Concentrated Solar Works Day and Night With No Batteries Required
By Paul Brown
The massive expansion of solar panels on rooftops and solar farms across the world has captured the headlines, but the other established way of generating electricity from sunlight—concentrated solar power (CSP), or solar tower power—is also making great strides.
For a long time, using mirrors to concentrate the sun's rays to heat molten salt and produce superheated steam to drive a generator's turbines was thought to be a more promising technology than photovoltaic panels (PV), because it was originally cheaper.
But as the price of the panels has dropped dramatically in the last five years, CSP fell out of favor, although some countries continued to support its development.
Now the cost of CSP is also falling. But it has another major advantage: unlike the panels, it can go on producing power long after the sun has set, and can store it for up to 15 hours, for use when it's needed.
Dubai, the largest city in the United Arab Emirates, where sunshine is almost guaranteed, is a fan of both solar technologies. It has just announced that electricity from a proposed 200 megawatt CSP project, to be completed in 2021, will be priced at 9.45 cents per kilowatt hour—40 percent below the previous world record.
The cost is well above the three cents per kilowatt hour of the cheapest solar PV, but has the advantage of running for 15 hours at full power during the night, doing away with the need for any fossil fuels for back-up generation.
CSP has many variations, all ways of concentrating solar power onto liquid to heat it and so create steam for driving turbines. The two main types use parabolic troughs or mirrors to aim the sunlight at a central tower. Troughs have been more widely used so far, but towers are gaining fast—the latest scheme, Dubai's, uses a tower.
Current technology for storage uses sodium nitrate and potassium nitrate together heated to 566°C to store the heat in a large tank until it is needed. It is then fed gradually through a heat exchanger to produce superheated steam for the turbines.
Dubai Electricity and Water Authority (Dewa) has ambitious plans to reach 1000 megawatts of CSP as part of plans to boost capacity for its solar park from 1,000 MW by 2020 to 5,000 MW by 2030. The first 13 MW of PV came on line in 2013. The city aims to have seven percent of clean energy by 2020, 25 percent by 2030 and 75 percent by 2050.
There were a number of bids for Dubai's CSP projects. Consortiums included Saudi Arabia's Acwa Power and China's Shanghai Electric, followed by the Abu Dhabi clean energy company Masdar, with partners EDF of France and Abengoa of Spain.
Saeed Al Tayer, the managing director and chief executive of Dewa, claimed: "The UAE's focus on renewable energy generation has led to a drop in prices worldwide and has lowered the price of solar and wind power bids in Europe and the Middle East."
Paddy Padmanathan, chief executive of Acwa Power, said it was exciting to see CSP technology with storage "offering dispatchable solar energy—day and night, competing with fossil fuel-based alternatives." Several of the companies involved said they would continue to compete for future projects.
The U.S. was one of the pioneers of CSP, and many sunny countries in the Middle East and Africa are now developing projects, including South Africa, but, as with many other renewable projects, China is hoping to take a lead.
China plans to build 1.3 GW of CSP capacity by 2018 in a first batch of 20 CSP projects which includes nine solar towers, seven parabolic trough plants and four linear Fresnel plants (using a form of lens which also concentrates solar power).
So far, the Chinese have yet to decide which is the most promising technology.
Reposted with permission from our media associate Climate News Network.
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If weather is your mood, climate is your personality. That's an analogy some scientists use to help explain the difference between two words people often get mixed up.
