Clean energy accounted for more than two-thirds of the new US electrical generating capacity added during the first six months of 2022, according to data recently released by the Federal Energy Regulatory Commission (FERC).
Wind (5,722 megawatts) and solar (3,895 MW) provided 67.01% of the 14,352 MW in utility-scale (that is, greater than 1 MW) capacity that came online during the first half of 2022.
Additional capacity was provided by geothermal (26 MW), hydropower (7 MW), and biomass (2 MW). The balance came from natural gas (4,695 MW) and oil (5 MW). No new capacity was reported for 2022 from either nuclear power or coal.
This brings clean energy’s share of total US available installed generating capacity up to 26.74%. To put that in perspective, five years ago, clean energy’s share was 19.7%. Ten years ago, it was 14.76%.
FERC reports that there may be as much as 192,507 MW of new solar capacity on the way, with 66,315 MW classified as “high-probability” additions and no offsetting “retirements.”
The “high-probability” additions alone would nearly double utility-scale solar’s current installed capacity of 74,530 MW, while successful completion of all expected projects would nearly quadruple it.
Notably, FERC’s forecast predates President Joe Biden signing into law the Inflation Reduction Act, and that will likely ramp up solar growth even more.
In addition, new wind capacity by June 2025 could total 70,393 MW, with 17,383 MW being “high probability” and only 158 MW of retirements expected. Thus, installed wind capacity could grow by at least 12%.
“High-probability” generation capacity additions for utility-scale solar and wind combined, minus anticipated retirements, reflect a projected net increase of 83,540 MW over the next three years, or over 2,300 MW per month. That figure does not include new distributed, small-scale solar capacity or additions by hydropower, geothermal, and biomass.
SUN DAY Campaign’s executive director Ken Bossong, who reviewed and reported on the data, said in an emailed statement:
With each new monthly Infrastructure report from FERC, the prospects for renewable sources, especially solar and wind, brighten while those for natural gas, coal, and nuclear power continue to slide. By the end of this decade, the mix of renewable energy sources should constitute the largest share of the nation’s electrical generating capacity.
A new cleaning method could remove dust on solar installations in water-limited regions, improving overall efficiency.
Solar power is expected to reach 10 percent of global power generation by the year 2030, and much of that is likely to be located in desert areas, where sunlight is abundant. But the accumulation of dust on solar panels or mirrors is already a significant issue — it can reduce the output of photovoltaic panels by as much as 30 percent in just one month — so regular cleaning is essential for such installations.
But cleaning solar panels currently is estimated to use about 10 billion gallons of water per year — enough to supply drinking water for up to 2 million people. Attempts at waterless cleaning are labor-intensive and tend to cause irreversible scratching of the surfaces, which also reduces efficiency. Now, a team of researchers at MIT has devised a way of automatically cleaning solar panels, or the mirrors of solar thermal plants, in a waterless, no-contact system that could significantly reduce the dust problem, they say.
The new system uses electrostatic repulsion to cause dust particles to detach and virtually leap off the panel’s surface, without the need for water or brushes. To activate the system, a simple electrode passes just above the solar panel’s surface, imparting an electrical charge to the dust particles, which are then repelled by a charge applied to the panel itself. The system can be operated automatically using a simple electric motor and guide rails along the side of the panel. The research is described today in the journal Science Advances, in a paper by MIT graduate student Sreedath Panat and professor of mechanical engineering Kripa Varanasi.
Despite concerted efforts worldwide to develop ever more efficient solar panels, Varanasi says, “a mundane problem like dust can actually put a serious dent in the whole thing.” Lab tests conducted by Panat and Varanasi showed that the dropoff of energy output from the panels happens steeply at the very beginning of the process of dust accumulation and can easily reach 30 percent reduction after just one month without cleaning. Even a 1 percent reduction in power, for a 150-megawatt solar installation, they calculated, could result in a $200,000 loss in annual revenue. The researchers say that globally, a 3 to 4 percent reduction in power output from solar plants would amount to a loss of between $3.3 billion and $5.5 billion.
“There is so much work going on in solar materials,” Varanasi says. “They’re pushing the boundaries, trying to gain a few percent here and there in improving the efficiency, and here you have something that can obliterate all of that right away.”
Many of the largest solar power installations in the world, including ones in China, India, the U.A.E., and the U.S., are located in desert regions. The water used for cleaning these solar panels using pressurized water jets has to be trucked in from a distance, and it has to be very pure to avoid leaving behind deposits on the surfaces. Dry scrubbing is sometimes used but is less effective at cleaning the surfaces and can cause permanent scratching that also reduces light transmission.
Water cleaning makes up about 10 percent of the operating costs of solar installations. The new system could potentially reduce these costs while improving the overall power output by allowing for more frequent automated cleanings, the researchers say.
“The water footprint of the solar industry is mind-boggling,” Varanasi says, and it will be increasing as these installations continue to expand worldwide. “So, the industry has to be very careful and thoughtful about how to make this a sustainable solution.”
Other groups have tried to develop electrostatic-based solutions, but these have relied on a layer called an electrodynamic screen, using interdigitated electrodes. These screens can have defects that allow moisture in and cause them to fail, Varanasi says. While they might be useful on a place like Mars, he says, where moisture is not an issue, even in desert environments on Earth this can be a serious problem.
