Solar power moves a step closer to parity

Space solar power promises wireless energy from orbital solar satellites via microwave or laser power beaming, using photovoltaics and rectennas. NRL and AFRL advances hint at 24-7 renewable power delivery to Earth and airborne drones.

Key Points

Space solar power beams orbital solar energy to Earth via microwaves or lasers, enabling continuous wireless electricity.

✅ Harvests sunlight in orbit and transmits via microwaves or lasers

✅ Provides 24-7 renewable power, independent of weather or night

✅ Enables wireless power for remote sites, grids, and drones

Earlier this year, a small group of spectators gathered in David Taylor Model Basin, the Navy’s cavernous indoor wave pool in Maryland, to watch something they couldn’t see. At each end of the facility there was a 13-foot pole with a small cube perched on top. A powerful infrared laser beam shot out of one of the cubes, striking an array of photovoltaic cells inside the opposite cube. To the naked eye, however, it looked like a whole lot of nothing. The only evidence that anything was happening came from a small coffee maker nearby, which was churning out “laser lattes” using only the power generated by the system as ambitions for cheap abundant electricity gain momentum worldwide.

The laser setup managed to transmit 400 watts of power—enough for several small household appliances—through hundreds of meters of air without moving any mass. The Naval Research Lab, which ran the project, hopes to use the system to send power to drones during flight. But NRL electronics engineer Paul Jaffe has his sights set on an even more ambitious problem: beaming solar power to Earth from space. For decades the idea had been reserved for The Future, but a series of technological breakthroughs and a massive new government research program suggest that faraway day may have finally arrived as interest in space-based solar broadens across industry and government.

Since the idea for space solar power first cropped up in Isaac Asimov’s science fiction in the early 1940s, scientists and engineers have floated dozens of proposals to bring the concept to life, including inflatable solar arrays and robotic self-assembly. But the basic idea is always the same: A giant satellite in orbit harvests energy from the sun and converts it to microwaves or lasers for transmission to Earth, where it is converted into electricity. The sun never sets in space, so a space solar power system could supply renewable power to anywhere on the planet, day or night, as recent tests show we can generate electricity from the night sky as well, rain or shine.

Like fusion energy, space-based solar power seemed doomed to become a technology that was always 30 years away. Technical problems kept cropping up, cost estimates remained stratospheric, and as solar cells became cheaper and more efficient, and storage improved with cheap batteries, the case for space-based solar seemed to be shrinking.

That didn’t stop government research agencies from trying. In 1975, after partnering with the Department of Energy on a series of space solar power feasibility studies, NASA beamed 30 kilowatts of power over a mile using a giant microwave dish. Beamed energy is a crucial aspect of space solar power, but this test remains the most powerful demonstration of the technology to date. “The fact that it’s been almost 45 years since NASA’s demonstration, and it remains the high-water mark, speaks for itself,” Jaffe says. “Space solar wasn’t a national imperative, and so a lot of this technology didn’t meaningfully progress.”

John Mankins, a former physicist at NASA and director of Solar Space Technologies, witnessed how government bureaucracy killed space solar power development firsthand. In the late 1990s, Mankins authored a report for NASA that concluded it was again time to take space solar power seriously and led a project to do design studies on a satellite system. Despite some promising results, the agency ended up abandoning it.

In 2005, Mankins left NASA to work as a consultant, but he couldn’t shake the idea of space solar power. He did some modest space solar power experiments himself and even got a grant from NASA’s Innovative Advanced Concepts program in 2011. The result was SPS-ALPHA, which Mankins called “the first practical solar power satellite.” The idea, says Mankins, was “to build a large solar-powered satellite out of thousands of small pieces.” His modular design brought the cost of hardware down significantly, at least in principle.

Jaffe, who was just starting to work on hardware for space solar power at the Naval Research Lab, got excited about Mankins’ concept. At the time he was developing a “sandwich module” consisting of a small solar panel on one side and a microwave transmitter on the other. His electronic sandwich demonstrated all the elements of an actual space solar power system and, perhaps most important, it was modular. It could work beautifully with something like Mankins' concept, he figured. All they were missing was the financial support to bring the idea from the laboratory into space.

