from the world's big
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.
WEF Fostering Effective Energy Transition 2020 edition<h3>The 10 countries most prepared for the energy transition</h3><p>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.</p><p>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.</p><p>The UK and France are the only two G20 economies in the top 10 however, which is otherwise made up of smaller nations.</p><p>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.</p>
Kevin Frayer/Getty Images<h3>China currently has the world's largest solar PV capacity</h3><p>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.</p><p>But high energy-consuming countries including the US, Canada and Brazil show little, if any, progress towards an energy transition.</p><p>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.</p><p>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.</p><p>Policy-makers need to develop a robust framework for energy transition at local, national and international levels, capable of guarding against such shocks.</p><p>"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.</p><p>"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."</p><p>Reprinted with permission of the <a href="https://www.weforum.org/" target="_blank">World Economic Forum</a>. Read the <a href="https://www.weforum.org/agenda/2020/05/energy-transition-index-2020-eti-clean-sustainable-power/" target="_blank">original article</a>.</p>
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.
We need a better battery<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjg2MTg0NC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYwMzA3MDMxM30.4K7F5A_Yo1Snm_EBYRSogm7iFhR-rF5TtBaE61q8Zik/img.jpg?width=980" id="a23c1" class="rm-shortcode" data-rm-shortcode-id="048195b51dcd498c33fcfe0867d50b04" data-rm-shortcode-name="rebelmouse-image" alt="box of batteries" />
Image source: PandaMath/Shutterstock<p>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.</p><p>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.</p><p>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.</p><p>So now imagine one made of durian fruit or jackfruit. Gomes' paper describes the potential:</p><p style="margin-left: 20px;"><em>"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."</em></p>
Jacking into durian fruit<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjg2MTkyOS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMDA1MjY1Mn0.XxkYjKWgCHdI6Kgc1ph7Gjz_XY0-3ueUcAk18tovhlc/img.jpg?width=980" id="6ea6d" class="rm-shortcode" data-rm-shortcode-id="b0ea222a429932e9d97cdab63487d436" data-rm-shortcode-name="rebelmouse-image" alt="Jackfruit and durian" />
The authors' conclusions<p>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.</p><p>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."</p>
A new device shows promising results in its ability to convert CO2 and water into useful fuels.
- Artificial photosynthesis devices have long been touted as a way to remove carbon dioxide from the atmosphere and turn it into useful products.
- New research describes a highly efficient and cheap device that could be used to turn waste carbon dioxide into methane.
- Natural gas, which mainly consists of methane, is a cleaner fuel than coal and has been characterized as a "bridge fuel" prior to transitioning to renewable energy sources, but not everyone thinks it's a good idea to burn yet more hydrocarbons.
Scalable and efficient<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjUwODYwMC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNzIwODcyOX0.LIOKon7G5sy9JaH2Q0-BVE2UI3W4bTRN_dJT_6qFNtc/img.jpg?width=980" id="86e85" class="rm-shortcode" data-rm-shortcode-id="3a3779c79178e0079e5be1d14e3d1d88" data-rm-shortcode-name="rebelmouse-image" alt="Artificial photosynthesis" />
An electron microscope image shows the semiconductor nanowires. These deliver electrons to metal nanoparticles, which turn carbon dioxide and water into methane.
Baowen Zhou<p>The new method, described in <em><a href="https://www.pnas.org/content/early/2020/01/02/1911159117" target="_blank">Proceedings of the National Academy of Sciences</a></em>, uses solar power to produce methane, which can be used as natural gas.</p><p>In the context of climate change, many environmentalists are probably groaning over the idea that the production and burning of yet more greenhouse gases should be portrayed as a good thing, but it's important to remember the practical benefits of devices such as this. Attached to the smokestacks of power plants, this artificial photosynthesis device can capture CO2 that would otherwise pollute the atmosphere and transform it into a far more efficient fuel that remains carbon neutral — so-called "green" methane. </p><p> Since our current infrastructure already supports the use of hydrocarbons for fuel, implementing tools such as these is an important first step to transitioning towards a more advanced but as-of-yet incomplete renewable energy infrastructure.</p><p>"Thirty percent of the energy in the U.S. comes from natural gas," said co-author Zetian Mi in a <a href="https://phys.org/news/2020-01-green-methane-artificial-photosynthesis-recycle.html" target="_blank">statement</a>. "If we can generate green methane, it's a big deal."</p><p>Most importantly, the device makes use of low-cost and easily manufactured components, meaning that it will be scalable. The fatal flaw of many magic bullet climate change solutions is that they are expensive or difficult to make and implement, preventing them from being used at the scale necessary to combat climate change.