For the first time ever, renewable energy supplied more power to the U.S. electricity grid than coal-fired plants for 47 days straight. The run is impressive because it trounces the previous record of nine continuous days last June and exceeds the total number of days renewables beat coal in all of 2019 (38 days).
In a recent report, the Institute for Energy Economics and Financial Analysis (IEEFA) details how the streak was first observed on 25 March and continued through to 10 May, the day the data was last analyzed.
“We’ll probably track it again at the end of May, so the period could actually be longer,” says Dennis Wamsted, an energy analyst at IEEFA. Already, the figures for April speak volumes: wind, hydropower, and utility-scale solar sources produced 58.7 terawatt-hours (TWh) of electricity compared with coal’s 40.6 TWh—or 22.2% and 15.3% of the market respectively.
In reality, the gap between the two sources is likely to be much larger, says Wamsted. That’s because the U.S. Energy Information Administration (EIA) database, where IEEFA obtains its data from, excludes power generated by rooftop solar panels, which itself is a huge power source.
The news that renewables overtook coal in the month of April isn’t surprising, says Brian Murray, director of the Duke University Energy Initiative. The first time this happened was last year, also in April. The month marks “shoulder season,” he says, “when heating is coming off but air-conditioning hasn’t really kicked in yet.” It’s when electricity demand is typically the lowest, which is why many power plants schedule their yearly maintenance during this time.
Spring is also when wind and hydropower generation peak, says Murray. Various thermal forces come into play with the Sun’s new positioning, and the melting snowpacks feed rivers and fill up reservoirs.
“Normally you would expect some sort of rebound of coal generation in the summer, but I think there’s a variety of reasons why that’s not going to happen this year,” he says. “One has to do with coronavirus.”
With the pandemic placing most of the country in lockdown and economic activity declining, the EIA estimates that U.S. demand for electric power will fall by 5% in 2020. This, in turn, will drive coal production down by a quarter. In contrast, renewables are still expected to grow by 11%. The reason behind this is partly due to how energy is dispatched to the grid. Because of cheaper costs, renewables are used first if available, followed by nuclear power, natural gas, and then finally coal.
Coronavirus aside, the transition has been a long time coming. “Renewables have been on an inexorable rise for the last 10 years, increasingly eating coal’s lunch,” says Mike O’Boyle, director of electricity policy at Energy Innovation, a San Francisco-based think tank. The average coal plant in the U.S. is 40 years old, and these aging, inefficient plants are finding it increasingly difficult to compete against ever-cheaper renewable energy sources.
A decade ago, the average coal plant generated as much as 67% of its capacity. Today, that figure has dropped to 48%. And in the next five years, coal production is expected to fall to two-thirds of 2014 levels—a decline of 90 gigawatts (GW)—as increasing numbers of plants shut.
“And that’s without policy changes that we anticipate will strengthen in the U.S., in which more than a third of people are in a state, city, or utility with a 100% clean energy goal,” says O’Boyle. Already, 30 states have renewable portfolio standards, or policies designed to increase electricity generation from renewable resources.
The transition towards renewables is one that’s being observed all across the world today. Global use of coal-powered electricity fell 3% last year, the biggest drop on record after nearly four decades. In Europe, the figure was 24%. The region has been remarkably progressive in its march towards renewable energy—last month saw both Sweden and Austria closing their last remaining coal plants, while the U.K. went through its longest coal-free stretch (35 days) since the Industrial Revolution more than 230 years ago.
But coal is still king in many parts of the world. For developing countries where electricity can be scarce and unreliable, the fossil fuel is often seen as the best option for power.
The good news, however, is that the world’s two largest consumers of coal are investing heavily in renewables. Although China is still heavily reliant coal, it also boasts the largest capacity of wind, solar, and hydropower in the world today. India, with it abundant sunshine, is pursuing an aggressive solar plan. It is building the world’s largest solar park, and Prime Minister Narendra Modi has pledged that the country will produce 100 GW of solar power—five times what the U.S. generates—by 2022.
Today, renewable energy sources offer the cheapest form of power in two-thirds of the world, and they look set to get cheaper. They now provide up to 30% of global electricity demand, a figure is expected to grow to 50% by 2050. As a recent United Nations report put it: renewables are now “looking all grown up.”
Billions of Internet-connected devices now adorn our walls and ceilings, sensing, monitoring, and transmitting data to smartphones and far-flung servers. As gadgets proliferate, so too does their electricity demand and need for household batteries, most of which wind up in landfills. To combat waste, researchers are devising new types of solar cells that can harvest energy from the indoor lights we’re already using.
The dominant material used in today’s solar cells, crystalline silicon, doesn’t perform as well under lamps as it does beneath the blazing sun. But emerging alternatives—such as perovskite solar cells and dye-sensitized materials—may prove to be significantly more efficient at converting artificial lighting to electrical power.
A group of researchers from Italy, Germany, and Colombia is developing flexible perovskite solar cells specifically for indoor devices. In recent tests, their thin-film solar cell delivered power conversion efficiencies of more than 20 percent under 200 lux, the typical amount of illuminance in homes. That’s about triple the indoor efficiency of polycrystalline silicon, according to Thomas Brown, a project leader and engineering professor at the University of Rome Tor Vergata.
To most of us, windows are little more than glass panes that let light in and keep bad weather out. But to some scientists, windows represent possibility—the chance to take passive parts of a building and transform them into active power generators.
