Saturday, March 20, 2010

The Net Energy of Pre-Industrial Agriculture

Following on from yesterday's discussion, I want to make a point that seems like it must have been made before, but I cannot quickly find a good discussion of it.  That is that the net energy of pre-industrial agriculture, taken as a whole energy-gathering system, must have been low, with EROEI probably on the order of 1.1-1.6 depending on place and time.

Prior to the industrial revolution, the main source of primary energy in society was biological - agriculture and forestry, with a significant assist from water mills.  The biological energy was used to feed horses (used themselves in ploughing, but also in transportation), as well as agricultural workers.  The water-mills were primarily used to mill flour (ie also used in agricultural production, for the most part).

My point is the following - we know that the vast bulk of the pre-industrial population were involved full-time in agricultural production, and so were essentially part of the input energy (they, and their horses, had to be fed in order to go out and till the ground, harvest the crops, etc).  Thus, most of the population was essential to the operation of the energy gathering system, and not part of the surplus generated by that system.  Peasants by and large had pretty close to the minimum in terms of housing, furnishings, and clothing, and children and the elderly can probably be assumed to be involved in household economies to the extent they were capable.  There were basically three places where an energy surplus generated by medieval agriculture could go:
  • Population growth
  • The church
  • Goods and services consumed by the rich, the middle class, and the military
Now, the first, population growth, was not very different from zero.  Here, and in most of the rest of the discussion, I am going to rely heavily on Braudel's classic three volume study Civilization and Capitalism, 15th-18th Century, particularly the first volume, The Structures of Everyday Life.  On p46, he gives estimates of annual population growth in Europe as follows - 0.62% between 1600 and 1650, 0.24% between 1650 and 1750, and 0.4% between 1750 and 1800, and 0.46%.  Ie consistently less than 1%.  Given that society was mostly fed on annual crops, in EROEI terms, this means that an EROEI of less than 1.01 would be required to explain population growth, and we can essentially neglect it compared to the other terms in the surplus.

The second factor, the church, we can bound because we know that the church was generally supported by a tithe, in which 10% of food production and craft goods had to be turned over to the church.  Now, some of this tithe was used for relief of the poor and hungry, and thus wasn't really surplus.  You could also argue that the religious functions of the church were actually necessary for the operation of pre-industrial society, and so weren't surplus on those grounds.  Also, I would guess that collection of the tithe was imperfect.  But for the purpose of establishing an upper bound, let's treat it that the church was entirely surplus to agricultural production and that the tithe was all collected.  Thus we need an EROEI of at most 1/0.9 = 1.11 in order to support the church as a surplus.  Let's call it 1.1 as a rough number.

The last factor, goods, housing, etc consumed by the non-peasantry is the hardest to estimate.  However, I argue that it must have been roughly bounded by the fraction of the population that lived in towns rather than in small villages and on isolated farms.  It's a reasonable assumption that the population of villages was for the most part either directly involved in agricultural labor, or in the production of goods and services immediately required in agriculture (the village blacksmith, the miller, etc).

Now, probably, the population of the towns were somewhat involved in good and services utilized in agriculture also (eg a central function of towns has always been to provide markets to allow trade in goods to occur in the surrounding countryside, and between regions).  Still, it's probably a reasonable assumption that non-agricultural production was primarily centered in the town - armorers, furniture makers, masons, etc.  And it's probably also a reasonable assumption that the ratio of horses to people was not markedly higher in the town than in the country given that horses were directly used for ploughing and also for transportation of agricultural goods.  In any case, only about a third of crop production was fed to horses, so it wouldn't devastate my case if this last assumption was somewhat wrong.  Given these assumptions, the energy consumption of town versus country will approximately scale with population - it's unlikely town dwellers ate vastly more than country dwellers - not more than 10-20% more or they would all have been grossly obese (it seems unlikely that town dwellers engaged in more physical labor than country peasants, so surplus food consumption would have gone to fat).