Jaffe invited Mankins to join a small team of researchers entering a Defense Department competition, in which they were planning to pitch a space solar power concept based on SPS-ALPHA. In 2016, the team presented the idea to top Defense officials and ended up winning four out of the seven award categories. Both Jaffe and Mankins described it as a crucial moment for reviving the US government’s interest in space solar power.

They might be right. In October, the Air Force Research Lab announced a $100 million program to develop hardware for a solar power satellite. It’s an important first step toward the first demonstration of space solar power in orbit, and Mankins says it could help solve what he sees as space solar power’s biggest problem: public perception. The technology has always seemed like a pie-in-the-sky idea, and the cost of setting up a solar array on Earth is plummeting, as proposals like a tenfold U.S. solar expansion signal rapid growth; but space solar power has unique benefits, chief among them the availability of solar energy around the clock regardless of the weather or time of day.

It can also provide renewable energy to remote locations, such as forward operating bases for the military, which has deployed its first floating solar array to bolster resilience. And at a time when wildfires have forced the utility PG&E to kill power for thousands of California residents on multiple occasions, having a way to provide renewable energy through the clouds and smoke doesn’t seem like such a bad idea. (Ironically enough, PG&E entered a first-of-its-kind agreement to buy space solar power from a company called Solaren back in 2009; the system was supposed to start operating in 2016 but never came to fruition.)

“If space solar power does work, it is hard to overstate what the geopolitical implications would be,” Jaffe says. “With GPS, we sort of take it for granted that no matter where we are on this planet, we can get precise navigation information. If the same thing could be done for energy, especially as peer-to-peer energy sharing matures, it would be revolutionary.”

Indeed, there seems to be an emerging race to become the first to harness this technology. Earlier this year China announced its intention to become the first country to build a solar power station in space, and for more than a decade Japan has considered the development of a space solar power station to be a national priority. Now that the US military has joined in with a $100 million hardware development program, it may only be a matter of time before there’s a solar farm in the solar system.

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California Heatwave Power Crisis strains CAISO as record demand triggers emergency alerts, demand response, and rolling blackout warnings. PG&E prepares outages while solar fades at peak, drought cuts hydropower, and reliability hinges on conservation.

Key Points

Extreme heat driving record demand in California, straining CAISO and prompting conservation to avert rolling blackouts.

✅ CAISO hit a record 52 GW peak load amid triple-digit heat

✅ Emergency alerts spurred demand response, cutting load spikes

✅ Solar drop and drought-weakened hydro worsened evening shortfall

California narrowly avoided blackouts for a second successive day even as blistering temperatures pushed electricity demand to a record and stretched the state’s power grid close to its limits.

The state imposed its highest level of energy emergency for several hours late Tuesday and urged consumers to turn off lights, curb air conditioners and shut off power-hungry appliances after a day of extraordinary stress on electricity infrastructure as temperatures in many regions topped 110 degrees Fahrenheit (43 Celsius).

Electricity use had reached 52 gigawatts Tuesday, easily breaking a record that stood since 2006, according to the California Independent System Operator. The state issued emergency alerts direct to cell phones in several counties asking for immediate power conservation, and grid data show that demand plunged in response. Emergency measures were finally lifted at about 9 p.m. local time.

Much of California remains under an excessive heat warning through Friday, with authorities already preparing for more severe pressure on the power system on Wednesday amid a looming supply shortage across the grid. “We aren’t out of the woods yet,” Governor Gavin Newsom said in a message posted on his office’s Twitter account. “We will see continued extreme temps this week and if we rallied today, we can do it again.”

The state’s largest power company, PG&E Corp. said earlier Tuesday that it had notified about 525,000 homes and businesses that they could lose power for up to two hours. That warning came as temperatures in downtown Sacramento hit 116 degrees Fahrenheit, topping a previous 1925 record.

Newsom earlier signed an executive order extending until Friday emergency measures to free up additional power supplies, rather than allowing them to expire as planned on Wednesday. Many state buildings were ordered to power down lights and air conditioning at 4 p.m., and he urged residents and businesses to conserve the equivalent of 3 gigawatts of power in order to stave off blackouts. 

