for farming using biomass energy are draft animals more efficient than biogas-powered tractor?

Factual Questions
1

my WAG would be that a tractor is better because it does not need to eat when it is not working. Plus, quality of biomass for methane or wood gas production is lower than what animals would eat.

OTOH maybe efficiency of gasification and engine nowadays is so sucky that animals beat that despite all limitations?

Or would animals make sense only if you can pasture them nearby on your own hopefully real plentiful tropical land that keeps producing the feed year round whereas the biogas and the tractor would be better if you buy the feed biomass from the outside or have to stockpile it for use during the autumn-winter season?

2

Somehow you’ll need to factor in the fact that farming using draft animals is massively more (human) labour-intensive than using tractors.

3

IAMNAExpert on this, but several things come to mind:

  1. Biogas-powered tractors are very uncommon. Most common is the question between gasoline-powered tractors and animals. In the 70s, development org.s gave a lot of tractors and other modern machines to 3rd world countries, because agrictulture with machines was more modern. Turned out that machines require maitenance and spare parts, often from overseas (takes time to train mechanics, and if your whole country doesn’t have a factory to produce spart parts, the tractor is laid up for months until the replacement arrives via ship), and gasoline prices rise.

Whereas animals can eat low-budget food and still work “good enough”. They also drop shit, which can be either composted for fertilizer or fermented into biogas for burning in the stove (healthier than directly burning wood or dried shit).

Also, when an animal is too old, you can kill and eat it, and animals replicate themselves. Vehicles can’t be eaten, need maintenance, and don’t replicate themselves.

As for quality of biomass production is lower … I haven’t heard of that. Usually, you use waste - grass clippings, waste from food production and shit - for fermentation to methane, but not stuff animals would eat.

Huh? Why would that be, considering that people spent the last decade improving the fermenation-for-biogas process? The problem I see first is the lack of gas-powered vehicles, which is probably related to lack of research because of safety problems.

However - assuming that you are thinking of 3rd world countries, as 1st world countries have completly different infrastructure and therefore solutions - the main problem is less efficiency and more “what’s available in this place?” If you’ve got lots of grass or similar, then animals make better use than that. If you plan on having a small factory nearby to further use the products of agriculture, or need to drive to the market, an all-purpose gas-powered vehicle might be more sensible.

One big difference between 1st and 3rd world for example is handling. A big farm in the first world doesn’t want the trouble of depending on experienced people to handle fickle animals with a mind of their own, when on a tractor, you just turn a key and the thing does what you want. Animals are too much trouble to be ever worth the work, only the meat or milk they produce.
In the typical small family 3rd world farm, handling of animals is just a given, everybody does it, and it’s much cheaper than a tractor.

If you have tropical land that produces feed year round, you wouldn’t waste it on feed, you would grow food for humans or cash crops on it. In Europe (and presumably the US, too?), Cow species are raised (for milk and cheese and meat) where there’s “grassland”, that is, above ca. 600 m above sea levels. Because only grass grows in those climate areas (long winters, too much snow and rain, short summer), not grain or other food.
If you ask any 1st world farmer or read Herriot’s books, farmers were very relived when they could stop relying on oxen to pull their tools, and no longer had to take care of their draught horses every day.

4

All but the most primitive farming operations use either draft animals or machines that replace draft animals. The question is assuming you need one or the other.

By what measure? One man can drive a team pulling a plow.

5

And one man can drive a tractor pulling a plow, too. But the tractor is faster, so that man will have to spend less time out in his acres plowing.

6

Maybe, but if the tractor itself is to be fueled by biomass, I think that’s going to require greater acreage under plow to begin with. That’s really the question here, isn’t it? Biomass tractors most certainly do need to “eat” while working–that is, they must consume resources that could otherwise, one way or another, be food. The better point on that front is that animals need to eat when they’re not working (though constanze has pointed out some of the collateral benefits of that).

7

Because hand-pulling a plow instead of using a machine is the worst kind of efficiency. There is a reason that domestication of animals for use in plow-pulling goes back thousands of years. An ox with a weight and strength many times more than a human can pull a plow that breaks the crust open much deeper, which is better for specific plants, meaning higher yield.

But after you’re done pulling the plow, the tractor is simply shut off; the oxen have to be cared for all the time. Depending on the circumstances, you have to watch them while they eat so they don’t run away, you have to clean them and give them breaks, and you have to use them and train them, otherwise they will become uncontrollable.

8

I do not have a cite for this, but recall reading somewhere that when draft animals were commonly used a farmer might have as much as 40% of his land tied up in growing feed for said animals. Of course, this does not address how much land would be needed to produce biomass fuel for powered machines to replace the draft animals, nor does it account for the benefits of animal power such as manure-for-fertilizer or environmental footprint. But the substitution of machines for animals definitely frees up land for production that otherwise would be used for feeding and boarding livestock.
SS

9

A recent NYT article on a (putative) trend towards draft animals on small farms is here.

10

ok so nobody here knows the conversion efficiencies for biogas and for draft animals?

11

I think that’s what I said.

I’m not sure that it’s ever been worked out in a rigorous and inclusive way. There’s some debate what factors to include and how to weight them.