The new system they developed only requires an electrode, which can be a simple metal bar, to pass over the panel, producing an electric field that imparts a charge to the dust particles as it goes. An opposite charge applied to a transparent conductive layer just a few nanometers thick deposited on the glass covering of the solar panel then repels the particles, and by calculating the right voltage to apply, the researchers were able to find a voltage range sufficient to overcome the pull of gravity and adhesion forces and cause the dust to lift away.
Using specially prepared laboratory samples of dust with a range of particle sizes, experiments proved that the process works effectively on a laboratory-scale test installation, Panat says. The tests showed that humidity in the air provided a thin coating of water on the particles, which turned out to be crucial to making the effect work. “We performed experiments at varying humidities from 5 percent to 95 percent,” Panat says. “As long as the ambient humidity is greater than 30 percent, you can remove almost all of the particles from the surface, but as humidity decreases, it becomes harder.”
Varanasi says that “the good news is that when you get to 30 percent humidity, most deserts actually fall in this regime.” And even those that are typically drier than that tend to have higher humidity in the early morning hours, leading to dew formation, so the cleaning could be timed accordingly.
“Moreover, unlike some of the prior work on electrodynamic screens, which actually do not work at high or even moderate humidity, our system can work at humidity even as high as 95 percent, indefinitely,” Panat says.
In practice, at scale, each solar panel could be fitted with railings on each side, with an electrode spanning across the panel. A small electric motor, perhaps using a tiny portion of the output from the panel itself, would drive a belt system to move the electrode from one end of the panel to the other, causing all the dust to fall away. The whole process could be automated or controlled remotely. Alternatively, thin strips of conductive transparent material could be permanently arranged above the panel, eliminating the need for moving parts.
By eliminating the dependency on trucked-in water, eliminating the buildup of dust that can contain corrosive compounds, and lowering the overall operational costs, such systems have the potential to significantly improve the overall efficiency and reliability of solar installations, Varanasi says.
The research was supported by Italian energy firm Eni. S.p.A. through the MIT Energy Initiative.
Target Corporation (NYSE: TGT) today announced its most sustainable store to date, as the site will generate more renewable energy than it needs annually to operate and will test multiple innovations to reduce the building’s emissions. The Vista, California, store’s retrofit and new features will inform Target’s investments in new stores and remodel programs that support its long-term growth and help guide the retailer’s efforts to achieve its sustainability goals.
The store will generate renewable energy through 3,420 solar panels across its roof and newly installed carport canopies. The site is expected to produce up to a 10% energy surplus each year that it can transmit back to the local power grid, and Target has applied for net-zero energy certification from the International Living Future Institute. The building also features elements to further reduce emissions, such as powering its HVAC heating through rooftop solar panels, instead of natural gas. Additionally, the store switched to carbon dioxide refrigeration, a natural refrigerant, that Target will scale chain-wide by 2040 to reduce its direct operations’ emissions by 20%.
“We’ve been working for years at Target to shift toward sourcing more renewable energy and further reducing our carbon footprint, and our Vista store’s retrofit is the next step in our sustainability journey and a glimpse of the future we’re working toward,” said John Conlin, senior vice president of properties, Target. “Our new stores and remodel programs are designed to help achieve our sustainability goals as we test, learn and scale our innovations over time across our operations.”
Sustainability Efforts Underway
Target is building on the many ways it innovates through its stores and facilities to support the company’s sustainability strategy Target Forward. The retailer has committed to achieving net-zero greenhouse gas emissions enterprise-wide by 2040, and since 2017 Target has already reduced its direct operations’ emissions by nearly 27%. One of the ways it intends to reach its net-zero goal is through sourcing 100% of its electricity from renewable sources for its operations by 2030.
Progress in action: Target’s offsite solar and wind energy contracts are helping the company move quickly toward its renewable energy goal, as it has secured additional partnerships that will allow it to purchase nearly half of its electricity from renewable sources later this year. Target also conserves 10% of its stores’ total energy use by using LED lighting instead of conventional lighting.
Industry leader: Target continues to be a retail leader in solar with more than 25% of its facilities with rooftop solar, helping the company save millions annually in energy costs and reducing its emissions. Its Vista store is one of 542 Target buildings nationwide with solar installations, and the Solar Energy Industries Association (SEIA) recognizes Target as the top U.S. Corporate Onsite Installer with 255 megawatts of energy.
Ongoing investments: The recycling, donations and composting operations at the Vista store, alongside Target’s other facilities, support the retailer’s goal to divert 90% of its U.S. operations’ waste away from landfills by 2030 as it aims for Zero Waste certification. Target is already diverting 80% of its operational waste. Additionally, the Vista site offers electric vehicle charging spaces, as the retailer provides more than 1,350 spaces at over 150 locations across more than 20 states.
“Target continues to be a top corporate solar user, and we’re excited to see Target double down on its clean energy commitments with new solar carports and energy-efficient buildings through this innovative and sustainable retrofit,” said Abigail Ross Hopper, president, and CEO, Solar Energy Industries Association (SEIA). “We commend the Target team for their leadership and commitment to sustainable operations as the retailer continues to raise the bar for how companies can invest in their business and create a more sustainable future.”
