The Energy of Agriculture: Calories and Community

Miguel Santistevan


The growing interest in renewable energy often overshadows the most basic relationship we have with energy: the energy that comes from our food. This is the energy that ultimately provides the wherewithal for us to even think about renewable energy, develop its infrastructure and advocate its application. Our current national food system provides the “low hanging fruit” for understanding and addressing our energy consumption patterns. As all of us have to eat, through the food choices we make we can lower our “ecological footprint,” or the impact our food choices have on the Earth’s resources.

An interesting aspect of agriculture is that energy can be harvested and refined for use in future food production and for other purposes. Understanding the dynamics of energy in agriculture requires creating a “budget” of all of the sources of energy, its expenditures and relative impacts. This exercise demonstrates that agriculture brings us closest to the purest transformation of energy: the conversion of solar energy into life.

Looking at calories spent to calories gained is a useful exercise in measuring sustainability. Calories are usually measures of energy expenditures in animal metabolism, but can also be used to measure energy dynamics in terms of a truly sustainable energy economy that can be made affordable through the use of renewable resources. If one evaluates contemporary agricultural practices based on energy expenditures as measured in calories, we find that for every calorie produced by the industrial food system, approximately 10 were expended through the underlying costs of mining, refining, processing, refrigeration and transport, among others. This inherently unsustainable equation is made possible by government subsidies in the Farm Bill (our tax dollars) that are supporting the large industrial farms. A traditional agricultural system, in contrast, creates 10 calories for every calorie expended. This stems from judicious and innovative uses of the land and water, animals, local materials, local seed, local markets and manual labor. However, given many constraints, such as land availability, labor potential and the availability of time (not to mention our attitudes), we are not geared toward actualizing these traditional agricultural dynamics.

The field of ecology provides some tools to measure and understand the energetic dynamics of agriculture as a potential source for the renewal of resources. A given area of land will receive so much sunlight. This sunlight is converted into biomass: roots, stems, leaves and seed. Energy will be embodied in all of these plant parts, some of which are particularly useful to us as consumers. We eat the seeds, the fruits, vegetative parts and roots for sustenance. When we feed the biomass to animals, as in grass or alfalfa, we can expect that roughly 10 percent of what they eat will become biomass in their bodies, while the other 90 percent is lost to metabolic processes that generate heat and waste, such as manure and urine.

However, the metabolic processes of animals can be directed to create work such as tillage or to just maintain grass levels while providing us with meat, dairy products and eggs. The animal waste can be combined with other organic materials such as fresh and dry weeds, wood chips, bark and fallen leaves to create compost. The compost can then amend soils to increase soil fertility and yields. Diversity can be incorporated into the long-term biological character and development of the landscape in the form of trees, bushes and other native plants as well as animals (especially beneficial insects), thereby enhancing ecological processes. Many of these plants can be self-perpetuating and can move the landscape into a more perennial character that over the long-term just needs to be maintained and harvested.

As the process of working with diversity and the landscape continues on for season upon season, many aspects of the energy embodied within the harvest can be utilized for multiple purposes. For example, ears of maize can be harvested for food, while the cobs and stalks can feed animals or even be inoculated with edible mushroom spawn and turned into more food while also becoming substrate for compost. Almost any crop can be thought of as having multiple purposes that serve different functions that can increase and support diversity, which ultimately results in biological character and food sources.

With all the sunlight and caloric energy embodied in a diverse and sustainable agricultural landscape, there have to be biological components that can be intercepted to generate power while still being able to provide food. The first priority has to be to have energy in the form of work to maintain and enhance the landscape to perpetuate the process of diversity. As stated earlier, animals will only incorporate about 10 percent of what they eat into their own biomass. So by utilizing their work, we can intercept some of the 90 percent of their consumed biomass that is lost as heat to do work. And later, we can manage the other waste products to generate other forms of energy.

The most efficient way of maintaining the landscape is by the management of grazing animals. The landscape evolved over millennia with grazing animals, and their return can mean great benefits, including tillage (herding), planting (stomping), fertilization (manure), irrigation (urine), water harvesting (hoof divots) and seed dispersal. Seed dispersal can be a problem, however, if the plant seed being dispersed is an invasive species. Invasive species can also have their purpose in this type of agricultural system where “the problem is the solution,” however, where the mass of invasive species is a substrate for energy production, be it for biomass, ethanol production or even feed for goats. The use of animals for this kind of work is efficient in that if the animals have a food and water source nearby and no other infrastructure except fencing, their natural activity can convert solar energy into animal power that manages the landscape. This approach just directs the natural behavior (and desires) of the animals to accomplish tasks.

But not everyone has the land land base or wherewithal to manage animals. This is where mutually beneficial networks of ranchers and farmers would be a great social component to managing vast areas of the landscape. But a small farmer thinking of energy security has many options. The first is to look for waste streams in the agricultural operation that can be converted into useable energy. This is where animals (including humans) can be beneficial. Where waste, a.k.a. “bio-solids,” is often a problem in cities and large-scale dairies, it is actually a solution to our many of our energy challenges. An anaerobic digestion process will produce methane, which can be burned in almost any propane-burning application. Bio-solids can be isolated from oxygen in some kind of tank or barrel, heated up, and the gas that is produced (methane) can be collected in something like a tractor tire tube. This gas can then be burned in anything that burns propane (with a simple conversion), including stoves and other appliances. Even a tractor can be converted to run on propane and, thus, methane. What is left in the tank or barrel from the process can still be composted in an aerobic process to augment soil fertility.

Another great opportunity for fuel sufficiency is to grow a crop that produces vegetable oil such as canola or sunflower. A diesel engine can run on vegetable oil if it is heated to a certain temperature. Many diesel engines run on vegetable oil today, but actual diesel gasoline is needed to start the engine and heat up the oil so it can combust in the engine. I have often thought that passive solar energy could be used to heat up the vegetable oil for combustion in a diesel engine. There is a 13-horsepower tiller at Red Willow Farms at Taos Pueblo that runs on vegetable oil or biodiesel, so there is at least one place this model is already somewhat in operation.

I have heard that an acre of sunflowers can yield 100 gallons of sunflower oil. All that is needed is some kind of oil press that is something like a small corn grinder with a candle under it. The nice thing about using sunflower or other oils for fuel is that they could be used for cooking first, then saved and filtered for use as a fuel. If we were to look at other uses for the biomass of sunflower, such as growing mushrooms from it, then we can have pearl oyster mushrooms sautéed in sunflower oil, for example, while we save the remaining oil for fuel needs. The question then is how much oil is needed to till how much land, and how much tillage is even necessary. Another potential source of “free” oil is to press the oil out of the garlic seed in the mature scape. In this way we can have both garlic and garlic oil, while only minimally affecting our ability to harvest garlic or her scapes.

With thoughts of optimization of diversity and its potential uses, we find many opportunities in agriculture that could support an innovative energy economy. This economy could be decentralized in a way that allows farmers and collaborators to innovate and work together to take care of our basic energy needs. This kind of economy will necessarily be defined by conservation, as there will likely not be enough energy to habitually leave on lights and appliances that are not in use. As we are currently being challenged to understand the limits of our activities that require energy, the good news is that there are vast incidental sources of energy in a diverse agricultural landscape. Since one of the tenets of Permaculture states “the yield of a system is infinite,” we need to get started in managing the diversity of our landscapes towards maximum optimization. If we start thinking of all the potential uses of living things under our care besides just the yields, we will find that our imagination and concept of priorities are the main limiting factors to our success in developing a sustainable energy economy.


Miguel Santistevan is executive director of the nonprofit Agriculture Implementation Research & Education. Email:,