Alcohol fuel - The obvious answer, Yes or No?

Discussion in 'Business & Economics' started by Billy T, Nov 18, 2005.

  1. Kittamaru Never cruel nor cowardly... Staff Member

    Starry... you been drinkin? Or are you just tired? Cause I'm not even entirely sure what you were trying to say... sorry...
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  3. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    I don't understand the gum problem. If you were using reg. gasoline adding 15% should help keep it cleaner, but not make much difference if you were using Hi-test (gas with oxidizers added)

    Your MPH is lower than it should be with 15% which has only 0.7 of the energy content, it should be: 0.85x22 + 0.7x0.15x22 = 21.01 mpg
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  5. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    “… Ethanol derived from Brazilian sugar-cane offers the best hope of replacing oil as the world's main source of fuel when it runs out,” according to Bob Dudley, BP's chief executive. He said Brazilian ethanol is the "best type of renewable energy" and offers the possibility of an "ultrapotent fuel that could revolutionize the market".
    “BP is channelling its research into renewable fuels accordingly, with 40pc of its $1bn (£625m) annual spend in this area targeted at Brazilian ethanol, Mr Dudley told the weekly Brazilian news magazine Veja. {= Brazilian "Time."}

    "The alcohol extracted from sugar cane is cheaper, less polluting and more efficient than that from corn, for example, produced in the US. "Brazil also has a huge advantage in relation to its competitors. The climate and soil are ideal and the sugarcane crop does not have to compete for areas with food crops, as happens in the case of America."

    "Of $1bn that we spend every year worldwide on research on renewable fuels, $400m (£250m) is destined for Brazilian alcohol," he said. "The goal is to develop cellulosic ethanol and create an ultrapotent fuel that may revolutionise the market."

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  7. ElectricFetus Sanity going, going, gone Valued Senior Member

    Billy I showed the numbers before, that Brazilians ethanol could not hope to satisfy even a fair percentage of the worlds demand for oil, I don't see how exaggerated claims by BP oil executives change that fact, certianly investment in Brazilian ethanol will be quite lucrative for BP but that won't change the fact the the majority of the world oil replacement needs will not come form Brazil, that Brazil will as best be a prominent singer in a concert screaming for energy.
  8. X-Man2 We're under no illusions. Registered Senior Member


    Why couldn't other Countries with similar weather help grow the sugar-cane? Is there good reason(s) why not? Just curious.
  9. ElectricFetus Sanity going, going, gone Valued Senior Member


    Now multiply that by ~3.5 if you want to supply all the gasoline needs of the world! So I serious don't all the worlds tropical croplands to handle the load. Certainly all the worlds agriculture biomass and satisfy some of our energy demands, but not all of it, probably not even a majority of it, not without something radical like algal fuel or something.
  10. Read-Only Valued Senior Member

    Quite true. And note that that does NOT even include diesel fuel (which is a huge number all by itself), bunker oil for ships nor the dozens of other applications of petroleum products - such as in drugs, plastics and lubricants.
  11. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    I agree. I have always said that tropical alcohol from sugar cane could replace oil for liquids fuels IF there is also considerable improvement in efficiency - that includes both public transport* and working from home via the internet which are more important than lighter weight cars, etc.

    I have admitted that some tropical forest would need to be cleared, much like the Ohio forest was etc. I think the BP CEO is assuming that cellulosic alcohol will be economical. - I am not so sure, if so, then crushed cane may be the only economical source as there is zero new cost to collect in the fields and zero new cost to transport it to the alcohol plant - two very costly extras for say switch grass.

    BP's CEO is also probably using the fact that the abandoned pasture in Brazil is several times larger than the land now producing cane, when saying it would not compete with food crops as it already does to a large extent in the US's corn based, highly subsidized, system. What I think he may be neglecting (and certainly should not as BP is also a chemical company) is the rapidly growing use of sugar as a chemical feed stock for plastic etc. production.