Anthony Chesman is one researcher working to develop such solar windows. “There are a lot of windows in the world that aren’t being used for any other purpose than to allow lighting in and for people to see through,” says Chesman, who is from Australia’s national science agency CSIRO. “But really, there’s a huge opportunity there in turning those windows into a space that can also generate electricity,” he says.
The latest development in “wind-assisted propulsion” comes from Japan. Eco Marine Power (EMP) recently unveiled a full-scale version of its EnergySail system at the Onomichi Marine Tech Test Center in Hiroshima Prefecture. The rigid, rectangular device is slightly curved and can be positioned into the wind to create lift, helping propel vessels forward. Marine-grade solar panels along the face can supply electricity for onboard lighting and equipment.
Greg Atkinson, EMP’s chief technology officer, says the 4-meter-tall sail will undergo shore-based testing this year, in preparation for sea trials. The device will deliver 1-kilowatt in peak solar power, or kWp, though the startup is still evaluating which type of photovoltaic panel to use. The potential sail power is yet to be determined, he says.
The EnergySail is one piece of EMP’s larger technology platform. The Fukuoka-based firm is also developing an integrated system that includes deck-mounted solar panels; recyclable marine batteries; charging systems; and computer programs that automatically rotate sails to capture optimal amounts of wind, or lower the devices when not in use or during bad weather. Atkinson notes that moving an EnergySail (mainly to optimize its wind collection) may affect how much sunlight it receives, though the panels can still collect solar power when lying flat.
The startup’s ultimate goal is to hoist about a dozen EnergySails on a tanker or freighter that has the available deck space. An array of that size could deliver power savings of up to 15 percent, depending on wind conditions and the vessel’s size, models show.
Gavin Allwright, secretary of the International Windship Association, says that figure is in line with projections for other wind-assisted technologies, which can help watercraft achieve between 5 and 20 percent fuel savings compared to typical ships. (EMP is not a member of the association.) For instance, the Finnish company Norsepower recently outfitted a Maersk oil tanker with two spinning rotor sails. The devices lowered the vessel’s fuel useby 8.2 percent on average during a 12-month trial period.
Shipping companies are increasingly investing in clean energy as international regulators move to slash global greenhouse gas emissions. Nearly all commercial cargo ships use oil or gas to carry goods across the globe; together, they contribute up to 3 percent of the world’s total annual fossil fuel emissions. Zero-emission alternatives like hydrogen fuel cells and ammonia-burning engines are still years from commercialization. But wind-assisted propulsion represents a more immediate, if partial, solution.
For its EnergySail unit, EMP partnered with Teramoto Iron Works, which built the first rigid sails in the 1980s. Those devices — called JAMDA sails after the Japan Marine Machinery Development Association—were shown to reduce ships’ fuel use by between 10 to 30 percent on smaller coastal vessels, despite some technical issues. However, the experiment was short-lived. Plunging oil prices eroded the business case for efficiency upgrades, and shipowners later took them down.
EMP is currently talking with several shipowners to start installing its full energy system, potentially later this year. For the sea trial, the startup plans to install a deck-mounted solar array with up to 25 kWp; battery packs; computer systems; and one or two EnergySails. Atkinson says it may take two to three years of testing to verify whether the equipment can weather harsh conditions, including fierce winds and corrosive saltwater.
Separately, EMP has started testing the non-sail portion of its platform. In May 2019, the company installed a 1.2-kWp solar array on a large crane vessel owned by Singaporean carrier Masterbulk. The setup also includes a 3.6-kilowatt-hour VRLA (valve regulated lead acid) battery pack made by Furukawa Battery Co. An onboard monitoring system automatically reports and logs fuel-consumption data in real time and calculates daily emissions of carbon and sulfur dioxide.
EMP previously tested Furukawa’s batteries on a vessel in Greece. During the day, solar panels recharged the batteries, which keep the voltage stable and could directly power the vessel’s lighting load. The batteries could also store the excess solar power to keep the lights on at night. It took the partners about five years of testing to ensure the system was stable.
Atkinson says that, so far, the COVID-19 pandemic hasn’t disrupted the company’s work or halted its plans for the year.
“We can do much of the design work remotely and by using cloud-based applications,” he says. “Also, we can use virtual wind tunnels and [Computer Aided Design] applications for much of the initial design work for the sea trials phase.”
Across the industry, however, the coronavirus outbreak is wreaking economic havoc. Allwright says that shipowner interest in wind-assisted propulsion was “absolutely crazy” until a few weeks ago.“Now, shipping companies are saying, ‘Look, we can’t invest in new technology right now because we’re trying to survive,’” he says.
Still, some technology developers are nonetheless accelerating their design work, in the hopes of launching projects as soon as the industry bounces back. “This pause gives the providers an extra 12 months to get these things tested and ready for action,” Allwright says.
When it comes to renewables, the big question is: How do we store all that energy for use later on? Because such energy is intermittent in nature, storing it when there is a surplus is key to ensuring a continuous supply—for rainy days (literally), at night, or when the wind doesn’t blow.
Using today’s lithium-ion batteries for long-term grid storage isn’t feasible for a number of reasons. For example, they have fixed charge capacities and don’t hold charge well over extended periods of time.
The solution, some propose, is to store energy chemically—in the form of hydrogen fuel—rather than electrically. This involves using devices called electrolyzers that make use of renewable energy to split water into hydrogen and oxygen gas.