California's Early Brush With Blackouts Bodes Ill For Days Ahead
The downtown skyline during a heatwave in Los Angeles.Photographer: Eric Thayer/Bloomberg
California faced a similar energy emergency Monday, which was alleviated in part by activating temporary gas-fired power plants operated by the California Department of Water Resources. The current heat wave, which began in the last week of August, is remarkable in both its ferocity and duration, according to officials. 

The prospect of outages underscores how grids have become vulnerable in the face of extreme weather as California transitions from fossil fuels to renewable energy, an approach it is increasingly exporting to Western states as well. California's climate policies have aggressively closed natural-gas power plants in recent years, leaving the state increasingly dependent on solar farms that go dark late in the day just as electricity demand peaks. At the same time, the state is enduring the Southwest’s worst drought in 1,200 years, sapping hydropower production.

The average 15-minute wholesale power price in Caiso surged to $1,806 a megawatt-hour at 4:45 p.m. local time, according to the grid operator’s website.

Average day-ahead prices top $300 a megawatt-hour in Southern California
  
A break from the heat will come across Southern California later this week, thanks to Tropical Storm Kay in the Pacific Ocean, according to weather officials. Kay is forecast to edge up the coastline of Mexico’s Baja California peninsula. As it moves north, the storm will pump moisture and clouds into Southern California and Arizona, taking an edge off the heat.

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Canada Clean Electricity Expansion is urged by the IEA to meet net-zero targets, scaling non-emitting generation, electrification, EV demand, and grid integration across provinces to decarbonize industry, buildings, and transport while ensuring reliability and affordability.

Key Points

An IEA-backed pathway for Canada to scale non-emitting power, electrification, and grid links to meet net-zero goals.

✅ Double or triple clean generation to replace fossil fuels

✅ Integrate provincial grids to decarbonize dependent regions

✅ Manage EV and heating loads with reliability and affordability

Canada will need more electricity capacity if it wants to hit its climate targets, and cleaning up Canada's electricity will be critical, according to a new report from the International Energy Agency (IEA).

The report offers mainly a rosy picture of Canada's overall federal energy policy. But, the IEA draws attention to Canada's increasing future electricity demands, and ultimately, calls on Canada to leverage its non-emitting energy potential and expand renewable energy to hit its climate targets.  

"Canada's wealth of clean electricity and its innovative spirit can help drive a secure and affordable transformation of its energy system and help realize its ambitious goals," stated Fatih Birol, the IEA executive director, in a news release.

The IEA notes that Canada has one of the cleanest energy grids globally, with 83 per cent of electricity coming from non-emitting sources in 2020. But this reflects nationwide progress in electricity to date; the report warns this is not a reason for Canada to rest on its laurels. More electricity will be needed to displace fossil fuels if Canada wants to hit its 2030 targets, the report states, and "even deeper cuts" will be required to reach net-zero by 2050.

"Perhaps more significantly, however, Canada will need to ensure sufficient new clean generation capacity to meet the sizeable levels of electrification that its net-zero targets imply."

Investing in new coal, oil and gas projects must stop to hit climate goals, global energy agency says
The Liberals have promised to create a 100 percent net-zero-emitting electricity system by 2035, with regulating oil and gas emissions and electric car sales as part of the plan; by then, every new light-duty vehicle sold in Canada will be a zero-emission vehicle. The switch from gas guzzlers to plug-in electric vehicles will create new pressures on Canada's electrical grid, as will any turn away from fossil natural gas for home heating.

To meet these challenges, the IEA warns, Canada would need to double or triple the power generated from non-emitting sources compared to today, a shift whose cost could reach $1.4 trillion according to the Canadian Gas Association. 

"Such a shift will require significant regulatory action," the report states, highlighting the need for climate policy for electricity grids to guide implementation, and that will require the federal government to work closely with provinces and territories that control power generation and distribution.

The report notes that the further integration of territorial and provincial electrical grids could allow fossil fuel-dependent provinces, like Alberta, to decarbonize and electrify their economies.

The report, entitled Canada 2022 Energy Policy Review, offers what it calls an "in-depth" look at the commitments Canada has made to transform its energy policy. Since the IEA conducted its last review in 2015, Canada has committed to cutting greenhouse gas emissions by 40 to 45 per cent from 2005 levels by 2030 and achieving net-zero by 2050 under an extended national target.

