqued NDB's interest as a potential means of producing electricity.
NDB purifies the graphite and then turns it into tiny diamonds. Building on existing technology, the company says they've designed their little carbon-14 diamonds to produce a significant amount of power. The diamonds also act as a semiconductor for collecting energy, and as a heat sink that disperses it. They're still radioactive, though, so NDB encases the tiny nuclear power plants within other inexpensive, non-radioactive carbon-12 diamonds. These glittery lab-made shells serve as, well, diamond-hard protection at the same time as they contain the carbon-14 diamonds' radiation.
NDA plans to build batteries in a range of standard—AA, AAA, 18650, and 2170—and custom sizes containing several stacked diamond layers together with a small circuit board and a supercapacitor for collecting, storing, and discharging energy. The end result is a battery, the company says, that will last a very long time.
NDB predicts that if a battery is used in a low-power context, say, as a satellite sensor, it could last 28,000 years. As a vehicle battery, they anticipate a useful life of 90 years, much longer than any single vehicle will last—the company anticipates that one battery could conceivably provide power for one set of wheels after another. For consumer electronics such as phones and tablets, the company expects about nine years of use for a battery.
The company's prospective investor video explains their process in greater detail.
Maybe a very big deal
"Think of it in an iPhone," NDB's Neel Naicker tells New Atlas. "With the same size battery, it would charge your battery from zero to full, five times an hour. Imagine that. Imagine a world where you wouldn't have to charge your battery at all for the day. Now imagine for the week, for the month… How about for decades? That's what we're able to do with this technology."
NDB anticipates having a low-power commercial version on the market in a couple of years, followed by a high-powered version in about five. If all goes as planned, NDB's technology could constitute a major step forward, providing low-cost, long-term energy to the world's electronics and vehicles. The company says, "We can start at the nanoscale and go up to power satellites, locomotives."
The company also expects their batteries to be competitively priced compared to current batteries, including lithium ion, and maybe even cheaper once they're being produced at scale—owners of nuclear waste may even pay the company to take their toxic problem off their hands.
One company's waste becomes another's diamonds.
By leveraging the difference between lit and shadowed areas, a new energy source perfect for wearables is invented.
- Mobile devices used both indoors and out may benefit from a new energy collection system that thrives on mixed and changing lighting conditions.
- Inexpensive new collection cells are said to be twice as efficient as commercial solar cells.
- The system's "shadow effect" would also maker it useful as a sensor for tracking traffic.
For all of its promise, solar energy depends on the capture of light, and the more the better. For residents of sunny climes, that's great, with rooftop collection panels, and solar farms built by utilities in wide open, sunny spaces that can provide power to the rest of us. Now, though, a team of scientists at the National University of Singapore (NUS) has announced success at deriving energy from…shadows.
We've got plenty of them everywhere. "Shadows are omnipresent, and we often take them for granted," says research team leader Tan Swee Ching, who notes how shadows are usually anathema for energy collection. "In conventional photovoltaic or optoelectronic applications where a steady source of light is used to power devices, the presence of shadows is undesirable, since it degrades the performance of devices." His team has come up with something quite different, and Tan claims of their shadow-effect energy generator (SEG) that, "This novel concept of harvesting energy in the presence of shadows is unprecedented."
The research is published in the journal Energy & Environmental Science.
How it works
Image source: Royal Society of Chemistry/NUS
The energy produced by the SEG is generated from the differential between shadowed and lit areas. "In this work," says Tan. "We capitalized on the illumination contrast caused by shadows as an indirect source of power. The contrast in illumination induces a voltage difference between the shadow and illuminated sections, resulting in an electric current."
SEG cells are less expensive to produce than solar cells. Each SEG cell is a thin film of gold on a silicon wafer, and an entire system is a set of four of these cells arrayed on a flexible, transparent plastic film. Experiments suggest the system, in use, is twice as efficient as commercial solar cells.
An SEG cell's shadow effect works best when it is half in light and half in shadow, "as this gives enough area for charge generation and collection respectively," says co-team leader Andrew Wee. When the SEG is entirely in shadow or in light, it doesn't produce a charge.
