Rooftop Wind Power Might Take off by Using Key Principle of Flight
By Andrea Thompson
Solar panels perched on the roofs of houses and other buildings are an increasingly common sight in the U.S., but rooftop wind systems have never caught on. Past efforts to scale down the towering turbines that generate wind power to something that might sit on a home have been plagued by too many technical problems to make such devices practical. Now, however, a new design could circumvent those issues by harnessing the same principle that creates lift for airplane wings.
Overall, electricity generated by renewable sources has grown in the U.S. in recent years, and wind power has been a major driver of that trend. It accounts for more than 40 percent of electricity from renewables in the U.S. (though only 7 percent of all electricity production). Unlike solar energy cells, which are limited to collecting energy during daylight hours, wind turbines can run all night in any place with the right conditions—namely, in open plains or gentle hills with consistently sufficient wind speeds. But in addition to those requirements, large turbines need open space, which is not always available near towns and sprawling cities. Installing rooftop wind systems on homes and city buildings could help harness more of this resource.
When it comes to wind power, size matters. The amount of energy an individual turbine can generate is proportional to the area its blades sweep—so devices that are small enough to fit on a roof are less powerful. "What's kept distributed wind from being successful is that most of the systems are basically miniaturized wind turbines," says Brent Houchens, a mechanical engineer at Sandia National Laboratories. The smaller devices do not produce enough energy to be cost-effective. Plus, their quickly spinning blades create noisy vibrations, and their many moving parts are more prone to breakage. Compared with passive rooftop solar panels, wind turbines have the potential to be quite high-maintenance.
Houchens and his colleagues think they have engineered a solution that overcomes these obstacles by borrowing from a fundamental principle of air flight. The curved shape of an airplane wing—called an airfoil—alters the air pressure on either side of it and ultimately produces lift. Houchens' colleague Carsten Westergaard, president of Westergaard Solutions and a mechanical engineer at Texas Tech University, says he hitched two airfoils together so that "the flow from one airfoil will amplify the other airfoil, and they become more powerful." Oriented like two airplane wings standing upright on their side, the pair of airfoils directly face the wind. As the wind moves through, low pressure builds up between the foils and sucks air in through slits in their partly hollow bodies. That movement of air turns a small turbine housed in a tube and generates electricity.
Thanks to this design, the device—which the researchers call an AeroMINE ("MINE" stands for Motionless, Integrated Extraction)—can pull wind energy from a larger area (essentially, the AeroMINE's rectangular face) than its turbine blades could on their own in a traditional setup. Houchens likens such standard turbines to cookie cutters that leave wasted dough behind. The new device makes use of all the available wind, allowing it to extract more energy.
AeroMINEs also do not generate the same vibrations and noise as regular turbines; they are "less noisy than a ventilation fan," Westergaard says. The relative simplicity of their design means there are fewer moving parts to malfunction. The turbine, which is housed inside a building, would be easier to access if it does need repairs. This arrangement also keeps the blades isolated from any contact with people or wildlife. The team is designing the system so that it could be used in conjunction with rooftop solar panels, plugging into the existing infrastructure to harvest the energy they generate.
"I do think this technology could be groundbreaking" for areas with good wind conditions, says Luciano Castillo, a mechanical engineer at Purdue University, who is not involved in the project but has worked with Westergaard in the past. He also thinks the simplicity of AeroMINEs could make them a good option for developing countries, because the new devices do not require specialized parts or tools and are relatively easy to fix. Castillo and Westergaard both see the potential to use the design underwater to harness tidal energy as well.
Jay Apt, co-director of the Carnegie Mellon Electricity Industry Center, who is also not involved in the project, agrees that the simplicity of the design is attractive. But he is unsure whether the system can be scaled up to efficiently generate energy at a low enough cost in a real-world setting. Houchens says that with suitable wind conditions, he and his colleagues think AeroMINEs can be competitive with the current cost of rooftop solar power.
The team, which has received funding from Sandia and the Department of Energy, has tested scaled-down models in wind tunnels to fine-tune the design. In June the researchers have plans to test a four-meter-tall version of the device on a single-story mock building at the Scaled Wind Farm Technology (SWiFT) facility, part of Texas Tech's National Wind Institute.
This story originally appeared in Scientific American and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.