The IEA is well-known for the production of its annual World Energy Outlook. The Paris-based autonomous intergovernmental organization provides analysis, data, and policy recommendations to promote global energy security and sustainability. Canada is a part of the intergovernmental body, which also conducts peer reviews of its members' energy policy.

Oil and gas emissions rising
Natural Resources Minister Jonathan Wilkinson responded to the report in the IEA news release.

"This report acknowledges Canada's ambitious efforts and historic investments to develop pathways to achieve net-zero emissions by 2050 and ensure a transition that aligns with our shared objective of limiting global warming to 1.5 degrees Celsius," Wilkinson's statement read.

The report notes that — despite that objective — absolute emissions from Canadian oil and gas extraction went up 26 per cent between 2000 and 2019, largely from increased production.

Minister of Natural Resources Jonathan Wilkinson responds to a question at a news conference after the federal cabinet was sworn in, in Ottawa, on Oct. 26, 2021. (Justin Tang/The Canadian Press)
"Canada will need to reconcile future growth in oil sands production with increasingly strict greenhouse gas requirements," the report states.

On the plus side, the IEA found emissions per barrel of oilsands crude have decreased by 20 per cent in the last decade from technical and operational improvements.

The improving carbon efficiency of the oilsands is a "trend that is expected to continue at even higher rates," said Ben Brunnen, vice-president of oilsands, fiscal and economic policy at the Canadian Association of Petroleum Producers.

That may become important, the IEA report notes, as energy investors and buyers look for low-carbon assets and more countries adopt net-zero policies.

Further innovation, such as carbon capture and storage, could help to turn things around for Canada's oil patch, the report says. The Liberals have also said they will place a hard cap on oil and gas emissions from production, but that does not include the burning of the fossil fuels. 

In 2021, the IEA released a report that determined to achieve net-zero by 2050, among many steps, investments needed to end in coal mines, oil and gas wells. Thursday's report, however, made no mention of that, which disappointed at least one environmental group.

"A glaring omission was that this assessment says nothing about production. We know that the most important thing we can do is to stop using and producing oil and gas," said Julia Levin, a senior climate and energy program manager at Environmental Defence.

"And yet that was absent from this report, and that really is a glaring omission, which is completely out of line with their [the IEA's] own work."

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Eviation Collapse underscores electric aviation headwinds, from Alice aircraft battery limits to FAA/EASA certification hurdles, funding shortfalls, and leadership instability, reshaping sustainability roadmaps for regional airliners and future zero-emission flight.

Key Points

Eviation Collapse is the 2025 shutdown of Eviation Aircraft, revealing battery, certification, and funding hurdles.

✅ Battery energy density limits curtailed Alice's range

✅ FAA/EASA certification timelines delayed commercialization

✅ Funding gaps and leadership churn undermined execution

The electric aviation industry was poised to revolutionize the skies through an aviation revolution with startups like Eviation Aircraft leading the charge to bring environmentally friendly, cost-efficient electric airplanes into commercial use. However, in a shocking turn of events, Eviation has faced an abrupt collapse, signaling challenges that may impact the future of electric flight.

Eviation’s Vision and Early Promise

Founded in 2015, Eviation was an ambitious electric airplane startup with the goal of changing the way the world thinks about aviation. The company’s flagship product, the Alice aircraft, was designed to be an all-electric regional airliner capable of carrying up to 9 passengers. With a focus on sustainability, reduced operating costs, and a quieter flight experience, Alice attracted attention as one of the most promising electric aircraft in development.

Eviation’s aircraft was aimed at replacing small, inefficient, and environmentally damaging regional aircraft, reducing emissions in the aviation industry. The startup’s vision was bold: to create an airplane that could offer all the benefits of electric power – lower operating costs, less noise, and a smaller environmental footprint. Their goal was not only to attract major airlines but also to pave the way for a more sustainable future in aviation.

