Tuesday, March 19, 2013

Energy-efficient food production – sure but within reason

The forest was burning and the area was in a smoky haze when I visited Pedro. He and the other farmers were clearing land for farming at the edge of the mighty Amazon forest. This was the first time I had visited a farmer practicing swiddening, or slash and burn agriculture. I’d arrived with the idea that swiddening was a primitive method used only by ignorant farmers. I  had this image from my school days, the media and from my own love of forests. Clearly, it must be wrong to burn a forest just to grow crops for a few years. After this visit to Pedro, several other farm visits and a good deal of reading, I realized I was wrong. Partly, at least.

Swiddening is a good example of a method of farming that is rational from the perspective of the farmer. It is also environmentally benign if practiced in a limited extent. Fire is part of nature, and also pristine forests have burnt. Human use of fire has shaped many of the most impressive landscapes in the world, including the savannah and the prairies but also most forest landscapes. However, when population grows, or forest resources dwindle, what was once a good practice becomes negative.

The success of a species is mainly about its ability to capture energy

We get a confusing array of messages about food and diets. Now and again we are advised to eat local, to become vegans, to eat raw food etc. In many of these messages, ethical, environmental and nutritional messages are mixed – and mixed up. Unfortunately it is quite possible to eat ethically produced or procured but nutritionally disastrous food! It is equally possible to eat environmentally benign foods that score badly on animal welfare.

This post is mainly about energy. The reason is that regardless of all other considerations, energy comes first. The whole ecological system is built on energy levels, and the success of a species is mainly about its ability to capture energy. The enormous ‘success’ of humans can, to a large extent, be seen as an ever increasing command over energy resources. 

When we were hunters and gatherers, we captured the energy in game, fish, leaves and plants. While expending energy for hunting or digging, we got energy—in the form of food. When we lived by ‘capture’, we could only skim the surplus of nature. We had to capture as much food-energy as possible from the system to produce and reproduce. Reproduce not only children, but also the small society, the band, to which we belonged. This also included taking care of the elderly and sick, throwing the odd big party to keep spirits high, diverting energy to rock paintings, hair braiding, nose ringing and other cultural expressions. This is the real iron law of human civilization:

A society must command sufficient energy to reproduce itself and its members. 

When we started using fire to cook, we made food more palatable. Some claim that we started getting20–25% more energy from cooked food and that this also allowed our brain to grow (In other words, we were smart to discover fire, and that discovery led us on to become even smarter). The energy contained in the wood we burned largely surpassed the increased energy uptake from the food we cooked. It is important to note that this also meant that at that point, we already developed an energy-deficient food system.

Some capturing societies did manipulate their environment a lot in order to ’”produce’ more of the kind humans like (such as bison) and less of those that humans don’t like (wolves and tigers). Some dropped nuts in fertile soils to have more nuts to collect, and cleared the bush that threatened to crowd out that mouth-watering herb. Some had a tame dog as part of the hunting party.  

Initially there was no distinct line between capturing societies and agrarian societies. A major shift happened when agrarian societies began to manipulate nature to serve man, and dramatically shifted the composition of plants and animals to those desired by man. Domestication of animals and plants to use them for directly servicing us were key steps in this shift. Some level of preparing the land was also part of this. Fire came in handy in this. My visits to farmers practicing slash and burn in Latin America, Africa and Asia taught me that burning down trees is one of the easiest ways to prepare land for farming.

Swiddening allows farmers to save on labor which is why farmers stick to this practice even today, regardless of how much environmentalists complain. However, the energy wastage is enormous. If we assume that about 100 cubic meters  of wood per hectare of land is burnt and that the land is used for farming for three years, it would mean that about 35 cubic meters of wood is ‘used’ per year. That would correspond to the energy of about 3 cubic meters of oil, which would mean appalling energy efficiency, worse than most industrial systems.

Even if agriculture is no longer the key source of income for most people, it still represents the main livelihood for at least one third of the planet’s population. Expenses on food and all its associated items is the key expenditure for perhaps half of the world’s households and it constitutes a big part of the household budgets of even the wealthy. Food and the consumption of food are important social institutions and social markers—tell me what you eat and I will tell you who you are!

Finally, agricultural landscapes now cover more than half of the earth’s land surface. This means that to a large extent, how we manage agriculture is how we manage the ecosystems of the land. Agriculture is also the key contributor to climate change after the energy sector. And if we count the whole food chain, including all ancillary energy use and emissions of all sorts in the chain, food and agriculture is even more important.

Therefore, how we farm and feed ourselves is still of utmost importance. And when food prices rise, which they did in 2008 and again in 2012, it worries even the rich parts of the world.

There is no coincidence that when oil prices soar, food prices follow suit.