Now, historians have attempted to estimate the fraction of the population living in towns at various times and places.  Braudel (p483-484) summarizes the situation as follows ([] insertions are my clarifications):
Recent calculations by Marcel Reinhardt conclude that in France in Cantillon's time [the early 1700s], the urban population was only 16% of the total.  And, of course, it all depends on the base level adopted.  If towns are considered to be settlements of over 400 inhabitants, then 10% of the English population was living in towns in 1500, and 25% in 1700.  But if 5000 is taken as the minimum definition, the figure would only be 13% in 1700, 16% in 1750, 25% in 1801.  It is therefore evident that all the calculations would have to be repeated using identical criteria, before one could make a valid comparison of the degree of urbanization of the different regions of Europe.  At present, all we can do is identify certain particularly low or high levels.

At the bottom of the scale, the lowest urbanization figures relate to Russia (2.5% in 1630; 3% in 1724; 4% in 1795, 13% in 1897).  So the figures of 10% for Germany in 1500 is not insignificant compared to the Russian figures.  The same percentage is found in colonial America in 1700, when Boston had 7000 inhabitants, Philadelphia 4000, Newport 2600, Charlestown 1100 and New York 3900.  And yet, in 1642, in New York (still known as New Amsterdam) 'modern' Dutch brick was already replacing wood in house-building, a clear sign of growing prosperity.  The urban character of these centres where the population was still of modest size is clear to see.  In 1690 they represented the degree of urban tension permitted by a total population of 200,000 or so, scattered over a vast area: about 9% of the whole.  In about 1750, of the already dense population of Japan (26 million) 22% were already living in towns.
(He then goes on to discuss the somewhat higher urbanization in 16th-18th century Holland, but I am going to discount that example because Holland was a small country that was already a major trading hub for all of Europe, and so I don't think can be taken as a reasonable sample).

Thus we see figures ranging from about 3% urban population (in Russia) to 20-25% in late pre-industrial England and Japan.

Expressed as EROEI then, and including the 10% church term, we get a range from 1/(1-0.1-0.03) = 1.15 in Russia to 1/(1-0.1-0.25) = 1.54 in England and Japan shortly before the industrial revolution.  Since we certainly don't have three significant figures of precision here, let's call it 1.1 to 1.6.  Note that, to the extent the church tithe was not surplus, and town economic production was actually required for agriculture, these estimates are probably upper bounds (with some possibility of slightly higher numbers if animal energy usage was higher in towns than I am assuming, or if agricultural peasant households actually had some consumption of goods that could reasonably be considered surplus).

So it's against this backround that one need to consider the introduction of fossil fuels, and their possible replacement now with other forms of energy.

It's also clear that modern biofuel EROEI's are in the same range as pre-industrial agriculture, and therefore are completely unsuited to support an industrial civilization.


Bill Pulliam said...

I think the numbers very close to 1 would be reasonable. If you think of it regionally, it's a nearly closed system with little net flow in or out. There was only slight long-term accumulation of capital, and possibly long-term decline of energy embodied in natural resources (the expansion of moorlands in northern europe suggests, for instance, a gradual net loss of soil capital over the centuries). In this situation almost the entire society is designed around supporting agriculture, even the nobility, so almost by definition the EROEI has to be very close to 1. If it were as high as 1.6 I think you would have seen a much larger prominence of the merchant class and much more rapid population growth.

Although one might need to figure in the cost of the outbreaks of plague and the resources those consumed in terms of population loss, labor shortages, etc.

Stuart Staniford said...


In response to "In this situation almost the entire society is designed around supporting agriculture, even the nobility, so almost by definition the EROEI has to be very close to 1. If it were as high as 1.6 I think you would have seen a much larger prominence of the merchant class".

I don't know Bill. Take a look at pictures of Blenheim Palace, for example, built between 1705 and 1724 (ie shortly before the industrial revolution). You really think that sucker should be accounted for as an input to the agricultural system, rather than a surplus?

Bill Pulliam said...

Well I was actually thinking more medieval than that...

Once long-distance transport got to be a bigger part of the picture I would expect the wealth structure shifted quite a bit. My image was more like textbook feudalism before the rise of the merchant and shipping classes, where you lived or died on what was grown in your own shire or even your own manor. Then you could sort of justify the energy that went in to subsidizing the nobility as necessary for protection of your own resources... of course the main thing you were protecting them from was probably the neighboring nobility, so there might be a flaw in the argument there! Is "protection money" and other graft an integral cost of doing business or an exploitation by an unproductive class? If you have to pay bribes to get your power plant licensed does that count against your EROI?

