• Scientists say we are on the cusp of a carbon dioxide recycling revolution
    54 replies, posted
I don't imagine that long range commercial battery aircraft will look like today's aircraft. They could cruise higher since they won't need oxygen for combustion, so less air resistance, and motors have a much higher power to weight ratio so that bit would weigh less as well. Batteries still have to improve a bit but I think in 10 years they will be there.
Motors have a higher power to weight ratio compared to car engines, but they don't beat out jet engines.
Going off Wikipedia we can see that the GE90-115B used in the Boeing 777 has a power to weight ratio of 10kW/kg, but we can see that the EMRAX268 motor has a power to weight ratio of 10.05kW/kg, although it's significantly smaller. So I guess in the end you are right, and it would probably be about the same rather than being lower. We are seeing 4% to 6% improvement in battery capacity every year. I don't think they will need to match jet fuel in density to be effective if you change the design of the aircraft. Intercontinental might be a few decades off but intracontinental will be doable in 10 years I would guess.
How would you propose changing the design of the aircraft and why haven't they already implemented such changes to existing designs? Reducing fuel consumption is the name of the game.
Well it doesn't really work with traditional aircraft if you fly much higher, as they require oxygen for combustion. Probably not worth it trying to carry LOX around on a commercial airliner... You can gimbal the motors for manoeuvring similar to how it's done with rockets, so you can remove the rudder, and maybe the elevators. Cruise at higher altitudes of upwards of 60,000 feet (similar to Concorde) to reduce drag. Electric aircraft should get more efficient as the altitude increases.
I'll beleive it when I see it. At the moment though you're gambling with humanity's future on the possibility one crucial technology will pan out just like that.
Opponents will probably ignore the energy loop requirement and insist we can use coal powerplants to power the thing,
Aviation is a rather small part of global CO2 emissions. While it certainly does need to be tackled, pretty much every other industry is more important. Counting on things like blue crude to be viable in the next 10 years is worse when we already have viable technologies to help us reduce emissions. If they can make carbon neutral things for aircraft then great, do it. But I think we should look more seriously at other ways to reduce emissions from the aviation sector until that point. Electric or hydrogen fuel cells seem like potential options.
It has been attempted for ages. The problem is that plants are leagues better than anything we come up with yet planting plants isn't so interesting to people
Electric aircraft may see use in replacing shortranged propeller driven aircraft, but it will be far longer for them to replace larger jet driven aircraft, if ever. Physics unfortunately plays a big issue in this, and it ties into the speed of the propeller tip. You aren't going to be able to drive propeller driven aircraft the same speed as fuel driven ever, because of the sound barrier and the effect it has on drag produces. Also, high speed propeller aircraft are noisy. Extremely so.
I really don't believe rudders or elevators will ever be removed from airliners. If the engines ever fail, you'd lose almost all control. It'll only add extra weight and possibilities for failure. It overcomplicates control systems with no gain. Because really, what do you gain from that? You only lose a small amount of drag while you're turning. During regular flight, there is no advantage. Unless you'd remove the entire rear stabilizers, which is a pretty bad idea unless you design the plane from ground up with that in mind. Engines don't limit an airliner's maximum altitude, air does. As your altitude increases, your minimum speed (to prevent you from stalling) also increases. At some altitude this will reach the critical mach number. Air over your wings goes supersonic, the plane pitches down, accelerates, and most likely loses it's wings in the process. You could of course design a new plane to fly supersonic, but it wouldn't be nearly as efficient as subsonic flight. Personally I think you shouldn't be making these claims without any sort of research. "higher altitude=more efficiency=electric engine" is a very bad thought process.
I really don't see how this technology is so revolutionary unless it's incredibly efficient. You'll need to power it using renewables for it to make sense, and unless you go nuclear you'll have to use wind or solar, which takes up space. At this point I'd wager it's more worth it to just plant trees there instead.
Do it! The more CO2 we scrub out of the atmosphere the less critical it comes to restrict production, and hell, if it becomes commercially viable enough we might even see people encouraged to emit more to feed the industries that scrub it out of the air and use it for other things! God speed you magnificent bastards! You have the hopes and dreams of every gearhead in the world pushing you along. Crack the code, solve the puzzle, and make it viable long-term for us to daily drive our hotrods!