The company’s early success was driven by substantial investments and partnerships. It garnered attention from aviation giants and venture capitalists alike, drawing support for its innovative technology. In fact, in 2019, Eviation secured a deal with the Israeli airline, El Al, for several aircraft, a deal that seemed to promise a bright future for the company.

Challenges in the Electric Aviation Industry

Despite its early successes and strong backing, Eviation faced considerable challenges that eventually contributed to its downfall. The electric aviation sector, as promising as it seemed, has always been riddled with hurdles – from battery technology to regulatory approvals, and compounded by Europe’s EV slump that dampened clean-transport sentiment, the path to producing commercially viable electric airplanes has proven more difficult than initially anticipated.

The first major issue Eviation encountered was the slow development of battery technology. While electric car companies like Tesla were able to scale their operations quickly during the electric vehicle boom due to advancements in battery efficiency, aviation technology faced a more significant obstacle. The energy density required for a plane to fly long distances with sufficient payload was far greater than what existing battery technology could offer. This limitation severely impacted the range of the Alice aircraft, preventing it from meeting the expectations set by its creators.

Another challenge was the lengthy regulatory approval process for electric aircraft. Aviation is one of the most regulated industries in the world, and getting a new aircraft certified for flight takes time and rigorous testing. Although Eviation’s Alice was touted as an innovative leap in aviation technology, the company struggled to navigate the complex process of meeting the safety and operational standards required by aviation authorities, such as the FAA and EASA.

Financial Difficulties and Leadership Changes

As challenges mounted, Eviation’s financial situation became increasingly precarious. The company struggled to secure additional funding to continue its development and scale operations. Investors, once eager to back the promising startup, grew wary as timelines stretched and costs climbed, amid a U.S. EV market share dip in early 2024, tempering enthusiasm. With the electric aviation market still in its early stages, Eviation faced stiff competition from more established players, including large aircraft manufacturers like Boeing and Airbus, who also began to invest heavily in electric and hybrid-electric aircraft technologies.

Leadership instability also played a role in Eviation’s collapse. The company went through several executive changes over a short period, and management’s inability to solidify a clear vision for the future raised concerns among stakeholders. The lack of consistent leadership hindered the company’s ability to make decisions quickly and efficiently, further exacerbating its financial challenges.

The Sudden Collapse

In 2025, Eviation made the difficult decision to shut down its operations. The company announced the closure after failing to secure enough funding to continue its development and meet its ambitious production goals. The sudden collapse of Eviation sent shockwaves through the electric aviation sector, where many had placed their hopes on the startup’s innovative approach to electric flight.

The failure of Eviation has left many questioning the future of electric aviation. While the industry is still in its infancy, Eviation’s downfall serves as a cautionary tale about the challenges of bringing cutting-edge technology to the skies. The ambitious vision of a sustainable, electric future in aviation may still be achievable, but the path to success will require overcoming significant technological, regulatory, and financial obstacles.

What’s Next for Electric Aviation?

Despite Eviation’s collapse, the electric aviation sector is far from dead. Other companies, such as Joby Aviation, Vertical Aerospace, and Ampaire, are continuing to develop electric and hybrid-electric aircraft, building on milestones like Canada’s first commercial electric flight that signal ongoing demand for green alternatives to traditional aviation.

Moreover, major aircraft manufacturers are doubling down on their own electric aircraft projects. Boeing, for example, has launched several initiatives aimed at reducing carbon emissions in aviation, while Harbour Air’s point-to-point e-seaplane flight showcases near-term regional progress, and Airbus is testing a hybrid-electric airliner prototype. The collapse of Eviation may slow down progress, but it is unlikely to derail the broader movement toward electric flight entirely.

The lessons learned from Eviation’s failure will undoubtedly inform the future of the electric aviation sector. Innovation, perseverance, and a steady stream of investment will be critical for the success of future electric aircraft startups, as exemplified by Harbour Air’s research-driven electric aircraft efforts that highlight the value of sustained R&D. While the dream of electric planes may have suffered a setback, the long-term vision of cleaner, more sustainable aviation is still alive.

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Calgary EV Charging for Apartments and Condos streamlines permitting for multi-unit dwellings, guiding condo boards and property managers to install EV charging stations, expand infrastructure, and advance sustainability with cleaner air and lower emissions.

