By Tina Casey, Cross-posted from Clean Technica
NASA announced last Friday that it is funding a new set of five cutting-edge “green” aviation concepts for two years of study and evaluation. If everything pans out for NASA’s green aviation plan, in a few years you could be flying in a plane with wings that shape-shift in flight. Pop the hood and you might also see 3-D printed electric motors powered by lithium-air batteries. An antenna foundation made of aerogel is also on tap for the drone market, if all goes according to plan.
Why Green Aviation
NASA is the first to admit that the five new concepts aren’t necessarily do-able as presented. However, researchers will get a crack at them anyway. The idea is to gather insights and information leading to next-generation improvements that propel NASA along its goals for reducing aviation emissions and other impacts.
The agency has its work cut out for it. Take a look at these numbers NASA compiled in 2012, for example:
…U.S. commercial air carriers burned 10.6 billion gallons of jet fuel at a total cost of $31.6 billion, while international carriers spent another $18.8 billion on 6.5 billion gallons of jet fuel. The Department of Defense in FY2011 used more than 3 billion gallons of aviation and jet fuel, costing another $10 billion.
All that jet fuel is an important contributor to global greenhouse gas emissions and other pollutants:
…Fuel consumed by the U.S. commercial air carriers and the military releases more than 250 million tons of carbon dioxide (CO 2 ) into the atmosphere each year…Other major emissions are nitric oxide (NO) and nitrogen oxide (NO 2 ), which together are called NO x and contribute to ozone creation; sulfur oxides (SO 2 ); and particulates (often referred to as soot).
If you caught that thing about “important,” you’re on to something. The raw numbers for aviation emissions are relatively modest compared to other sources, and the industry already has a decades-long track record of improving fuel efficiency. However, aviation does play a significant role in the transportation sector, and within that sector its contributions are significant.
In the US, transportation accounted for 26% of all greenhouse gas emissions in 2014, putting it just behind the electricity generating sector, which clocked in at 30%. Add the rapid growth of wind and solar in the US, and transportation could begin to edge into the top spot. That will put more pressure on the aviation industry to clean up its act.
Earlier this year, the Environmental Protection Agency issued a finding that addressed its authority to regulate greenhouse gas emissions from aircraft under the Clean Air Act. The agency toted up the numbers for all US domestic flights and international flights from the US. The results weren’t pretty.
All together, aviation accounted for:
- 12 percent of GHG emissions from the transportation sector in the US
- 3 percent of total US GHG emissions
- 29 percent of all global aircraft GHG emissions
- 0.5 percent of total global GHG emissions
Three Electric Flight Projects
As a group, the five projects underscore NASA’s growing interest in electric flight. That’s especially so for these three:
- Lithium Oxygen Batteries for NASA Electric Aircraft (LION) — This project has the ambitious aim of developing Lithium-Air (Li-Air) batteries that don’t decompose. If you’re familiar with Li-Air technology, that’s a pretty tall order. However, the payoff is worth it. Li-Air batteries have the potential to be much lighter, less expensive, and more energy-dense than today’s crop of Li-ion batteries.
- Compact Additively Manufactured Innovative Electric Motor — This one aims to leverage 3-D printing for ramping up the power density of the electric motors that are used to generate thrust. The main advantage of 3-D printing over other fabrications is a significant savings in weight. GE has already begun to apply 3D printing to jet engines.
- Fostering Ultra-Efficient Low-Emitting Aviation Power: NASA is also looking at fuel cells for electric flight, leveraging a history of experience that goes all the way back to the 1960s. That experience, though, focuses on onboard storage of hydrogen and oxygen at super-low temperatures. For larger aircraft such systems would be prohibitively expensive, and they would be practically impossible for smaller planes. The solution being pondered by NASA involves a system that uses oxygen from ambient air, combined with hydrogen drawn from standard aviation gas. That opens all sorts of cans of worms in terms of continued fossil fuel dependency. On the bright side, the aviation industry and its stakeholders (the US Navy, for one) have been accelerating the transition to bio-based aviation fuel, so by the time NASA is ready to demo its new fuel cell they might be able to gas up with hydrogen from bio-avgas.
Fold-away Rudders/Tails or Shape-Shifting Wings
A fourth project called Spanwise Adaptive Wing applies to both electric and non-electric aircraft. The project seeks to significantly reduce the size of the vertical tail that characterizes conventional aircraft.
Larger tails are built into aircraft primarily as a safety precaution, to keep the plane on the runway in case of engine failure during takeoff or landing. That’s all well and good but the result is unnecessary mass and drag whenever the plane is safely in the air, which is basically all the time.
NASA’s solution would be to shift the runway-centering task to the wings, making them fold up and act as rudders when needed. The challenge would be to design a mechanism that works seamlessly and does not add excessive weight to the plane.
What About The Drones?
“Lightweight, Conformal Antennas for Beyond Line of Sight Communications” is the fifth project. Like the name suggests, it involves creating a form-fitting antenna foundation based on ultra lightweight aerogel aka “liquid smoke.” The new foundation is meant to enable the use of satellite tracking systems for drones without adding excessive weight and drag.