Kilometers off the coast of Basque Country in northern Spain, a new twist on offshore wind energy will soon face its final test. The Spanish firm Saitec Engineering made headlines late last year with its distinctive floating turbine concept, and promised to deploy a prototype in April. Last week, that launch took on new significance when Saitec announced a partnership with the renewables division of the German energy titan RWE.
The potential to harvest wind from beyond the shoreline is substantial. “The farther from shore [the wind farm is located], the bigger the wind resource is,” said Luis González-Pinto, chief operating officer of Saitec Offshore Technologies.
Scientists continue to tinker with recipes for turning sunlight into electricity. By testing new materials and components, in varying sizes and combinations, their goal is to produce solar cells that are more efficient and less expensive to manufacture, allowing for wider adoption of renewable energy.
The latest development in that effort comes from researchers in St. Petersburg, Russia. The group recently created a tiny prototype of a high-efficiency solar cell using gallium phosphide and nitrogen. If successful, the cells could nearly double today’s efficiency rates—that is, the degree to which incoming solar energy is converted into electrical power.
The new approach could theoretically achieve efficiencies of up to 45 percent, the scientists said. By contrast, conventional silicon cells are typically less than 20 percent efficient.
A vast supply of heat lies beneath our feet. Yet today’s drilling methods can barely push through dense rocks and high-pressure conditions to reach it. A new generation of “enhanced” drilling systems aims to obliterate those barriers and unlock unprecedented supplies of geothermal energy.
AltaRock Energy is leading an effort to melt and vaporize rocks with millimeter waves. Instead of grinding away with mechanical drills, scientists use a gyrotron—a specialized high-frequency microwave-beam generator—to open holes in slabs of hard rock. The goal is to penetrate rock at faster speeds, to greater depths, and at a lower cost than conventional drills do.
The Seattle-based company recently received a US $3.9 million grant from the U.S. Department of Energy’s Advanced Research Projects Agency–Energy (ARPA-E). The three-year initiative will enable scientists to demonstrate the technology at increasingly larger scales, from burning through hand-size samples to room-size slabs. Project partners say they hope to start drilling in real-world test sites before the grant period ends in September 2022.
AltaRock estimates that just 0.1 percent of the planet’s heat content could supply humanity’s total energy needs for 2 million years. Earth’s core, at a scorching 6,000 °C, radiates heat through layers of magma, continental crust, and sedimentary rock. At extreme depths, that heat is available in constant supply anywhere on the planet. But most geothermal projects don’t reach deeper than 3 kilometers, owing to technical or financial restrictions. Many wells tap heat from geysers or hot springs close to the surface.
That’s one reason why, despite its potential, geothermal energy accounts for only about 0.2 percent of global power capacity, according to the International Renewable Energy Association.
“Today we have an access problem,” says Carlos Araque, CEO of Quaise, an affiliate of AltaRock. “The promise is that, if we could drill 10 to 20 km deep, we’d basically have access to an infinite source of energy.”
The ARPA-E initiative uses technology first developed by Paul Woskov, a senior research engineer at MIT’s Plasma Science and Fusion Center. Since 2008, Woskov and his colleagues have used a 10-kilowatt gyrotron to produce millimeter waves at frequencies between 30 and 300 gigahertz. Elsewhere, millimeter waves are used for many purposes, including 5G wireless networks, airport security, and astronomy. While producing those waves requires only milliwatts of power, it takes several megawatts to drill through rocks.
To start, MIT researchers place a piece of rock in a test chamber, then blast it with high-powered, high-frequency beams. A metallic waveguide directs the beams to form holes. Compressed gas is injected to prevent plasma from breaking down and bursting into flames, which would hamper the process. In trials, millimeter waves have bored holes through granite, basalt, sandstone, and limestone.
The ARPA-E grant will allow the MIT team to develop their process using megawatt-size gyrotrons at Oak Ridge National Laboratory, in Tennessee. “We’re trying to bring forward a disruption in technology to open up the way for deep geothermal energy,” Araque says.
Other enhanced geothermal systems now under way use mechanical methods to extract energy from deeper wells and hotter sources. In Iceland, engineers are drilling 5 km deep into magma reservoirs, boring down between two tectonic plates. Demonstration projects in Australia, Japan, Mexico, and the U.S. West—including one by AltaRock—involve drilling artificial fractures into continental rocks. Engineers then inject water or liquid biomass into the fractures and pump it to the surface. When the liquid surpasses 374 °C and 22,100 kilopascals of pressure, it becomes a “supercritical” fluid, meaning it can transfer energy more efficiently and flow more easily than water from a typical well.
However, such efforts can trigger seismic activity, and projects in Switzerland and South Korea were shut down after earthquakes rattled surrounding cities. Such risks aren’t expected for millimeter-wave drilling. Araque says that while beams could spill outside their boreholes, any damage would be confined deep below ground.
Maria Richards, coordinator at Southern Methodist University’s Geothermal Laboratory, in Dallas, says that one advantage of using millimeter waves is that the drilling can occur almost anywhere—including alongside existing power plants. At shuttered coal facilities, deep geothermal wells could produce steam to drive the existing turbines.
The Texas laboratory previously explored using geothermal power to help natural-gas plants operate more efficiently. “In the end, it was too expensive. But if we could have drilled deeper and gotten higher temperatures, a project like ours would’ve been more profitable,” Richards says. She notes that millimeter-wave beams could also reach high-pressure offshore oil and gas reservoirs that are too dangerous for mechanical drills to tap.
