performance

Better Paint For Cooler Buildings | Earth Wise

August 20, 2020 By EarthWise 2 Comments

A research team led by scientists at UCLA have developed a super-white paint that reflects as much as 98% of incoming heat from the sun. Such paint, if used on rooftops and other parts of buildings, could have a major impact on reducing the costs of keeping buildings cool.

Passive daytime radiative cooling is a well-known method to keep buildings cooler. By having building surfaces reflect sunlight and radiate heat into space, building temperatures can be significantly lowered. This in turn cuts down on air conditioner use and associated carbon emissions.

A roof painted white will result in lower indoor temperatures than a darker roof. But a white roof will do even more: it can reject heat at infrared wavelengths that are invisible to our eyes. This results in even more radiative cooling.

The best performing white paints currently available reflect about 85% of incoming solar radiation. The rest is absorbed by materials in the paint. The new research has identified simple modifications in paint ingredients that lead to a major increase in reflectivity.

Current reflective white paints use titanium dioxide, which absorbs UV radiation and therefore heats up under sunlight. The researchers studied replacing it with other substances such as barite – an artist’s pigment – or with powdered Teflon, both of which allow the paint to reflect more of the sun’s radiation.

Many cities are encouraging the use of cool-roof technologies on new buildings. Using the most reflective coatings possible on rooftops, if applied on a sufficiently large scale, could have a real impact on climate change as well as saving significant amounts of energy used for running air conditioners in buildings.

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UCLA-led Team Develops Ways to Keep Buildings Cool with Improved Super White Paints

Photo, posted August 15, 2012, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Second Life For Electric Car Batteries | Earth Wise

June 17, 2020 By EarthWise Leave a Comment

The number of electric cars around the world is growing steadily. Battery technology continues to improve and the battery packs in the cars can have a long life. Generally, the batteries are considered to require replacement only when their range has dropped below 80% of its original value. Many are warranted to last for 8 to 10 years or more than 100,000 miles. Some seem to do much better than that.

But however long it takes, there will eventually be a wave of used batteries whose performance is no longer deemed sufficient for vehicle use. A new study, published in the journal Applied Energy, looked at the application of used vehicle batteries as backup storage for grid-scale solar photovoltaic installations where they could perform for more than a decade in this less demanding role.

The study looked at the economics of several scenarios including running a solar farm with no battery back up, running the same farm with brand-new batteries, and running the farm with a battery array made of repurposed vehicle batteries.

They found that the used EV battery array, if managed properly, could be a good, profitable investment provided that the batteries cost less than 60% of their original price. They looked at the technical issues of screening batteries and combining batteries from different cars to work together. They also looked at the economics of removing batteries from cars, collecting them, checking them over, and repackaging them.

Overall, they found that reusing vehicle batteries could ultimately meet half the forecasted demand for renewable energy backup storage over the next 10 years and would be both a technical and an economic success story.

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Solar energy farms could offer second life for electric vehicle batteries

Photo, posted June 10, 2011, courtesy of Nick Ares via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Strategies To Promote Green Products | Earth Wise

March 26, 2020 By EarthWise Leave a Comment

Green products are environmentally-friendly products with features that are less harmful to people and the planet. For instance, green products may require fewer resources to produce, consume less energy, contain non-toxic ingredients, or create fewer emissions. Some examples include biodegradable waste bags, LED light bulbs, low-flow shower heads, organic cotton clothing, and reusable coffee cups and water bottles.

But according to new research from two universities in the United Kingdom, companies looking to promote their latest environmentally-friendly product should actually downplay its greenness if they want consumers to buy it.

The study, by researchers from the University of East Anglia and the University of Leeds, found advertising that highlights a product’s green attributes can lead consumers to associate it with weak performance. The findings, which were recently published in the Journal of Advertising, indicate that companies should downplay a product’s green qualities and instead promote it on more traditional aspects.