    One 200,000 ton/year plant has been producing for several months and another of the same size is will be in less than a year. Already, this plus the growing number of flex fuel cars has driven up the price of alcohol at the filling stations so it is no bargain compared to gasoline. As I don't want to fill tank so often, I typically use gasoline now even if that is giving up a couple of percent savings.
    * Super flywheel powered buses are best for urban areas, I think. They have essentially more charge/ deep discharges cycles than than can be used in the life of a few buses, even if bus recharges at each terminal (30 cycles per day) and the only limit on the charge rate is the power supply and charge motor capacity. (Recharge can easily be done while driver gets a cup of coffee and goes to the bathroom, if the power is available as it would be at the bus terminal.) The super flywheel has more energy density than any battery, Li-ion included. It is also made of relatively cheap materials, like carbon fibers.
    Last edited by a moderator: Feb 15, 2011
  12. X-Man2 We're under no illusions. Registered Senior Member

    Do Bio-Fuels in the US have a running chance? Will the US use the most cost effective crops? I am extremely doubtful and I see many are too.Will the US spend billions of dollars to find out the hard way that bio-fuels arn't the answer?

    Today's News:

    "The USDA tells us that more than 500 biorefineries will be need to be built between now and 2022 in the United States to meet the added requirements for advanced biofuels. With those refineries costing somewhere around $8 per gallon of capacity, or north of $300 million each, the total price tag for bioenergy expansion will be in the region of $150 billion"
  13. ElectricFetus Sanity going, going, gone Valued Senior Member

    Depends on incentives, if the political will is in place for self-relevant energy production the USA it could be done. Heck USA corn ethanol production has manged so far. But Biofuels are A answer, not THE answer, biofuels can supply some of our needs and do so cheaply, for example cellulosic ethanol made from agriculture waste could replace 20-30% of our gasoline usage with a feedstock that is presently thrown away, electrified transportation could replace 80% of our gasoline usage, just those two options together could replace gasoline usage.

    And we been over that: the efficiency improvements would not only need to account for growth of economies but also reduce energy consumption by 2/3rds! There is no way we could get every up to 1st world standard of living without increasing our energy usage tremendously. Even if we brought everyone to a standard of living like Germany with high speed rail and efficient usage of energy at half the rate per person of hedonistic USA it would require doubling all the worlds energy consumption to get everyone to that standard.

    And we have been down that road as well: better Ohio then cut down more rainforest, use nutrient poor soil and threaten the biogenic enhance rains that keep northern Brazil wet and not Savannah or worse desert.

    Assuming the existing infrastructure could handle the load, as soon as you have to make new infrastructure then the economics of transport and processing are the same. As is even in Brazil alcohol fuel infrastructure still has much to grow.

    And I already shown that all the agriculture land in Brazil combined could not supply the USA need for gasoline let alone the world, let alone all oil usage of the world!

    Try 12.6 Million tons a day, that how much oil the world uses. The upscaling needed for any alternative is mind boggling, and certainly should not be done by choosing just one or even a handful of alternatives at a time, this will require many alternatives simultaneously. Alcohol fuels are one of those alternative but it will likely not represent a majority share of the generalized alternative energy market in the long term.
    Last edited: Feb 15, 2011
  14. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    You are moving the goal posts on me - I never suggested that tropical alcohol could replace global ENERGY NEEDS. I said LIQUID FUEL NEEDS, AND THEN ONLY WITH GREAT REDUCTION OF THEM by things like your 80%
    Probably true that doubling of ENERGY would be required but tropical alcohol could supply the needed liquid fuel, given greatly expanded mass transit, telecommuting etc.
    That doubling will be made by natural gas mainly for the first decade, but then by nuclear power.

    But I don't think even the US will be at current German living standards in a couple of generations. Already this generation has lower living standards than their parents had. A depression is coming (soon after Halloween 2014, at the latests, if my long standing prediction is correct. It was made when GWB still had a couple of years as POTUS as I understood how badly he damaged the US.) Living standards in China will still improve, but be far below current German standards. I don't know what to think of India, but unless they get their population growth reduced, their standards will only go down from current levels, except for the wealthy few.
    Last edited by a moderator: Feb 15, 2011
  15. ElectricFetus Sanity going, going, gone Valued Senior Member

    And I originally calculated for gasoline alone, even that Brazil could not hope to replace. 80% reduction, how the fuck can that be done?