This article appears in the March 2020 print issue as “AltaRock Melts Rock For Geothermal Wells.”
It’s 10 a.m. and Indian peanut farmer Venkeapream is relaxing at his family compound in Pavagada, an arid area north of Bangalore. The 67-year-old retired three years ago upon leasing his land to the Karnataka state government. That land is now part of a 53-square-kilometer area festooned with millions of solar panels. As his fields yield carbon-free electricity, Venkeapream pursues his passion full time: playing the electric harmonium, a portable reed organ.
With a capacity of 2 gigawatts and counting, Pavagada’s arrays represent the world’s largest cluster of photovoltaics. It’s also one of the most successful examples of a solar “park,” whereby governments provide multiple companies land and transmission—two big hurdles that slow solar development. Solar parks account for much of the 25.5 GW of solar capacity India has added in the last five years. The states of Rajasthan and Gujarat have, respectively, 2.25-GW and 5.29-GW solar parks under way, and Egypt’s 1.8-GW installation is one of several new international projects.
Alas, even as they speed the growth of renewable energy, solar parks also concentrate some of solar energy’s liabilities.
Sheshagiri Rao, an agricultural researcher and farmer based near Pavagada, says lease payments give peanut farmers such as Venkeapream a steadier income. But Rao says shepherds who held traditional rights to graze their fields were fenced out without compensation, and many have sold out. In Venkeapream’s village, flocks once totaled 2,000 to 3,000 sheep. There are now only about 600 left.
The constant need to keep dust off the panels, meanwhile, has put more strain on already overtapped groundwater supplies. Local farmers bring water to clean the more than 400,000 panels at the Pavagada site of Indian energy developer Acme Cleantech Solutions. “At least 2 liters of water is required to clean one panel. This is huge,” says B. Prabhakar, Acme’s site manager. Robotic dusters allow Acme to clean just twice a month, but most operators lack such equipment.
Then there are the power surges and drops created as clouds pass over Pavagada—generation swings that must be countered with coal-fired and hydropower plants. Balancing renewable energy swings is a growing challenge for grid operators in Karnataka, which leads India in solar capacity and also has more than 4 GW of variable wind power.
Karnataka capped new solar parks at 0.2 GW after launching Pavagada. Analysts heralded the state’s apparent shift toward distributed installations, such as rooftop solar systems, during a November 2019 meeting on sustainable energy in neighboring state Tamil Nadu. As Saptak Ghosh, who leads renewable energy programs at the Bangalore-based Center for Study of Science, Technology & Policy (CSTEP), put it: “Pavagada will be the end of big solar parks in Karnataka. Smaller is the future.”
Just a few days later, though, news broke that Karnataka’s renewable energy arm was acquiring land for three 2.5-GW solar megaparks. The state’s move may reflect pressure from the national government to accelerate solar installations, as well as confidence that Pavagada’s shortcomings can be fixed.
Instead of harming shepherds, for example, solar operators could open their gates. Grass and weeds growing amidst the panels pose a serious fire risk, according to Acme’s Prabhakar. Increasingly, operatorsinothercountries rely on sheep to keep vegetation down.
Higher-tech solutions may ultimately address Pavagada’s water consumption and cloud-induced power swings. Israeli robotics firm Ecoppia is already providing what it calls “water free” cleaning at the Pavagada site operated by Fortum, a Finnish energy company.
Karnataka’s solution for power swings at its new megaparks, meanwhile, is to plug the parks straight into the national grid’s biggest power lines. The trio of plants are a joint project with the national-government-owned Solar Energy Corporation of India, and designed to export renewable electricity to other states. Power stations outside of Karnataka will balance the solar parks’ generation, according to Ghosh’s colleague, CSTEP senior research engineer and power-grid specialist Milind R.
India’s government is eager to help, having promised to boost renewable capacity to 175 GW by March 2022 and to 450 GW by 2030. As Thomas Spencer, research fellow at the Energy and Resources Institute, a New Delhi–based nonprofit, noted at the November meeting in Tamil Nadu, India is “well off the track” for meeting either target.
This article appears in the February 2020 print issue as “India Grapples With Vast Solar Park.”
In September a modern-day Mayflower will launch from Plymouth, a seaside town on the English Channel. And as its namesake did precisely 400 years earlier, this boat will set a course for the other side of the Atlantic.
Weather permitting, the 2020 voyage will follow the same course, but that’s about the only thing the two ships will have in common. Instead of carrying pilgrims intent on beginning a new life in the New World, this ship will be fully autonomous, with no crew or passengers on board. It will be powered in part by solar panels and a wind turbine at its stern. The boat has a backup electrical generator on board, although there are no plans to refuel the boat at sea if the generator backup runs dry.
The ship will cross the Atlantic to Plymouth, Mass., in 12 days instead of the 60 days of the 1620 voyage. It’ll be made of aluminum and composite materials. And it will measure 15 meters and weigh 5 metric tons—half as long and 1/36 as heavy as the original wooden boat. Just as a spacefaring mission would, the new Mayflower will contain science bays for experiments to measure oceanographic, climate, and meteorological data. And its trimaran design makes it look a little like a sleek, scaled-down, seagoing version of the Battlestar Galactica, from the TV series of the same name.
