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from the the-Hindenberg-steam-engine-crossbreed dept.
‘They said we were eccentrics’: the UK team developing clean aviation fuel:
“Anyone passing would have wondered why these people were staring at a pipe and whooping and laughing,” says Bobby Sethi, associate professor of gas turbine combustion at Cranfield University. “But we were almost certainly the only people in the world right then burning anything without producing CO2.”
[...] “We were able to demonstrate successful ignition and safe combustion of pure hydrogen and air at high temperature and pressure – producing no carbon emissions,” he says. Even if, he adds, the passing layperson would have only seen a pipe and some steam.
[...] Sethi recalls the scepticism of even five years ago, when he was pursuing funding for the hydrogen research project, known as Enable H2: “They said we were eccentrics. Now they’re queueing up to be on our advisory board.”
There are broadly three strands of work that the aviation industry is frantically investigating for an environmentally acceptable future. One is to create greener fuels for the large aircraft currently in service. A second is electric flight, which appears feasible for smaller aircraft and short-haul hops. And a third is hydrogen.
Two projects pioneered at Cranfield are using hydrogen in the form of fuel cells to power electric motors and propel planes: ZeroAvia flew a six-seater from here last September, and hopes to scale up the technology for commercial short-haul flights in the coming decades. Another, Project Fresson, is planning to use fuel cells for a green, short-hop passenger service around the Orkney islands as soon as 2023.
But the ambitions for direct combustion of hydrogen are on a bigger scale; whether a radically different plane and propulsion system could replace the modern, paraffin-fuelled passenger jet. Which is where Sethi’s research comes in.
Nothing yet in the sheds looks anything like a plane. The rig here is a unique facility, Sethi says, assembled to show that hydrogen can be clean, safe and efficient for aviation, and produce data showing the optimum temperature and pressure to minimise other harmful emissions such as nitrogen oxides or NOx, a family of highly poisonous gases.
Not the only scientists looking for controlled ignition of hydrogen. What's described still seems a long way away from something that produces thrust, which is the ultimate need. However, technology usually advances in small steps, and that's fine as long as there's an ultimately reachable goal.
(Score: 2) by Immerman on Thursday August 19 2021, @10:10PM (11 children)
And your point is?
NOx gasses are a result of heating nitrogen to high temperature in the presence of oxygen - it's a problem with practically every form of combustion. Gasoline engines produce them, I think diesels tend to produce even more (higher operating temperature), heck even your kitchen stove produces them, assuming it's not electric.
(Score: 0) by Anonymous Coward on Thursday August 19 2021, @10:19PM
It's a wonder any of us still live!
(Score: 2) by tizan on Thursday August 19 2021, @10:39PM (3 children)
That is what catalytic converters are for ...otherwise we would be killing ourselves with acid rain.
(Score: 3, Informative) by Immerman on Thursday August 19 2021, @11:29PM (2 children)
I'm pretty sure a typical catalytic converter is designed to oxidize the incompletely burned hydrocarbons left over from the fuel, dramatically reducing the emission of organic pollutants and carbon monoxide. NOx has already been oxidized, that's the problem. Oxidizing it more wouldn't help anything.
They do make NOx catalytic converters, but it doesn't sound like those are what's included in a typical car. Rather it's the conditions within the combustion chamber that are optimized to reduce NOx production in the first place.
(Score: 4, Informative) by Beryllium Sphere (r) on Friday August 20 2021, @12:39AM
These days, I think "three way" converters are typical:
https://en.wikipedia.org/wiki/Catalytic_converter [wikipedia.org]
They include a function of breaking nitrogen oxides into nitrogen and oxygen.
(Score: 2) by tizan on Tuesday August 24 2021, @10:13PM
these things are de-rigueur on diesel vehicles (remember VW dieselgate)
Nox is converted to N2 and water vapor
https://www.sae.org/publications/technical-papers/content/2019-01-0047/ [sae.org]
(Score: 0) by Anonymous Coward on Friday August 20 2021, @12:34AM (5 children)
I think his point was that nitrogen oxides wash out of the air as nitrates and nitrites, which are basically fertilizer. In other words "what plants crave".
Trace levels are harmless or beneficial. Calling them highly poisonous is disingenuous. Yes, they are poisonous in high concentrations, but that is not what "highly poisonous" means.
(Score: 3, Insightful) by Beryllium Sphere (r) on Friday August 20 2021, @12:42AM (4 children)
They wash out as acid rain.
I'm OK calling something highly toxic if it has to be kept in the parts per million range:
https://www.google.com/search?q=nitrogen+dioxide+danger+level&rlz=1CATTSD_enUS821&oq=nitrogen+dioxide+danger+&aqs=chrome.1.69i57j0i512j0i22i30l8.26326j1j7&sourceid=chrome&ie=UTF-8 [google.com]
(Score: 2, Informative) by Anonymous Coward on Friday August 20 2021, @01:29AM (3 children)
Once again, doomsayers conflating things. Nitrate acid rain washes out quickly and is basically fertilizer. It is also far below the ppm level you talk about, even with heavy air traffic. Heavy ground traffic in cities might produce damaging levels.
Sulphate acid rain is the stuff that caused all the damage. Dirty coal-fired power stations were stationary sources that produced huge quantities that killed forests and dissolved marble buildings down wind from them.
(Score: 2) by KilroySmith on Friday August 20 2021, @03:52AM (2 children)
As a kid who grew up East of Los Angeles, in its air sewer, we routinely had to deal with smog alerts caused by NOx. No playing, stay indoors, etc. Doesn't sound like it "washed out quickly" enough to keep from being a hazard to children and adults at the concentrations found in the atmosphere, now does it? And I'm not sure what you mean by "washes out" - are you implying that there might be rain in the LA basin in the summertime, often enough to impact air quality?
(Score: 0) by Anonymous Coward on Friday August 20 2021, @04:53AM
Did you often get jet airliners flying along the streets of LA?
(Score: 0) by Anonymous Coward on Friday August 20 2021, @05:00AM
Smog alerts weren't due solely to the NOx from traffic, but to the interactions with unburnt hydrocarbons from shitty engines and diesel particulates, and industries that just dumped their shit in the atmosphere. Pollution controls have mostly made that go away, and electric cars will finish the job.
The level of NOx that you would get from even ten times the current level of jet aircraft is so widely dispersed and disappears so quickly that it is not a problem.