    Again the numbers don't lie, the tropics could never provide enough to even make up for gasoline usage alone.

    But general energy demand world wide is likely to keep going up, and if not a general depression will prevent new infrastructure from being built.
  16. quadraphonics Bloodthirsty Barbarian Valued Senior Member

    The technologies in the R&D phase now (i.e., the stuff being invested in) deal with underground coal liquefaction. I.e., certain fluids and chemicals are pumped into the coal seams at specific temperature and pressure, and the conversion to liquid fuel takes place in-situ. This avoids open-pit mining, allows the extracton of fairly deep reserves, and leaves the excess carbon that is shed in the coal liquefaction in the ground. But, it is unclear how economical this will be, or what other drawbacks it may have. It's still in the early R&D phases.
  17. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    I don't think 80% of tranport could be converted to electric energy at least not for more than three decades, but did not want to argrue with you claiming it could:
    True, numbers don't lie, but liers can use numbers to support their claims.

    Let's try to make a quick estimate of the max potential of tropical alcohol production we can agree upon:
    I suggest we assume 5% of the forested land between + and - 30 degrees latitude were growing sugar cane. (Note most of the cane grown in Brazil is grown in the state of Sao Paulo, south of the tropics so cane grows well in this 60 degree band around the equator.) Also assume that 3% of the sun's energy in this 5% of the 60degree band is converted to net gain of alcohol energy (and make that 6% if cellulosic alcohol is economically made from the crushed cane) Adjust these assumed numbers if you like and can justify them being lower. I am just trying to get a simple agreed methodology for the calculation.

    I am too lazy to do the calculation, especially before you agree that this is a reasonable estimate of the potential production of "tropical" alcohol; however I'm quite confident that is enough alcohol production for the liquid fuel need of much more than just the US's needs when the needs are greatly reduced, mainly by more mass transit (I like super flywheel buses for urban use, and electric train between cities.) and more tele-commuting. I note than natural gas will also replace liquid fuels in cars, but I am not very happy about that as unlike sugar cane alcohol, it adds to the CO2 release and uses up a valuable chemical feed stock.

    I will let you suggest what annual energy is needed in the US as liquid fuel after reasonable reduction by these two factors has been made (Plus a few percent more reduction would result if lighter European or Brazilian cars, still using liquid fuels were on the roads, instead of US big gas eating monsters.)

    With your "if" I can agree, but think there will be a deep, long lasting depression in US and EU before the end of 2015. The US can not recover from its current and growing debt to GDP ratio, especially once the bond vigilantes swing into action and drive up the interest rates on the growing debt. To do that would be a global first in history for a nation which does not have a monopoly on manufacturing of goods.

    US and EU sinking into deep depression for more than a decade, will more than compensate for the growing energy demand of Asia so global energy use is near it peak now, if I am correct about GWB's depression being unavoidable already when he left office. (Two years after I predicted it due to GWB's two recessions, two new wars, destruction of the purchasing power of wages and huge job deficit he made. (20 million new jobs were needed to just keep up with the growing labor force and he made only 8 million - That is why real wages dropped during his 8 years.)
    Last edited by a moderator: Feb 16, 2011
  18. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    That is interesting. Who is doing that R&D? - do you have a link?