“It doesn’t conform to any specific class, regulations, or rules,” says Rachel Nicholls-Lee, the naval architect designing the boat. But because the International Organization for Standardization has a set of standards for oceangoing vessels under 24 meters in length, Nicholls-Lee is designing the boat as close to those specs as she can. Of course, without anyone on board, the new Mayflower also sets some of its own standards, too. For instance, the tightly waterproofed interior will barely have room for a human to crawl around in and to access its computer servers.
“It’s the best access we can have, really,” says Nicholls-Lee. “There won’t be room for people. So it is cozy. It’s doable, but it’s not somewhere you’d want to spend much time.” She adds that there’s just one meter between the waterline and the top of the boat’s hull. Atop the hull will also be a “sail fin” that juts up vertically to exploit wind power for propulsion, while a vertical turbine exploits it to generate electricity.
Nicholls-Lee’s architectural firm, Whiskerstay, based in Cornwall, England, provides the nautical design expertise for a team that also includes the project’s cofounders, Greg Cook and Brett Phaneuf. Cook (based in Chester, Conn.) and Phaneuf (based in Plymouth, England) jointly head up the marine exploration nonprofit Promare.
Phaneuf, who’s also the managing director of the Plymouth-based submersibles consulting company MSubs, says the idea for the autonomous Mayflower quadricentennial voyage came up at a Plymouth city council meeting in 2016. With the 400th anniversary of the original voyage fast approaching, Phaneuf said Plymouth city councillors were chatting about ideas for commemorating the historical event.
“Someone said, ‘We’re thinking about building a replica,’ ” Phaneuf says. “[I said], ‘That’s not the best idea. There’s already a replica in Massachusetts, and I grew up not far from it and Plymouth Rock.’ Instead of building something that is a 17th-century ship, we should build something that represents what the marine enterprise for the next 400 years is going to look like.” The town’s officials liked the idea, and they gave him the resources to start working on it.
The No. 1 challenge was clear from the start: “How do you get a ship across the ocean without sinking?” Phaneuf says. “The big issue isn’t automation, because automation is all around us in our daily lives. Much of the modern world is automated—people just don’t realize it. Reliability at sea is really the big challenge.”
But the team’s budget constrained its ability to tackle the reliability problem head-on. The ship will be at sea on its own with no crewed vessel tailing it. In fact, its designers are assuming that much of the Atlantic crossing will have to be done with spotty satellite communications at best.
Phaneuf says that the new Mayflower will have little competition in the autonomous sailing ship category. “There are lots of automated boats, ranging in size from less than one meter to about 10 meters,” he says. “But are they ships? Are they fully autonomous? Not really.” Not that the team’s Mayflower is going to be vastly larger than 10 meters in length. “We only have enough money to build a boat that’s 15 meters long,” he says. “Not big, by the ocean’s standards. And even if it was as big as an aircraft carrier, there’s a few of them at the bottom of the ocean from the years gone by.”
Cook, who consults with Phaneuf and the Mayflower project from a distance in his Connecticut office, says the 400-year-anniversary deadline was always on researchers’ minds.
“There are a lot of days when you think we’ll never get this done,” Cook says. “And you just keep your head down and power through it. You go over it, you go under it, you go around it, or you go through it. Because you’ve got to get it. And we will.”
When IEEE Spectrum contacted Cook in October, he was negotiating with the shipyard in Gdańsk, Poland, that’s building the new Mayflower’s hull. The yard needed plans executed to a level of detail that the team was not quite ready to provide. But parts of the boat needed to be completed promptly, so the day’s balancing act was already under way.
The next day’s challenge, Cook says, involved the output from the radar systems on the boat. The finest commercial radars in the world, he says, are worthless if they can’t output raw radar data—which the computers on the ship will need to process. So finding a radar system that represents the best mix of quality, affordability, and versatility with respect to output was another struggle.
Nicholls-Lee specializes in designing sustainable energy systems for boats, so she was up to the challenge of developing a boat that one day might not need to refuel. The ship will have 15 solar panels, each just 3 millimeters thick, which means they’ll follow the curve of the hull. “They’re very low profile; they’re not going to get washed off or anything like that,” Nicholls-Lee says. On a clear day, the panels could potentially generate some 2.5 kilowatts.
The sail fin is expected to propel the boat to its currently projected average cruising speed of 10 knots. When it operates just on electricity—to be stored in a half-ton battery bank in the hull—the Mayflower should make from 4 to 5 knots.
The ship’s eyes and ears sit near the stern, Nicholls-Lee says. Radar, cameras, lights, antennas, satellite-navigation equipment, and sonar pods will all be perched above the hull on a specially outfitted mast.
Nicholls-Lee says she’s been negotiating “with the AI team, who want the mast with all the equipment on it as high up as possible.” The mast really can’t be placed further forward on the boat, she says, because anything that’s closer to the bow gets the worst of the waves and the weather. And although the boat could keep moving if its sail fin snapped off, the loss of the mast would leave the Mayflower unable to navigate, leaving it more or less dead in the water.
The problem with putting the sensors behind the sail fin, Nicholls-Lee says, is that it means losing a fair portion of the field of view. That’s a trade-off the engineers are willing to work with if it helps to reduce their chances of being demasted by a particularly nasty wave or swell. In the worst case, in which the sail fin gets stuck in one position, blocking the radar, sonar, and cameras, the fin has an emergency clutch. Resorting to that clutch would deprive the ship of the wind’s propulsive power, but at least it wouldn’t blind the ship.
Behind all that hardware is the software, which of course ultimately does the piloting. IBM supplies the AI package, together with cloud computing power.
