What is the EROI ?

EROI = energy returned on investment, is closely related to EROEI = energy returned on energy invested.

Tese are economic rather than thermodynamic quantities and denote the amount of free solar energy delivered in the form of fuel per unit of money or fuel input. Unfortunately, the concepts are not yet properly standardized so some researchers include inputs such as fertilizer and the farm machinery itself while others do not, yielding wildly incongruous results. Even with identical methodology, results vary because some input parameters (such as future prices) must be estimated.

Biofuel projects are attractive only if the EROEI is sufficiently above 1. First-generation bioethanol from corn is a booming business for political/air quality reasons but its EROEI is actually only barely above 1. Depending on the vested interest that funds any given study, it may even come out as below 1.

It's important to realize that EROEI depends very much on the type of feedstock and where it is grown. In tropical countries, per-acre yields can be 10-fold those in temperate climes. Moreover, agricultural labor is much cheaper. Well-connected businessmen can often obtain land and water rights at low cost. Little-known dirty secret: often, land for energy crops becomes available only after clear-cutting virgin rainforest.

Processes such as this one that are able to turn not just the fruit but the whole plant into fuel achieve superior EROEI. However, as the presentation says, the economical production of biofuels for automotive use requires a fairly large biorefinery.

Portable small-scale units for simple CHP are desirable because transporting solid biomass - much of it water - is relatively expensive.

If you are looking for a BTL technology, this has promise. Of course, producing ethanol for fuel has serious drawbacks (including the inability of existing vehicles to run on blends with a higher ethanol content than E10, ethanol's water absorbtion properties which leads to corrosion and related inability to pump ethanol with gasoline, etc. etc.) It only makes sense to produce ethanol as long as Uncle Sam distorts the market, thinking he's doing the powerful farm lobby a favor.

The logical endproduct is the top line in the diagram shown in green.

BTL (syngas) yields roughly 50% more vs fermentation ethanol. For example, a ~400 ga/acre from fermentation corn ethanol may be ~600 ga/acre with BTL. This due to more effcient processes, and use all of the input material (otherwise for animal feed). With fermentation, you get DDG (and maybe some oil) as leftovers. You can also use the cob and stover as feedstock (in BTL), further improving yields per acre, and energy balance.

SJC:

Biomass gasification technology is just like steam-engined bicycles. Antique, well-researched, and totally inefficient. Prove me wrong: how much fuel is produced currently from biomass gasification?

Andrey,

I don't get into the "prove it" stuff, that is for children. Now be quiet and be a good little poster.

Hi, Robert.

I enjoy a lot your thoughtful posts on energy subjects, thanks.

Biomass gasification. Current US and Canadian legislation in different jurisdictions more and more prohibits wasteful incineration of lumber and forestry wastes. Such wastes currently more and more are converted to different products, notably clean combustion firelogs and pellets. Using directly for space heating, wood wastes are too polluting. For electricity generation wood wastes are not very good: due to low calorific value and moisture content, wood-fired steam boilers produce low-parameter steam, and as a result thermal efficiency of electricity generation is very low – about 28% compare to coal fired boilers with efficiency close to 40%. The accepted solution is co-combustion of pulverized wood dust on coal-fired boilers, with wood calorific contribution at about 5%. This way parameters of steam are practically not affected.

It is very tempting to convert wood wastes to much more valuable product, like liquid transportation fuel. Unfortunately, it is extremely technically complicated. Any wood gasification technology suffers from very high level of fly ash and sticky tars, which choke upstream heat exchange and catalytic surfaces in no time. One company, Dynamotive, actually trying to use it to the advantage: they use partial combustion with high yield of pyrolytic liquids, and condense them to use as liquid fuel.

Hopefully, these technical hurdles will be overcome by somebody, but for now it is not the case, notwithstanding rosy claims of venture companies working in the field.

Now, I was talking about relatively dry biomass, already collected and posing high disposal costs. Collecting of dry biomass for sole purpose of gasification is not even on horizon of being economical. Wet biomass, well, you probably know the answer.

Andrey,
Unfortunately, in America everybody seems to be drunk on ethanol when it comes to renewable fuel. The closer you get to Washington, the worse it gets. Great con job by the powerful Ag lobby! Have a drink, you deserve it!

You need to look accross the pond, at work being done in the EU, notably the Netherlands and Germany. The German company, Choren, is building a 4,500 bbl/d biomass gasification plant. We'll see how it pans out, but calling gasification a steam-engined bicycle is quite inappropriate. And asking how much fuel is currently produced this way is equally so.

How much CO2 are we currently producing? Are we just going to sit on our hands and keep doing the same things, or are we going to try and improve things a bit?

this was a little help but it didnt realy provide the adequate information about the production of ethanol from biomass gasificaton...
the links are not clearly hightlight to related material, however it wa some help thanks.. if you find info on ethonal production processes derived from plants... include PLEASE