Bill Pulliam said...

An additional thought... I wonder if it was improvements in agricultural technology (better tools, better strains, better methods) that increased the EROI of agriculture to significantly above 1, thus leading to the enlightenment, age of discovery, rise of the merchant class, technological advancement that enabled the extraction and use of fossil fuels and the industrial revolution, etc.? Now I'm getting all Jared Diamond...

porsena said...

A not-insignificant portion of production went to the support of wars, a persistent feature of pre-industrial Europe. Wars were supported by taxes, which came out of the agricultural and commercial produce of the land. To fund his 1414-1420 campaign in France, Henry V of England imposed eight successive taxes levied at the rate of 10% in towns and 6.7% in the country, and 10% on the church. Eight levies in seven years – a double tax was levied in 1414. These taxes were raised on the value of moveable goods, so were not taxes on surplus production but taxes on total production and its accumulated surplus.

While Henry was unusually good at raising taxes, maybe another 10% to account for the direct cost of war would be worth considering. War, along with Blenheim Palace, was a drain on the agricultural surplus.

Greg said...

A few quibbles:

1. Some agricultural production was for "materiel," not energy -- e.g., wool in Europe, timber, cotton and silk in east Asia. As much as 20% of the rural working population may have been fully occupied with non-energy production.

2. High mortality, particularly of pre-productive members of society (children) would have absorbed a fraction of gross energy production.

3. The standard of living of townspeople was higher than that of peasants and other rural dwellers, so in energy terms, they are a a greater weight than their numbers suggest. Perhaps as much as double.

It seems to me that an average gross EROEI of at least 2 would have been required before the agricultural revolution of the late 17th C. In "normal" years, the EROEI was probably higher, and when the Four Horsemen were abroad, much lower.

A final point.

4. Post-harvest wastage was immense.

This is much less likely to be the case with a future renewables-based society, so 'past performance is no guide to the future'.

Greg said...

Clarifying point 3:

The issue is not that townspeople and elites directly consumed a greater number of calories, but that they consumed secondary calories: not only grain, but also grain-fed geese; not only milk and cheese, but also milk-fed veal; and so on.

The feed conversion ratios of these secondary foods were probably atrocious, since most breed improvement occurred during and after the time of the industrial revolution.

So although realized net EROEI may have been small, gross EROEI was higher. This helped the system to survive 'down' times - when the harvest was poor, the geese and pigs got slaughtered, not fed, and the townspeople and elites ate bread, not meat.

Jaime M. de Zubeldia said...

Sorry Greg, but aside from taking issue with at least a few other of your points that I don't entirely agree with, I'd have to say that your quote (?), "'past performance is no guide to the future'" is dim, regardless of who it came from. Sounds like economist talk.

That's almost akin to saying, 'we have nothing to learn from history.'

I would say Stuart's work here is extremely important, and a good attempt at defining a starting point from which to assess potential future possibilities without fossil fuels - renewables included or not.

The increase of 1.1 to 1.6 just before the industrial era also makes sense in terms of being a notable increase in efficiency/ingenuity mostly without non-renewables. A pending collapse of 0.9 instead of 1.6, and then a transition to an industrial era would not have made sense. In this sense the numerical trend objectively makes sense with historical events.

Good work Stuart.

Greg said...

"It's also clear that modern biofuel EROEI's are in the same range as pre-industrial agriculture, and therefore are completely unsuited to support an industrial civilization."

This is not at all clear to me, Stuart.

I'll grant that we needed high-EROEI energy sources in order to develop an industrial civilization: early iterations of energy technologies are almost certain to be inefficient. And history shows that they were.

But now we have developed an industrial civilization, with relatively efficient energy consumption (and scope for much more efficiency). We've got over the development hurdle. The question is not "can we start?", but "can we keep going?"

