Welcome to part one in a four part exploration. This exercise is intended to stimulate thought and imagination. What might future Local Energy Farm Demonstration projects look like? What issues will they attempt to confront? What are some of the guiding agricultural principles and how will the research and actions at these farm sites connect with community needs or local economy?

Certain energy farms will confront the issue of Food Security. To be certain, energy prices and the price of food are interconnected. Today’s' agricultural system uses massive amounts of energy as petroleum mediates almost every aspect of food production. Petroleum based fuel is required for the tractors, it is used in the transport of produce, natural gas is used to make fertilizer, herbicides and pesticides are saturated with petrol, and large amounts of electricity is required for the processing of food. Intense dependency on petroleum is not only costly economically, but is also taxing to the surrounding ecosystem.

The Post Carbon Institute is practicing and experimenting with methods of food production that are adapted to a post-peak world.These methods are intended to minimize excess energy inputs where ever possible and to generate quality organic food to be distributed locally. Resource management and curtailment are the cornerstones of crop production methods that improve rather than deplete the quality of the soil, water and surrounding eco-systems.

Local food production farms will demonstrate the foundations of sound agricultural practice. These sites will typically contain rich, arable land, ideal for the cultivation of healthy crops. The aim in such a farm is to maintain the health and fertility of the land by utilizing a basket of sustainable agricultural practices. These farms are designed to meet the food needs of the immediate community and are intended to be a model of community participation and the processes of relocalization.

The following agricultural practices will be our foundation:

• Permaculture design
• Integrated pest management
• Preservation of the soil foodweb
• Crop diversity and crop rotation
• Reduced use of petroleum
• Chemical free weed management
• Composting practices utilizing activated compost tea
• Companion planting
• Water management
• Local distribution of produce
• Utilization of renewable energy

While many communities may choose a strictly vegan diet, other communities may adapt differently. In anticipation of the diversity of transition methods the food security of livestock and labor animals needs to be addressed. These crops would be grown on decent to marginal land to meet the dietary needs of free range dairy cows, plow horses, goats, pigs, or chickens. It is clear that goats, dairy cows, and chickens have secondary benefits that outweigh their meat value. While it is indeed true that many of these animals can and will exist without supplementary food, they will not produce high quality milk or eggs on a consistent basis. These products are large sources of stored energy and considered to be staples in many food regimes.

The following examples illustrate what energy farms addressing food security might look like:

Example 1: Two acres of an unused baseball field would be converted into an organic farm. Energy and water needed for irrigation and food processing would be secured via an onsite well and renewable energy technology. A mix of perennial and biointensive cultivated annual plants would be grown. An onsite composting system would be essential in recycling crop wastes and maintaining the vitality of the soil. A farm tractor from the local tractor co-op might be used to incorporate over-winter cover crops into the soil and prepare the seed bed for new spring crops. Although tractors are available, the farm site does not rely on them on consistent basis as farm managers may decide on a low-till system. Integration of a greenhouse would allow farmers a jump on the each season to ensure as much food production as possible.

Example 2: Four acres is used to grow organic chicken feed. Crops including corn, oats, barley, sunflower, flax, and fava bean would be grown with minimal water or labor input. To preserve the vitality of the land these crops would be rotated and intercropped with legumes to create land better suited for human food. Supplying a community with supplementary chicken feed is a way to secure quality egg production from multiple flocks of chickens.

It is also probable that food producing farms could grow small amounts of energy crops in combination with food crops. For example, flax, an energy crop because of it fiber and oil seed, has been known to enhance the growth and flavor of carrots and potatoes. Flax also repels the dreaded potato bug. This is not only a form of integrated pest management, but also a small effort toward energy security if the oil was used for small scale biofuel production.

It has been a week since the initiation of the probiotic fertilizer and the batch-style biogas system at the Local Energy Farm Demonstration Project located at UBC. At present, certain aspects of daily farm upkeep rely on the work of dedicated volunteers. I considered this in the creation of the biogas digesters and attempted to make a system that was as easy to maintain as possible for the volunteer workforce.

At minimum, the biogas digesters need to be agitated once a day. In my perfect world, agitation would occur three times—once in the morning and twice during the heat of the day. Remember, agitation breaks up the hard layer of scum that tends to form on the surface of plant based substrates and it mixes the plant matter in order to allow bacteria to come into contact with new material to digest. Agitation should take about thirty seconds for each digester. A volunteer cycles the handle clockwise for about 5-10 revolutions and then counter clockwise for another 5-10 cranks. Simple!-Finished and on to the next farm task!

