We’ve witnessed several attempts to produce an “artificial leaf,” a device emulating the photosynthesis of plants, but providing hydrogen and oxygen that could power fuel cells in electric vehicles instead of plant sugars to make trees and flowers grow. One of the biggest problems so far has been the rare and costly materials necessary to generate hydrogen. Ècole Polytechnique Fédéral de Lausanne (EPFL) scientists have come up with a low-cost alternative, using abundant materials called perovskites and budget electrodes to produce hydrogen from water with a 12.3 percent conversion efficiency – a record for fairly common materials. Perovskites are a calcium titanium oxide mineral that come in a variety of colors and can be bog-common or extremely rare, approaching rare earth mineral status. The CaTiO3 used by Michael Grätzel is of the common variety, but that doesn’t seem to detract from its performance as a hydrogen-production agent. That, and the inexpensive materials used in the device’s electrodes cause Jingshan Luo, a post-graduate …
3D Printed Power Inverter Meets, Beats DOE 2020 Targets
Reduced weight and component volumes are important for both cars and aircraft, allowing lighter overall construction and greater flexibility in fitting those components into compact spaces. The U. S. Department of Energy has set 2020 targets for things like batteries and power inverters – the device that turns direct current from batteries into alternating current to run electric motors. Researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL)used 3D printing and “novel silicon carbide (SiC) wide band gap (WBG) semiconductors to craft a prototype power inverter for electric vehicles that is lighter and can handle more power than current units. It nearly meets the DOE’s power density and specific power targets and exceeds the efficiency target handily. Metric DOE 2020 target ORNL prototype Power density 13.4 kW/L 13.33 kW/L Specific Power 14.1 kW/kg 11.5 kW/kg Efficiency >94% Power <99% DOE has put 1.45 million into integrating WGB technology, novel circuit architectures and advanced packaging into electric drive systems. …
Five Years, 685 Entries, Great Readers
Today marks the completion of your editor’s fifth year collecting and reporting on progress that will make electric aircraft and green flight a reality. It is only possible with the well informed, highly intelligent and unbelievably kind readers who respond to these efforts. Thank you for your continued readership and excellent critiques of fact and opinion. Let’s make the future of our dreams happen.
NTU Develops Ultra-fast Charging Batteries That Last 20 Years
Singapore is only 276.5 square miles, about 27 miles long, and has five and a half million people, according to Wikipedia. It’s an enormously productive country with an excellent education program from kindergarten on up to graduate schools. Recently, one of those graduate programs announced an “ultra-fast charging batter[y] that can be recharged up to 70 per cent in only two minutes.” This breakthrough from Nanyang Technology University (NTU) is also claimed to have a 20-year lifespan, 10 times that of existing lithium-ion cells. Part of the new battery’s success comes from replacement of the traditional graphite anode with a new gel materal made from titanium dioxide, “an abundant, cheap and safe material found in soil. It is commonly used as a food additive or in sunscreen lotions to absorb harmful ultraviolet rays.” Although naturally found in spherical shape, titanium dioxide was rolled into nanotubes thousands of times thinner than the diameter of a human hair by the NTU researchers. …
Speedy – and No Range Anxiety
Breaking a record that stood for 26 years, a team of University of New South Wales engineering students have gained FIA recognition for their 500 kilometer (310 mile) drive at an average speed of 106.966 kilometers per hour (66.32 mph) in their solar-powered Sunswift automobile. The Fédération Internationale de l’Automobile (FIA), world motorsport’s governing body, ratified the record for the run set by the team in July. The old record was 73 km/hr. (45.26 mph), making the new record a decisive advancement in electric vehicle technology. The new record is particularly impressive because it’s set by students, more than 100 of whom contributed to the project over the last two years. Students are now working on their fifth car, eVe, to be built and raced since the team was founded in 1996. The University’s press release noted, “’It’s not often you can confidently say you made history before you even graduated,’ Sunswift’s project director and third-year engineering student Hayden Smith …