Gold in them that shadows
To be sure, the amount of energy that NUS researchers have thus far extracted is small, but it's enough to power a digital watch. The researchers envision the SEG system harvesting ambient light to power smart phones and AR glasses that are used both outdoors and indoors. While such devices can run on solar batteries, solar is only replenished outdoors, and the SEG could "scavenge energy from both illumination and shadows associated with low light intensities to maximize the efficiency of energy harvesting," says Tan. It seems clear that we're on the cusp of the era of wearables — AR visionwear, smart fabrics, smart watches, and so on — and so Tan considers the arrival of the SEG "exciting and timely."
The researchers also note an additional application for which the SEG seems a natural: It can function as a self-powered sensor for monitoring moving objects. The shadow caused by a passing object would trigger the SEG sensor, which can then record the event.
Next up for the team is investigating constructing cells using other, less costly materials than gold to make them even less expensive to produce.
Sweden tops the ranking for the third year in a row.
What does COVID-19 mean for the energy transition? While lockdowns have caused a temporary fall in CO2 emissions, the pandemic risks derailing recent progress in addressing the world's energy challenges.
The current state of the sector is described in the World Economic Forum's Energy Transition Index 2020. It benchmarks the energy systems of 115 economies, highlighting the leading players in the race to net-zero emissions, as well as those with work to do.
With pressure to get idle economies back to “normal", the short-term shift to a more sustainable energy sector could be in doubt. But the current crisis also presents an opportunity to rethink how our energy needs are met, and consider the long-term impact on the planet.
The past decade has seen rapid transformations as countries move towards clean energy generation, supply and consumption. Coal-fired power plants have been retired, as reliance on natural gas and emissions-free renewable energy sources increases. Incremental gains have been made from carbon pricing initiatives.
Since 2015, 94 of 115 countries have improved their combined score on the Energy Translation Index (ETI), which analyzes each country's readiness to adopt clean energy using three criteria: energy access and security; environmental sustainability; and economic development and growth.
But the degree of change and the timetable for reaching net-zero emissions differ greatly between countries, and taken as a whole, today's advances are insufficient to meet the climate targets set by the Paris Agreement.
WEF Fostering Effective Energy Transition 2020 edition
The 10 countries most prepared for the energy transition
Sweden tops the overall ETI ranking for the third consecutive year as the country most ready to transition to clean energy, followed by Switzerland and Finland. There has been little change in the top 10 since the last report, which demonstrates the energy stability of these developed nations, although the gap with the lowest-ranked countries is closing.
Top-ranked countries share a reduced reliance on imported energy, lower energy subsidies and a strong political commitment to transforming their energy sector to meet climate targets.
The UK and France are the only two G20 economies in the top 10 however, which is otherwise made up of smaller nations.
Powerful shocks Outside the top 10, progress has been modest in Germany. Ranked 20th, the country has committed to phasing out coal-fired power plants and moving industrial output to cleaner fuels such as hydrogen, but making energy services affordable remains a struggle.
Kevin Frayer/Getty Images
China currently has the world's largest solar PV capacity
China, ranked 78th, has made strong advances in controlling CO2 emissions by switching to electric vehicles and investing heavily in solar and wind energy - it currently has the world's largest solar PV and onshore wind capacity. Alongside China, countries including Argentina, India and Italy have shown consistent strong improvements every year. Gains over time have also been recorded by Bangladesh, Bulgaria, Kenya and Oman, among others.
But high energy-consuming countries including the US, Canada and Brazil show little, if any, progress towards an energy transition.
In the US (ranked 32nd), moves to establish a more sustainable energy sector have been hampered by policy decisions. Neighbouring Canada grapples with the conflicting demands of a growing economy and the need to decarbonize the energy sector.
The COVID-19 pandemic serves as a reminder of the impact of external shocks on the global economy. As climate change increases the likelihood of weather extremes such as floods, droughts and violent storms, the need for more sustainable energy practices is intensified.
Policy-makers need to develop a robust framework for energy transition at local, national and international levels, capable of guarding against such shocks.
"The coronavirus pandemic offers an opportunity to consider unorthodox intervention in the energy markets, and global collaboration to support a recovery that accelerates the energy transition once the acute crisis subsides," says Roberto Bocca, Head of Energy & Materials at the World Economic Forum.
"This giant reset grants us the option to launch aggressive, forward-thinking and long-term strategies leading to a diversified, secure and reliable energy system that will ultimately support the future growth of the world economy in a sustainable and equitable way."
