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Sustainable Fuels

I saw a headline (during a related search) about aviation biofuel produced from McDonalds biowaste.

Probably a fair reservoir of energy stored in that ◊◊◊◊.
 
rjh01 said:
For starters in the last 10 years solar and wind power to generate electricity has become a lot more common. I know in parts of Australia most electricity is generated by a combination of the two.
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You haven't read the book, have you?

As someone who has read the book, one area of technology that may make significant strides is solar cell efficiency. I think recent lab experiments have found a way around the theoretical maximum conversion efficiency of ~30%, raising it to ~47%. How practical these new materials are to manufacture I don't know.
 
Ivor the Engineer said:
You haven't read the book, have you?

As someone who has read the book, one area of technology that may make significant strides is solar cell efficiency. I think recent lab experiments have found a way around the theoretical maximum conversion efficiency of ~30%, raising it to ~47%. How practical these new materials are to manufacture I don't know.
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I have not read the book. Did not know I had to do so.

Solar cell efficiency has improved over the years, as has cost per Joule created. Hence there are far more solar cells now than in the past. Makes even more sense in remote areas.
 
rjh01 said:
I have not read the book. Did not know I had to do so.
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I find that other people who have read a book often find it more credible when those who are criticising the contents of that book have actually read it.
rjh01 said:
Solar cell efficiency has improved over the years, as has cost per Joule created. Hence there are far more solar cells now than in the past. Makes even more sense in remote areas.
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Yes, the book actually talks about that and the trade-offs, though on this it is mainly focussed on the geography and population of the UK. However, there are sections that discuss topics relevant to this thread, such as why cars can become significantly more efficient (compared to ICE-powered vehicles) but planes cannot.

The main point of the book is about determining if we could power our existing lifestyles with sustainable energy and giving reasonable estimates for energy density for each of the sustainable options. In the final section the book several plans are presented with different mixes of sustainable energy sources. All of them require trade-offs to be made.

What is rather depressing is that the book is coming on for 20 years old and very few countries have made serious plans about what mix of renewable energy sources to transition to. Instead we mostly have piecemeal and sporadic developments.
 
EHocking said:
But will they technically be “jets”?
I’m ready for them to be (erroneously) called eJets, but at the moment all the viable ones are eProps, or eScrews?
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Likely true.
acbytesla said:
I don't think so. Not at 3 to 5 times the cost. Entire fleets of commercial aircraft are replaced with 5% gains in efficiency.
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Possibly, maybe with a heavy tax on fossile fuels. Like I said, this is the one place they may be useful as far as I can tell. Otherwise its just a subsidy to farmers of various kinds.
 
ahhell said:
Likely true.

Possibly, maybe with a heavy tax on fossile fuels. Like I said, this is the one place they may be useful as far as I can tell. Otherwise its just a subsidy to farmers of various kinds.
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Which only results in travel costs skyrocketing. Close to impossible to get society to buy in. This will be one of the toughest sectors to replace fossil fuels.
 
We have no trouble with the concept of fueling nuclear reactors with a form of fuel that's not used for most other purposes. Ditto ammunition.

In a sustainable energy economy with adequate electrical storage for usage balancing, liquid fuels will be synthesized (whether from crops or from other feedstocks) as a way to concentrate and store energy. If this process is inefficient, it will only be used where energy density is a key concern; e.g. long-range aircraft, non-nuclear warships, rockets, and backpacking stoves. Operating those will become significantly more expensive (by a factor of about the reciprocal of the fuel synthesis efficiency, all other things being equal) relative to e.g. electrically powered trains and efficient electric cars. But the economy will adjust. Some long range air travel might be an economic necessity in a global industrial society, but cheap air travel is not (unless you're employed in e.g. Las Vegas or Orlando, so make long-term plans accordingly).
 
More likely scenario is that we switch to wind, solar, nuclear for electricity and stick with petroleum for things like aircraft. But we shall see. I'm not placing bets.
 
