Don't have time to do all the reearch required.

I have seen a figure of 6 EROEI for sunflower oil. That compares with a figure I have seen for ethanol of 1.35 - or maybe even <1. If one rigs up an old-time horse-powered press right on the farm, maybe the EROEI could even be a little better for the sunflowers. Running straight veg oil in cold weather is a problem, but as most farm machinery tasks are in warm weather that should not be much of a problem.

How much acreage would have to be dedicated to growing sunflowers to power a tractor for a year? According to the source below, 1 acre of sunflowers should yield 102 gal of sunflower oil per year; rapeseed does a little better at 127 gal/ac.

http://journeytoforever.org/biodiesel_yield.html

The total amount of fuel needed to run a farm for a year will depend upon the size of a farm, but I would guess that for most farms we are talking about a few acres at most. The source below lists typical farm fuel consumption per acre for most common mechanized tasks.

http://www.extension.iastate.edu/AGDM/crops/html/a3-27.html

Looking at this table, it would appear that the total fuel consumption may run somewhere in the range of 2.5-5 gal/acre, depending upon crop. That would suggest that a single acre of sunflowers should provide enough fuel for at least a 20-40 acre farm. A 160 acre farm may require between 4-8 acres of sunflowers. That would seem to me to leave plenty of acreage for food production.

Sounds bad, i can not find an argument that contradicts what you say. Perhaps Europe can cope with the AG issues somewhat better than US, because we have not yet gone so far in the industrial AG buissnes as you have in US.

1. It takes a lot of fuel to transport ag products to consumers that live far away from the fields. Not only do you need to grow the fuel to run the tractor, but the fuel to transport it (refrigerate it), process and package it.

Yes, there are other issues besides fuel for the tractors. We really need electrified rail (large PV arrays in remote locations could provide the power, if most trains were scheduled to run during the day). Biodiesel could also fuel barges and ships for bulk transport of grains. As for the tractors themselves, the oilseeds could be grown and pressed right on the farm.

2. A lot US ag. relies on depleting aquifers. Less water means less productivity.

Yes, water is a big problem - it deserves to be far higher up on the list of problems than the fuel supply for farm equipment. Global climate change should open up more northerly, better watered lands for cultivation to replace the arid lands that are running out of water; not only do northerly lands have more precipitation, they will also have less evaporation, so salinization will be less of a problem. Agriculture is going to have to get a lot better about managing and conserving water, just like we are all going to have to get a lot better about managing and conserving energy.

3. US ag. yields are deplendant on petro-chemical inputs (eg. Fertializer, Pesticides). Costs for chemical inputs are already rising, and we have yet to experience an serious declines in energy resources. Before the green revolution, AG yields were about 25% of todays yield. If we abandon the green revolution, we will need to farm 4 times the amount of land to achieve the same production level today.

Or we could all cut beef out of our diet and make up most of the difference right there. It wouldn't even be necesary to all become vegans - just cut out the beef and that will get us most of the way there.

Fertilizers are the least important input in crop productivity. Making sure the plants get plenty of sunlight and water (& thus keeping the weeds from competing from the plants for water) and keeping all the other life forms from eating the crop before we do are the most important thing. Putting plenty of manure or compost (or now charcoal) back into the land, plus crop rotation that includes legumes, is the only sustainable method of maintainging soil fertility; such an approach also has the advantage of increasing the soil's ability to hold water (see 2 above).

Oh, and one more little silver lining on a black cloud: increasing CO2 levels will INCREASE crop yields.

4. Fixing the AG issues does not resolve social issues with declining energy resources. Millions of Jobs will be lost that are dependant on cheap energy. Most of these people with not be able to adapt (ie retrain, choose a completely different career path), as the major of workers are specialists. In most cases a new career would take at least a decade or more to gain the same level of knowledge base in a new career.

5. This does not also resolve loss of energy for other vital systems and services that are dependant on cheap energy. Transportion, construction, industial processes, electricity, maintanance, etc.

There are a huge number of problems, the list is almost endless. My point was just that there is no need to put fuel for tractors at the top of it.

There are any number of oilseed crops that can do the job. Most diesel engines can run filtered straight veg oil with no or minimal modification. The problem is cold temps. Sunflower oil remains liquid to a little lower temp than most veg oils, which is one thing to say in its favor. The growing conditions in much of the US are optimal for sunflowers; as a Brassica, rapeseed is a better fit for northerly climes like Canada and N Europe, but can be grown in much of the US as well.

It should be noted that sunflowers, rapeseeds, and other oilseeds are increasingly being cultivated as cover crops in a crop rotation scheme, and can thus play a part in preserving soil fertility. Like all crops, sunflower yields can increase with the application of nitrogen and other fertilizers. It should be noted, however, that the root systems of sunflowers are considerably wider and deeper than is the case with corn, and they are thus able to make good use of the fertility latent in a sustainably managed field with less need for fertilizer supplementation than is the case for some other crops.

My impression is that sunflowers are a relatively easy crop to grow, and are feasible to grow on a small scale; they are one of the few oilseeds that even home gardeners could and routinely do grow. Sunflower seeds are relatively easy to harvest and to process on a small-scale, low-tech basis. My thinking is that what is needed is an oilseed crop that could be processed into biodiesel right on the farm, eliminating the need for energy to transport the seeds to a factory and the oil back to the farmer -- that is what really kills you on EROEI.

Humans have been pressing oils from oilseeds for millennia before the modern industrial age, so it certainly can be done. Rig up a solar roaster to pre-heat the seeds before pressing and you can probably get farmstead production yields that may still be lower than what can be achieved by industrial production, but not that much lower.