100 Percent Efficiency? Great! and So What?
A particularly brilliant and demanding manager for whom your editor used to work had a “SO WHAT?” stamp with which he would critique our technical papers and proposals. His point in defacing our papers was not to be snide, but to force us to defend why we included certain facts – interesting though they may be in themselves. Two different and equally brilliant discoveries by University of Cambridge and University of California, Riverside researchers bring the “so what?” stamp to mind. Even with their breakthroughs, approaching 100-percent efficient solar cells in the first instance, solar cells may not yet be a perfect fit for aircraft propulsion. Each square foot of the earth’s surface receives about 15 Watts of solar energy during a bright day. 100 square feet of solar cells (about what we could expect for an average-size wing on an average light plane) would see 1.5 kilowatts hitting that surface – not enough to sustain flight on anything but …
A New British Club for HPAs
For the last six decades, the Royal Aeronautical Society (RAeS) has overseen records keeping for human powered aircraft (HPAs). They report, “The Man Powered Aircraft Group of the Royal Aeronautical Society originated in 1959 when the members of the Man Powered Group of the College of Aeronautics at Cranfield were invited to become a group of the Society. Its title was changed from ‘Man’ to ‘Human’ in 1988 in recognition of the many successful flights by woman pilots.” Mr. Henry Kremer turned the wistful dreams of many to serious competition by donating over 275,000 pounds sterling ($440,000 at today’s exchange rates) in prize money for achievements such as flying a figure eight around to markers a half-mile apart and starting and finishing 10 feet above the ground – won by Paul MacCready, the airplane’s designer and Brian Allen, the pilot. The won their 50,000 pound prize on August 23, 1977, and scored a second win on June 12, 1979 by …
Adam and Jamie are Paying Attention
Dr. Seeley alerted your editor this morning that Adam Savage and Jamie Hyneman’s web site, Tested.com, featured an entry on electric aircraft, “Fuel-Free Flight: the State of Electric Airplanes,” by Terry Dunn. Dunn does a good job of covering history and advantages of electric aircraft – complete with a quote from Dr. Seeley about the good neighbor aspect of quiet electric airplanes. He also discusses the barriers to electric aircraft development beyond current motor gliders and light aircraft – mainly the question of obtaining batteries that have much better energy densities than those currently available. “The batteries currently available are adequate to provide suitable range for some flyers. As the pool of available batteries improves, so will the range of electric aircraft and the number of pilots who embrace them. Despite continued progress, I think that a ground-breaking battery breakthrough is necessary before electric powered airplanes can become commonplace in the near term.” Despite the obstacles, he notes that the …
Ohio State’s Solar-Air Potassium Battery
Ohio State University researchers have come up with a two-in-one solar cell/battery combination that promises great efficiency and low costs. What’s not to like? Unfortunately for readers of the blog, it’s initially only a stationary system that will make energy storage a viable circumstance for large power plants, but it seems that the technology could be adapted to lighter, portable applications, such as electric vehicles. Ohio State is keeping somewhat mum about the patent-pending device, which they are developing as a commercial entity under the auspices of their spin-off, Kair (K for potassium, plus air and pronounced “care”). We’ve heard a great deal about upcoming lithium-air batteries, but potassium-air is unique. Even more unique, this battery stores energy from its own solar cell, the world’s first solar battery. A mesh solar panel allows air to enter the battery, and a special process transfers “electrons between the solar panel and the battery electrode. Inside the device, light and oxygen enable different …
The motor inside every Formula E Racer Today
In this YouTube video, Robert Llewellyn visits the McLaren Technology Centre to talk to Peter van Manen about the motor that McLaren developed in the last four years and that is now in every Formula E racer. (Next year, other motors and car designs will enter the fray, but the current effort is exciting enough for now.) One thing stands out: 26 kilograms (57.2 pounds) for 225 horsepower. That’s almost four horsepower per pound. Compare that to the average of about two pounds per horsepower on a modern aircraft engine and marvel at the 8:1 power density ratio between McLaren’s motor and what we fly behind today. Old-school aircraft design wisdom said that for every pound of engine weight one could lose, one could reduce airframe weight by two pounds. Even granted the additional weight required for propeller speed reduction, what does this portend for a truly radical future for light aircraft design?