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245 comments on Requesting Feedback on Renewable Diesel Essay

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concerned on July 14, 2007 - 4:42am

How about some discussion on scale.

How much space required to harvest enough fuel to drive a car/truck x miles/klm/s and extrapolate that for a much larger global car fleet.

You could even calculate what area would be requited to be cultivated to offset global oil declines of say 3% 5% 8% 12% etc

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paal myrtvedt on July 14, 2007 - 9:15am

I agree with you Concerned – the scaling issue is THE Alfa and Omega in understanding biofuels and ethanol, today and for the future. Obviously alongside the reality of EROEI.

I recall the essay titled “That Cubic mile…”, depicting the annual world wide crude oil consumption to be approximately 1 cubic mile. And if we agree that oil is virtually gone in 100 years for all practical uses – the frenetic chase taking place today to substitute this must be done with renewable crops ….

And if memory serves – hardwood (threes) may render 25% of it’s volume/mass to be converted into ethanol – I think ….

Now from my metric part of the world I reached for my calculator – and defined my standard three to be ½ cubic meters (that’s a square trunk 0.25mX0.25mX 8.0m height- a realistic three-volume …)

And the cubic mile is equals 4096000000 m3, and some math on this give me 8192000000 threes, and for that size of threes I need 5 meters between them in a grid pattern. Making a square patch from this I’m getting 453 km X 453 km.

Wowww….

And for ease I round up to 500 km X 500 km – NOW these threes are PURE OIL THREES (from my original cubic) – so I have to make real threes from it by multiplying this amount with 4…

My hardwood-patch suddenly grew to 1000km X 1000 km, and such an area is the same as the whole central Europe – EVERY YEAR

The energy needed to convert this square patch into actual fuel is coming on top of this, and should hopefully NOT overshoot the initial energy content contained in it….

If it takes say 50years to grow one of these sample trees, we WOULD CONSTANTLY HAVE THE WHOLE OF THE AREA OF AFRICA GOING AS A PERMANENT FUEL-GENERATING-AREA FOR THE WORLD –

I’m sighting U-t-o-p-i-a all over the place here …

I'm afraid simular utopian issues apply for all other crops as well ...

THE singlemost constraints of scaling stuff is - mass,volume,seasons,timelines and the boogeyman EROEI.

FOSSIL FUELS CAME BY DURING MILLIONS OF YEARS - How come we think we can do the same in A SINGLE YEAR ? ....and BTW we have to eat some inbetween ....

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WNC Observer on July 14, 2007 - 9:28am

We obviously cannot produce enough biofuels to keep everything running at present levels. Just as obviously, not everything we presently run is of equal importance.

The world can probably live without fast sports cars. the truth of the matter is that the number of private passenger vehicles and the amount to which they are used could be reduced to a small fraction of present levels with the implementation of a serious electrified mass transit program in places that don't yet have it.

Agricultual equipment, ambulances, fire trucks, shuttle buses, ships, heavy equipment, etc. - that is a different matter. It is truly a matter of life or death that we keep these high priority devices running.

We undoubtedly CAN produce enough biodiesel to at least keep the high-priority equipment running. That is why RR's article is so important.

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