</p><p>The device itself can be characterized as a solar panel studded with nanoparticles of iron and copper. The copper and iron nanoparticles hang onto molecules of CO2 and H2O by their carbon and hydrogen atoms. Using the sun's energy or an electrical current, the bonds between atoms in the CO2 and H2O are broken down, enabling the water's hydrogen atoms to connect to the carbon dioxide's carbon atom. The end result is one carbon atom bonded with four hydrogen atoms — methane. What's more, the new device does this work far more efficiently than other artificial photosynthesis systems.</p><p>"Previous artificial photosynthesis devices often operate at a small fraction of the maximum current density of a silicon device, whereas here we operate at 80 or 90 percent of the theoretical maximum using industry-ready materials and earth abundant catalysts," said Baowen Zhou, a postdoctoral researcher on this project.</p><p>Methane is merely one of the more useful products this device can produce; it can also be configured to produce syngas — a fuel consisting of hydrogen, carbon monoxide, and some carbon dioxide — or formic acid, which is used as a preservative in livestock feed.</p>
A bridge too far?<p>The use of natural gas is on the rise in the U.S., but not everybody sees this as a positive. It's a cleaner fuel than coal, for instance, or diesel. It's been characterized as a bridge fuel that economies can lean on while waiting for the renewable energy sector to mature. Then again, its advantages make it awfully attractive, so much so that <a href="https://www.climaterealityproject.org/blog/natural-gas-not-bridge-fuel-got-many-alternatives" target="_blank">critics claim</a> we may pay too much attention to it when we ought to be pivoting to renewable energy in a more focused fashion. </p><p>Nearly everyone (except for certain politicians and industry leaders) are on the same page regarding the ultimate fate of the world's energy sources — renewable energy like solar and wind power are going to be the main way we generate power in the future. In the meantime, however, the next-best thing is to implement CO2-scrubbing technology like the artificial photosynthesis device described in this article. Burning natural gas that we've sucked out of the Earth will certainly trash the atmosphere, but converting existing emissions into carbon-neutral fuels is far more practical, regardless of whether natural gas should be considered a bridge fuel or a barrier.</p>
You've likely heard of solar energy, but what is osmotic energy?
- Osmotic power plants harvest energy from the difference in pressure or salinity between salt and freshwater using a semi-permeable membrane.
- One of the major challenges for this kind of renewable energy, however, has been developing effective and durable membranes.
- Now, new research demonstrates a durable and effective membrane that could significantly improve osmotic energy collection.
What exactly is osmotic energy?<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjI1MDU0NS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0Nzg1NTY0Nn0.haCsWHBjZYMF56WC2KLZ81eMzBVB7znv5M-qkdzatrs/img.jpg?width=980" id="36a21" class="rm-shortcode" data-rm-shortcode-id="ca6296f8cec0b65bab3c7fd449d43f78" data-rm-shortcode-name="rebelmouse-image" alt="Tofte Osmotic Power Plant" />
An image taken inside of the world's first osmotic power plant at Tofte, Norway, 2009. The project has since been shelved due to its high operating costs, highlighting the need for better, more efficient technology.
POPPE, CORNELIUS/AFP via Getty Images<p>Osmotic energy takes advantage of the differences in pressure and salinity between fresh and seawater to generate electricity. Its only waste product is brackish water, which is simply water that is saltier than freshwater but less so than seawater. While it doesn't generate large amounts of energy compared to other renewable energy sources, it is remarkably consistent. The energy derived from wind turbines and solar panels fluctuates tremendously with the weather, time, and local climate, but osmotic energy works more or less the same year-round wherever fresh and saltwater meet.</p><p>Osmosis, in general, is the process by which liquid moves from a dilute to a concentrated solution through a semi-permeable membrane. It occurs in your body all the time, as its critical for fundamental biological processes. </p><p>Osmotic power plants typically use one of <a href="https://www.nationalgeographic.com/news/energy/2013/01/130107-osmotic-energy-norway/" target="_blank">two major techniques</a>. In pressure-retarded osmosis (PRO), freshwater is gathered in one tank while saltwater is kept in another. In between, a membrane separates the two. This membrane has special properties that only permit freshwater to pass through, but not saltwater. As a result, the freshwater is drawn through the membrane, diluting the saltwater in the corresponding tank but also raising the pressure. From this pressure, we can derive energy. </p><p>The other technique, reverse electrodialysis osmosis (RED), takes advantage of the fact that saltwater contains more positive and negative ions than fresh water. Normally, these ions would travel into the freshwater, balancing out the solution. But when harvesting osmotic energy, a membrane can selectively allow only the positive or negative ions to pass through, turning tanks of salt and fresh water into a kind of battery that passively generates electricity.</p>