Key Points

A Calgary program simplifying permits and guidance to add EV charging stations in multi-unit residential buildings.

✅ Streamlined permitting for condo boards and property managers

✅ Technical assistance to install EV charging stations

✅ Boosts property value and reduces emissions citywide

As the demand for electric vehicles (EVs) continues to rise, and as national EV targets gain traction, Calgary is taking significant strides to enhance its charging infrastructure, particularly in apartment and condominium complexes. A recent initiative has been introduced to facilitate the installation of EV charging stations in these residential buildings, addressing a critical barrier for potential EV owners living in multi-unit dwellings.

The Growing EV Market

Electric vehicles are no longer a niche market; they have become a mainstream option for many consumers. As of late 2023, EV sales have surged, with projections indicating that the trend will only continue. However, a significant challenge remains for those who live in apartments and condos, where high-rise charging can be a mixed experience and the lack of accessible charging stations persists. Unlike homeowners with garages, residents of multi-unit dwellings often rely on public charging infrastructure, which can be inconvenient and limiting.

The New Initiative

In response to this growing concern, the City of Calgary has launched a new initiative aimed at easing the process of installing EV chargers in apartment and condo buildings. This program is designed to streamline the permitting process, reduce red tape, and provide clear guidelines for property managers and condo boards, similar to strata installation rules adopted in other jurisdictions to ease installations.

The initiative includes various measures, such as providing technical assistance and resources to building owners and managers. By simplifying the installation process, the city hopes to encourage more residential complexes to adopt EV charging stations. The initiative also emphasizes practical support, such as providing technical assistance, including condo retrofit guidance, and resources to building owners and managers. This is a significant step towards creating an eco-friendly urban environment and meeting the growing demand for sustainable transportation options.

Benefits of the Initiative

The benefits of this initiative are manifold. Firstly, it supports Calgary's broader climate goals by promoting electric vehicle adoption. As more residents gain access to charging stations, the city can expect a corresponding reduction in greenhouse gas emissions, contributing to cleaner air and a healthier urban environment.

Additionally, providing charging infrastructure can enhance property values. Buildings equipped with EV chargers become more attractive to potential tenants and buyers who prioritize sustainability. As the market for electric vehicles expands, properties that offer charging facilities are likely to see increased demand, making them a sound investment for landlords and developers.

Overcoming Challenges

While this initiative marks a positive step forward, there are still challenges to address. Property managers and condo boards may face initial resistance from residents who are uncertain about the costs associated with installing and maintaining EV chargers, though rebates for home and workplace charging can offset upfront expenses and ease adoption. Clear communication about the long-term benefits, including potential energy savings and the value of sustainable living, will be essential in overcoming these hurdles.

Furthermore, the city will need to ensure that the installation of EV chargers is done in a way that is equitable and inclusive. This means considering the needs of all residents, including those who may not own an electric vehicle but would benefit from a greener community.

Looking Ahead

As Calgary moves forward with this initiative, it sets a precedent for other cities, as seen in Vancouver's EV-ready policy, facing similar challenges in promoting electric vehicle adoption. By prioritizing charging infrastructure in multi-unit residential buildings, Calgary is taking important steps towards a more sustainable future.

In conclusion, the push for EV charging stations in apartments and condos is a critical move for Calgary. It reflects a growing recognition of the role that urban planning and infrastructure play in supporting the transition to electric vehicles, which complements corridor networks like the BC Electric Highway for intercity travel. With the right support and resources, Calgary can pave the way for a greener, more sustainable urban landscape that benefits all its residents. As the city embraces this change, it will undoubtedly contribute to a broader shift towards sustainable living, ultimately helping to combat climate change and improve the quality of life for all Calgarians.

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Carbon Nanotube Solvent Electricity enables wire-free electrochemistry as organic solvents like acetonitrile pull electrons, powering alcohol oxidation and packed bed reactors, energy harvesting, and micro- and nanoscale robots via redox-driven current.

Key Points

Solvent-driven electron extraction from carbon nanotube particles generates current for electrochemistry.