Why, in principle, can industrial civilization not be sustained with lower EROEI energy sources, now that it is up and running? Keep in mind that we could, if we really wanted to, double or triple agricultural production on the same land area as is now used, with relatively modest investment. And there is quite a bit of usable land still unused.

(It seems to me that there is no EROEI problem in principle, so I'd like to be enlightened. The practise -- the social difficulty of transitioning to different fuels -- is a different, and thornier, question.)

Stuart Staniford said...


I concur that the trend of gradually increasing fraction of urban population through the late medieval period and renaissance does seem like it was probably a critical enabler to the industrial revolution, and that must have come from gradually improving agricultural productivity.

Stuart Staniford said...


I take your point on higher fraction of animal food in town.

An offsetting factor - it appears to me likely there was more waterwheel energy in the country - Braudel quotes a figure of 1 watermill per 29 inhabitants (which is amazing - every tiny hamlet must have had one), and it's hard to see how towns of any size could have had such a high ratio, .

Another potential confounding factor is if wood use for heat was higher or lower in town versus country - not obvious one way or the other, but certainly contributing to the error bar.

Stephan Sander said...

Dear Mr Staniford, your article was very interesting, although I may wish to point something out:

The two first points you mentioned (population growth, tithe) need to take into account that, although varying throughout western Europe, the farmers/labourers renting (landed) property usually gave away the tithe AND another part of the harvest to the landlord, usually between a quarter and a third of the entire harvest, for the farmer/labourer had to give away the tithe (1/10 of the harvest) in addition to the produce belonging to the landlord (1/4 to /1/3), thus the total “surplus“ must have been significantly higher than you suggested, i.e. between 35% (the tithe + the quarter) and 43% (the tithe + the third).

Thus, it is my opinion, that leaving this factor out may (or may not) slightly alter the EROEI number, don't you think? In addition, one may consider that the quarter/third of the harvest belonging to the landlord may/may not be the third factor, i.e. the non-farming artisans, urban commoners and nobles dwelling in the cities not engaged in agricultural production.

Any comments?

sofistek said...

When you say the vast majority of the population were involved full time in agriculture, can you quantify that?

No doubt, both men and women worked in that pursuit but how much of the day did they work in that pursuit? 10 hours? 16 hours? Certainly not 24 hours. There must have been some time for other pursuits, otherwise there would be no children. They must eat. They had ceremonies and entertainment of sorts. They had small children who didn't work and many of whom died before they could work. Women presumably didn't work in the fields as long as men and there wouldn't have been too many older folk to help with the children (if there were, then they weren't directly involved in the production of food or, it could be argued, indirectly). Then there would have been some professions and pursuits that also weren't involved in agriculture, as well as the gentry. Accommodation also needed to be built and maintained, for peasants and gentry alike.

It's hard to imagine that such a society could be sustained on an EROEI of 1.1, or even 1.6, unless there was a very large energy contribution from non-food sources. Could water have supplied that energy?

Anonymous said...

Hi Stuart,

I read your article at Energy Bulletin “The Net Energy of Pre-Industrial Agriculture”, and it got me thinking again about how to assess quality of life in a way which gives an advantage to small towns and villages with a low ecological footprint and a high “wisdom quotient”.

I have written a 1,700 word response, but that is too many characters for posting a comment at this “Early Warning” Blog site. So what I have done is post that 1,700 word response as an entry on my Facebook page (not a busy place; just where I post items for “extra-curricular” reference), and there it will be—unless you have some objection (in which case, I will remove it). Here I will provide what excerpts I can, in case there are readers who would like to explore the whole piece.

“…While this formulation also leaves out much, there is a key insight to be gained from thinking about it, and it is accessible through a quote from Gandhi (in an article by Satish Kumar titled “Gandhi’s Swadeshi: The Economics of Permanence”, see ). The key insight: “The satisfaction of one’s physical needs must at a certain point come to a dead stop before it degenerates into physical decadence.”….

“… and thus it is technological innovation which has accounted for most of the higher quality of life we now have. For my part, I would say that the most advanced societies are the ones which are successful at integrating spiritual wisdom into the everyday circumstances of community life. And I would suggest that there is a point where human settlements become so massive and complex that there are diminishing returns on attempts to integrate spiritual wisdom into community life. So much of my work is an effort to identify processes, resources, and ideas which will be useful for people who are working towards achieving high quality of life in post modern small towns and villages.”….