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Democrats in the House and Senate have introduced legislation to ban some of the most toxic pesticides currently in use in the U.S. D-Keine / E+ / Getty Images
By Jake Johnson
Democrats in the House and Senate on Tuesday introduced sweeping legislation that would ban some of the most toxic pesticides currently in use in the U.S. and institute stronger protections for farmworkers and communities that have been exposed to damaging chemicals by the agriculture industry.
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BP, the energy giant that grew from oil and gas production, is taking its business in a new direction, announcing Tuesday that it will slash its oil and gas production by 40 percent and increase its annual investment in low-carbon technology to $5 billion, a ten-fold increase over its current level, according to CNN.
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By Alex Thornton
The Australian government has announced a A$190 million (US$130 million) investment in the nation's first Recycling Modernization Fund, with the aim of transforming the country's waste and recycling industry. The hope is that as many as 10,000 jobs can be created in what is being called a "once in a generation" opportunity to remodel the way Australia deals with its waste.
Waste Mountain<p>The need for a dramatic increase in Australia's recycling capacity pre-dates the COVID-19 pandemic. <a href="https://www.abc.net.au/news/2019-12-27/where-does-all-australias-waste-go/11755424" target="_blank">Australians create approximately 67 million tons of waste a year</a>, and like in many wealthy countries, much of that was sent overseas. That all changed when China announced it was <a href="https://www.weforum.org/agenda/2017/10/china-has-banned-foreign-waste-so-whats-the-future-of-world-recycling" target="_blank">banning the import of a huge range of foreign waste</a> and recyclables. Soon <a href="https://www.weforum.org/agenda/2019/05/malaysia-flooded-with-plastic-waste-to-send-back-some-scrap-to-source" target="_blank">other countries followed suit</a>, and Australia was forced to look for alternative solutions.</p>
Biggest exporters of plastic. Statista
Waste Export Ban<p>Australia has adopted a strategy of taking responsibility for its own waste. Starting in January 2021, it is phasing in <a href="http://www.environment.gov.au/protection/waste-resource-recovery/waste-export-ban" target="_blank">bans on the export of different forms of waste</a>. By mid 2024, Australia's home-grown recycling industry will have to deal with an extra 650,000 tons of waste plastic, paper, glass and tires.</p><p>"As we cease shipping our waste overseas, the waste and recycling transformation will reshape our domestic waste industry, driving job creation and putting valuable materials back into the economy," federal environment minister Sussan Ley said in a <a href="https://uk.reuters.com/article/us-australia-waste/australia-to-set-up-132-million-fund-to-boost-recycling-following-export-curbs-idUKKBN247060" target="_blank">statement to Reuters</a>.</p>
Timeline for Australia's waste export ban. Australian Government
Trash Into Treasure<p>The benefits to the environment of boosting recycling rates are well known – less landfill, less plastic in our ocean, reduced need for virgin materials, and lower carbon emissions. The Recycling Modernization Fund initiative aims to divert more than 10 million tons of waste from landfill, part of an <a href="http://www.environment.gov.au/protection/waste-resource-recovery/publications/national-waste-policy-action-plan" target="_blank">overall strategy to reduce the total waste generated per person by 10%</a>, and push <a href="https://www.environment.gov.au/system/files/resources/7381c1de-31d0-429b-912c-91a6dbc83af7/files/national-waste-report-2018.pdf" target="_blank">Australia's total resource recovery rate from 58% in 2017</a> to 80% by 2030.</p><p>But like many countries, Australia is focusing on the economic benefits of better waste management as well.</p><p>"This will mean Australia converts more waste into higher valued resources ready for reuse locally by manufacturers and brands in their packaging and products," Rose Read, CEO of the National Waste and Recycling Industry Council, <a href="https://uk.reuters.com/article/us-australia-waste/australia-to-set-up-132-million-fund-to-boost-recycling-following-export-curbs-idUKKBN247060" target="_blank">told Reuters</a>.</p>
Green Jobs<p>The great potential of the circular economy to create green jobs is being recognized across the world.</p><p>In the UK, the Waste and Resources Action Program has launched a <a href="https://wrap.org.uk/buildbackbetter" target="_blank">six-point plan which it claims could add $90 billion to the economy, and create 500,000 new jobs</a>. Investment in the circular economy forms a significant part of the <a href="https://www.nytimes.com/2020/07/14/us/politics/biden-climate-plan.html" target="_blank">$2 trillion climate plan that Democratic candidate Joe Biden</a> is taking into November's US presidential election. And the <a href="https://ec.europa.eu/commission/presscorner/detail/en/ip_20_940" target="_blank">European Union has put its Green New Deal at the heart of its plans for recovery</a> from the economic shock of COVID-19.</p><p>The World Economic Forum's <a href="http://www3.weforum.org/docs/WEF_The_Future_Of_Nature_And_Business_2020.pdf" target="_blank">Future of Nature and Business</a> report identifies 15 systemic transitions with annual business opportunities worth $10 billion a year that could create 395 million jobs by 2030.</p><p>As is the case with Australia's Recycling Modernization Fund, a combination of private enterprise and government investment can offer ways to get people back to work by building a more environmentally sustainable economy.</p>
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The Great American Outdoors Act is now the law of the land.