12

. To optimize the amount of work that they can do, draft animals need appropriate feed, a worming program, and vaccinations so they don’t die of common dieases or communicate diseases to humans (west nile, tetanus, etc). Their hooves need regular care. They need appropriate enclosures to protect them from predators. Those enclosures must be cleaned regularly, or else they must be so large the animal’s waste presents no health concern (for horses, 2-3 acres per animal; horses can be kept on 1 acre, but that requires rotational programs which are also work). They have a limit to how many hours per day they can work. They die in breeding. They die from overwork. They die from parasites. They pull muscles and get sores and cut themselves, making them unable to work for a time. To be sure an animal is always available for work, you need to have more than one.

All that animal caretaking is hours the farmer is not farming. It is not just about how many men it takes to drive a plow. This, I believe, is the human labor Gorsnak was referring to. I am not aware of a draft animal that does not require these things, at least sometimes, for optimal productive capacity.

13

Whenever someone talks about “efficiency” they always forget to mention what variable they’re looking at. Energy? Labor? Capital? Land? Time?

14

You’re assuming the biomass used to produce fuel is equally well-suited for use as food. Once you get past the corn-growers’ lobby, you’ll find that a lot of “waste” material (cornstalks, etc.) is unsuitable for food, but perfectly suited for conversion into liquid or gaseous fuel (“wood alcohol” or methane, for example).

15

energy.

16

In regards to the efficiency of one tractor vs one oxen/horse…

Don’t forget that the animals would need to rest fairly regularly. Depends on the work of course. The farmer would too, as handling the equipment (plow, cultivator, etc) is VERY physical work, everything is hand lifted. Not to mention the constant walking needed, unless you have “sulky” plows/equipment (where you ride…which increases the load on the horse)

But the tractor can continue working all day long, with no rest. It can operate 24 hours a day, 7 days a week if necessary, with proper driver swaps, etc. It would only need to stop to fuel up, for maintenance, etc. Especially with modern improvements, tractors can be operated by anyone, even children (this was very common years ago, and honestly still is in some ways). Horse equipment can require strength and stamina beyond that of a child.

Not to mention that it takes a TEAM of horses for heavy tillage work (such as plowing), even then, the biggest horse plows were usually only two bottoms. Otherwise the teams would become massive and unwieldy.

The SMALLEST tractors (probably even garden tractors) can handle a one or two bottom plow fairly easily. Or larger tractors to very large sizes, all the time running this equipment non stop.

When a tractor breaks, it’s bad, but can often be fixed within a period of hours, days or a week at the most if you can get the parts, then it can go back to work immediately. If your horse is sick…if the problem can be found, it has to be rested, fed, and put on light or no duty at all until healed. And if the horse can’t be fixed…it will need to be put down.

With proper maintenance and proper use, tractors can be used for decades (admittedly getting more cost prohibitive the older it gets). Several examples of 70+ year old equipment could continue doing the work they did when new if necessary. How long is the average life of a working horse (as opposed to a show horse)? I’d guess a decade or less.

In remote locations where fuel and parts would be hard to come by, the animal makes more sense, despite being less efficient.

The horse hasn’t been competitive on the modern farm since the 1930s.

17

A very interesting question - sadly I don’t know the answer.

I tend to lean towards the tractor for the reasons Deereman points out. I think the old standard was a good team of oxen could plow an acre a day - whereas even a medium size tractor could do that in less than half an hour. (actually much less - one tractor can do the 50 acre paddock outside our house overnight - say 10 hours - it’s a pretty big tractor though).

Sticking just to fuel efficiency then to win the animal team would have to use maybe 100 times less ‘fuel’ per unit ploughed, which I just can’t see as realistic.

18

A little more thought on this:

Animal power uses “fuel” that is found locally. Hay. Grain. Water. Straw for bedding. Back in the day, this would all come from the farm that they worked, and this meant less land was available for cash crops. The farm would be growing enough food to support itself, and what little extra (if any) food could be sold for cash.

Tractor power uses fuel that is shipped in from other areas (oil, diesel fuel, gas…from refineries, etc). This fuel is often more efficient (BTUs per weight maybe a good comparison though I have no numbers). Since the farm is not using it’s own land for this fuel, it can increase the cash crop acreage, and so far, history has shown that this has been more efficient…farmers make more than enough money off of the extra acreage to pay for the brought in fuel, oil, etc. Most of this is due to the better efficiency/speed of tractor power.

In areas where there is not an infrastructure to support the mass transport of fuels and products, animals still make sense. But no where else.

The fuel source argument gets a little foggy when you consider farm made biofuels. I still haven’t heard whether this is actually efficient (though it reduces foreign dependency)…but those arguments are a totally different subject?

There is also the idea that animal powered farms wouldn’t be able to supply the sheer amount of food needed for the current human population, I believe at this point demand has grown far beyond that. Even if they were 100% efficient, animal power can’t keep up with the demand in acres worked per hour. I have no cite, but it seems very plausible to me.

Also, modern farm equipment demands types of power that horses simply cannot produce. Not just traction or movement. Equipment needs Electrical. Hydraulic. Powershaft. And much more power than even a very large team could supply, even if it were somehow possible. To use old horse equipment would throw all the modern crop growing efficiency out the window.

And with all that…many many more people would be working on the farm, whether they want to or not.

This discussion is interesting and fun. I’d expect it more during the 1930s than the 2010s.

19

I’ll stop after this one…

Don’t forget that the vast majority of farm equipment is diesel powered. The last hurrah of gasoline powered tractors was the 1970s. Gas is too inefficient for the power produced once you get probably to 40 horsepower and up (which would be really small today). All the typical diesel features, like weight, noise, fuel efficiency, and dependability are all suited perfectly for farm use.

So we’re looking at the comparison of biomass and biodiesel production, not biogas. Just sayin’