    I own stock in an advanced in situ shale oil company, PBEGF, now testing on large scale their patented air only injection process. (The air feeds an underground fire. I'm not sure but think all the CO2 produced is trapped. Perhaps as the last stage of their process water is injected to absorb the CO2? I would do that anyway but don't know if they do.) Here from my more than year old notes are some facts:

    "In-situ technologies currently in use include steam-assisted gravity drainage (SAGD) and cyclic steam simulation (CSS). Potentially more cost-effective and less environmentally intrusive technologies. are vapor extraction (VAPEX), which uses hydrocarbon solvents instead of steam to release bitumen from the sand and to oil flow more easily for extraction at lower heat and thus with lesser energy input. Petrobank Energy and Resources Ltd (TSX: PBG, OTC: PBEGF) is testing toe-to-heel air injection (THAI) at its Whitesands project. Excelsior Energy Ltd (TSX-V: ELE, OTC: EXEYF) is developing combustion overhead gravity drainage (COGD), which it claims will recover twice the oil with only 20 percent of the energy input necessary for traditional SAGD. Cenovus Energy (TSX: CVE, NYSE: CVE) plans to test a solvent-assisted steam process that it says could cut greenhouse gas emissions by 25 to 30 percent."

    PS if you look at a stock price graph (I have not in 2011) you may see a drop in January because: PMGLF, their quite profitable Colombian Petrominerales was free spin off from PBEGF effective on 7Jan11 so I now own it too.
    Last edited by a moderator: Feb 16, 2011
  19. ElectricFetus Sanity going, going, gone Valued Senior Member

    As a matter of building infrastructure of course three decades to reach 80% market penetration is unlikely for electric transport, but it is even worse for biofuels. 80% is feasible without the need for new powerplants (but the need to smart gridding, but that is a much smaller infrastructure change than new powerplants) and of course new car manufacture, materials production and mining would need to be uprated to support the construction of an electric car fleet. Biofuels need millions tons of feeds stock, need to be grown, transported, processes, transported for distribution, with ethanol that means new pipelines and new cars that can operate on ethanol and ethanol blends. Even if we assume bio-petroleum instead of ethanol, thus forgoing new pipelines and new cars, all the background infrastructure from growing to converting would still be more then electric cars.

    Do you remember this?

    So I've done the calculation for you before. So 3% conversion is highly unrealistic, unless they somehow manage a more then 3 times improvement in cane production and 100% efficiency of converting that biomass to ethanol!

    The world needs ~85 million barrels of oil a day, or 2.2*10^18 watts of power, lets take the 175 w/m^2 of sunlight on average in that region per sec over a daily average, or 15 Mw per day, that would mean only 1.7% of brazils total land area would be needed to support the world oil demands, assuming 100% conversion efficiency. But Ok lets use your 3% figure, that would mean 57% of Brazil total land area would be needed, but you claim we could somehow get world energy demand down to 1/5 (80% reduction) that would still mean 7% of Brazil total land area is required. But this is all based on assumptions many highly unlikely: 3% efficiency from sunlight to ethanol from sugar can is impossible, even 0.86% assume all sugarcane biomass is 100% converted to ethanol without energy expense. Than of course there your "massive reduction" in energy usage, to maintain a high standard of living 80% reduction is extremely unlike, again we have the European states to compare: a state like Germany or France with all there high speed rail only managed a 50% reduction at best compared to American hedonism.

    what you think is also another "if", now I'm just projecting off of the most direct global trends that world demand for energy has generally gone up throughout the last 200 years, and certainly has not gone negative for several decades!

    Perhaps, than again Japan has significantly more debt to GDP and they somehow manage a steady state economy despite an aging and dieing off population.

    Wondrous speculation, hey I think a breakthrough in fusion energy will come about soon from people like this and all the world will live with greater prosperity then ever before... see I can speculate off the wall too!

    As much as I would love to blame it all on GWB rather America economic uncertain future is has been caused by many factors of which GWB is only one. I would say the general spend more and tax less policies started by Reagan is the biggest contributor, Bush merely perpetuated it.