An example of these two distinct advertising strategies – green emphasis versus green understatement – can be found in the auto industry. Car manufacturer Toyota prominently highlights the low emissions and low fuel consumption features of the Prius, employing what the researchers term as ‘explicit signals’. In contrast, automaker Tesla reduces the prominence of its green attributes, focusing instead on its cars’ acceleration, handling, and other performance-related characteristics. This is known as the ‘implicit signals’ marketing approach.

After conducting two experiments, the research team found that the implicit, rather than explicit, marketing approach about greenness leads to higher performance evaluations and purchase intent.

Consumers appear more likely to engage in pro-social actions when it’s accompanied by some form of personal benefit.

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Highlighting product greenness may put consumers off buying

Photo, posted December 21, 2019, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

New Membranes For Carbon Capture

October 2, 2019 By EarthWise Leave a Comment

Drastically reducing the amount of carbon dioxide being emitted into the atmosphere is an essential goal in the effort to mitigate the effects of climate change. While the ultimate solution is to avoid combustion of fossil fuels by the use of clean alternative energy sources, that transition will take time – possibly more time than we have. As a result, there is a great deal of effort underway to develop techniques for capturing the carbon emitted by fossil fuel combustion and either recycling it or storing it.

There are multiple ways to capture carbon emissions, but the ultimate goal is to find a technique that is both inexpensive and scalable. One promising technique involves the use of high-performance membranes, which are filters that can specifically pick out CO2 from a mix of gases, such as those coming out of a factory smokestack.

Scientists at a Swiss laboratory have now developed a new class of high-performance membranes that exceeds the targeted performance for carbon capture by a significant margin. The membranes are based on single-layer graphene with a selective layer thinner than 20 nanometers – only about 40 atoms thick. The membranes are highly tunable in terms of chemistry, meaning that they can be designed to capture specific molecules.

The membranes are highly permeable – meaning that they don’t impede gas flow too much – but highly selective. The CO2/N2 separation factor is 22.5, which means that 22.5 times more nitrogen can get through the membrane than carbon dioxide.

The work is just at the laboratory stage at this point, but it is a very promising step towards developing a practical scheme for keeping carbon dioxide from escaping from power-plant and factory smokestacks.

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Next-gen membranes for carbon capture

Photo, posted December 28, 2010, courtesy of Emilian Robert Vicol via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Another Way To Make Solar Cells

March 21, 2019 By EarthWise Leave a Comment

Millions of rooftops now contain solar panels and the majority of the solar cells that make up those panels today are made from silicon. Silicon solar cells require expensive, multi-step processing conducted at very high temperatures in special clean room facilities. Despite these complications, the price of solar panels has continued to drop dramatically over the years.

But even as the price of solar cells gets lower and lower, there are still widespread efforts to find even better ways to make them. One of those ways is with perovskite solar cells. Perovskites are materials with a characteristic crystal structure and are quite common in nature. Perovskites can be formed with a wide range of elements and can exhibit a variety of properties.

They were first used to make solar cells about 10 years ago and those first cells were unimpressive in most respects. However, there has been steady progress since that time. The potential advantages of perovskite solar cells are that they can be made from low-cost materials and can be manufactured using liquid chemistry, a far cheaper process than what is used to make silicon cells.

Researchers at MIT and several other institutions have recently published the results of research on how to tailor the composition of perovskite solar cells to optimize their properties. What used to be a trial-and-error process can now become much more engineered and should lead to perovskite solar cells with performance that could exceed that of silicon cells.

Silicon solar panels are a huge, worldwide industry and displacing them in favor of an alternative technology is a tall order. But if perovskite cells can be optimized for large-scale manufacturability, efficiency and durability, they could definitely give silicon a run for its money.

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Unleashing perovskites’ potential for solar cells

Photo courtesy of Ken Richardson/MIT.

Earth Wise is a production of WAMC Northeast Public Radio.

More Renewables Without Storage In Texas

February 27, 2019 By EarthWise Leave a Comment

Texas has a Texas-sized appetite for electricity and relies most heavily on natural gas, coal and nuclear power to get it. But in recent times, wind power has grown tremendously in the Lone Star State and it has already leapfrogged past nuclear power. Coal could be the next domino to fall.