“One of the points of reference I will offer is a list of positive factors I associated with small towns and villages… “How Modern Agriculture-Based Villages Can Contribute to the Continuity of Peaceful Human Settlements”…. a summary statement of my thinking on the value of ecovillages and sustainable communities at that time. The list is accessible from my Facebook profile page (the 14th entry from the top)….”….

“The second point of reference I will offer here (as a way of starting a discussion aimed at gathering together just those kinds of processes, resources, and ideas which will be useful for people who are working towards achieving high quality of life in post modern small towns and villages) is the current outreach message for a document I just completed titled “The IPCR Workshop Primer”…..

(Two excerpts from that current outreach message--)

“One of the main goals of Community Visioning Initiatives is to maximize citizen participation in identifying challenges, and in solution-oriented activity. In 1984, the non-profit organization Chattanooga Venture [Chattanooga, Tennessee (USA)] organized a Community Visioning Initiative that attracted more than 1,700 participants, and produced 40 community goals—which resulted in the implementation of 223 projects and programs, the creation of 1,300 permanent jobs, and a total financial investment of 793 million dollars.”

“I believe it is possible to use Community Visioning Initiatives, ‘Community Teaching and Learning Centers’, and ‘sister community’ relationships to discover processes, resources, and ideas which will be useful for people who are working towards achieving high quality of life in post modern small towns and villages. “

With Kind Regards,

Stefan Pasti, Founder and Outreach Coordinator
The Interfaith Peacebuilding and Community Revitalization (IPCR) Initiative

porsena said...

Stephen Sander, I too wrestled with the idea that serfs/peasants were bound to directly work the lord's land or to provide a share of their produce in lieu. The obligation varied from place to place and time to time, but two days a week might be a representative number for the medieval period.

However, this work on the lord's land, or the equivalent in produce, was all agricultural production. In Stuart's context, it seems to me that it was part of the energy gathering system. While the profit went elsewhere, into wars for example, the produce was all used to support the population somewhere.

Tim Auld said...

It's also clear that modern biofuel EROEI's are in the same range as pre-industrial agriculture, and therefore are completely unsuited to support an industrial civilization.

This statement deserves more specific qualification. By 'modern' I expect you are referring to ethanol derived from industrially grown corn, which studies have put at about the range you state. This is a relatively inefficient way of producing ethanol (200-300 gallons per acre minus significant inputs).

For comparison, nipa palms which do not need chemical inputs or annual propagation can produce about 2200 gallons per acre, cassava about 1600-2000, and cattails potentially 10,000+ per acre when grown in sewage (partially replacing expensive conventional sewage treatment). The co-products of fermentation carbon dioxide, heat and leftover mash are all valuable too. Sources: Wikipedia (nipa palms); David Blume Alcohol Can Be A Gas).

With productive systems designed using permaculture it's not inconceivable that the necessary and many unnecessary functions of industrial civilisation could be supported. Industrial agriculture is likely far less profitable (actually significantly negative) compared to pre-industrial agriculture if you consider fossil fuels, rock minerals and top soil as inputs.

The difficulty is in convincing people now to act in that direction (permaculture), and conclusions like this don't help. They paint the picture as if there's only two options: wasteful industrial agriculture, and sustainable but unprofitable subsistence farming.

Simon said...