    But anyways, if the world was to go into such a depression that global energy usages went down to 1/5 of what it is, then fossil fuels could supply that demand for many decades and certainly bio-fuels would not grow in such a competitive and difficult to find financing future. Thus you have shot your self in the foot, in such a depression infrastructure will remain as build on only the most conventional and cheapest models, thus bio-fuels become nonsensical unless its infrastructure already built, why convert when converting is so very hard in the cash strapped future and when oil will be so cheap because world demand from the depression will be so low?
    Last edited: Feb 16, 2011
  20. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Vaguely, but I'm just now starting to try to follow in detail. I only got to end of first line under the drawing before getting lost by your impossible conversion between apples and oranges. I.e. what are you trying to do with:
    "sugarcane produces at most 6.1 GJ/ton/yr of total biomass (leaves, stem, everything) or 6.10E+9 w/ton/yr. (1E9 w/GJ) " ???

    "w" is for watts, is it not? and GJ is for giga Joules is it not? There is no such conversion factor as they are not measures of the same thing. The first is power and the second is energy. Also you need to tell the size of the field, square meters etc. That are producing X tons per year. Your link states: "In prime growing regions, such as India, Pakistan, Peru, Brazil, Bolivia, Colombia, Australia, Ecuador, Cuba, the Philippines, El Salvador and Hawaii, sugarcane can produce 20 lb (9 kg) for each square meter exposed to the sun." Did you use this some where?

    Before other comments on your post, I'll wait for you to explain, what you are doing here.

    I do think it is worth the effort for us to agree on some estimate of the max reasonable potential annual energy in the form of sugar cane alcohol possible from the 60 degree wide "tropical" band centered on the equator.

    Do you accept that 5% of the existing land area in this 60degree band (only from forest now in this band -no conversion of crop land) could be converted to sugar cane production? You may be by nature a "tree hugger" but the realistic alternatives for at least two decades are economic collapse for lack of liquid fuel or much higher cost as petroleum production cost rise and continued CO2 release, at increasing rates, which may also lead to economic collapse. (Assuming there is no "magic solution" via unknown or at least unproven in large scale technology.)

    I think the people now leaving this land in forests have the same right as the US exercised to clear to forests of Ohio, etc. to make a conversion of small part of their forests to a higher economic use. When many in the world are on the edge of starvation, especially in this tropical band, it is immoral not to fully employ the world's assets to give them the income with which to buy food.

    One of the moral justifications for taxation is that it encourages the conversion of assets to their highest economic use. (Prevent holding of assets in an un-productive state.) It is a fundamental principle of economics that assets should be made as productive as possible. It is, I think, a fundamental principle of ecology that fossil fuels should not be burned to release heat, but used as irreplaceable chemical feed stocks. Until our agreed numbers show it is not possible, I believe that the conversion of ~5% of these forests to sugar cane production helps to achieve both these fundamental objectives.
    Last edited by a moderator: Feb 16, 2011
  21. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Rather than wait for your (ElectricFetus) explanations, I decide to do a quick calculation. I will give the summary of its results first:

    SUMMARY: Five percent of the currently forested “tropical” lands could supply four times more energy in alcohol than the US used in gasoline in 2009. Or approximately the world’s total use of gasoline could be supplied by this 5% of currently unused land.. But of course, this demand for gasoline, can, should and must be drastically reduced as Asia, especially China will be buying more of the available petroleum. I.e. much greater use must be made of tele-computing and electric energy based public transport.

    A Google search on “Land mass by latitude bands” had as first hit a book published by the Brookings Institution Press which is found at: mass by latitude bands&f=false In case a later Google search yields other results.

    At the bottom of page 216 it states: “The tropical land mass is 45 million km^2.” The next page presents graphically the land mass in 10 degree wide latitude bands, but in acres and it is not immediately clear what the scale units are. Their 45E6Km^2 of land in the “tropics” is clearly stated to be the band between 23.45N and 23.45S latitude.

    To adjust to the 60degree band assumed for high yield sugar production, I suggest we simply multiply the 45 by 60/47 and take 5% of that, now in forests, for growing sugar cane. I.e. we could have approximately 2.87E6 new km^2 or 2.87E12 square meters in sugar cane.