<div id="e0008" class="rm-shortcode" data-rm-shortcode-id="ffc07febbf5d2d585ad06d3f43e2be56"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1290667833999929344" data-partner="rebelmouse"><div style="margin:1em 0">🚨Breaking News: The President has just signed the bipartisan #GreatAmericanOutdoorsAct. It will help: 🏗️ Restore… https://t.co/RPefKPMn7S</div> — Fix Our Parks (@Fix Our Parks)<a href="https://twitter.com/FixOurParksUS/statuses/1290667833999929344">1596554165.0</a></blockquote></div>
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By Andrew J. Whelton and Caitlin R. Proctor
In recent years wildfires have entered urban areas, causing breathtaking destruction.
Survivors left everything to flee the Camp Fire's path. Andrew Whelton / Purdue University
Wildfires and Water<p>Both the Tubbs and Camp fires destroyed fire hydrants, water pipes and meter boxes. Water leaks and ruptured hydrants were common. The Camp Fire inferno spread at a speed of one football field per second, chasing everyone – including water system operators – out of town.</p><p>After the fires passed, testing ultimately revealed widespread hazardous drinking water contamination. Evidence suggests that the toxic chemicals originated from a combination of <a href="https://doi.org/10.1002/aws2.1183" target="_blank">burning vegetation, structures and plastic materials</a>.</p>
Pipes, water meters and meter covers after wildfires destroyed them. Caitlin Proctor, Amisha Shah, David Yu, and Andrew Whelton/Purdue University
Dangerous Contamination Levels<p>Benzene was found at concentrations of 40,000 parts per billion (ppb) in drinking water after the Tubbs Fire and at more than 2,217 ppb after the Camp Fire. According to the California Office of Environmental Health Hazard Assessment, children exposed to benzene for a single day can suffer <a href="https://engineering.purdue.edu/PlumbingSafety/resources/Benzene-Levels-in-Water.pdf" target="_blank">harm at levels as low as 26 ppb</a>.</p><p>The U.S. Environmental Protection Agency recommends limiting children's short-term acute exposure to <a href="https://www.epa.gov/sites/production/files/2018-03/documents/dwtable2018.pdf" target="_blank">200 ppb</a>, and long-term exposure to less than <a href="https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations" target="_blank">5 ppb</a>. The EPA regulatory level for what constitutes a hazardous waste is <a href="https://19january2017snapshot.epa.gov/sites/production/files/2015-06/documents/tclp.pdf" target="_blank">500 ppb</a>.</p><p>In early 2019, California conducted contaminated water testing on humans by taking contaminated water from the Paradise Irrigation District and asking persons to smell it. The state found that even when people smelled contaminated water that had less than 200 ppb benzene, <a href="https://engineering.purdue.edu/PlumbingSafety/resources/Dissipatiion-of-Burn-Related-VOC-From-Water.pdf" target="_blank">at least one person reported nausea and throat irritation</a>. The test also showed that water contained a variety of other benzene-like compounds that first responders had not sampled for.</p><p>The officials who carried out this small-scale test did not appear to realize the significance of what they had done, until we asked whether they had had their action approved in advance by an institutional review board. In response, they asserted that such a review was not needed.</p><p>In our view, this episode is telling for two reasons. First, one subject reported an adverse health effect after being exposed to water that contained benzene at a level below the EPA's recommended one-day limit for children. Second, doing this kind of test without proper oversight suggests that officials greatly underestimated the potential for serious contamination of local water supplies and public harm. After the Camp Fire, together with the EPA, we estimated that some plastic pipes needed <a href="https://engineering.purdue.edu/PlumbingSafety/opinions/Final-HDPE-Service-Line-Decontamination-2019-03-18.pdf" target="_blank">more than 280 days</a> of flushing to make them safe again.</p>
Plastic pipes can be damaged by heat and fire contact. Andrew Whelton / Purdue University