When oil prices soar, food prices normally follow. There are many reasons for this:
“Farming uses energy in many different forms: diesel for tractors and pumps; electricity for pumps, fans and indoor machinery such as milking machines, etc. Fertilizers represent a big energy use. Energy represents 90% of the production costs for nitrogen fertilizers, 30% for phosphorus fertilizers and 15% for potassium fertilizers. For production in the United States, energy costs represented 22–27% of the production costs for wheat, maize and cotton and 14% of the production costs for soybeans. These figures do not include embedded costs in buildings, machinery, etc., so the actual share of the costs is substantially higher. In Argentina, energy costs were calculated to 43% of production costs in 2006. [...] Increased energy prices influence food prices:
·     by making the production more expensive;
·     by making biofuel more interesting to produce and, therefore, reducing the production of food, leading to higher prices;
·     through increased transport costs that directly reflect on food prices; and
·     through reduced competition in the food sector (increased transport costs means that the pressure of global competition is reduced).
(Garden Earth, Gunnar Rundgren 2012)

Energy plays a big role after the farm gate as well. As a matter of fact, energy use is much higher after the farm gate. This is particularly marked in industrialized countries. For example, the whole food chain consumes around 16% of the total US energy use. Farm operations consume only 14% of the total energy in the food sector while handling, processing and retail on the one hand and preparation on the other, use more or less equal shares of the rest. 

As we saw earlier, considerable quantities of energy is used in cooking in agricultural societies as well. “Cooking represents more than a fifth of the total energy consumption in Africa and Asia and up to over 90% of household energy consumption in some countries. Another observation is that energy used for cooking is more than the total energy in food. So while farming in developing countries and by traditional systems is energy efficient, cooking is not.” (Garden Earth, Gunnar Rundgren 2012). Some figures point towards the fact that consumers in rich countries use less energy for food preparation. Admittedly, the food industry in these nations has a large proportion of pre-cooked food in the markets.

The United States Department of Agriculture (USDA) estimates that to deliver the average American’s 2,000 Calorie diet requires nearly 32,000 Calories of energy inputs (Energy Use in the U.S Food System, Canning et al., 2010).

Horrified by this, Eric Ganza wrote an interesting essay, In Pursuit of an Energy-Positive Food System, in which he calls for “the need to adopt a food system with a positive energy balance”. I believe this is overshooting the target. Also in the old days, there were several steps in the food chain that used more energy than they produced. Water or wind mills used a lot of energy to grind the grains into flour. Baking is not very energy efficient when compared to making porridge. And not to mention  the enormous expense in terms of both money and man-power to get spices from the East Indies to Europe.

That our food system has a bad energy ratio by itself is not an argument that it is fundamentally wrong. If that were so, all human civilization would be fundamentally wrong. Well, even life is wrong as plants are highly inefficient as well.

Approximately 130 Joules of energy per square centimeter reaches the earth as solar radiation. Some of this energy is absorbed by the atmosphere directly or is reflected. Of the 91 J reaching the surface of the planet, 18 J is reflected, 31 J is radiated as heat, 36 J is used for the evaporation of water, 6 J heats the soil and only about 1 J is locked by plants as chemical energy. It is this little part, less than 1% of the sunlight that reaches the earth’s surface that is the plants’ share of solar energy. And it is this tiny fraction that is used for food, fodder, fiber and biofuels. Or rather, it is only a part of this tiny fraction as the whole plant is rarely used. If one calculates backwards from the crops actually harvested, we find that in 1993 harvested products represented only 0.4% of the solar energy reaching the fields. Of this 0.4%, only 61% was actually used; that is, real use was only around 0.25% of the solar energy reaching the ground.

Therefore, when seeking alternatives to today’s food chains, to have net energy production as a prerequisite might lead us in the wrong direction. Even worse would be to say that we should not use any ancillary energy in the farming system. Additional energy is not always wrong. For example, a smaller quantity of water for irrigation, such as in a nursery or at a critical period of the growth of the crop, can make an enormous difference in yield. Cooking remains an essential part of human life even if it is “a waste of energy”.

The problem today is more with the scale and quantity. As I write in Garden Earth:
“...the total energy harvested per hectare can increase with increased use of ancillary energy; one can increase yield per hectare fivefold with the use of more energy. This energy can be in the form of better (and more timely) soil preparation, irrigation, fertilizers, etc. The ratio between energy output and energy input (i.e. efficiency in use of energy) seems to be fairly constant to a certain level after which it rapidly deteriorates. In industrial farming systems, the optimal use level has since long been passed”.

Energy ratios in agriculture present an interesting perspective but conclusions can’t be taken to the extreme. First we are, at least not yet, in a situation where we have to equalize energy in food and energy in oil, nuclear power and hydro-power. At first glance, one might even consider such comparisons absurd. And they are absurd, if we think that there will be unlimited supplies of energy in the future. Not too many believe that any more. All staple foods (i.e. the foods that provide the bulk of nutrition) are foods with a positive energy balance in their traditional way of production. If that were not the case, they would never have been staple foods in the first place. Second, calories alone don’t give value to food. In such a case, it would be best to stick to sugar (and sugar cane is one of the most energy-efficient crops). Vegetables will always be inferior to grain when it comes to energy ratios. They contain a lot of minerals and vitamins, however. Meat is not primarily consumed for its energy content but for its protein content. Finally, some food is eaten simply because it tastes good or for religious or cultural reasons.

 Bon appetite! 

Market i Vang Vien, Lao PDR Jan 2012

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