The 8 to 10 core team members are now adapting the hardware and software to the problem of transatlantic navigation, Phaneuf says. An example of what they’re tweaking is an element of the Mayflower’s software stack called the operational decision manager.
“It’s a thing that parses rules,” Phaneuf says. “It’s used in fiscal markets. It looks at bank swaps or credit card applications, making tens of thousands or millions of decisions, over and over again, all day. You put in a set of rules textually, and it keeps refining as you give it more input. So in this case we can put in all the collision regulations and all sorts of exceptions and alternative hypotheses that take into account when people don’t follow the rules.”
Eric Aquaronne, a cloud-and-AI strategist for IBM in Nice, France, says that ultimately the Mayflower’s software must output a perhaps deceptively simple set of decisions. “In the end, it has to decide, Do I go right, left, or change my speed?” Aquaronne says.
Yet within those options, at every instant during the boat’s voyage are hidden a whole universe of weather, sensor, and regulatory data, as well as communications with the IBM systems onshore that continue to train the AI algorithms. (The boat will sometimes lose the satellite connection, Phaneuf notes, at which point it is really on its own, running its AI inference algorithms locally.)
Today very little weather data is collected from the ocean’s surface, Phaneuf notes. A successful Mayflower voyage that gathered such data for months on end could therefore make a strong case for having more such autonomous ships out in the ocean.
“We can help refine weather models, and if you have more of these things out on the ocean, you could make weather prediction ever more resolute,” he says. But, he adds, “it’s the first voyage. So we’re trying not to go too crazy. I’m really just worried about getting across. I’m letting the other guys worry about the science packages. I’m mostly concerned with the ‘not sinking’ part now—and the ‘get there relatively close to where it’s supposed to be’ part. After that, the sky’s the limit.”
In research, sometimes the investigator becomes part of the experiment. That’s exactly what happened to Efraín O’Neill-Carrillo and Agustín Irizarry-Rivera, both professors of electrical engineering at the University of Puerto Rico Mayagüez, when Hurricane Maria hit Puerto Rico on 20 September 2017. Along with every other resident of the island, they lost power in an islandwide blackout that lasted for months.
The two have studied Puerto Rico’s fragile electricity infrastructure for nearly two decades and, considering the island’s location in a hurricane zone, had been proposing ways to make it more resilient.
They also practice what they preach. Back in 2008, O’Neill-Carrillo outfitted his home with a 1.1-kilowatt rooftop photovoltaic system and a 5.4-kilowatt-hour battery bank that could operate independently of the main grid. He was on a business trip when Maria struck, but he worried a bit less knowing that his family would have power.
Irizarry-Rivera [top] wasn’t so lucky. His home in San Germán also had solar panels. “But it was a grid-tied system,” he says, “so of course it wasn’t working.” It didn’t have storage or the necessary control electronics to allow his household to draw electricity directly from the solar panels, he explains.
“I estimated I wouldn’t get [grid] power until March,” Irizarry-Rivera says. “It came back in February, so I wasn’t too far off.” In the meantime, he spent more than a month acquiring and installing batteries, charge controllers, and a new stand-alone inverter. His family then relied exclusively on solar power for 101 days, until grid power was restored.
In “How to Harden Puerto Rico’s Grid Against Hurricanes,” the two engineers describe how Puerto Rico could benefit from community microgrids made up of similar small PV systems. The amount of power they produce wouldn’t meet the average Puerto Rican household’s typical demand. But, Irizarry-Rivera points out, you quickly learn to get by with less.
“We got a lot of things done with 4 kilowatt-hours a day,” he says of his own household. “We had lighting and our personal electronics working, we could wash our clothes, run our refrigerator. Everything else is just luxuries and conveniences.”
This article appears in the November 2019 print issue as “After Maria.”
The idea is simple: Send kites or tethered drones hundreds of meters up in the sky to generate electricity from the persistent winds aloft. With such technologies, it might even be possible to produce wind energy around the clock. However, the engineering required to realize this vision is still very much a work in progress.
Dozens of companies and researchers devoted to developing technologies that produce wind power while adrift high in the sky gathered at a conference in Glasgow, Scotland last week. They presented studies, experiments, field tests, and simulations describing the efficiency and cost-effectiveness of various technologies collectively described as airborne wind energy (AWE).
In August, Alameda, Calif.-based Makani Technologies ran demonstration flights of its airborne wind turbines—which the company calls energy kites—in the North Sea, some 10 kilometers off the coast of Norway. According to Makani CEO Fort Felker, the North Sea tests consisted of a launch and “landing” test for the flyer followed by a flight test, in which the kite stayed aloft for an hour in “robust crosswind(s).” The flights were the first offshore tests of the company’s kite-and-buoy setup. The company has, however, been conducting onshore flights of various incarnations of their energy kites in California and Hawaii.
Wind turbines have certainly grown up. When the Danish firm Vestas began the trend toward gigantism, in 1981, its three-blade machines were capable of a mere 55 kilowatts. That figure rose to 500 kW in 1995, reached 2 MW in 1999, and today stands at 5.6 MW. In 2021, MHI Vestas Offshore Wind’s V164 will rise 105 meters high at the hub, swing 80-meter blades, and generate up to 10 MW, making it the first commercially available double-digit turbine ever. Not to be left behind, General Electric’s Renewable Energy is developing a 12-MW machine with a 260-meter tower and 107-meter blades, also rolling out by 2021.
