Solar Energy

Major advance in fabrication of low-cost solar cells also locks up greenhouse gases

Published

3 years ago

June 5, 2021

sarosh

Major advance in fabrication of low-cost solar cells also locks up greenhouse gases

Perovskite solar cells have progressed in recent years with rapid increases in power conversion efficiency (from 3% in 2006 to 25.5% today), making them more competitive with silicon-based photovoltaic cells. However, a number of challenges remain before they can become a competitive commercial technology.

Now a team at the NYU Tandon School of Engineering has developed a process to solve one of them, a bottleneck in a critical step involving p-type doping of organic hole-transporting materials within the photovoltaic cells. The research, “CO2 doping of organic interlayers for perovskite solar cells,” appears in Nature.

Currently, the p-doping process, achieved by the ingress and diffusion of oxygen into the hole transporting layer, is time intensive (several hours to a day), making commercial mass production of perovskite solar cells impractical.

The Tandon team, led by Andre D. Taylor, an associate professor, and Jaemin Kong, a post-doctoral associate, along with Miguel Modestino, assistant professor – all in the Department of Chemical and Biomolecular Engineering – discovered a method of vastly increasing the speed of this key step through the use of carbon dioxide (CO2) instead of oxygen.

In perovskite solar cells, doped organic semiconductors are normally required as charge-extraction interlayers situated between the photoactive perovskite layer and the electrodes. The conventional means of doping these interlayers involves the addition of lithium bis(trifluoromethane)sulfonimide (LiTFSI), a lithium salt, to spiro-OMeTAD, a p-conjugated organic semiconductor widely used for a hole-transporting material in perovskite solar cells. The doping process is then initiated by exposing spiro-OMeTAD:LiTFSI blend films to air and light.

Not only is this method time consuming, it largely depends on ambient conditions. By contrast, Taylor and his team reported a fast and reproducible doping method that involves bubbling a spiro-OMeTAD:LiTFSI solution with CO2 under ultraviolet light. They found that their process rapidly enhanced electrical conductivity of the interlayer by 100 times compared to that of a pristine blend film, which is also approximately 10 times higher than that obtained from an oxygen bubbling process. The CO2 treated film also resulted in stable, high-efficiency perovskite solar cells without any post-treatments.

“Besides shortening the device fabrication and processing time, application of the pre-doped spiro-OMeTAD in perovskite solar cells makes the cells much more stable,” explained Kong, the lead author. “That’s partly because most of the detrimental lithium ions in the spiro-OMeTAD:LiTFSI solution were stabilized as lithium carbonates during the CO2 bubbling process.”

He added that the lithium carbonates end up being filtered out when the investigators spincast the pre-doped solution onto the perovskite layer. “Thus, we can obtain fairly pure doped organic materials for efficient hole transporting layers.”

The team, which included researchers from Samsung, Yale University, Korea Research Institute of Chemical Technology, The Graduate Center of the City University, Wonkwang University, and the Gwangju Institute of Science and Technology also found that the CO2 doping method can be used for p-type doping of other p-conjugated polymers, such as PTAA, MEH-PPV, P3HT, and PBDB-T. According to Taylor the researchers are looking to push the boundary beyond typical organic semiconductors used for solar cells.

“We believe that wide applicability of CO2 doping to various p-conjugated organic molecules stimulates research ranging from organic solar cells to organic light emitting diodes (OLEDs) and organic field effect transistors (OFETs) even to thermoelectric devices that all require controlled doping of organic semiconductors,” Taylor explained, adding that since this process consumes quite a large amount of CO2 gas, it can be also considered for CO2 capture and sequestration studies in the future.

“At a time when governments and companies alike are now looking to reduce CO2 emissions if not de-carbonize, this research offers an avenue for reacting large amounts of CO2 in lithium carbonate to improve next generation solar cells, while removing this greenhouse gas from the atmosphere,” he explained, adding that the idea for this novel approach was a counterintuitive insight from the team’s battery research.

“From our long history of working with lithium oxygen/air batteries we know that lithium carbonate formation from exposure of oxygen electrodes to air is a big challenge because it depletes the battery of lithium ions, which destroys battery capacity.

“In this Spiro doping reaction, however, we are actually exploiting lithium carbonate formation, which binds lithium and prevents it from becoming mobile ions detrimental to the long term stability of the Perovskite solar cell. We are hoping that this CO2 doping technique could be a stepping stone for overcoming existing challenges in organic electronics and beyond.”

