October 19th, 2020 by Tina Casey
Hey, does anybody remember FutureGen? The billion-dollar showcase for cutting edge carbon capture technology was supposed to be the salvation of the US coal industry, only things turned out differently. The project was mothballed back in 2015, and nowadays the US is taking a long, hard look at energy efficiency to cut carbon pollution from coal power plants. The latest twist on that score involves one of our favoritest topics, solar windows.
What’s The Big Deal About Energy Efficiency & Windows
Everybody knows that buildings suck up a huge amount of energy in the US, and windows are the suckiest of all.
“Heat gain and heat loss through windows are responsible for 25%–30% of residential heating and cooling energy use,” explains the US Department of Energy.
In a warming world, attention is focusing especially hard on air conditioning. AC use in the US is also expected to trend upwards as the population continues shifting from colder states to warmer ones.
Here’s the US Energy Information Agency on that score:
“…Delivered energy for air conditioning will increase more than any other end use in residential and commercial buildings (also known as the buildings sector) through 2050, while energy consumption for space heating will decline. Higher residential and commercial energy consumption for air conditioning and lower energy consumption for space heating resut (sic) from projected population shifts from colder to warmer parts of the United States, assumptions of warmer weather, and regional differences in sector growth.”
Combined, residential and commercial AC already accounted for 10% of US electricity consumption in 2019, which means that a lot of kilowatts are going to be flying out the window in the coming years.
A Better Window For A Better Tomorrow
Into this picture trots the idea of a solar window. Instead of acting as a portal for energy loss, solar windows could generate electricity from sunlight, and then somehow that electricity could be shunted off and put to use somewhere.
The problem, of course, is that you can’t see through conventional solar panels. You have to find materials that are transparent enough to let sunlight through while making some of those photons produce clean kilowatts, and you have to figure out how to engineer the whole system to make sense from a dollars-and-cents perspective.
If that sounds complicated, it is. However, help is on the way.
Last week the Energy Department’s National Renewable Energy Laboratory announced a breakthrough step in their search for a “thermochromic photovoltaic” window that can reduce the need for air conditioning by blocking sun glare, and generate electricity, to boot.
“Heat generated by sunlight shining through windows is the single largest contributor to the need for air conditioning and cooling in buildings,” explains NREL. “Because residential and commercial buildings use 74% of all electricity and 39% of all energy in the United States, the shading effect from tinting windows helps buildings use less energy.”
Energy Efficiency With A Perovskite Perk
Thermochromic photovoltaic windows are also designed to handle more sunlight on cooler days, when sunblock is not needed. The change is manifested in a change of color, and that’s where the new research comes in.
Earlier NREL research in the field involved a solar window that deployed perovskites, a relatively new class of inexpensive, synthetic crystalline materials that has provided PV researchers with many new opportunities to explore next-generation PV applications.
The earlier version simply went from transparent to a reddish-brown color as sunlight increased, which limited its appeal to architects and designers. In addition, the earlier window required temperatures in the range of 150-175 degrees Fahrenheit before triggering the switchover, which is not a particularly realistic scenario for any building anywhere on Earth, at least not today.
In the new iteration, the solar window activates at temperatures down to the 95-115 degree range, with a more attractive display of colors, too.
“This increases design flexibility for improving energy efficiency as well as control over building aesthetics that is highly desirable for both architects and end users,” NREL explains.
For all the juicy details, look up “Reversible Multicolor Chromism in Layered Formamidinium Metal Halide Perovskites” in the journal Nature Communications.
But wait there’s more. The NREL team also improved the speed of the switchover, from an initial rate of three minutes down to just seven seconds.
This all sounds great, but don’t set the table for your new solar window just yet. The research team is anticipating a prototype within the next year or so, which means a long haul is ahead.
Aside from solar windows, the team is also anticipating other clean tech applications.
“Realizing reversible chromism in MHPs [Metal Halide Perovskites] unlocks a new class of functional materials that couples a dynamic element to their remarkable optoelectronic properties. We envision dynamically tunable semiconductors to have applications that span switchable photovoltaics to energy storage and neuromorphic computing,” they enthuse.
Energy Efficiency & The Death Of Coal
Speaking of FutureGen, that project bit the dust in 2015 during the Obama administration, just before the 2016 presidential election cycle got into gear.
The writing was already on the wall for coal, but President* Trump rode into office partly on an oft-repeated promise to save coal jobs.
The coal jobs have continued to evaporate during his administration, and it appears that the President himself dropped the whole idea of saving coal jobs barely more than two years into his term. He touted oil and gas in his January 2019 State of the Union address and failed to mention coal at all.
The love affair with oil and gas continues right on up to this month, when the Energy Department touted a new report on the benefits of the domestic oil and gas industry. Coal, not so much.
Meanwhile, though, the Energy Department has been busy at work fostering a clean power revolution that will send oil, gas, and coal scurrying to the dark corners of the energy landscape.
I know, right? Weird!
Energy efficiency is not a particularly sexy topic but it does play a major role in the Energy Department’s plans for a fossil free future. In addition to new demands on electricity from increased AC use, data center efficiency is a big, fat target that will impact future energy demand.
That brings us right back around to the FutureGen debacle. The idea of investing big bucks in a system that depends on pushing carbon up from underground where it isn’t bothering anybody, then chasing it back down underground, stopped making sense a few years ago when the cost of renewable energy began to fall.
Now the three-part killer combo is renewable energy, plus energy storage, plus energy efficiency.
With that in mind, take a look at another carbon capture showcase project that was supposed to be the next FutureGen, with the aim of keeping the coal units at the San Juan Generating Station in New Mexico humming along.
Unfortunately for coal fans, doubts about the financial viability of the project soon began to percolate, and the abandonment of the Petra Nova carbon capture project in Texas has done little to soothe frayed nerves.
The Energy Department is still attempting to shore up support for the San Juan project, but the attempt appears half-hearted in light of the agency’s longstanding focus on New Mexico as as a showcase for clean tech innovation and the new green economy of the future.
Adding to the heat in New Mexico is an emerging financial instrument called coal-for-solar swaps, which makes it easier for utilities to drop obsolete fossil resources from their portfolios.
With San Juan set to close in 2022, the clock is ticking.
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Photo (cropped): “NREL researcher Lance Wheeler holds samples of perovskite-based window technology (credit: Dennis Schroeder, NREL).
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