WCA November 2020

From the Americas

Duke’s commercial renewable sites, and Sara Weaver, who worked on the new technology as part of her doctorate at Texas State University. Awareness of the need for the technology first arose in the Rio Grande Valley in Texas, where Duke discovered a far higher bat population around its Los Vientos wind projects than had showed in pre-construction surveying. Bats are vital for seed dispersal, pollination and insect control – a study found that insect consumption by bats reduces the pesticide spending of the US agriculture industry by about $22.9bn per year. Mr Hayes stressed how important bat conservation is for the local farmers: “Rio Grande Valley is an area rich in agricultural production; local farmers rely on those bats for pest control services and we just want to do our part to minimise our impact.” Duke made contact with Ms Weaver through Bat Conservation International (BCI). With the support of the Texas Parks and Wildlife Department, Texas State and BCI, Ms Weaver partnered with Duke over the next two years to conduct a study using NRG Systems’ new bat deterrent technology at the Los Vientos wind sites. The device consists of speakers, mounted in various locations on each turbine’s nacelle and emitting a high frequency sound tuned to mirror the unique echolocation frequency of the local bat species. Preventing bats from hearing their own echolocation makes it difficult for them to hunt or socialise and they leave the immediate environs for more favourable areas. The results of the study were largely successful, reducing bat fatalities over 54 per cent for the Brazilian free-tailed bat and almost 80 per cent for the Hoary bat. The latter is a species of conservation concern that is found throughout the USA. Of the early successes for the technology, Mr Hayes commented, “It’s our responsibility to operate our projects and have the least amount of impact possible. We hope to set an example.” As an incentive to other operators, the bat deterrent systems also show benefits for energy producers. The alternative method to reduce bat fatalities would require shutting down the turbines at night and, so, generating less power (known as curtailment). “In power generation it’s all about energy yield, you want to squeeze every electron out of your facility that you can,” said Mr Hayes. Allowing turbines to generate their maximum amount of electricity and avoiding curtailment means more zero-carbon power, and greater climate benefits. Though the first study has yielded good results, Ms Weaver says there is still more work to be done. She hopes to study different ways to increase effectiveness, and with more species, to inform better system designs as the technology evolves. “We’re going to continue working on this because it can always get better,” she said. Copper is being re-examined in the interests of PPE Research has shown that a face mask of two-ply tightly woven cotton material, sandwiching a layer of chiffon or silk to add an electrostatic barrier, can reduce the passage

Research A long-term research project has succeeded with a concentrated solar power heat concept

BigStockPhoto.com Photographer: Aispl

A team of researchers from Tulane University, San Diego State University, Boeing-Spectrolab and Otherlab has developed a hybrid solar energy converter capable of generating electricity and steam. The project, supported with funding from the US Department of Energy (DOE) ARPA-E programme, began in 2014. The hybrid system captures more from the sunlight spectrum by using multi-junction solar cells to generate electricity and redirect infrared rays to a thermal receiver, which converts those rays to thermal energy. The thermal energy can be stored and later dispatched for applications that demand heat, such as food processing, chemical production or water treatment. Tulane University reported that the research teams carried out comprehensive prototype and field tests, where the system demonstrated 85.1 per cent efficiency and delivered steam at up to 240°C. The next step in the process will be pilot-scale validation, funded by the Louisiana Board of Regents and a local commercialisation partner, the gas and chemical technology company Reactwell. Matthew Escarra, associate professor of physics and engineering physics at Tulane, said, “Thermal energy consumption is a huge piece of the global energy economy – much larger than electricity use. There [is] a rising interest in solar combined heat and power systems, to deliver both electricity and process heat for zero-net-energy and greenhouse-gas-free development.” The work is led by Matthew Escarra and Daniel Codd, an associate professor of mechanical engineering at the University of San Diego. Prototype development was carried out at Tulane and field testing in San Diego. The research was detailed in the science journal Cell Reports Physical Science . Balancing wind power with bat habitat The impact of climate change on humans and habitats continues to be a huge threat, but the development of cleaner, more sustainable power sources also has repercussions that must be addressed. Apart from the role wind energy can play in reducing carbon emissions, the wind energy industry is working with government agencies, environmental groups and technology developers to provide conservation benefits to species and habitats. Recent results from new technology testing at Duke Energy Renewables’ Los Vientos wind sites, in Texas, offer promising findings for wind power’s coexistence with bats. Working with NRG Systems, Duke has deployed deterrent devices that produce high frequency sounds around the turbine blades. The sounds block the bats’ echolocation capability, causing them to avoid the area. The research is led by Tim Hayes, environmental development director for

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Wire & Cable ASIA – November/December 2020