The probiotic fertilizer needs less frequent agitation (once a week instead of daily). The “airtight” lid is taken off the brew, a wooden oar is inserted into the mix, and the contents are mixed and churned for a minute or two. Usually this makes a lot of foam as carbon dioxide is released from the mixture. After mixing the lid is re-secured and awaits the next week.

As you consider the infrastructure and process you are going to develop on your farm try to make it use as less energy as possible for up keep and maintenance. To invest a little extra thought and energy in the planning and design phase can allow you to have multiple initiatives underway, which, once started, can continue without a lot of extra physical input.

I have been using a template presented by the United Nations Department of Food and Agriculture as a general guide for the creation of the biogas system at the Energy Farm at UBC. This booklet suggested using rubber tire inner tubes as the gas capture system, a suggestion that I eventually chose against at the Energy Farm.

The U.N.’s suggestion is that tire inner tubes are simple to repair, easy to acquire, and can suitably store biogas for later use. While I find this idea appealing in situations of scarcity and as a means of reusing rubber that might be simply thrown out, I feel that taking a little more time to build a drum style gasholder is better overall choice for this biogas system.

The basic design of the dome style gasholder is as follows:

1.Invert a drum so that the holes on the lid face toward the ground

2.Remove or cut off the top of the drum

3.Insert a PVC pipe into one of the holes in the lid so that it stands vertically inside the inverted drum

4.Fill the main drum with water to about 3 inches below the top of the pipe and place another drum inside (inverted so that can collect the gas)

This “floating dome” style of gas collection captures a large amount of gas that is distributed using only one outlet. Moreover, all biogas digesters can have their gas routed to this single gas collecting dome. As the gas collects under the drum, the water acts as a seal so no gas escapes. Weight is put on the top of the second drum in order to determine the pressure of the system when connected to a stove or appliance. As the drum is pushed closer to the water more pressure is created and gas flows out through the PVC pipe toward the appliance.

I inverted a 50 gallon plastic drum, cut the top off, filled it up with water and placed a 20 gallon plastic garbage can to form the gasholder. I liked the fact that I could use plastic in this part of the system because it ensures the long life of the gasholder. While the inside of digesters Ludwig and David had to be painted with a protective paint, the plastic drums need less preparation and are guaranteed not to corrode from the gas.

Gasholder of Prototype Biogas System

The biogas construction project has been completed! On Tuesday I was able to connect the digesters to the gasholder, buffer the substrate, and add the seed cultures.

I found that buffering the substrate required much less alkaline material than I expected to use. It took 40grams of baking soda to buffer the clover/leaf batch inside digester David, while digester Ludwig used 35grams. This was enough to change the acidic solution (pH 5) to a more basic solution between pH 7-8. I checked the pH with litmus paper multiple times during the day and the pH of the clover/leaf substrate remained a constant 7-8. Farm manager, Mark Bomford, noted that the leafs inside the substrate have an excellent buffering capacity and will be able to absorb a lot of the baking soda. So, while the substrate seemed adequately buffered at 7-8 on the day that I added the seed cultures, it might become more acidic after the leaves absorb the baking soda water. I am nervous about his suggestion as we are now left to monitor how the buffering plays out.

Four different anaerobic seed cultures were used to inoculate the digesters. I used a culture of lama and sheep manure, a culture of lama and clover manure, a mixture of sheep and clover, and a mix of only clover and leaves. These cultures were maintained under protection inside a glass greenhouse for over five weeks. During that time I had observed gas production on the surface of all cultures using the sheep and lama dung and felt that those cultures offered a large population of methane forming bacteria. However, the mixture of only leafs and clover did not seem as active and I did not expect it to be a suitable seed. As I added the seed cultures to the digesters I checked the pH of each one. As I expected, the cultures using lama dung were defiantly basic at a pH of 7-8. The leaf and clover mix was very acidic at pH 5.

The acidic clover leaf culture lends us insight into the necessity of brewing appropriate bacteria cultures for seeding. Anaerobic bacteria can and will grow inside plant only mixtures, however, even in optimal growth conditions, it might take months. That is why a source of dung is useful when creating live cultures in a shorter period of time. I think it is reasonable to suggest that the plant only seed was stuck in the acid forming phase, where bacteria are breaking down the plant material into fatty acids. Without a suitable amount of methane forming bacteria to gobble up those acids the process gets stuck and the solution remains acidic. Literature suggests that this process will correct itself eventually because the bacteria that form the fatty acids will begin to drown in their own toxins, slowing their reproduction and allowing methane forming bacteria to make headway against the overabundance of the acids.