That is clearly pushing the envelope, although it must be noted that still larger designs have been considered. In 2011, the UpWind project released what it called a predesign of a 20-MW offshore machine with a rotor diameter of 252 meters (three times the wingspan of an Airbus A380) and a hub diameter of 6 meters. So far, the limit of the largest conceptual designs stands at 50 MW, with height exceeding 300 meters and with 200-meter blades that could flex (much like palm fronds) in furious winds.
To imply, as an enthusiastic promoter did, that building such a structure would pose no fundamental technical problems because it stands no higher than the Eiffel tower, constructed 130 years ago, is to choose an inappropriate comparison. If the constructible height of an artifact were the determinant of wind-turbine design then we might as well refer to the Burj Khalifa in Dubai, a skyscraper that topped 800 meters in 2010, or to the Jeddah Tower, which will reach 1,000 meters in 2021. Erecting a tall tower is no great problem; it’s quite another proposition, however, to engineer a tall tower that can support a massive nacelle and rotating blades for many years of safe operation.
Larger turbines must face the inescapable effects of scaling. Turbine power increases with the square of the radius swept by its blades: A turbine with blades twice as long would, theoretically, be four times as powerful. But the expansion of the surface swept by the rotor puts a greater strain on the entire assembly, and because blade mass should (at first glance) increase as a cube of blade length, larger designs should be extraordinarily heavy. In reality, designs using lightweight synthetic materials and balsa can keep the actual exponent to as little as 2.3.
Even so, the mass (and hence the cost) adds up. Each of the three blades of Vestas’s 10-MW machine will weigh 35 metric tons, and the nacelle will come to nearly 400 tons. GE’s record-breaking design will have blades of 55 tons, a nacelle of 600 tons, and a tower of 2,550 tons. Merely transporting such long and massive blades is an unusual challenge, although it could be made easier by using a segmented design.
Exploring likely limits of commercial capacity is more useful than forecasting specific maxima for given dates. Available wind turbine power [PDF] is equal to half the density of the air (which is 1.23 kilograms per cubic meter) times the area swept by the blades (pi times the radius squared) times the cube of wind velocity. Assuming a wind velocity of 12 meters per second and an energy-conversion coefficient of 0.4, then a 100-MW turbine would require rotors nearly 550 meters in diameter.
To predict when we’ll get such a machine, just answer this question: When will we be able to produce 275-meter blades of plastic composites and balsa, figure out their transport and their coupling to nacelles hanging 300 meters above the ground, ensure their survival in cyclonic winds, and guarantee their reliable operation for at least 15 or 20 years? Not soon.
This article appears in the November 2019 print issue as “Wind Turbines: How Big?”
The suit has a bit of a spy novel twist in that Celgard alleges in its complaint that one of its senior scientists left the company in October 2016 and moved to China to join Senior, after which he changed his name to cover up his identity. This scientist is alleged to be the source through which Senior acquired Celgard’s intellectual property.
Keeping food cold is an energy-gobbling endeavor. Refrigerated food warehouses and factories consume immense amounts of energy, and this cooling demand is expected to increase as the climate warms while global incomes and food consumption rise. A team of researchers and companies in Europe are now developing a cryogenic energy storage system that could reduce carbon emissions from the food sector while providing a convenient way to store wind and solar power.
The CryoHub project will use extra wind and solar electricity to freeze air to cryogenic temperatures, where it becomes liquid, and in the process shrinks by 700 times in volume. The liquid air is stored in insulated low-pressure tanks similar to ones used for liquid nitrogen and natural gas.
When the grid needs electricity, the subzero liquid is pumped into an evaporator where it expands back into a gas that can spin a turbine for electricity. As it expands, the liquid also sucks heat from surrounding air. “So you can basically provide free cooling for food storage,” says Judith Evans, a professor of air conditioning and refrigeration engineering at London South Bank University who is coordinating the CryoHub project.
Amid the sand dunes of the western Sahara, workers are putting the finishing touches on one of the world’s largest solar installations. There, as many as 7.2 million photovoltaic panels will make up Benban Solar Park—a renewable energy project so massive, it will be visible from space.
The 1.8-gigawatt installation is the first utility-scale PV plant in Egypt, a nation blessed with some of the best solar resources on the planet. The ambitious project is part of Egypt’s efforts to increase its generation capacity and incorporate more renewable sources into the mix.
“I think Benban Solar Park is the first real step to put Egypt on the solar production world map,” says Mohamed Orabi, a professor of power electronics at Aswan University.
Last week, the city of Los Angeles inked a deal for a solar-plus-storage system at a record-low price. The 400-MW Eland solar power project will be capable of storing 1,200 megawatt-hours of energy in lithium-ion batteries to meet demand at night. The project is a part of the city’s climate commitment to reach 100 percent renewable energy by 2045.
Electricity and heat production are the largest sources of greenhouse gas emissions in the world. Carbon-free electricity will be critical for keeping the average global temperature rise to within the United Nations’ target of 1.5 degrees Celsius and avoid the worst effects of climate change. As world leaders meet at the United Nations Climate Action Summit next week, boosting renewable energy and energy storage will be major priorities.
Transmission lines in the United States and Canada require approval from every state and province traversed, and that political fragmentation hinders deployment of long power links of the type connecting vast swaths of territory in regions such as China, India, and Brazil. As a result, few studies detail how technologies that efficiently move power over thousands of kilometers, such as ultrahigh-voltage direct current (UHV DC) systems, might perform in North America. Earlier this week, the Beijing-based Global Energy Interconnection Development and Cooperation Organization (GEIDCO) stepped in to fill that gap, outlining an ambitious upgrade for North America’s grids.