In the past few years, solar power has become competitive with wind in terms of price. Texas is a large, coastal state in the sunny southwestern U.S. and has significant solar resources. As a result, the amount of solar power in Texas is now growing rapidly.

In order for a combination of solar and wind power to address the bulk of electricity demand in Texas, there needs to be a way to provide reliability that these intermittent sources don’t necessarily provide. Energy storage is a solution that ultimately is likely to be part of most electricity grids, but currently it is still expensive on a utility scale.

A new study from Rice University looked at the complementarity of solar and wind power in Texas. Complementarity refers to balancing the output of solar and wind systems. The peak performance of wind and solar occurs at very different times in different regions of the state. The study suggests that the right mix of solar and wind systems in the right parts of Texas could provide a continuously reliable energy system. On both a yearly and daily basis, wind and solar power resources in Texas complement each other in terms of peak performance. It is a matter of locating the solar power and wind farms in the right places.

With the Texas solar industry really starting to boom, there is a real opportunity to integrate far more renewable energy into the Texas grid.

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More Renewables with Less Energy Storage: Texas Shows How

Photo, posted June 8, 2018, courtesy of Laura Lee Dooley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A Battery That Eats Carbon Dioxide

October 30, 2018 By EarthWise Leave a Comment

Fossil fuel-based power plants are increasingly considering the use of carbon capture technologies as a way to reduce emissions. The biggest challenge to the wide-spread adoption of such technology is its energy cost, which of course equates to economic cost. Present-day power plants equipped with carbon capture systems can use up to 30% of the electricity they generate just to power the capture, release, and storage of carbon dioxide.

Using The Sun To Remove Ice

October 3, 2018 By EarthWise Leave a Comment

Ice buildup can cause all sorts of problems ranging from performance issues to catastrophic failures. For example, ice buildup can negatively impact things like airplanes, power lines, wind turbines, and the like. Preventing this ice buildup typically requires energy-intensive heating systems or environmentally-harmful chemical sprays.

Bacteria-Powered Solar Cell

August 29, 2018 By EarthWise 1 Comment

Commercially-available solar panels are composed of solar cells that are most often made from various forms of silicon. Some panels use thin-film cells made from other semiconductor materials. Solar cells utilize a property of semiconductors that allows them to convert light energy into electrical energy.

Advantages Of Plug-In Hybrids

January 24, 2018 By EarthWise Leave a Comment

Plug-in hybrid vehicles are ones that can run both on electricity provided by a power outlet as well as on gasoline. There are many of them on the market these days built by quite a few car makers. But these vehicles have an undeserved reputation as being the fig leaf of electric mobility. Many environmental organizations and political decision-makers don’t consider them to be “real electric cars.”

An Aluminum Battery

June 28, 2017 By EarthWise

The battery industry is currently dominated by lithium-ion batteries. We have them in our phones and computers. They power electric cars. And they are increasingly being used to store energy generated by solar panels and other renewable energy sources.

[Read more…] about An Aluminum Battery

Delivery By Fuel Cell

June 19, 2017 By EarthWise

UPS recently announced a demonstration project that will put a prototype electric truck powered by a hydrogen fuel cell through the delivery company’s challenging paces. Fuel cells have been used in some commercial vehicles to power auxiliary systems, but this is the first time that they will be used to propel a vehicle.

Building A Better Solar Cell

December 14, 2016 By EarthWise

The great majority of solar cells being manufactured today are based on silicon crystals. That technology has come a long way over time and has gotten cheaper and more plentiful as the industry has grown.

Improving Wave Energy

October 28, 2016 By WAMC WEB

Ocean energy is still one of the biggest untapped clean energy sources on the planet. There are many studies that have shown that it could provide power for millions of homes in the U.S. alone. But despite this, the technology is still in its infancy and it is unclear when and if it can become a major contributor to our energy needs.