US commercial and military aviation consumes 20 billion gallons of jet fuel annually.
Best biofuel generation from crop seeds (canola) runs 80-120 gallons/acre/year. Let's call it 100 gallons even.
Replacing that fuel would require 200 million acres of land. The US has 409 acres of arable land.
Would you prefer to eat as much as you are now, and stick to ground (or airship) transport, or go on a 50% calorie reduction but retain the ability to fly at speeds over 130 MPH?
Fracking increases extraction temporarily with very rapid well depletion rates. Continued extraction requires drilling more wells. Compare this with oil production from traditional "whale" fields in which a single well can deliver for decades. This vastly increases capital costs and reduces EROEI.
Methane hydrates are yet unproven, and present their own very serious challenges.
In either case, the prospects for global warming and emissions management attack the other side of my statement: cheap abundant fossil fuels. While coal exist to supply needs for (depending on whom you talk to) 100-1000 years, the evidence suggests that the climate and our economy won't tolerate the emissions resulting from its consumption.
Coal-to-liquids infrastructure is very expensive and takes a long time to ramp up.
What are your source(s) for fracking production? Sincerely interested.
Definitely. If the methane thing pans out .. well, in 10 years time we'll probably be totally desensitised to news headlines that read something like "Reflective cloud seeding program starting over Pacific basin" or "Mirror assembly nearing completion at LaGrange Point".
I just don't think we have the ability to stop ourselves huffing at that hydrocarbon crack pipe so I think we'll have to switch to management rather than prevention in this generation.
Captain Dave Ryter earned so little when he was a co-pilot for a major airline that he lived in a gang area of Los Angeles, commuted for hours to work and made less money than a bus driver.
Many are forced to fly half way around the country before they even begin work. Others sleep in trailers at the back of Los Angeles airport, in airline lounges across the country or even on the floors of their own planes. Some co-pilots, who typically take home about $20,000 (£12,500) a year, hold down second jobs to make ends meet.
A commodity is any good or service ("products" of "activities") produced by human labour and offered as a product for general sale on the market. Some other priced goods are also treated as commodities, e.g. human labor-power, works of art and natural resources, even although they may not be produced specifically for the market, or be non-reproducible goods.
The obvious lesson: A profitable company, whether UPS, FedEx or Southwest, can pay its workers more.
For the Graf Zeppelin, at 776' x 100' (7209 meter^2), and with 20% efficient solar PV (higher efficiencies are possible), 1.4 mW (1.8 million HP) of power are available. The original Graf sported 5 V12 diesel engines of 550 HP max (450 HP cruise) power. Solar would be able to deliver over 1 _million_ horsepower (unless I'm goofing my math badly here). Enough that reducing the cell coverage and including batteries or combustible fuel for backup would be viable.
Sure they are - just use the nuclear power to make hydrocarbon fuels for them.
> As I've noted above, _solar_ powered airships are:
Solar powered airships are also very silly and wasteful (they are heavy which wastes energy, they can't be pointed optimally, they are out of service a lot (i.e. not flying), and when the airship wears out you wasted the solar cells which can last longer than an airship). Put the solar cells on the ground where they can do the most good, and power the airship with liquid hydrocarbons.
It's not hard. Just need some energy. Well, energy is specifically the problem.
You also need feedstocks. And a source of CO2. And limits on fossil CO2 emissions. That last pretty much rules out any use of fossil (or methane hydrate) sources and requires you stick to present cycling carbon within the carbon cycle (biomass, atmosphere).
If your time horizon is more than decades to a century or so, feedstocks rules out petroleum (which doesn't make sense anyway), natural gas, or coal.
Conventional non-breeder uranium reactors will suffer from fuel shortages if used for significant amounts of power generation well within a century. Thorium breeders offer a possible alternative, though the technology is unproven. Fusion is even more unproven.
Which leaves solar, wind, wave, and geothermal, all of which have distinctly limited upper bounds, and very considerable infrastructure requirements. Yes, we could get all the energy we need from solar by covering 0.5 - 1% of the Earth's surface with collectors. It's helpful to note that the built environment -- cities, towns, and villages, is on the order of this size. So we're talking about effectively doubling the size of the built environment (though in some cases solar infrastructure can be built over existing structures), with a much more technically complex instance (solar PV arrays, inverters, and power transmission infrastructure are more complex and demanding than ordinary buildings and structures). That's ... a pretty major undertaking, even if we grant ourselves several decades to complete it.
Energy is the problem.
On top of that, Fischer-Tropsch plant and capital are expensive and would take a long time and vast investments (trillions of dollars) to replace the 20 million barrels of oil consumed daily in the US.