    Now with your figure for tropical annual average of solar power per meter square (175W/ m^2) and fact that there are 60x60x24x365.25 = 31557600 = 3.16E8 seconds in a year and fact a watt for a second is a Joule, we have 175x3.16E8 = 5.53E8 Joules per meter square solar energy input each year per meter square.

    The link: has a section, based on a book published in 2005 (with earlier harvest in Brazil as the data source) called “Cane Ethanol.” It concludes with the statement that the solar energy to ethanol’s higher heating energy (steam condensed) conversion efficiency is 0.13, but (1) that does not include the energy of sugar which may someday come from processing the now burned bagasse (cellulosic alcohol, if economical) nor (2) the significant increases in yields per acre that have been achieved in the last 7 or 8 years since the harvest data of the book. Thus, considering that alone, I will take 0.2 as the energy conversion efficiency (which is less than ¼ of your value.)

    Combining the above facts, we expect sugar cane to produce as energy when burned 0.2x5.53E8x2.87E12 = 3.17 E20 joules from 5% of the 60 degree wide band of “tropical” land now in forest annually but recognizing that during part of the year the crop is not growing, there are clouds, etc. let guesstimate the world could produce 2E20 Joules of energy in sugar cane alcohol if 5% of the now forested land in the band 30S to 30N latitude were converted to this productive end.

    “Americans used about 378 million gallons per day of gasoline in 2009”
    From: That is 365.25 x 378E6 = 1.38E11 gallons per year. And each gallon has 131E6 Joules in it. Thus the annual US energy use in gasoline is:1.38E11 x 1,31E8 = 4.95E19 joules, call it 5E19 Joules
  22. ElectricFetus Sanity going, going, gone Valued Senior Member

    Watt = 1 joule per second = 1 j/s. If I was to burn one ton of sugarcane in one second I would get 6.1 GW of power. Now if I was to burn that over a day it would still be 6.1 GJ energy was available, but only 70 kW of power, here the kicker though: its 70 Kw-day of power or 70,000 joules per second over one day, or 6.1 billion watts total or 6.1 billion joules per second, the ratio of joules to watts is 1:1, thus joules and watts are interchangeable as long as time is in units of seconds.

    The same units are used for say measuring utility usage where they are measuring in watt-hours or Kilo-watt-hours, which of course is really just joules per second consumed over one hour. So say you have a 100 watt-hour light bulb, how much energy does it use over one hour, easy: 100 watt*hour * 3600 second/hour equals 360,000 watts*seconds or 360,000 J/s*s or 360,000 joules, how about in one second, very easy: 100 joules, I can say 100 watts a second which is W*s or J/s*s, its still the same as units of energy in joules.

    No, I just need to know how much energy per ton, how many tons per unit of area (acres, m^2, etc) and finally how much energy comes in sunlight per unit area. Here is the math:

    6.10 GJ/ton Given
    31.5 tons/acre/yr Given
    192.15 GJ/acre/yr both above multiplied
    4046.86 m^2/acre conversion
    0.04748 GJ/m^2/yr both above divided
    47,481,299 J/M^2/yr above multiplied 10^9

    175 w/m^2/d Given
    15,120,000 J/m^2/d multiplied by seconds in day
    5,518,800,000 J/M^2/yr multiplied by days in a year

    0.86% Difference both bold divided

    Now the link specifies 31.5 tons per acre (table on page 5) now if it was 9 kg it would come out to 36 tons per acre, a difference but not much of an improvement.

    Perhaps, would it make viable crop land is a good question, considering the poor quality of the soil in most of those regions, but that 5% would not provide much certianly not enough even to replace oil under your impossible to achieve numbers of 3% efficiency from sunlight to fuel and 80% reduction of use.

    No its not a realistic alternative, there simply not enough land, biofuels will only provide a minority percentage of our needs! And again if your scenario is true that world wide depression is coming then oil prices will actually drop as demand drops because of depression, we saw it happen after the oil peak of 2008 when the world wide recession droped oil prices down to from all time highes to manageable prices, price reductions that I personally saw kill many start-up ethanol companies in the states, that had come about in the price peak.

