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41 comments on How a market for sustainable bio-energy is being developed
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41 comments on How a market for sustainable bio-energy is being developed
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12. As long as biomass can displace (save)fossil fuels in electricity and heat/district heat production, it is only allowed to use biomass for transport fuels in order to gain experience in production, preparing us for the fossil scarce future.
The point is the simple, that combustion of biomass for electricity /district heat results in an EROEI of 4-6. Whereas biofuel from biomass gives an EROEI of 1.4 - 3.
As long as we have fossil it is far more energy and pollution efficient to use fossil for transport and biomass for electricity and heat. And be efficient- and conserve as much as possible.
As people in the middle ages found out, biomass is easily consumed and grows slowly.So it must be used wisely and extremely energy efficient.
kind regards And1
"Whereas biofuel from biomass gives an EROEI of 1.4 - 3."
Source?
Re Syntec, source? Here - one of many similar studies for corn/US
http://lfee.mit.edu/public/Groode_Current%20Corn%20Ethanol%20Results_Jun...
A recent LCA study in Denmark gave 1.4 MJ (wheat)biofuel for input of 1.0 MJ fossil. If we add the benefit of animal feed the figure goes to approx 1.7 MJ for input of 1.0 MJ fossil.
For Wood cellulose the figuers are a little Better.
As you might know the Danish biotech company Novozymes http://www.biomass.novozymes.com/files/documents/2007-05380.pdf is making enzymes for bioethanol from cellulose breakdown and the company has published energy data for the process.
I have seen oil drum values for Brazilian Ethanol on the production still higher.
But the everlasting problem for traditional bioethanol is that you have to ferment in water- heat water-and later you have to destill the ethanol. These steps are very energy intensive, with a lot of waste heat. Hopefully the effecivity can be oimproved- by gasification + catalyst , for example.
If you, however put your corn, wheat or straw- wood in a modern Danish domestic oven you will at least get 85% out as heat. If you put cellulose into a gas generator you can run a car with the fumes. This was done extensively in denmark in WW2 when Gasoline was almost non existent. Terribly polluting, but still transport.
LCA's of Danish Wheat crops gives approx 5-6 MJ out for each MJ invested in growing, fertilizers, machinery , crop drying and storing etc. Compared to this, bioethanol has a poor Energy return.
You can see a popular discussion of the dillemma on how to use biomass in this pesentation by Henrik Wenzel (Danish, I'm sorry but graphs are self explaining. http://www.tekno.dk/pdf/praesentationer/alternative-braendstoffer-6_Henr...
In Denmark we have been burning municipial waste for disposal and later for energy since ww2 and agricultural waste/wood waste for electricity and district heat for +/-40 years, so biomass/waste is integrated into our energy system together with other renewables like wind. Likewise the discussion of how to use biomass most efficient has been running on and off the last 30 years in Danish science.
The conclusion is so far. Burn excess biomass for heat and electricity and use fossil for transport as long as available. At that point Biofuel might be one of the options for transport.
This is all for now.
Kind regards/And1
Thanks And1.
I think it was the wording of the sentence that made for the confusion as the EROI numbers you cite, could not possibly cover 'all' biofuels derived from biomass.
And1 -
perhaps it should be noted here that while your Eroei figure quoted may be accurate for AGRI-biofuels,
it is far from accurate for the best of SYLVI-biofuels,
that is, biofuels produced from sustainable forestry,
in particular Coppice & Standards woodland.
The difference includes a total lack of inputs for
plowing, fertilizing, biocides, and, potentially, harvest/extraction by tractor,
as the latter is readily managed by oxen or horses to minimize counter-productive soil compaction.
While I'd agree that biofuels could in theory displace fossil fuels,
I wonder if you'd agree that this cannot and will not happen
unless & untill there is a global treaty limiting all nations' entitlement to release fossil fuel emissions ?
Regards,
Billhook