Myriad said:
We have no trouble with the concept of fueling nuclear reactors with a form of fuel that's not used for most other purposes. Ditto ammunition.

In a sustainable energy economy with adequate electrical storage for usage balancing, liquid fuels will be synthesized (whether from crops or from other feedstocks) as a way to concentrate and store energy. If this process is inefficient, it will only be used where energy density is a key concern; e.g. long-range aircraft, non-nuclear warships, rockets, and backpacking stoves. Operating those will become significantly more expensive (by a factor of about the reciprocal of the fuel synthesis efficiency, all other things being equal) relative to e.g. electrically powered trains and efficient electric cars. But the economy will adjust. Some long range air travel might be an economic necessity in a global industrial society, but cheap air travel is not (unless you're employed in e.g. Las Vegas or Orlando, so make long-term plans accordingly).
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I'm really not sure what you're trying to say.

Everything is a function of its usefulness. Cost is an extremely important factor. If it is too expensive, it's usefulness decreases substantially. Fossil fuels for long range aviation especially over oceans, is not likely to be replaced by any technology I currently see in development. Electric aviation in 10 to 15 years might start replacing shorter flights. I'm a big believer in electric trains. Europe uses electric trains on trips that in the US would certainly be a short flight. And very little of it falls under the high speed train designation. (250kmph) Electric trains accelerate faster and are more dependable.

I have nothing against biofuels other than they usually require fossil fuels to create and they are exorbitant in cost. Land based agriculture to create fuel doesn't make sense. It robs Peter to pay Paul.

From my perspective, let's not worry about solving the aviation issue today. Instead let's eliminate fossil fuels, from passenger, truck and train traffic, then construction and heating. I can see that is possible and possibly affordable. In other words, concentrate on the steak, not the peas.
 
acbytesla said:
I'm really not sure what you're trying to say.

Everything is a function of its usefulness. Cost is an extremely important factor. If it is too expensive, it's usefulness decreases substantially. Fossil fuels for long range aviation especially over oceans, is not likely to be replaced by any technology I currently see in development. Electric aviation in 10 to 15 years might start replacing shorter flights. I'm a big believer in electric trains. Europe uses electric trains on trips that in the US would certainly be a short flight. And very little of it falls under the high speed train designation. (250kmph) Electric trains accelerate faster and are more dependable.

I have nothing against biofuels other than they usually require fossil fuels to create and they are exorbitant in cost. Land based agriculture to create fuel doesn't make sense. It robs Peter to pay Paul.

From my perspective, let's not worry about solving the aviation issue today. Instead let's eliminate fossil fuels, from passenger, truck and train traffic, then construction and heating. I can see that is possible and possibly affordable. In other words, concentrate on the steak, not the peas.
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I absolutely agree with this statement. Get the easy stuff and big stuff first then work on the rest. Biofuels, sure, keep duing research, maybe we find some cheap energy efficient process but in the mean time, its not the best way to reduce carbon.
 
acbytesla said:
I'm really not sure what you're trying to say.

Everything is a function of its usefulness. Cost is an extremely important factor. If it is too expensive, it's usefulness decreases substantially. Fossil fuels for long range aviation especially over oceans, is not likely to be replaced by any technology I currently see in development. Electric aviation in 10 to 15 years might start replacing shorter flights. I'm a big believer in electric trains. Europe uses electric trains on trips that in the US would certainly be a short flight. And very little of it falls under the high speed train designation. (250kmph) Electric trains accelerate faster and are more dependable.

I have nothing against biofuels other than they usually require fossil fuels to create and they are exorbitant in cost. Land based agriculture to create fuel doesn't make sense. It robs Peter to pay Paul.

From my perspective, let's not worry about solving the aviation issue today. Instead let's eliminate fossil fuels, from passenger, truck and train traffic, then construction and heating. I can see that is possible and possibly affordable. In other words, concentrate on the steak, not the peas.
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I'm describing a hypothetical (and reasonably likely IMHO) eventual future situation in which (as one characteristic) use of airline travel is greatly reduced compared to today, as one of the necessary conditions for it being sustainable. (Sure, switching to biofuels for aviation while trying to maintain current flight schedules would be impossible as well as disastrous, even in a hypothetical future with plenty of renewable electricity.)