GEIDCO’s plan promises to greatly shrink North America’s carbon footprint, but its boldest prescriptions represent technical and economic optimizations that run counter to political interests and recent trends. “Thinking out of the box is how you solve complicated, difficult problems,” said former Southern California Edison CEO Ted Craver in response to the plan. But GEIDCO’s approach, he said, raises concerns about energy sovereignty that could prove difficult to settle. As Craver put it: “There’s theory and then there’s practice.”
Through GEIDCO, Liu is proselytizing for UHV deployment worldwide. At the Vancouver meeting, Liu warned of “unimaginable damage to mankind” if greenhouse gas emissions continued at their current pace. He argued that beefy grids moving power across and between continents are a prerequisite for accessing and sharing the world’s best wind, solar, and hydropower resources, and thus dialing-down fossil fuel consumption.
GEIDCO’s plan for North America mirrors the combination of UHV AC and DC transmission deployed by State Grid in China. In that scheme, a series of 800-kV UHV DC lines running east to west across the U.S. would share wind and solar power widely, while north-south lines would provide continent-wide access to Canada’s giant hydropower plants [see map below]. One more UHV DC line—a 5,200-kilometer stretch from Mexico to Peru—would enable power exchanges with South America.
As in China, UHV AC lines would be added atop North America’s five existing AC grids, strengthening them so they could safely absorb the 8-gigawatt output of each DC line. In two cases, UHV AC would eventually cross boundaries between distinct AC grids to create larger and more stable synchronous zones: Mexico’s grid would fold into the larger grid that currently covers the Western U.S. and Canada; and Texas’ grid would merge with North America’s big Eastern grid.
Consolidating grids helps explain the benefit of GEIDCO’s plan. Texas’ grid is only weakly linked to its neighbors at present, which limits its ability to share resources such as extra wind power that may go to waste for lack of in-state demand or to important renewable power when its wind farms are still. GEIDCO’s UHV build-out unlocks such resources by enabling each power plant to serve a larger area.
The payoffs are numerous. Electrification to decarbonize vehicles, home heating, and industries would proceed 60 percent faster than the most ambitious U.S. electrification scenarios projected by the Electric Power Research Institute. Renewable energy installation would also accelerate, pushing the share of zero-carbon energy on the continent from 40 percent of the power supply in 2017, to 64 percent in 2035, and 74 percent in 2050. Nuclear energy’s contribution would fall by nearly half to just 11 percent of generation in 2050—mostly due to its higher cost, according to GEIDCO director of energy planning Gao Yi. Overall, energy-related greenhouse gas emissions would drop 80 percent by 2050, relative to a business-as-usual scenario—even as average power generating costs drop.
However, consolidating grids is also where the political sensitivity begins. Texas fiercely guards its independent AC grid, which shields its power industry from oversight by federal regulators. Craver’s take on the prospects for bringing Texas into the fold: “Good luck on that.”
Broader political concerns, meanwhile, could hold up international UHV links. Deeper integration of power supplies across borders implies a high level of trust between nations. That cuts against the recent trend toward populist governments advocating more nationalist agendas, as exemplified by the U.K.’s ongoing effort to leave the European Union.
A populist Mexican President elected last year has blocked international investment in renewable energy and could undo recent efforts to expand the country’s grid interconnections. U.S. President Trump has decreased trust in the United States as an international partner with his America-first trade policies and plans to withdraw the U.S. from global pacts such as the Paris Agreement on Climate Change.
At the Vancouver forum, organized by the Edison Electric Institute, a Washington-based trade group, most grid experts identified politics and social acceptance as the greatest challenges to power network expansion. In the U.S., climate and energy policy has made it more difficult for government researchers to even study North American grid integration.
Last year, political appointees at the U.S. Department of Energy blocked publication of a modeling study exploring integration of the Eastern and Western grids via DC lines. The study, led by the grid modeling group at the National Renewable Energy Lab (NREL) in Boulder, Colo., projected that long DC lines linking the grids would reduce power costs and accelerate renewable energy development. According to the study’s leader, it showed that “building national-scale transmission makes sense.”
NREL’s grid modelers are now wrapping up a larger continent-wide study looking at the challenges and opportunities for grid integration of very large levels of wind, solar and hydropower. That North American Renewable Integration Study is a collaborative effort by the U.S., Mexican, and Canadian governments. It was supposed to be completed this month, but remains under review by the three governments.
Japanese scientists have developed a thermal battery that converts heat into electricity when buried in a geothermal zone
You can fry an egg on the ground in Las Vegas in August, but try that in Iceland or Alaska and you’ll just end up with the stuff on your face—unless you know how to tap into the Earth’s vast reservoirs of geothermal energy.
Researchers at the Tokyo Institute of Technology have developed a new kind of battery that can reliably generate electric power from heat in environments with temperatures ranging from 60 degreesC to 100 degreesC—which is low enough to mimic geothermal heat.
In an earlier experiment, the researchers developed sensitized thermal cells (STCs) that employed dye-sensitized solar cells to convert light into electric power. In their latest advance, team leader Sachiko Matsushita, an associate professor at Tokyo Tech, explained that they replaced the dye with a semiconductor to enable the cells to operate using heat instead of light.
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