Some of you may remember this from many years ago. I recently redid the math for the 2014 to see if the problem went away. it didn't.

You may copy, quote or repost this anywhere as long as no one else takes credit for it.

Green Gasoline
Restated 6/3/2014

Every day in the news we hear about alternative fuels and energy and how this politico has the solution that will save us all. Disturbingly, no one ever checks the math on these solutions. So lets do just that now.
“We need to replace automotive fuels with ethanol”.
Ok, sounds good, how much fuel is that exactly? How much gasoline does the US consume in a year?
Note, this is JUST gasoline. Not truck, bus, train, plane or ship fuel, just gasoline.
So next we must ask, how much ethanol can we derive from farming the plants used for producing ethanol? If we use corn - the traditional favorite – and use current harvesting rate trends we find:
Doing math we find that we need 360261905 harvested acres. The number of acres harvested lags the number of acres planted due to many reasons which we don’t care about at this time. We will use the 360 million acres rounded down.

How much land is currently used for farming?

Again doing math, we find that 88% of our current farmed land would be needed to grow corn for ethanol production. This puts our goal of replacing gasoline with ethanol at odds with our unstated continuing goal of producing food for the population. And there are a couple constraints we need to keep in mind:

• Gasoline consumption may go down with increased fuel efficiency across the board, but it will go down fractionally, not by halving or halving again
• Unknown advances in planting and harvesting may make the crop yield increase somewhat, but it will not increase by an order of magnitude
• There are no known plans to reduce to population or appetite of the population in order to decrease the amount of crops needed for food.

The next logical step would be to increase the land used for crop production. Does the US have more land available? Yes, we have the bulk of over 2billion acres to select from. Assuming we do not select paved areas, malls, parks etc we can whittle this down to some number. This number may not be as choice as the land currently under cultivation for a variety of reasons. After 300+ years as an inhabited land we discovered by trial and error which land is tillable. But we have machines and technology and smarts, we can make land tillable to some degree. We just need one major item: water.

How much water do we use? According to the USDA:





We do not hear often about there being too much water except in times of flood. And at that time, it is not useful for crops and in fact may be destroying crops. Lakes, rivers, and groundwater tables are at the low end of acceptable levels – or worse. We do not want to increase fossil fuel usage at all so a coal or oil sourced desalination plant is off the table, leaving nuclear. This makes that particular discussion for another day.

In summary we take away a couple of key points from this exercise:
We can also make a few logical assumptions from this exercise:
To increase the tillable land, and assuming a 1:1 ratio of water needed per acre for the 'new' ground vs. the currently produced ground, would indicate we need to increase our current freshwater consumption by 80%

• Assuming we want to grow 'gas corn' on separate ground as to not affect our food supply
• and we cannot decrease current river, lake or groundwater table levels any further
• dictates we must find this 80% increase from somewhere else.

This does not address a known fact about fuels in an automotive engine: ethanol fuel economy is at least 15% lower than gasoline because there is less energy available per gallon. (BTU's per pound is used to level the playing field and take into account the different densities.)

• BTUs per gallon of gasoline: ~ 114000
• BTUs per gallon of ethanol: ~76000

While this is greater than 15%, consider that a gallon of ethanol is less dense than gasoline. We need to merely increase jet size/injector pulse size to compensate for this as well as carry larger fuel tanks – which in itself is counter productive to mileage desires.

Choose wisely!

 

Don't forget the additional fuel that will be needed to develop, plant, water, and harvest those acres.

 

Lets also not forget the additional taxes assessed to Hybrid cars. If we achieve too high of an MPG rating on certain cars, the taxes would likely increase.

 

Bring the passenger car/truck fleet to 80% diesel usage......Our consumption of oil would go down 30% right there. Increase CNG usage and watch the consumption go down even more.

But yeah.....The math for ethanol (like you stated) never really panned out......and is just a needless competitor for food crops.......

Regarding the CNG, there's an infrastructure issue (much fewer pumps), but many municipalities have been switching over transit and 'fleet' vehicles to CNG...which makes sense for them since they can use their own fueling stations, etc.

And the U.S. has PLENTY of natural gas. Hell, plenty of oil too for that matter.

 

Butanol from glycerol as a byproduct of biodiesel.
Much better numbers for BTU's and greater density.

Still, it's crazy to try and grow a replacement for gasoline.

 

Using the parts of the corn stalk they are currently throwing away would probably cut the need for corn acreage in half. Why did they never use the stalks and the leaves for ethanol? Political reasons. The same reason we don't use other types of vegetation to create ethanol: those plants and plant by products don't put money into the pockets of corn farmers.

 

How is stover being "thrown away"?
It is turned into the field to control erosion and give back to the soil.

Do you want MORE use of petroleum based fertilizers in America's breadbasket, and the equipment to apply it?

At the moment cellulosic ethanol is far behind the hype...
Range Fuels, $156M U.S.Government backed Soperton, Georgia plant was closed in 2011 because they were unable to produce ethanol instead of methanol.
This boondoggle -far- predates Solyndra and was sold for pennies on the dollar.
Range Fuels Cellulosic Ethanol Plant Fails, U.S. Pulls Plug - Bloomberg

Butanol still comes out on top.
One of the most promising enzymes is being extracted from zebra dung, at Tulane University.
http://www.nytimes.com/2012/01/10/sc...anted=all&_r=0

 

zebra dung? Are there enough zebras ANYWHERE, let alone the US to pull this off?

