I suspect that they are able (like TDP) to use dirty waste fat/oils (lipids) unlike biodiesel. Hence I would imagine the following feedstocks would be important:
1. Slaughterhouse waste
2. Restaurant grease
3. Wastewater scum (?)

The cetane number is indeed sky high. I see two ways to address that: further refining and blending with fossil diesel. As a hydrocarbon fuel it can be blended in any ratio with fossil diesel without problems, again unlike biodiesel (i.e. methyl esters).

"An Engineer" needs to go back to school.

Biodiesel can be made from restaurant waste oil...see 'Appleseed'. Biodiesel CAN be blended with Dino diesel in any ratio without problems. We have been running biodiesel in our TDI's from 20% to 99% since 2000 without any problems.

And I might add that if "An Engineer" wants to post ignorant info such as what he posted above, he would be better off on a child's website.

The problems as I see it are the requirements for fat and external hydrogen. FT diesel from sawdust (eg Choren process) needs neither but seems to be stalled.
True - the quantity of hydrogen would be very low though: on the order of 27 kg/ton of product (2.7%). I doubt the hydrogen would sink the project.

As you point out, getting enough fat/oil (lipids) to make enough oil to notice will probably be the main challenge.

"An Engineer" needs to go back to school.
NOOOO... Anything, but not THAT!!!!

Biodiesel can be made from restaurant waste oil...see 'Appleseed'.
Indeed it can. Tell me, how much work ($$) is it to clean up the restaurant waste to the point where is can be used for biodiesel? I guess I need to be more specific...

Biodiesel CAN be blended with Dino diesel in any ratio without problems. We have been running biodiesel in our TDI's from 20% to 99% since 2000 without any problems.
Well, good for you. As I am sure you are aware, they had some problems in Minnesota this winter, and that was at what 5%? Again, it can be done, but the Minnesota experience suggests it is not a slam dunk. Mixing chemically identical compounds is much simpler...

And I might add that if "An Engineer" wants to post ignorant info such as what he posted above, he would be better off on a child's website.
Wow, you ARE worked up. Come on, play nice.

Joseph, I still see biodiesel as more of a project for the backyard enthusiast (no offense). Once you go to industrial scale TDP or NExBTL makes more sense. But I am sure you have a different opinion on that.

I think the Minnesota biodiesel problems have been greatly exaggerated. Look at this page on this very site:
http://www.greencarcongress.com/2006/01/biodiesel_group.html

It appears that some of the problems were poor quality biodiesel, probably made only in response to the state mandate. It also says that some problems were likely unrelated to biodiesel.

It is well established that soy-based biodiesel gels at a much higher temp than #2 diesel. In Minnesota, Canada and Alaska this greatly limits winter use. However, properly made B2 should work even in Alaska, because the biodiesel % is so small that the effect on gel point is tiny. In much of the world it is a non-issue. I live in Michigan, only slightly warmer than Minnesota, and I used B20 in two diesels (Jeep CRD and Dodge Ram) through last winter with zero problems. The Dodge was always parked outside, and I never used the plug-in engine heater for either one. I suspect the difference is largely that I was getting quality fuel made properly.

It's my understanding that the city bus fleet in Des Moines, IA uses B20 year round with no problems. Des Moines gets cold. I also understand that the school buses in St. Johns, MI (central part of the lower peninsula) use B20 with no problems. Winter weather in either of these towns is pretty similar to that in southern Minnesota.

One big plus for biodiesel is the oxygen content, as noted in the table in the article. Soot and exhaust smoke is dramatically lower when I run B20 in my vehicles - as little as B5 makes a really noticeable difference, and B10 or higher makes smoke essentially disappear.

Anyway, I'm not saying that biodiesel is the one true solution to all environmental problems, only that it is an excellent fuel within certain limitations that are very well known.

Engineer? Biodiesel a project for backyard enthusiast? Plz check biodiesel.org...Currently 65 plants producing over 1/2Billion gpy. By next summer will be over 150 doing well over 1B, including ADMs 85Mgpy.
And yes, all diesels best be warm when its -0.
Where can I buy Neste stock in US?

So they can feed it to customers but not pour it down the drain? Sounds about right. Like banning trans fat while cigarettes are legal. Or banning prostitution when big party politics is legal.

Allen:

Practically any combustible hydrocarbons (cooking and engine oil and sludge, solvents, etc.) were, and some of them are, combusted at cement kilns together with coal. Produced contaminants are neutralized harmless by cement mass. Recently more and more of such feedstock is refined and recycled, or converted to something else (biodiesel) with better resale value.

Restaurants are prohibited to pour spent oil and grease down the drain – it severely affects biological treatment of sewage on STP. Converting it into biodiesel is the most economical way to get rid of this garbage.
If you are going to do this long term, it would be cheaper to install a two tank system and use the grease as-is (after filtration). No cost of chemicals. Almost no time to do the fuel preparation. You get the idea.

Biodiesel a project for backyard enthusiast? Plz check biodiesel.org...Currently 65 plants producing over 1/2Billion gpy. By next summer will be over 150 doing well over 1B, including ADMs 85Mgpy.
Good for them. Good to get all that renewable fuel going. It is still my opinion that biodiesel (methyl esters) will not be cheaper to produce on large scale than TDP or NExBTL. We'll see.

This will take a while to shake out. Government subsidies further complicate the picture. Give it 10 - 20 years. By then we should know who can produce the oil the cheapest...

Choren seems to be progressing nicely with the construction of the "beta" plant: Biomass-to-liquid (BTL) technologies are therefore currently attracting attention – in a thermochemical conversion process, BTL technology uses the entire plant. At the forefront of developments, German company Choren Industries believes BTL fuels could meet 10 percent of Germany’s transport fuel needs by 2015. Its ‘Carbo-V’ process turns wood and other biomass into ‘SunDiesel’, capturing the attention of major corporations such as Volkswagen and
DaimlerChrysler. A 200,000 tonnes/year facility is under construction and Choren is embarking on securing partners and investors to roll out the technology in the years ahead. First article here.