Research Report: “CO2 doping of organic interlayers for perovskite solar cells”

Source link

Solar Energy

MIT, Harvard and Mass General lead 408 MW green energy push

Published

1 day ago

November 24, 2024

sarosh

MIT, Harvard and Mass General lead 408 MW green energy push

by Nicole Morell | MIT Office of Sustainability

Boston MA (SPX) Nov 25, 2024

MIT is co-leading an effort to enable the development of two new large-scale renewable energy projects in regions with carbon-intensive electrical grids: Big Elm Solar in Bell County, Texas, came online this year, and the Bowman Wind Project in Bowman County, North Dakota, is expected to be operational in 2026. Together, they will add a combined 408 megawatts (MW) of new renewable energy capacity to the power grid. This work is a critical part of MIT’s strategy to achieve its goal of net-zero carbon emissions by 2026.

The Consortium for Climate Solutions, which includes MIT and 10 other Massachusetts organizations, seeks to eliminate close to 1 million metric tons of greenhouse gases each year – more than five times the annual direct emissions from MIT’s campus – by committing to purchase an estimated 1.3-million-megawatt hours of new solar and wind electricity generation annually.

“MIT has mobilized on multiple fronts to expedite solutions to climate change,” says Glen Shor, executive vice president and treasurer. “Catalyzing these large-scale renewable projects is an important part of our comprehensive efforts to reduce carbon emissions from generating energy. We are pleased to work in partnership with other local enterprises and organizations to amplify the impact we could achieve individually.”

The two new projects complement MIT’s existing 25-year power purchase agreement established with Summit Farms in 2016, which enabled the construction of a roughly 650-acre, 60 MW solar farm on farmland in North Carolina, leading to the early retirement of a coal-fired plant nearby. Its success has inspired other institutions to implement similar aggregation models.

A collective approach to enable global impact

MIT, Harvard University, and Mass General Brigham formed the consortium in 2020 to provide a structure to accelerate global emissions reductions through the development of large-scale renewable energy projects – accelerating and expanding the impact of each institution’s greenhouse gas reduction initiatives. As the project’s anchors, they collectively procured the largest volume of energy through the aggregation.

The consortium engaged with PowerOptions, a nonprofit energy-buying consortium, which offered its members the opportunity to participate in the projects. The City of Cambridge, Beth Israel Lahey, Boston Children’s Hospital, Dana-Farber Cancer Institute, Tufts University, the Mass Convention Center Authority, the Museum of Fine Arts, and GBH later joined the consortium through PowerOptions.

The consortium vetted over 125 potential projects against its rigorous project evaluation criteria. With faculty and MIT stakeholder input on a short list of the highest-ranking projects, it ultimately chose Bowman Wind and Big Elm Solar. Collectively, these two projects will achieve large greenhouse gas emissions reductions in two of the most carbon-intensive electrical grid regions in the United States and create clean energy generation sources to reduce negative health impacts.

“Enabling these projects in regions where the grids are most carbon-intensive allows them to have the greatest impact. We anticipate these projects will prevent two times more emissions per unit of generated electricity than would a similar-scale project in New England,” explains Vice President for Campus Services and Stewardship Joe Higgins.

By all consortium institutions making significant 15-to-20-year financial commitments to buy electricity, the developer was able to obtain critical external project financing to build the projects. Owned and operated by Apex Clean Energy, the projects will add new renewable electricity to the grid equivalent to powering 130,000 households annually, displacing over 950,000 metric tons of greenhouse gas emissions each year from highly carbon-intensive power plants in the region.

Complementary decarbonization work underway

In addition to investing in offsite renewable energy projects, many consortium members have developed strategies to reduce and eliminate their own direct emissions. At MIT, accomplishing this requires transformative change in how energy is generated, distributed, and used on campus. Efforts underway include the installation of solar panels on campus rooftops that will increase renewable energy generation four-fold by 2026; continuing to transition our heat distribution infrastructure from steam-based to hot water-based; utilizing design and construction that minimizes emissions and increases energy efficiency; employing AI-enabled sensors to optimize temperature set points and reduce energy use in buildings; and converting MIT’s vehicle fleet to all-electric vehicles while adding more electric car charging stations.

The Institute has also upgraded the Central Utilities Plant, which uses advanced co-generation technology to produce power that is up to 20 percent less carbon-intensive than that from the regional power grid. MIT is charting the course toward a next-generation district energy system, with a comprehensive planning initiative to revolutionize its campus energy infrastructure. The effort is exploring leading-edge technology, including industrial-scale heat pumps, geothermal exchange, micro-reactors, bio-based fuels, and green hydrogen derived from renewable sources as solutions to achieve full decarbonization of campus operations by 2050.

“At MIT, we are focused on decarbonizing our own campus as well as the role we can play in solving climate at the largest of scales, including supporting a cleaner grid in line with the call to triple renewables globally by 2030. By enabling these large-scale renewable projects, we can have an immediate and significant impact of reducing emissions through the urgently needed decarbonization of regional power grids,” says Julie Newman, MIT’s director of sustainability.