I didn't claim or imply that cheap long-range passenger aviation will ever be replaced by something equally cheap and capable. When you're broke and your personal car is replaced by public transit buses (if you're lucky), that doesn't mean the bus line will be as fast or convenient or comfortable as your car was. It means you make do. Same if you're taking trains instead of airlines.

And just because I can imagine a sustainable stable future condition doesn't mean I can imagine any smooth peaceful path from status quo to there. My imagination has limits! The most likely "solution" to the "aviation issue" is that the airlines and passengers will just keep flying until something happens to cause severe aviation fuel shortages or some other disruption, by which time it will be too late to implement any immediate solution apart from getting by with a lot less aviation for some significant period if not permanently. Discussions in many different places, including here, have made it clear that no one is willing to give up any comfort or convenience until forced to. If there's one tank of gas left in a town, it'll be used to take the mayor's daughter to the prom in a limousine, not to keep the local ambulance running.
 
Myriad said:
I'm describing a hypothetical (and reasonably likely IMHO) eventual future situation in which (as one characteristic) use of airline travel is greatly reduced compared to today, as one of the necessary conditions for it being sustainable. (Sure, switching to biofuels for aviation while trying to maintain current flight schedules would be impossible as well as disastrous, even in a hypothetical future with plenty of renewable electricity.)

I didn't claim or imply that cheap long-range passenger aviation will ever be replaced by something equally cheap and capable. When you're broke and your personal car is replaced by public transit buses (if you're lucky), that doesn't mean the bus line will be as fast or convenient or comfortable as your car was. It means you make do. Same if you're taking trains instead of airlines.

And just because I can imagine a sustainable stable future condition doesn't mean I can imagine any smooth peaceful path from status quo to there. My imagination has limits! The most likely "solution" to the "aviation issue" is that the airlines and passengers will just keep flying until something happens to cause severe aviation fuel shortages or some other disruption, by which time it will be too late to implement any immediate solution apart from getting by with a lot less aviation for some significant period if not permanently. Discussions in many different places, including here, have made it clear that no one is willing to give up any comfort or convenience until forced to. If there's one tank of gas left in a town, it'll be used to take the mayor's daughter to the prom in a limousine, not to keep the local ambulance running.
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Here is what is likely. We will replace fossil fuels in those other sectors. There will remain an oversupply of jet and aviation fuels. The ONLY way that biofuels replace fossil fuels is If they can be cost competitive which seems highly unlikely. . t don't buy that biofuels will ever be part of the mix. So called "sustainable fuels" are not actually sustainable. They require fossilfuels to grow, refine and distribute. I think long range electric aviation is more probable than the scenario you are positing.
 
acbytesla said:
Highly skeptical. But definitely interesting article about turning cow manure into biomass or aviation fuel. Says it is very affordable.

interestingengineering.com

US reactor turns cow manure into jet fuel at fraction of normal cost

Over 20,000 large livestock farms in the U.S. produce nearly a trillion pounds of manure annually, but less than 6% capture the biogas from this waste.
interestingengineering.com interestingengineering.com
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I wonder how easy it is to take the manure from the ground and get it into the machine?
 
rjh01 said:
I wonder how easy it is to take the manure from the ground and get it into the machine?
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Probably surprisingly easy. They already have mounds of cow poop around. I've been involved in couple of biogas projects, I not sure how they get all the poop in one place but it's there.
 
rjh01 said:
I wonder how easy it is to take the manure from the ground and get it into the machine?
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ahhell said:
Probably surprisingly easy. They already have mounds of cow poop around. I've been involved in couple of biogas projects, I not sure how they get all the poop in one place but it's there.
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The only reason I see this as a greater possibility is that this is a waste product of another industry. Biogas reactors for methane production is not new. Still, it all comes down to numbers. If it isn't cost competitive, it's a no starter.
 
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