I don't imagine they would go the propeller route. I imagine it would have to be supersonic, maybe going even higher to try and offset the losses even more. You will probably have to redesign the aircraft from scratch to minimise drag in every little way possible to do electric aircraft in the near future. Rolls Royce, Siemens, and Airbus are working on a hybrid jet that can hold 50 - 100 people, the electric engine is a 2MW motor powered by a generator. This post made me remember Musk talking about a supersonic electric jet a few years ago. Musk and JB straubel (CTO at Tesla) met each other talking about electric jets. Tesla might do it if no one else does apparently. https://youtu.be/erjdYiwoYAo Anyway my point is more about how I think we shouldn't put our eggs in one basket, electrification should be pursued as well as carbon neutral fuels, and whatever else. All avenues need to be pursued and if more than one way actually works then we will be able to choose the best option down the road. Maybe electric planes won't work, maybe they will work really well, who knows until someone with the resources actually does it.
Great idea and all, but flying higher means you have to fly faster. This means you have to break the sound barrier, which isn't economical in the slightest. Flying faster than the speed of sound requires almost 200% of the thrust required to fly subsonic. There's substantially more drag, which causes more wear on the plane's structure. This whole idea is just very stupid when you've got modern commercial aircraft. At some point you said there were already electric aircraft engines with the power to weight ratio of regular turbofans. This might be true, but they are not anywhere near the size of them. Once you try to scale them up to reach the power of a real engine, it will generate a lot of heat as well. Try cooling your engines when you're flying even higher than current airplanes. Modern batteries aren't nearly as energy dense as jet fuel. In fact, even the most energy dense batteries only have about 2% of jet fuel's energy per kg. But even if technology advances and you can get 100% of jet fuel's energy density, it wouldn't be enough. A modern Boeing 737-800 can take off with a full tank, but it needs to burn about 13 tonnes of fuel before it can land. If they flight isn't that long, they will only fill it up to 80% for example. An electric plane can't do this. It doesn't shed weight during flight. It's batteries are always the same weight. This means you HAVE to limit the maximum range on it, otherwise it wouldn't be able to land safely.
If batteries got to the density of jet fuel it would be amazing... doubt that will happen for a long time if ever though. Motors are more efficient than engines as well though so to match it equally on the output side of things I guess you'd probably only need about half of the density? But that's still a big stretch. Current aircraft are built around the idea of using fuel, anything electric would have to be a complete redesign. Not a lot of companies are going to want to commit to that level of development.
Batteries would have to be almost 50x as efficient as they are now. Current small and tiny electric motors can reach the efficiency of some turbofans, but scaling them up causes problems with heat management. And you want them to fly even higher than modern commercial airliners, making that an even bigger problem. That's not a big stretch, it's an unimaginably huge one.
I don't want to imagine the security concerns surrounding batteries with the energy density of liquid fuel. You'd be basically looking at the most powerful high explosives in use everywhere to power household items.
Just fyi, in regards to battery related tech there are some serious limitations barring something extreme in innovation (extreme as in discovering an entirely new area of physics kind of extreme). If you want to go off of traditional electrochemical cells, there is a theoretical max energy density that can be achieved, with the limitation being the elements the cathode and anode are composed of themselves. Lithium is the latest and greatest material, cheap and relatively plentiful. One battery technology that is possible in the future is the lithium - air battery
Just a thought, would there be any kind of negative impact if there's a large amount of carbon dioxide lost in a short period of time? If there isnt and the recycling thing goes well maybe we'll be able to generate potentially unlimited fuels while other energy sources like solar can be improved to be used in a wider scale
I'd think there could be. There are life forms on this planet that depend on CO2 to live called Plants.
Thread might be dead at this point, but anyways. There's always a catch in regards to any natural resource, CO2 is very important to regulating the earth's climate such that a reduction to below a certain threshold may herald a new ice age or mass die offs of certain species as a result. However, the atmosphere is currently sitting at about 400+ ppm concentration in the atmosphere, which doesn't seem like much (it's less than 1% of gas constituents in our atmosphere) but is quite high in comparison to historical figures. According to the Robert Kunzig in National Geographic, we currently have the highest concentration of CO2 since we started recording it 55 years ago, and from some extrapolation of the data is probably the highest in close to the last 3 million years. A graph to illustrate this: https://commons.wikimedia.org/wiki/File:Carbon_Dioxide_400kyr.png#/media/File:Carbon_Dioxide_400kyr.png Long story short, you could in theory, but it would ultimately not seem to be very practical to reduce the earth's CO2 levels to super low concentrations over our lifespans via recycling technologies, as at the moment we have the opposite problem of too much of in the atmosphere, considering that the last time that they were this high, dinosaurs walked the earth.
News just in, time traveller announces the existence of trees.
One of my lecturers does a lot of climate change research. One of his projects got defunded, and a planned test was banned, because he was told his research enabled further damage to the environment by giving people excuses. His argument was roughly: if human-caused climate change is inevitable (which seems fairly certain), now is the time to start researching solutions to minimise the death and destruction.
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