+ Fast Forward: MIT’s Climate Action Plan for the Decade

Source link

Solar Energy

Engineers develop additive for affordable renewable energy storage

Published

1 day ago

November 24, 2024

sarosh

Engineers develop additive for affordable renewable energy storage

by Clarence Oxford

Los Angeles CA (SPX) Nov 25, 2024

Advancing the promise of renewable energy sources like solar and wind, University of Wisconsin – Madison researchers have designed a water-soluble chemical additive to improve bromide-based aqueous flow batteries. This innovation addresses critical challenges in energy storage, paving the way for safer and more cost-effective solutions.

“Bromide-based aqueous flow batteries are a promising solution, but there are many messy electrochemical problems with them. That’s why there’s no real successful bromide-based products today,” said Patrick Sullivan, a UW – Madison PhD graduate in chemistry. “Yet, our one additive can solve so many different problems.”

Sullivan, alongside PhD student Gyohun Choi and Assistant Professor Dawei Feng, engineered the additive to enhance battery performance and efficiency. The team’s findings were published in ‘Nature’ on October 23, 2024.

Aqueous Flow Batteries: A Safer Alternative

While lithium-ion batteries are widely used for grid-scale energy storage, their limitations include safety risks, such as fires and explosions, and reliance on a fragile international supply chain. By contrast, aqueous flow batteries, which use water-based electrolytes, offer scalability, sustainability, and improved safety.

The most established flow batteries rely on expensive and scarce vanadium ions. Bromide, a less costly and more abundant alternative, has similar theoretical performance potential. However, bromide-based batteries face practical obstacles. Bromide ions often escape through the membrane, lowering efficiency, or precipitate into an oily residue that disrupts functionality. Worse, the ions can form toxic bromine gas, raising safety concerns.

Solving Challenges with Molecular Engineering

To tackle these issues, Choi and the team developed over 500 molecular candidates, narrowing them to 13 engineered “soft-hard zwitterionic trappers.” These multifunctional additives proved highly effective in resolving bromide flow battery problems.

The additive encapsulates bromide ions, preventing them from passing through the membrane while maintaining their water solubility. It also stabilizes the ions, avoiding the formation of residue or harmful gases. The results have been remarkable. “Our devices with the additive functioned without decay for almost two months compared to ones without it, which typically fail within a day,” Feng explained.

This improvement significantly extends the operational life of the battery, a key factor for renewable energy storage systems designed for long-term use.

Looking Ahead

Choi plans to delve deeper into the science behind additives for halide flow batteries, while Sullivan, now CEO of renewable energy startup Flux XII, will work on scaling the additive for industrial applications. Early tests indicate the additive is viable for large-scale production.

The innovation marks an important step toward achieving reliable and affordable energy storage solutions, a critical component of the renewable energy future.

Research Report:Soft – hard zwitterionic additives for aqueous halide flow batteries

Source link

Solar Energy

Atomic-6 partners with Starpath Robotics for Lunar Power Tower development

Published

1 day ago

November 24, 2024

sarosh

Atomic-6 partners with Starpath Robotics for Lunar Power Tower development

by Erica Marchand

Paris, France (SPX) Nov 25, 2024

Atomic-6 has entered into a development contract with Starpath Robotics to design and build a deployable composite boom for Starpath’s advanced solar power generation system. This collaboration brings together Atomic-6’s innovative composite manufacturing techniques and Starpath’s vision for lunar infrastructure development.

Starpath Robotics is working to establish robotic mining operations on the Moon, aiming to produce hundreds of tons of liquid oxygen annually for use in refueling and space industry applications. Long-term plans include scaling up production to tens of thousands of tons annually to support broader space exploration initiatives.

Saurav Shroff, CEO of Starpath Robotics, emphasized the importance of the project: “The Power Tower’s deployable mast is a challenging component to manufacture. A stiff, reliable, and lightweight mast is important in optimizing power-per-mast and, equally importantly, increasing the visible land area on the Moon that can be serviced by high-data-rate long-range communication systems at the top of the tower. In the not-so-distant future, tens, and then hundreds, and then thousands, of Power Towers establish cislunar capabilities suited for a multiplanetary species. To give a size perspective, the Power Tower will be a colossal structure, equivalent to almost one and a half NBA regulation size basketball courts!”

Atomic-6’s Space Mast technology, offering a 15% increase in specific strength compared to traditional composites, is a key enabler of this initiative. The company’s experience with high-performance composites, demonstrated in USAF STTR projects and its Light Wing solar arrays, positions it as a critical partner in this lunar endeavor.

The collaboration aims to deliver and evaluate a high-performance composite mast for the Power Tower. A successful outcome could lead to a follow-on contract to mass-produce and deploy the system on the Moon, with operational testing anticipated by 2026. This project aligns with Starpath’s mission to cut the costs of deep space missions and supports NASA’s Artemis Program goal of establishing a long-term human presence on the Moon.