Ever smell a durian fruit? Don't. Think of it as nature's stinky battery.
- New research finds that jackfruit and durian, often called the world's smelliest fruit, make outstanding supercapacitors.
- Supercapacitors are useful because they can be used as infinitely rechargeable batteries.
- The study, published in the Journal of Energy Storage, also demonstrates the development of carbon aerogels for the bodies of the fruit batteries.
It's said to be delicious, but you probably haven't encountered any durian fruit-scented candles. That's because it smells, as the late gourmand Anthony Bourdain put it, "indescribable, something you will either love or despise…Your breath will smell as if you'd been French-kissing your dead grandmother."
Eye-watering odor aside, Vincent G. Gomes of the University of Sydney and his colleagues have discovered that durian fruit has an amazing and potentially useful property: It's a natural supercapacitor. In a paper published in the Journal of Energy Storage, Gomes explains that supercapacitors are "promising for energy storage due to their superior cycling stability and excellent charge–discharge ability." Unfortunately, they also often suffer from low capacitance and stability. Stinky durian fruit and its cousin, jackfruit, don't have those issues.
We need a better battery
Image source: PandaMath/Shutterstock
Researchers have been trying to move away from existing lithium-ion batteries that contain chemicals whose interactions produce electricity. When those chemicals are depleted, what's left is a little bundle of toxic waste.
A capacitor, on the other hand, stores energy by building up a static electricity charge on the surfaces of two metal plates. (You might think of how static electricity builds up on your hair when you rub a balloon against your head, for a sense of how this works.) However, capacitors can't hold a lot of energy, nor can they hold it for long. Still, they are infinitely rechargeable, unlike lithium-ion solutions.
Supercapacitors begin to address some of these problems. They typically contain metal plates which have more surface-area and are coated with a second layer of activated charcoal or a similar material. This makes them better at soaking up and holding a charge. Still, supercapacitors are expensive to produce and have their own stability issues.
So now imagine one made of durian fruit or jackfruit. Gomes' paper describes the potential:
"The structural precision of natural biomass with their hierarchical pores, developed over millions of years of biological evolution, affords an outstanding resource as a template for the synthesis of carbon-based materials. Their integrated properties of high surface area, in-plane conductivity and interfacial active sites can facilitate electrochemical reactions, ionic diffusion and high charge carrier density."
Jacking into durian fruit
The bodies of the fruit batteries are made of aerogels: durian carbon aerogel (DCA) and jackfruit carbon aerogel (JCA). The process of deriving them seems complicated, but hey, science is hard.
First, the researchers scrubbed small bio samples from the spongy core of each fruit. Next, the samples were rinsed with ionized water several times to clean them. Placed in autoclaves, they were steamed hydrothermally for 10 hours at 180° C. After cooling off, they were rinsed again and then freeze-dried in a -80° C vacuum over the course of 24 hours. Following that, they were heated to 800° C and held at that temperature for an hour. Overnight ambient cooling yielding black, highly porous, ultralight aerogels. Easy-peasy.
For electrodes, each DCA and JCA battery was fitted with two electrodes, and two different electrode arrays were tested.
The first array, designed to allow an electrochemical measurement of the batteries' performance, incorporated a pair of glass substrates, each coated with an ink comprised of either DCA or JCA powder, respectively, and mixed with carbon black, polyvinylidene fluoride, or a PVDF binder.
The second electrode array used a pair of glass substrates coated with indium tin oxide, with a prepared PP (Celgard) separator between them. This architecture allowed appraisal of the battery's gravimetric capacitance.
The authors' conclusions
The paper concludes that "both electrodes are attractive candidates for the next generation, high performance, yet low-cost supercapacitors for energy storage devices derived from biowastes." In both the DCA and JCA variants, "the electrodes…displayed long-term cycling stability, and rapid charge–discharge processes. " It turns out that the durian fruit battery has a bit more power-storage capacity than its jackfruit cousin. The paper makes no mention of the final olfactory personality of the batteries.
In addition to offering proof of the potential for using durian fruit and jackfruit for energy storage, the authors point out that for the first time, they've demonstrated the development of carbon aerogels "via a facile, chemical-free, green synthesis procedure."