I think there has been a rather large misunderstanding leading to some completely erroneous assumptions in this discussion. What Staniford is actually talking about when he gives an EROEI of 1.1-1.6 for pre-industrial agriculture is not the energy produced for each unit of energy put in by farmers but the total energy produced by those farmers, which are 2 completely different, and in many ways unrelated, things. Using population figures, guesses on population distribution and food needs for armies and the non-productive upper classes, Staniford comes up with the amount of food each farmer must have produced to sustain these demographics. Up until this point he is on firm ground , but when he claims that this figure equals the EROEI he mistakes total energy produced for return on energy invested. Let me explain.
In agriculture, EROEI is not an easy thing to estimate, particularly when there is human labour involved. In industrial agriculture human input is negligible and therefore you can take the amount of fossil fuels needed for the fertilizer, pesticides, tractor etc and compare it to the calories in the food produced. once you take transport and packaging into account the EROEI is hugely negative, atleast 7:1. However, in agriculture without fossil fuels the equation is more difficult. For example, if animals are used then we cannot, as with a tractor, simply say that the mule was needed for x hours of ploughing for this acre of potatoes which needs x kg of hay which contains x calories etc. Because you must feed the mule all year, if it does 10 hours or 100 hours of work the EROEI changes radically. In addition, how the food for the mule was raised is vitally important. But for humans things are much less clear. Say a human ate 2000 calories daily in pre-industrial times. Implicit in the argument given by Staniford is the assumption that we must take the 365 days a year that the farmer ate and the food that the farmer produced in that year to get EROEI. But this is foolish unless the farmer is either a) working exclusively in farming and doing nothing else in the off-season or b) working every day all year farming, neither of which can be true. The truth is that the farmer did other things other then just farm, some useful (chopping wood for fuel for example) and some purely recreational (the myriad festivals that took place is pre-industrial peasant societies for example), but all adding to the complexity of society, unlike the mule who is either working or grazing. This shows that the more efficient the farmer was (ie the higher the EROEI) the more complex society could be even if he produced no more food in total.
The complexity of society is based on its source of energy – how easy it is to get and how much there is of it. With a renewable energy like food, there are physical limits to how much can be produced sustainably each year but not to the EROEI of the production (in the sense that continual improvements can be made always approaching, but never reaching, ‘free energy’). The higher the EROEI is the more people can do work other than farming or the more work farmers can do off the farm – either way society becomes more complex. Society cannot grow physically (ie population) but that doesn’t mean it’s a static society.
I am an organic farmer in Italy. I grow vegetables using only human labour and olive oil using mostly human labour. I have been able to do some rough estimates of the EROEI of my labour and they range from 1:6 to 1:8. This I would contend is much closer to the real figure of pre-industrial agriculture, even if we take into account that I have much better variety’s and wider knowledge then our forbearers’ had. However, I have read that in the Nile delta during the time of the pharaohs a farmer could feed 5 people, thus giving a minimum EROEI of 1:5 but using my logic above giving one much higher. Daniel Quinn cites a number of 1:2 for the first farmers 10 000 years ago.

Fred said...

I believe the use of fossil fuels began long before your discussions indicate. "Sea Coales" were gathered before 1000 CE and quickly came to replace wood in pottery manufacture and metallurgy. Before 1200 the first air pollution laws railed against the noxious "odoures" and filth of coal combustion with penalties as severe as death. Of course regulation was no match for the power of coal and an examination of any urban landscape image in England after 1400 or so attests to the dominance of coal chimneys in virtually all buildings and literature is filled with accounts of woes from resulting air pollution. The unarguable utility of coal and its near total replacement of wood fuels, was long complete by the 1700s. Coal seems to have displaced the Dutch wind power revolution where windmills supplanted watermills because they were sited without regard to running water from 1500 to 1600. The TOD piece on windmills nicely details this, the fourth human power revolution (after fire, agriculture, then water power). The coal fossil fuel revolution in Britain allowed that country to continue developing (ca 1200-1300)long after substantial depletion of its wood resources (1400) should have brought the country to ruin as it had for Mesopotamia, Greece and many others (see A Forest Journey, John Perlin). I think is curious that your accountings of EROEI completely miss the course of the whole coal revolution and the essential part it played in establishing the British Empire long after the English had plundered their own forests, but went to build a merchant culture that could afford to armor its troops and ships and conquer & colonize much of the world.

One of the great legacies of that coal fossil fuel revolution (that began 1000 years ago) and which may be gaining new momentum with petroleum's decline, is that it seems to be fueling the almost complete (final for humans?) destruction of Earth's forest resources and the extreme biodiversity harbored in tropical forests. Our forest journey will then be complete. Many millions of years will be required for Life to recover if we continue ecosystem destruction at the present pace in this our sixth great extinction in Earth's life history.