When reading articles like the one quoted, it is often illuminating to check the figures.
I'm guessing the figures being bandied about here are for the USA?
The figure quoted is:
140 billion gallons of algae biodiesel to replace petroleum-based products each year.
... assuming zero growth of course.
Checking the figures:
According to the EIA: total petroleum consumption is 6.98billion barrels of petroleum products in 2013.
1 barrel 159 liters or 42 US gal. So that is 276.36 billion gallons just in 2013.
Almost twice the quoted figure... unless biodiesel is twice as energy-dense as the equivalent petroleum product? Is that likely?
Checking the zero-growth assumption: imagine my surprise when I see almost flat growth in consumption projected.
http://www.eia.gov/forecasts/aeo/MT_liquidfuels.cfm
... looking closer - the total consumption looks to have about 1% pa growth in the projection, averaged from 2010 to 2015. Something like that. It is hard to gauge the projection but 1% kinda seems small anyway...
Is the 95 million acres a lot of land?
95mil acres is 148440 sq miles ... about the area of Montana.
Montana is the 4th biggest state by area, about 4% of the total US territories.
Sounds doable.
Checking the maths:
If we accept the figure: 100 acres would produce 10 million gallons - that's 10 acres/mil.gal.
(Really need a proper citation for this figure - where did the author get it from?)
So we take the area in acres, divide by ten, to get the number of millions of gals produced.
i.e. 95 acres produces 9.5mil gal pa
so 95 mil acres produces 9.5 mil-mil gal pa = 9500bil.gals pa.
Only wanted 140bil... seems a bit puzzling to be that far out.
Note: "experts estimate" is one of those marketing terms - goes with models in white coats holding clipboards ... clinical studies show that our product removes stains faster than a leading competitor... that should raise a red flag every time it appears in an article. Probably the discrepancy here is an artifact of a journalist using several sources and not checking the maths... but it does give reason to look sideways at the article's claims. But I am not trying to disprove what the author has said... let's keep going:
If 95mil.acres is really what goes with the 140 bil.gal figure, then we should really need 187mil.acres to go with the actual, recent consumption figure. This is a bit bigger than Texas, or about 8% of the USA.
Sounds promising.
What happens if the growth is not zero? It seems reasonable to think that there should be some small increase in fuel consumption, we just want to, ideally, supply that in alternative fuels.
Using a 1%pa growth, this means that consumption would double roughly every 70 years ... to maintain that growth, you'd need to double the land devoted to bio-diesel every generation.
Seeing as how we are starting from scratch - that means we have to build 16%USA-area worth of algal bio-diesel plants in the next 70 years, just to catch up. (Assuming negligible algal-biodesel plants now).
In the 70 years after that, must add another 16%, then 32% ... by the year 2224, following the plan to replace all petroleum consumption with algal-bio-diesel plants of the kind discussed in the article, the plants will occupy an area 64% of the entire territorial USA.
Maybe some sort of state-spanning high-rise: I know, build the plants over roads!
Roads occupy about 2% (need to check) of USA surface ... so we'd have a 32 story building on top of all the roads in 200-odd years?
Mind you - we could slow that down a bit by using up the oil as well - the above kinda assumes a faze-out of oil use over the next 70 years. But whatever the fade-in time, 140yr, 210yr, the same figures will have to be met at the end of that.
But none of us will be around then ;)
I should add that all this assumes that the fuel cost of making the bio-diesel is about the same as that for extracting crude oil already. I suspect the fuel cost will be higher - but it may be less. I don't exactly have figures and algal-bio-diesel looks like it is still at the early proposition stage.
Of course this won't happen. What will happen is that consumption will have decreased somehow.
The trick is to choose what we want to give up before Nature chooses for us.
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Caveat: I've been a bit under the weather so I may have messed up or misunderstood something.
Do check my arithmetic. The main point of above is to show the kind of thinking and checking needed when we read these sorts of projections.