Cellulose ethanol 3

[0707]

Bio diesels are not new Brasil are great producers but, Richard Branson announced Virgin Fuel as a revolutionary Fuel.

Richard Branson He said “cellulose ethanol "is the by-product you get from the waste product (of plants), the bits in the field that get burned up," as opposed to ethanol which is produced from fruit or corn for example.”

Cellulose ethanol exhibits net energy content three times higher than corn ethanol and emits a low net level of greenhouse gases.

Some challenges of cellulose ethanol are: Corn requires an abundance of fertilizer to grow and carbon dioxide is emitted during ethanol production. The biggest opportunity for expanded production of ethanol will be from cellulose resources, however, this process is very expensive. The advancement and development of technologies for cellulose ethanol production is critical to expanding use of this fuel.

Luis

 

[KENAT]

Conservation of Energy.

What is often termed power or energy generation is really energy conversion.

Certain types of energy are more useful for certain applications.

e.g. you could have a car with some kind of steam power plant burning crop waste. However, perhaps a vehicle burning ethanol derived from the crop waste is more efficient and/or easier to use and/or less costly and/or easier to fit into existing infrastructure etc.

So even though the efficiency from a pure thermodynamic stand point may not look good it may be worth the effort when you consider all factors, or at least the ones you can think of.;-)

 

[btrueblood]

The bottom line will always be - can you make any money at it?

 

[moltenmetal]

stephenw22: I know all about Iogen- we've been hiring people they've been laying off. If there really were money in it, I'd think they'd be hiring...

 

[nbucska]

Cellulose + water + acid --> sugar

Since only C, O and H is used up, the minerals may be
recycled to fertilize the field either by composting or drying and burning -- the later needs more energy and
would lose more N2.


Plesae read FAQ240-1032
My WEB: <

http://geocities.com/nbucska/>

 

[0707]

"Cellulose ethanol can be produced from a wide variety of cellulose biomass feed stocks including agricultural plant wastes (corn stover, cereal straws, sugarcane bagasse), plant wastes from industrial processes (sawdust, paper pulp) and energy crops grown specifically for fuel production, such as switchgrass. Cellulose biomass is composed of cellulose, hemi cellulose and lignin, with smaller amounts of proteins, lipids (fats, waxes and oils) and ash. Roughly, two-thirds of the dry mass of cellulose materials is present as cellulose and hemi cellulose. Lignin makes up the bulk of the remaining dry mass.

As with grains, processing cellulose biomass aims to extract fermentable sugars from the feedstock.

But the sugars in cellulose and hemi cellulose are locked in complex carbohydrates called polysaccharides (long chains of monosaccharides or simple sugars). Separating these complex polymeric structures into fermentable sugars is essential to the efficient and economic production of cellulose ethanol.

Two processing options are employed to produce fermentable sugars from cellulose biomass. One approach utilizes acid hydrolysis to break down the complex carbohydrates into simple sugars. An alternative method, enzymatic hydrolysis, utilizes pre-treatment processes to first reduce the size of the material to make it more accessible to hydrolysis. Once pre-treated, enzymes are employed to convert the cellulose biomass to fermentable sugars. The final step involves microbial fermentation yielding ethanol and carbon dioxide.

Grain based ethanol utilizes fossil fuels to produce heat during the conversion process, generating substantial greenhouse gas emissions.

In the Cellulose ethanol production, fossil fuels are substituted by biomass. This property changes the emissions calculations.

Cellulose ethanol showed greenhouse gas emission reductions of about 80% [over gasoline], Corn ethanol showed 20 to 30% reductions. Cellulose ethanol's favourable profile stems from using lignin, a biomass by-product of the conversion operation, to fuel the process. Lignin is a renewable fuel with no net greenhouse gas emissions. Greenhouse gases produced by the combustion of biomass are offset by the CO2 absorbed by the biomass as it grows.

Feedstock sources and supplies are another important factor differentiating the two types of ethanol. Agricultural wastes are a largely untapped resource. This low cost feedstock is more abundant and contains greater potential energy than simple starches and sugars. Currently, agricultural residues are plowed back into the soil, composted, burned or disposed in landfills. As an added benefit, collection and sale of crop residues offer farmers a new source of income from existing acreage.

Industrial wastes and municipal solid waste (MSW) can also be used to produce ethanol."

 

[moltenmetal]

It's all nice in theory, but in practice there are a few things to worry about. Firstly the enzymes- you need to "grow" and extract them (energy, effort and money). And like any catalyst, they deactivate, at a rate dependant on factors associated with the feedstock. And in the end, you're still running a fermentation yielding a comparatively low concentration of ethanol in water- it takes a hell of a lot of energy, biomass-derived or otherwise, to turn that into anhydrous fuel-grade ethanol.

If your goal is energy efficiency, it would be better to simply burn the biomass feedstock to produce heat and use that to offset fossil fuels currently used for that purpose, until all such large stationary users of fossil fuels have their fuel needs satisfied. The "minerals" don't burn, so those can still be used for fertilization. Any screwing around you do to convert biomass to liquid fuels suitable for transportation invariably has a high energy efficiency penalty associated with it. Something about shaving off the edges of square pegs to fit round holes just bothers me.

 

[owg]

Moltenmetal - Ontario Power Generation tested biomass burning at Nanticoke in 2005.

http://www.opg.com/pdf/NanticokeFall2006.pdf

They appear to be building two large hoppers to do more of the same.

HAZOP at

http://www.curryhydrocarbons.ca

 

[Grubbyky]

Why would ethanol companies' investors (corn growers) want to switch to ethanol from switch grass? The ethanol company would make higher profits, but the corn prices would crash. The main purpose people have invested in ethanol plants in the U.S. is that it provides more of a market for corn, profits from ethanol are just kind of nice.

Does a cellulose process for ethanol create a usable byproduct like corn ethanol does?

 

[moltenmetal]

Yes, a lot of people conveniently forget about the use of the leftover mash as an animal feedstock, and you do have to consider that fact when doing the calcs in relation to corn ethanol's net energy conversion efficiency. But even considering the beneficial use of the mash, the proof is in the subsidies. Corn ethanol is ultimately an agricultural subsidy program masquerading as a fuel. Cellulose ethanol might actually be a reasonably efficient means to store solar energy for use in transportation. That's the difference. But the jury's still out on the latter point.

But your energy needs are stationary rather than for transportation, it's still far better to use the biomass feedstock for burning rather than going through all these energy-lossy conversion steps first. And until all our stationary energy needs are satisfied by renewable energy sources, why would we even BOTHER going after transporation fuels? Last time I checked, we were still burning a sh*tload of coal and natural gas and even bunker oil to make electricity?!?!