Nuclear powered aircraft You're side-stepping your original statement. Producing hydrocarbons at that scale from electricity is unproven. Producing hydrogen might work, and for aircraft (limited in number, limited in servicing points) could prove viable, though with significantly more airframe volume devoted to fuel storage, and with much more complex storage parameters -- most likely LH2 -- than existing fuels.
Solar powered airships I'd suspect that either PV costs would come down, or array designs would be designed to be transferrable between airships, or both. My point was to demonstrate that where solar powered heavier-than-air craft are only just feasible (see the Solar Impulse, with the wingspan of a 747 but just able to carry a pilot), solar-powered airships are highly feasible. Of course, any fuel which would work for an HTA craft would also work for an airship.
You can use wood, coal, or CO2 from the air. The carbon from all the stuff we burned didn't go away, it's all still here. Most of it is in the ocean or in plants.
If you "extended" coal by adding hydrogen then you can quintuple the energy content (since each atom of carbon gets 4 of hydrogen, for longer chain hydrocarbons the ratio is less, but at a minimum it's tripled). So instead of the estimated 100 years of coal we now have, we'd have 500 years.
And on top of that most of the coal is used for electrical production (with the rest of steel making), if we stopped doing that and used nuclear power for electricity and saved the coal to make liquid fuel we would have at least 10,000 years of coal left.
> Conventional non-breeder uranium reactors will suffer from fuel shortages if used for significant amounts of power generation well within a century. Thorium breeders offer a possible alternative, though the technology is unproven.
So don't use non-breeder and switch to breeders. I once calculated that if we used breeding reactors, plus thorium, we have enough energy in those two elements alone for 10,000 to 100,000 years! (The range is because energy consumption will inevitably go up.)
So no, energy is NOT the problem. We have enough for longer than recorded history.
> On top of that, Fischer-Tropsch plant and capital are expensive and would take a long time and vast investments (trillions of dollars) to replace the 20 million barrels of oil consumed daily in the US.
Sure. But have you seen the unbelievable size of the equipment used today for petroleum production? If there was demand for these fuels, it would get built. No problem at all. No one is expecting this to happen overnight - I think it would take 20 to 50 years.
> You're side-stepping your original statement. Producing hydrocarbons at that scale from electricity is unproven.
Of course it's proven. And you don't make it from electricity, you make it directly from heat. The only reason it's not done right now is that it's not needed. But the technology is there.
> Producing hydrogen might work
?? Why would this work if producing hydrocarbons won't? You could make hydrogen the same way - by heating water. But hydrogen is extremely hard to transport or store. It leaks right through everything, and damages most metals if stored under pressure. You need special materials to store hydrogen, and those are expensive and not plentiful. Hydrogen is not the fuel of the future - methane is.
> My point was to demonstrate that where solar powered heavier-than-air craft are only just feasible
If I'm understanding you right, your argument is that we won't be able to fly anymore because we'll run out of energy (or fuel), and your proof is that solar powered airships are only just barely workable.
You mistake is a: thinking that we'll run out of energy, and we won't. And b: that we would use solar power for an air transport, and we won't do that either.
I ran my math several times, and the values seemed, literally, incredible. The first time I did this I got something on the order of 4x the power of the original engines of the Hindenberg / Zeppelin. I'm still trying to figure out where I went wrong this time.
Units: dimensions in feet multiplied to give surface area. Convert to meters. Insolation at 1 kW/m^2, PV efficiency of 20%. Oh. I got kW and MW confused. Wups.
I'm actually getting 1900 HP now, which is closer to my original results. Brain damage....
Also, the dimensions for the zeppelin are diameter (not radius) and length, so multiply by Pi - and then divide by 3 since not all of it will be visible to the sun at once.
Converting feet^3 to meter^3 is non obvious because of the ^3 - that would be my guess for where you had an error.
> mW == megawatt.
1.4 MW is not 1.8 million HP, it's 1.8 thousand hp.
For quick calculations like these I've found that the GNU 'unit's command is actually very useful. Keep your prefixes straight and it will confirm your units as well:
Given the pretty resounding lack of positive news from biofuel replacement projects (where is that MASBI report that's due out this year). Ah, here we go: http://www.masbi.org/content/assets/MASBI_Report.pdf
US commercial and military aviation consumes 20 billion gallons of jet fuel annually.
Best biofuel generation from crop seeds (canola) runs 80-120 gallons/acre/year. Let's call it 100 gallons even.
Replacing that fuel would require 200 million acres of land. The US has 409 acres of arable land.
Would you prefer to eat as much as you are now, and stick to ground (or airship) transport, or go on a 50% calorie reduction but retain the ability to fly at speeds over 130 MPH?