    There land is not as directly profitable as Ohio's. The forest will not make fertile farms as the soil is too nutriment poor, at best it can make open parries for cattle after a few growing seasons. They will technically end up with less indirectly profitable land then they started with, the only difference is today few people pay the land owners for the profits their land provides in rainfall and carbon sequestration.

    Its immoral to destroy assets that are technically providing the world more. Why not demand people across the globe pay them for keeping the forest, pay them to get jobs in factories that will provide them far more income than as plantation workers.

    By that logic we should use ALL the coal and oil and natural gas in the world, I don't see why your worrying about CO2, ever, because to ameliorate such worries would prevent us from maximizing economic usage. perhaps your worried about all the suffer that might be caused by climate change, tough tits, highest economic use is all important, immorality is of no concern.

    I disagree, biomatter can be converted to petroleum and thus replaced any organic chemical feedstock that petroleum provides. More so by converting biomatter into biofuels and bioproducts makes for a carbon sequestration and thus you don't simply reduced but actually have a negative carbon production and begin reversing climate change. Continued use of fossil fuels to make chemical products will ultimately mean some of it will end up back in the atmosphere as CO2. Oooh that right you don't care about that, you only care about maximum economic value, so here is what I say, I say cut down the whole forest and make what ever you can on it, now if it all turns to savannah and even desert oh well you said maximum economic value and clearly not over how long a period of time or you would have consider the value of the forest as is as worth more.

    More so maximum economic value dictates that we change nothing and keep using existing infrastructure (fossil fuels) and the coming global depression will make that even more so, with the reduced demand and lack of financing to change.

    Now if you just want ~5% of the forest, I don't see why when you have already cut down ~18%, that is 725,000 km^2 or 180 million acres, that is more then Brazil's existing crop land area, why not use that? Ooooh that right most if is cattle pastures for some reason, I wonder why?
  23. ElectricFetus Sanity going, going, gone Valued Senior Member

    Oh so all tropical land is forested? Certainly they mean all land between 23.45N and 23.45S latitude, as the earth has 148,300,000 km^2 total of land area and it hard to believe that 30% of the earth is tropical forest. Lets see what kind of land is between in this 60 degree band or 30N and 30S, well there is the Sahara, yeah sugarcane will grow well there, there is also the Arabian Peninsula, that got to be worth something, there is most of India and China I'm sure they don't have much of there land already covered in farming. So clearly only a fraction of your 57 million km^2 is forested land for which you want to take off 5%.

    and you were giving me shit about joules to watts when you your self were aware of the conversion!

    You made a big error, its 0.13% not 0.13, likewise its 0.2% not 0.2 that means you need to divide your answer by 1/100. And of course that you mean 5% of tropical forest and not all tropical area and so in conclusion you clearly have just proven your self wrong. World oil usages is 0.18 ZJ or 1.8*10^20 Watts consumed in a year, and your saying 2*10^18 Joules can be produced (using 0.2% and not 0.2) from the 5% of TOTAL land area in an estimated tropical area between 30N and 30S.

    Lets try it in reverse:
    6.10 GJ/ton
    31.5 tons/acre/yr
    192.15 GJ/acre/yr
    47481.3 GJ/km^2/yr
    4.75E+13 J/km^2/yr
    1.80E+20 J/yr needed
    3,790,966 Km^2 needed

    So that means we would need 7% of ALL tropical lands between your estimated total land area in this 60 degree band is needed assuming 0.86% efficiency of solar to biomass and not 0.2% solar to advanced ethanol your propose. If we use 0.13% as you found of solar to ethanol then we would need 25 Million km^2 or 17% of the earths total land surface area in sugar can production or 44% of the total estimated area in your 60 degree band. But Ok lets go with your 0.2% estimate, that is 16.3 million km^2 needed. Now how much forest would that be, Well the amazon rainforest is ~3.3 million Km^2 large so you would need nearly 5 amazon rainforests in land area!
    Last edited: Feb 17, 2011

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