Size Matters<p>Climates are a bit like woven tapestries. The big picture is important, no question. But so are all the seemingly minor details found inside the larger whole.</p><p><a href="https://research-information.bris.ac.uk/en/persons/tommaso-jucker" target="_blank">Tommaso Jucker</a> is an environmental scientist at the University of Bristol. In an email, Jucker says he'd define the term microclimate as "the suite of climatic conditions (temperature, rainfall, humidity, solar radiation) measured in localized areas, typically near the ground and at spatial scales that are directly relevant to ecological processes."</p><p>We'll talk about that last bit in a minute. But first, there's another criteria to discuss. According to some researchers, a microclimate — by definition — must differ from the larger area that surrounds it.</p><p><a href="https://www.cfc.umt.edu/research/paleoecologylab/publications/Davis_et_al_2019_Ecography.pdf" target="_blank">Forests</a> provide us with some great examples. "The climate near the ground in a tropical rainforest is dramatically different from the climate in the canopy 50 meters [164 feet] above," says University of Montana ecologist <a href="https://www.cfc.umt.edu/personnel/details.php?ID=1110" target="_blank">Solomon Dobrowski</a> in an email. "This vertical gradient among other factors allows for the staggering biodiversity we see in the tropics."</p><p>Likewise, scientists observed that a 2015 partial <a href="https://animals.howstuffworks.com/insects/bees-stopped-buzzing-during-2017-solar-eclipse.htm" target="_blank">solar eclipse</a> caused the air temperature of an Eastern European meadow to <a href="https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/wea.2802" target="_blank">change more dramatically</a> than it did in a nearby forest. That's because trees provide not only shade, but their leaves also reflect solar radiation. At the same time, forests tend to reduce wind speeds.</p><p>All those factors add up. A 2019 review of 98 wooded places — spread out across five continents — found that forests are 7.2 degrees Fahrenheit (4 degrees Celsius) <a href="https://natureecoevocommunity.nature.com/posts/47363-forests-protect-animals-and-plants-against-warming" target="_blank">cooler on average</a> than the areas outside them.</p><p>Now if you hate the cold, don't worry; there's a cozy exception to the rule. According to that same study, forests are usually 1.8 degrees Fahrenheit (1 degree Celsius) warmer than the external environment during the wintertime. Pretty cool.</p>
A Bug's Life<p>When does a microclimate stop being, well, micro? In other words, is there a maximum size we should be aware of when discussing them?</p><p>Depends on who you ask. "In terms of horizontal scale, some have defined 'microclimate' as anything that is less than 100 meters [328 feet] in range," Jucker says. "I'm personally less prescriptive about this."</p><p>Instead, he says the "scale at which we want to measure [a particular] microclimate" ought to be "dictated" by the questions we're trying to answer.</p><p>"If I want to know how temperature affects the photosynthesis of a leaf, I should be measuring temperature at centimeter scale," Jucker explains. "If I want to know if and how temperature affects the habitat preference of a large, mobile mammal, it's probably more relevant to capture temperature variation across [tens to hundreds] of meters."</p><p>For instance, solitary plants have the power to generate itty-bitty microclimates. Just ask <a href="https://www.colorado.edu/geography/peter-blanken-0" target="_blank">Peter Blanken</a>, a geography professor at the University of Colorado, Boulder and the co-author of the 2016 book, "<a href="https://amzn.to/2XN6FT8" target="_blank">Microclimate and Local Climate</a>."</p>
The urban heat island effect is a good example of how microclimates work. NOAA
Microclimates on a Grand Scale<p>It's no secret that our planet is going through some rough times at the macro level. The global temperature is <a href="https://climate.nasa.gov/vital-signs/global-temperature/" target="_blank">climbing</a>; nine out of the <a href="https://www.noaa.gov/news/2019-was-2nd-hottest-year-on-record-for-earth-say-noaa-nasa" target="_blank">10 hottest years on record</a> have occurred since 2005. And by one recent estimate, roughly 1 million species around the world are <a href="https://ipbes.net/sites/default/files/2020-02/ipbes_global_assessment_report_summary_for_policymakers_en.pdf" target="_blank">facing extinction</a> due to human activities.</p><p>"One of the big questions that ecologists and environmental scientists are trying to answer right now is how will individual species and whole ecosystems respond to rapid climate change and habitat loss," says Jucker. "...To me, [microclimates are] a key component of this research — if we don't measure and understand climate at the appropriate scale, then predicting how things will change in the future becomes a lot harder."</p><p>Developers have long understood the impact small-scale climates have on our daily lives. <a href="https://science.howstuffworks.com/environmental/green-science/urban-heat-island.htm#pt0" target="_blank">Urban heat islands</a> are cities that have higher temperatures than neighboring rural areas.</p><p>Plants release vapors that can moderate local climates. But in cities, natural greenery is often scarce. To make matters worse, plenty of our roads and buildings have a bad habit of absorbing or re-emitting heat from the sun. <a href="https://www.google.com/books/edition/Microclimate_and_Local_Climate/LHUZDAAAQBAJ?hl=en&gbpv=1&bsq=urban%20heat%20island" target="_blank">Vehicle emissions</a> don't exactly help the situation.</p><p>Still, it's not like Boston or Beijing are thermal monoliths. Sometimes, the documented temperatures <a href="https://e360.yale.edu/features/can-we-turn-down-the-temperature-on-urban-heat-islands" target="_blank">within a single city</a> vary by 15 to 20 degrees Fahrenheit (8.3 to 11.1 degrees Celsius).</p><p>That's where metro parks and city trees come in. They have nice cooling effects on nearby neighborhoods. "Several cities around the world have developed programs to increase urban green spaces," says Blanken. "Tree planting programs and green roof programs, have been shown to lower surface temperatures, decrease air pollution and decrease surface water runoff (urban flash-flooding) in urban areas."</p>
An "explosive" wildfire ignited in Los Angeles county Wednesday, growing to 10,000 acres in a little less than three hours.