✅ 0.7 V per particle via solvent-induced electron flow

✅ Packed bed reactors drive alcohol oxidation without wires

✅ Scalable for micro- and nanoscale robots; energy harvesting

MIT engineers have discovered a new way of generating electricity, alongside advances in renewable power at night that broaden what's possible, using tiny carbon particles that can create a current simply by interacting with liquid surrounding them.

The liquid, an organic solvent, draws electrons out of the particles, generating a current, unlike devices based on a cheap thermoelectric material that rely on heat, that could be used to drive chemical reactions or to power micro- or nanoscale robots, the researchers say.

"This mechanism is new, and this way of generating energy is completely new," says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. "This technology is intriguing because all you have to do is flow a solvent through a bed of these particles. This allows you to do electrochemistry, but with no wires."

In a new study describing this phenomenon, the researchers showed that they could use this electric current to drive a reaction known as alcohol oxidation—an organic chemical reaction that is important in the chemical industry.

Strano is the senior author of the paper, which appears today in Nature Communications. The lead authors of the study are MIT graduate student Albert Tianxiang Liu and former MIT researcher Yuichiro Kunai. Other authors include former graduate student Anton Cottrill, postdocs Amir Kaplan and Hyunah Kim, graduate student Ge Zhang, and recent MIT graduates Rafid Mollah and Yannick Eatmon.

Unique properties
The new discovery grew out of Strano's research on carbon nanotubes—hollow tubes made of a lattice of carbon atoms, which have unique electrical properties. In 2010, Strano demonstrated, for the first time, that carbon nanotubes can generate "thermopower waves." When a carbon nanotube is coated with layer of fuel, moving pulses of heat, or thermopower waves, travel along the tube, creating an electrical current that exemplifies turning thermal energy into electricity in nanoscale systems.

That work led Strano and his students to uncover a related feature of carbon nanotubes. They found that when part of a nanotube is coated with a Teflon-like polymer, it creates an asymmetry, distinct from conventional thermoelectric materials approaches, that makes it possible for electrons to flow from the coated to the uncoated part of the tube, generating an electrical current. Those electrons can be drawn out by submerging the particles in a solvent that is hungry for electrons.

To harness this special capability, the researchers created electricity-generating particles by grinding up carbon nanotubes and forming them into a sheet of paper-like material. One side of each sheet was coated with a Teflon-like polymer, and the researchers then cut out small particles, which can be any shape or size. For this study, they made particles that were 250 microns by 250 microns.

When these particles are submerged in an organic solvent such as acetonitrile, the solvent adheres to the uncoated surface of the particles and begins pulling electrons out of them.

"The solvent takes electrons away, and the system tries to equilibrate by moving electrons," Strano says. "There's no sophisticated battery chemistry inside. It's just a particle and you put it into solvent and it starts generating an electric field."

Particle power
The current version of the particles can generate about 0.7 volts of electricity per particle. In this study, the researchers also showed that they can form arrays of hundreds of particles in a small test tube. This "packed bed" reactor, unlike thin-film waste-heat harvesters for electronics, generates enough energy to power a chemical reaction called an alcohol oxidation, in which an alcohol is converted to an aldehyde or a ketone. Usually, this reaction is not performed using electrochemistry because it would require too much external current.

"Because the packed bed reactor is compact, it has more flexibility in terms of applications than a large electrochemical reactor," Zhang says. "The particles can be made very small, and they don't require any external wires in order to drive the electrochemical reaction."

In future work, Strano hopes to use this kind of energy generation to build polymers using only carbon dioxide as a starting material. In a related project, he has already created polymers that can regenerate themselves using carbon dioxide as a building material, in a process powered by solar energy and informed by devices that generate electricity at night as a complement. This work is inspired by carbon fixation, the set of chemical reactions that plants use to build sugars from carbon dioxide, using energy from the sun.

In the longer term, this approach could also be used to power micro- or nanoscale robots. Strano's lab has already begun building robots at that scale, which could one day be used as diagnostic or environmental sensors. The idea of being able to scavenge energy from the environment, including approaches that produce electricity 'out of thin air' in ambient conditions, to power these kinds of robots is appealing, he says.

"It means you don't have to put the energy storage on board," he says. "What we like about this mechanism is that you can take the energy, at least in part, from the environment."

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