Maybe it’s not too late to stop catastrophic climate change after all. Researchers at the Lawrence Berkeley National Laboratory in California have been mining the unglamorous world of energy efficient roofing for solutions, and last week they came up with a simple vanadium-based roof coating that can both cool and warm a building as needed. There being no such thing as a free lunch, there has to be a catch, and there is: where is all the vanadium going to come from?
Electric Cars Good, Energy Efficient Buildings Good, Too
For all the attention lavished on the latest zero emission electric cars (raises hand) as a planet saving replacement for gasmobiles, energy efficient buildings should also get some love. As with the transportation sector, buildings are a leading contributor to greenhouse gas emissions, at least here in the US. Let’s have our friends over at the US Department of Energy explain:
“The buildings sector accounts for about 76% of electricity use and 40% of all U. S. primary energy use and associated greenhouse gas (GHG) emissions, making it essential to reduce energy consumption in buildings in order to meet national energy and environmental challenges and to reduce costs to building owners and tenants.”
If you separate electricity generation out of the mix and only focus on the end use in buildings, which is what the US Environmental Protection Agency does, the numbers drop considerably. However, that’s just a different perspective on the same problem, which is that buildings use a lot of energy
The good news is that energy efficient technology is not rocket science.
“Opportunities for improved efficiency are enormous. By 2030, building energy use could be cut more than 20% using technologies known to be cost effective today,” the Energy Department observes, adding that new technology could pile another 15% savings on top of that, or more.
Saving The Planet, One Energy Efficient Roof At A Time
That brings us to the new research at Berkeley Lab. The team was searching for a way to make “cool roof” coatings work across a broader range of temperatures when they hit on a solution based on vanadium.
The cool roof movement focuses on painting rooftops white or using other materials that deflect heat in warm weather, which lowers the interior temperature and avoids higher energy use for air conditioning or fans. The problem is that the same cool roof deflects sunlight in cold weather, robbing the household of the natural warmth from sunlight and bumping up the use of energy for home heating.
Berkeley Lab has come up with the solution: a new energy efficient material based on vanadium, called TARC for temperature-adaptive radiative cooling.
“Our all-season roof coating automatically switches from keeping you cool to warm, depending on outdoor air temperature. This is energy-free, emission-free air conditioning and heating, all in one device,” enthuses Berkeley Lab lead researcher Junqiao Wu, who is on the faculty at the lab’s Materials Sciences Division and a professor of materials science and engineering at UC-Berkeley.
How Does It Work?
Vanadium is a silvery transition metal, not to be confused with vibranium. It pops up regularly on the CleanTechnica radar mainly on account of its use in flow battery technology. In addition to safety and durability advantages, vanadium has multiple charge states, meaning that you can make a flow battery with just vanadium instead of having to deploy two different materials.
Most metals heat up when they conduct electricity, but vanadium does not heat up much at all, and that’s the key to the whole thing.
“Vanadium dioxide below about 67 degrees Celsius (153 degrees Fahrenheit) is also transparent to (and hence not absorptive of) thermal-infrared light. But once vanadium dioxide reaches 67 degrees Celsius, it switches to a metal state, becoming absorptive of thermal-infrared light,” Berkeley Lab adds.
“This ability to switch from one phase to another — in this case, from an insulator to a metal — is characteristic of what’s known as a phase-change material,” they explain.
The team fabricated samples that resemble Scotch tape, tested them, and combined their data with other data sets to model the results for buildings representing 15 climate zones in the continental US.
The results were impressive. Although TARC still reflects about 75% of sunlight for the year in total, it deflects more heat in warmer weather, and it retains more heat in colder weather.
“With TARC installed, the average household in the U.S. could save up to 10% electricity,” said Kechao Tang, a co-lead author of the study (formerly a postdoctoral researcher in the Wu lab, Tang is currently an assistant professor at Peking University in China).
The Fight For The Vanadium Roof Of The Future
Don’t hold your breath for TARC to show up in the toolkit of your friendly neighborhood roofer any time soon. The team still has to scale up the prototype and determine if it really is a practical solution.
By practical, they may be thinking of who’s gonna get all the vanadium together. Vanadium is an earth-abundant material but as of just a few years ago, the domestic supply of vanadium in the US was lagging.
Regardless, the vanadium flow battery field started to pick up steam around 2014 with support from the US Department of Energy and it shows no signs of slowing down. If that energy efficiency vanadium roof business really does take off, the roofers will have to fight the battery makers for a cut of the supply chain, and both of them will have to beat down the metallurgical industry, which accounted for more than 90% of vanadium usage in the US as of 2019.
Meanwhile, vanadium production is picking up here in the US. Some of the activity involves refining raw material shipped in from overseas (hello, U.S. Vanadium company). As of 2019, the US Geological Survey noted that “small quantities” were also being produced from various domestic sources including uraniferous sandstones on the Colorado as well as waste materials such as petroleum residues, spent catalysts, utility ash, and pig iron slag.
If all goes according to plan you can add spent vanadium flow batteries to the supply chain. U.S. Vanadium claims a 97% recovery rate for recycling the vanadium-based electrolyte from its flow batteries.
The next steps for Berkeley Lab’s energy efficient roof coating also involve getting the funds together to continue the research, and things just got a bit stickier now that US Senator and coal stakeholder Joe Manchin (D-West Virginia) has almost single-handedly tanked the stock market and blown up President Biden’s signature Build Back Better climate action bill.
The Energy Department was counting on Build Back Better funds to ramp up its funding for R&D focusing on energy efficient buildings among other clean technologies, but that appears to have evaporated after Manchin declared he will not vote for the bill during an appearance Sunday on a Fox News program.
All is not lost, though. Help may be coming from an unlikely source. The United Mine Workers of America has been shifting into energy transition mode, and earlier this year the union came down on the side of creating new green jobs for union workers.
To be clear, UMWA continues to advocate for keeping coal jobs in the mix, Still, the point is that coal workers are — or should be — a constituency for a US Senator representing the iconic coal-producing state of West Virginia.
Senator Manchin has just poked his own constituents in the eye by killing off the extension of the child tax credit, among other aid to working coal families and retirees in the Build Back Better bill, aside from choking off that thing about new green jobs for unemployed coal workers.
Apparently UMWA is not taking this lying down. On Monday the union issued a polite but blunt statement detailing all the reasons why Build Back Better should pass.
“We urge Senator Manchin to revisit his opposition to this legislation and work with his colleagues to pass something that will help keep coal miners working, and have a meaningful impact on our members, their families, and their communities,” they concluded.
Of course, none of this would matter if just one Senator from the Republican side of the aisle would step in to replace Manchin’s vote. Looking at you, Republican US Senator Shelley Moore Capito of West Virginia. After all, why should Manchin take all the blame when all 50 Republican senators have also dug in their heels, including one representing his own home state.
It looks like UMWA has a message for both of them.
“I also want to reiterate our support for the passage of voting rights legislation as soon as possible, and strongly encourage Senator Manchin and every other Senator to be prepared to do whatever it takes to accomplish that,” the UMWA statement concludes, adding that “Anti-democracy legislators and their allies are working every day to roll back the right to vote in America. Failure by the Senate to stand up to that is unacceptable and a dereliction of their duty to the Constitution.”
Follow me on Twitter @TinaMCasey.
Photo: Kaichen Dong (left) and Jiachen Li adjust a Pulsed Laser Deposition (PLD) device used to develop the TARC smart-roof coating for energy efficient buildings (credit: Thor Swift/Berkeley Lab).
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