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Note: This story was originally published on August 6, 2020
If asked to recall a hurricane, odds are you'd immediately invoke memorable names like Sandy, Katrina or Harvey. You'd probably even remember something specific about the impact of the storm. But if asked to recall a heat wave, a vague recollection that it was hot during your last summer vacation may be about as specific as you can get.
<div id="ecf36" class="rm-shortcode" data-rm-shortcode-id="c2dcc9d48a6cd61f247df1544539a783"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1290959314132361216" data-partner="rebelmouse"><div style="margin:1em 0">Naming heatwaves is a good idea—making the abstract concrete, the invisible visible. Why should hurricanes and wild… https://t.co/hDWgYb79Ob</div> — Ed Maibach (@Ed Maibach)<a href="https://twitter.com/MaibachEd/statuses/1290959314132361216">1596623660.0</a></blockquote></div>
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One of the challenges of renewable power is how to store clean energy from the sun, wind and geothermal sources. Now, a new study and advances in nanotechnology have found a method that may relieve the burden on supercapacitor storage. This method turns bricks into batteries, meaning that buildings themselves may one day be used to store and generate power, Science Times reported.
Bricks are a preferred building tool for their durability and resilience against heat and frost since they do not shrink, expand or warp in a way that compromises infrastructure. They are also reusable. What was unknown, until now, is that they can be altered to store electrical energy, according to a new study published in Nature Communications.
The scientists behind the study figured out a way to modify bricks in order to use their iconic red hue, which comes from hematite, an iron oxide, to store enough electricity to power devices, Gizmodo reported. To do that, the researchers filled bricks' pores with a nanofiber made from a conducting plastic that can store an electrical charge.
The first bricks they modified stored enough of a charge to power a small light. They can be charged in just 13 minutes and hold 10,000 charges, but the challenge is getting them to hold a much larger charge, making the technology a distant proposition.
If the capacity can be increased, researchers believe bricks can be used as a cheap alternative to lithium ion batteries — the same batteries used in laptops, phones and tablets.
The first power bricks are only one percent of a lithium-ion battery, but storage capacity can be increased tenfold by adding materials like metal oxides, Julio D'Arcy, a researcher at Washington University in St. Louis, Missouri, who contributed to the paper and was part of the research team, told The Guardian. But only when the storage capacity is scaled up would bricks become commercially viable.
"A solar cell on the roof of your house has to store electricity somewhere and typically we use batteries," D'Arcy told The Guardian. "What we have done is provide a new 'food-for-thought' option, but we're not there yet.
"If [that can happen], this technology is way cheaper than lithium ion batteries," D'Arcy added. "It would be a different world and you would not hear the words 'lithium ion battery' again."
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By Jessica Corbett
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<div id="79024" class="rm-shortcode" data-rm-shortcode-id="4ac086eab58b9713f2ad777c40938252"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1293578984148606977" data-partner="rebelmouse"><div style="margin:1em 0">This actively puts peoples' lives at risk. https://t.co/GKF0Xgjyex</div> — CAP Action (@CAP Action)<a href="https://twitter.com/CAPAction/statuses/1293578984148606977">1597248238.0</a></blockquote></div>
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