After the seed cultures were added to the digesters I put the lids on and sealed them closed. I stuck plumbers putty under the lip of the lids so that I could assure a gas tight seal and then bolted the lids down. Agitation of the material was not hampered by the lid or the temperature sensors and the entire system seemed to be functioning as expected.

Prototype Biogas Digesters (David and Ludwig)

Gasholder for Digesters 

Today I was able to complete the probiotic compost tea I learned about while in Ecuador. The brew was made of clover, sawdust, yeast, molasses, humus (finished compost), rock phosphate, urine, garlic, and comfrey. I decided to throw the garlic and comfrey in to act as a natural insect repellent. This batch will be stirred once a week and will be stored next to the biogas digesters in the hoop-style greenhouse at the UBC Energy Farm. It should be ready in 45-90 days depending on winter temperatures-my guess is around a safe 75 days. The tea can be used as a foliar spray at a 1:10 ratio or as a soil improver at a 50/50 mix with water. I expect the batch to yield around 100 liters of concentrate. If you want the exact recipie email me at --> chrishansen@postcarbon.org .

The biogas project is near completion, and the lids are ready to be tightened down. I stuffed 19.5kg of mildly composted material into digester David and 10kg into Ludwig. Then I topped each digester off with water until there was about 10cm of space from the lip of the drum. The agitation system works fine but can be a little tough when digester David gets a pile of leaves pressed between the lid of the drum and the agitation arm. If I could make an improvement it would be to make the handles of the system a little bigger as to allow the user to get more torque and therefore make it a little easier to bring the arm around. However, perfection aside, the agitation system does not leak and works fine-I count that as a success.

I have some litmus papers that I have been using to check the pH of the water and substrate mixture. It is very acidic right now. On the color sheet between 4 and 5. That means that I have a long way to go to buffer the system to a pH of 7-8 to make the mixture hospitable for the methane forming bacteria that I plan to seed the digesters with tomorrow. My idea is that the substrate will seep into the water overnight and allow a substantial amount of acids to form. Then, tomorrow, I will use lime or baking soda to buffer the solution. I am leaning towards baking soda right now; however, there is plenty of lime at the farm.

For a little over a day, the feedstock materials have been undergoing aerobic decomposition in hopes of breaking down the plant matter before feeding the digesters. One of the digesters (a.k.a. David) will be fed a charge of 9Kg clover and 11Kg of dry maple leaves. Once David is filled with water the substrate will have a total solids concentration of about 11 %. The other digester (a.k.a. Ludwig) will be fed a mix of 4.5Kg of clover and 5.5Kg of dry maple and alder leaves. At about 6% solids this is a less dense concentration of material.

When these prototype batch-style digesters I decided to make two subtly different machines. Ludwig’s agitation system differs from David’s in one way—the depth of the agitation shaft. While David’s agitator is situated 6 inches below the top of the lid, Ludwig’s is positioned at 8 inches below the top. What this difference amounts to is as follows:

Ludwig’s system will be able to disrupt scum formation and will be able to mix the slurry from a deeper position. The intended idea was that the deeper agitation position would churn the substrate and allow the bacteria to come in contact with new bits of material to eat. In contrast, David’s agitation system is position higher on the drum. It too will be able to disrupt the scum formation and it has the advantage of allowing more material to be put into the digester. Given suitable conditions, more material is more biogas. Hence, I have decided on a smaller solids concentration in digester Ludwig because it might be too hard to turn the agitation handle through such a dense mixture. David, on the other hand, can handle the denser material and will break up the scum, allowing the digestion process to sort itself out below. In subsequent tests of the machines more material will be added to Ludwig to really get a test of what is the limit of the deeper agitation system as it attempts to churn dense plant matter.

Today was a very exciting day for the biogas project. The construction of the agitation system is completed! I worked with Vic at C.W. Brockley to install the agitation arms earlier this afternoon. I also gave the inside of the drums, the lids, and the agitation arms a thick coating of paint. Since the environment for biogas digestion is corrosive to steel, we must use corrosion resistant paint to give the digester protection and a longer lifespan. I decided that stainless steel would not be used on these digesters because (1) it contains chromium-a poison to the anaerobic bacteria and (2) it is very expensive. If this design is going to be practical to replicate, specialized or expensive metals probably won't be the best choice.