Building Codes Could Make Areas Disaster-Ready<p>Our research underscores that community building codes are inadequate to prevent wildfire-caused pollution of drinking water and homes.</p><p>Installing one-way valves, called backflow prevention devices, at each water meter can prevent contamination rushing out of the damaged building from flowing into the larger buried pipe network.</p><p>Adopting codes that required builders to install fire-resistant meter boxes and place them farther from vegetation would help prevent infrastructure from burning so readily in wildfires. Concrete meter boxes and water meters with minimal plastic components would be less likely to ignite. Some plastics may be practically impossible to make safe again, since all types are susceptible to fire and heat.</p><p>Water main shutoff valves and water sampling taps should exist at every water meter box. Sample taps can help responders quickly determine water safety.</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="9540d7e271306ed417112042a3efc9a4"><iframe lazy-loadable="true" src="https://www.youtube.com/embed/GnlrzI1wdAI?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
The Smell Test Doesn’t Work<p>Under no circumstance should people be told to <a href="https://www.waterboards.ca.gov/press_room/press_releases/2018/pr122418_voc.pdf" target="_blank">smell the water</a> to determine its safety, as was recommended for months after the Camp Fire. Many chemicals have no odor when they are harmful. Only testing can determine safety.</p><p>Ordering people to boil their water will not make it safe if it contains toxic chemicals that enter the air. Boiling just transmits those substances into the air faster. "Do not use" orders can keep people safe until agencies can test the water. Before such advisories are lifted or modified, regulators should be required to carry out a full chemical screen of the water systems. Yet, <a href="https://doi.org/10.1002/aws2.1183" target="_blank">disaster</a> after <a href="https://pubs.rsc.org/en/content/articlehtml/2017/ew/c5ew00294j" target="_blank">disaster</a>, government agencies have failed to take this step.</p><p>Buildings should be tested to find contamination. <a href="https://www.purdue.edu/newsroom/releases/2020/Q1/study-your-homes-water-quality-could-vary-by-the-room-and-the-season.html" target="_blank">Home drinking water quality can differ from room to room</a>, so reliable testing should sample both cold and hot water at many locations within each building.</p><p>While infrastructure is being repaired, survivors need a safe water supply. Water treatment devices sold for home use, such as refrigerator and faucet water filters, are not approved for extremely contaminated water, although product sales representatives and government officials may <a href="https://undark.org/2019/09/19/camp-fire-california-drinking-water-carcinogens/" target="_blank">mistakenly think</a> the devices can be used for that purpose.</p><p>To avoid this kind of confusion, external technical experts should be called in assist local public health departments, which can quickly become overwhelmed after disasters.</p>
<div id="71cf9" class="rm-shortcode" data-rm-shortcode-id="e059d199e8368d282a31601e372e4dda"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1204068265980547075" data-partner="rebelmouse"><div style="margin:1em 0">The Los Angeles City Council's Planning and Land Use Committee signed off on an effort to expand the city's fire-re… https://t.co/fP8Z8mUq7R</div> — IntlCodeCouncil (@IntlCodeCouncil)<a href="https://twitter.com/IntlCodeCouncil/statuses/1204068265980547075">1575907219.0</a></blockquote></div>
Preparing for Future Fires<p>The damage that the Tubbs and Camp fires caused to local water systems was preventable. We believe that urban and rural communities, as well as state legislatures, should establish codes and lists of authorized construction materials for high-risk areas. They also should establish rapid methods to assess health, prepare for water testing and decontamination, and set aside emergency water supplies.</p><p>Wildfires are coming to urban areas. Protecting drinking water systems, buried underground or in buildings, is one thing communities can do to prepare for that reality.</p>
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By Zulfikar Abbany
"We don't have a definition of life," says Kevin Peter Hand, one early California morning when we speak via video. "We don't actually know what life is."