There are a lot of ideas out there and unfortunately all they do is make a moving band of select people/businesses wealthy for a few year.

By chance or design, we hit on the most efficient way to make an internal combustion engine, and the most efficient way to fuel it. And it depends on things that we do not have an infinite supply of.

A dozen or more years ago I saw a report that the KNOWN gallons of oil, gas etc we have consumed from crude, far outstrip the PREDICTED gallons of crude in the ground that would be there from plants, dinosaurs and aliens dying off since the first microbe formed. Which means we do not in any way shape or form understand how the resources get in the ground. mebbe god puts them there as a joke. Or perhaps our planet was more neptunish in the early years (Neptune is full of methane, benzene, and hydrocarbons of all types.)

Also not mentioned is the fact that as long as we continue to grow PEOPLE unchecked, this aint gonna get any better. Realistically, the max holding capacity of this planet is about 3.5bn people. We are about double that. And set to double again in all of our lifetimes. That, is a problem in of itself. (the max holding number is taken from various studies that objectively look at people as net consumers vs net contributors to the furthering of the species. No offense and not political or commentary at all, but a person on the dole, who spends the day on a cell phone checking facebook likely consumes more resource, than value added.)

 

I can't argue about the 'known' amount of fossil fuel in the earth, but I'm not convinced that it isn't renewing itself, albeit probably not at the rate we're using it.
As for the last paragraph of your comment, the population of the world will fit comfortably into the state of texas. Population is predicted to max out in the year 2050 or so at the 9 billion person level, then is going to begin contracting. As for those on the dole, there ain't much we can do about it.

 

It is not about collecting Zebra poop.
It is about using microbes to create massive amounts of the enzyme discovered in Zebra poop.
Many... MANY things are made this way, not just medicines like insulin.
In fact- you mention microbes in the creation of oil...

The otto cycle engine in current automobiles s AT BEST 30% efficient.
Then you have drivetrain losses!
If "heat is horsepower", think of how much heat is shed from the radiator and exhaust.

The "Peak Oil" argument is dead.
New extraction processes have led to untold extraction of resources, like fracking gas from shale deposits.
The U.S. is a net exporter of petroleum product.

I agree 100% with your population point.
We are looking at population estimates of10 Billion by 2100.
There are more people alive today than in all of recorded history.
Infant mortality rates dropping, modern medicine and the agricultural productivity have led to this.
Maybe some new plague will put a dent in it for us.

With the trending "Climate Change" why is no one investing in methyl hydrate?
If we don't consume it it will destroy what we have left of our atmosphere.
Talk about massive amounts of an untapped resource.

 

population contraction:
The Great Contraction: Experts Predict Global Population Will Plateau - SPIEGEL ONLINE

as for the 2050 prediction, here's a wikipedia article (so take it or leave it):
http://en.wikipedia.org/wiki/Projections_of_population_growth
"It is not about collecting Zebra poop.
It is about using microbes to create massive amounts of the enzyme discovered in Zebra poop.
Many... MANY things are made this way, not just medicines like insulin."

I loved the idea of having the algae creating the biodiesel. Science is cool, and we should be able to find a way to do these things, eventually.

 

define comfortably? I get 26000 people per square mile. or about 1100 sq ft per person. this does not take into account roads, parks etc. So you have to build UP. This essentially, within a few percent (do the math) gives you a new York city the size of texas.

Ever drive across texas?

at any rate, no one is complaining we have TOO MUCH food now or TOO MUCH water now. In fact, those complaints drove my little research project. If we double the population, don't we in fact place the same strain on the food supply that ethanol proposals do now?

As for another comment, even at 30% the internal combustion engine is at its most efficient design and the fuel if the best discovered. WE have spent well over 100 years putting all sorts of crap in the tank. Gas works the best, MPG, buts per gallon, btus per lb you name it. might we grab another % here or there with some wonderful expen$ive breakthrough? sure. But its not a doubling which is needed NOW or a quadrupling which is needed in a few years.

the biggest lesson you can take away from this: we need another new as of yet undiscovered way to move people from point a to point b. Id look into using the transporter, but over the internet. :-)

 

If you put all humans on a pile, they would take a really small space





Zoomed out...



Don't worry.
Within a few years we will all be driven in autonomous thorium fueled sky cars!
These fusion powered quadracopters will whisk you to whatever destination you think of.
http://www.independent.co.uk/life-st...s-9506963.html

 

Corn yields have increased roughly 6 fold since about 1940, and we're just scratching the surface of the potential of transgenics, so I wouldn't rule this one completely out. I do sincerely believe the day will come when transgenic plants will grow ready or almost ready to use biofuels that need little to no further processing beyond extraction from the plant, that will be far more efficient than the current ethanol process.

But to expect to yield sufficient fuels from biofuels without massive new infrastructure commitment is unrealistic regardless of the source. Unless we figure out cold fusion or car sized fission reactors, it will be a massive undertaking, regardless of the fuel.

 

I don't know about the 'sky' part.....but the thorium-fuel nuke cars are entirely doable.....

Someone here on FTE had a thread about that not too long ago.......I forget the guy's name.........