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Biogas Demonstration and Build in Budapest

Co-creating a better biodigester at the Godor Culture Center in Budapest

August 5, 2011

As a result of our Slovakia workshop, we held a biogas building workshop in Budapest, where I demonstrated the Solar CITIES IBC system for colder climates. I enjoyed the crowd sourcing and collective intelligence nature of the participants who came up with many great ideas for improvements!

We completed a insinkerator-based biogas system at the Godor Culture Center in Budapest (though sans manure and water). Kovách Eszter and Attila Mester did a masterful job of interweaving presentations, breakout-groups, panel discussions and actual BUILDING. As a result the two-day event was both informative and practical. Thank you guys, and thank you Hungary! Let us continue the momentum, transformation “demonstrations” from protests into true “demonstrations” of better ways of living!

Despite the enthusiasm for the project of transducing wastes into gas and fertility, the last message we got from our colleagues in Hungary was that they could not continue the project because “authorities” determined that biogas was somehow “too dangerous” to be brought to the Roma communities. They discouraged our stalwart innoventors and practitioners from going further.

But the beat does go on. The workshop was attended by Swiss Permaculturist Simon Westermann, who took what he learned back to the Damanhur Eco-village in Italy, center of the Global Eco-village Network (GEN), and their scientists built their own IBC based biodigester and are sharing it with the world.

Renewable Energy in the Latino Community

“Flame on” demonstrated by Alvaro Silva, Director of Solar South Central and Los Angeles and colleague of Solar CITIES, bringing renewable energy systems to the Latino community.

January 5, 2010

Alvaro is the poster-boy for the success of the green-collar immigrant job training concept. As a graduate of Trade Tech College’s renewable energy program and of T.H. Culhane’s early “Eutopia” Class at Jefferson High School in the 1990s where he worked with Culhane on electric and alternative fuel car conversions and green building and solar energy construction. Alvaro worked for Real Goods and for Photovoltaic Installation companies throughout California and now runs his own business in the construction/green retrofit trades and makes instructional videos for the hispanic community. He also brings his ideas to his native Mexico to share with his family and friends and engage in community development.

Building Biodigesters in Alaska

December 5, 2009

In late 2009, after developing our Solar CITIES IBC-based biogas system in Cairo, Egypt in anticipation for building in cold climates, we went to Alaska to experiment with psychrophilic microbial biodigesters in IBC tanks.

Read more about the project in this Free Wheelings blog post.

Experiments with IBCs at Sekem Farm

Students from the Sekem science program inspect the Solar CITIES solar heated IBC biogas system that they helped build

May 12, 2009

At the Sekem Farm and Science School outside of Cairo, Egypt Thomas Culhane, Hanna Fathy and Solar CITIES intern Mike Rimoin deployed their invention of the open-source solar heated three IBC Solar CITIES biodigester. This is perhaps the first use of International Bulk Containers (IBCs) for biogas in the world.  Culhane felt it necessary to build a biogas system out of IBCs because he had just won a National Geographic Emerging Explorer’s Blackstone Ranch Innovation Challenge Grant with Dr. Katey Walter Anthony from the University of Fairbanks in Alaska and had to come up with a small scale biogas system that would work in cold weather conditions.  The open ARTI India systems they had been building in Cairo wouldn’t work outside in the cold because they would lose heat too quickly. They would also not work indoors because they would create odors and release methane.  Meanwhile, typical cylindrical water tanks were either unavailable in Alaska or far too expensive to be feasible.

Culhane and Fathy passed discarded IBCs on the roadside in Cairo and wondered if they could make effective digesters. With a little bit of research, Culhane found that they could be found in almost every country in the world. They are, after all, international bulk containers.

The problem they faced was that unlike the ARTI design, which uses a telescoping tank to hold the gas, the IBC has no storage possibility. Culhane came up with the idea of using three IBCs—one as digester, one to hold the gas, and one to create displacement water pressure to force the gas to the kitchen or generator.

It ended up being easier to produce the gas in an IBC but store it in a typical ARTI. Another option is to use the IBC as the digester and store the gas in a large PVC bag and use a pump to create pressure.  But for situations where IBCs are the ONLY tanks available and there are no bags or gas pumps, the the IBC system works rather well. 

Culhane, Fathy, and Rimoin tried three different variants of the system. One was a traditional ARTI system with black plastic irrigation pipe surrounding it connected to a solar hot water system. The hot water system is also made with black plastic irrigation pipe as heat exchanger rather than copper.   The second was an IBC connected to an ARTI.  The third was the three IBC system for places like Alaska where cylindrical water tanks for gas collection are not an option.

Based on these experiments, Solar CITIES demonstrates different options for digesters for different environmental conditions around the world.

SolarCITIES Cold Climate Digester

The second of Solar CITIES’ experimental all-climate biodigester. The first is in Egypt.

May 5, 2009

This system is built from three identical IDB tote HDPE tanks. To the rear, one can just make out the biodigester itself. The top of the digester is connected by 1/2 inch clear plastic tubing to the top-side of the water displacement tank (WDT) . Water from this tank is forced by gas coming from the digester out of a length of clear 1/2 inch plastic tubing from the bottom of this tank that loops over the top of the WDT into the sump. The sump is a 20-gallon plastic garbage bucket that can be seen in the foreground of the picture.  The more gas is forced in, the more water is forced out until the sump is about 3/4 full. At this point a float switch turns on a pump inside the sump which carries the water up the blue 1/2 inch tube to the top of the water pressure tank (WPT).  The pump is powered by a rechargeable battery with an inverter. It is the orange box in the bottom right of the photo.  When the WDT is filled with gas and the WPT is filled with water, a valve in the one-inch white PVC pipe connecting the two is opened and the water pressure forces the gas out of the top of the WDT to the kitchen stove or barbecue via another 1/2 inch blue plastic tube.

From our Zabaleen Trash Recycler friends in Cairo we learned the truth of the adage, “waste not, want not”. Taking this concept to heart led to a trip to Pune, India where Dr. Anand Karve of the ARTI Institute taught us how to make simple biogas digesters that turn yesterday’s kitchen waste into today’s cooking gas. It is possible to get about two hours per 1000 liters per day from about two kg of stuff everybody else calls garbage. In addition to the clean burning gas, we get about 10 liters of liquid compost fertilizer which goes to the garden to make more nutritious and delicious food.

At 460 we have implemented the second “Solar CITIES cold-climate digester” based on a design T.H. Culhane came up with to take advantage of ubiquitous HDPE (“High Density Poly-Ethylene”) IBD (“Intermediate Bulk Delivery”) Tote Tanks (1000 liters or 275 gallons).  As shown above, we also use two of these tanks for our greywater system.  Other people recycled them for use in biodiesel systems. They make great trellises for plants and the sturdy metal frame are easy to climb on to do work without damaging the tanks. The frame also makes it easy to “roll” one into place. We had ours delivered on the street and T.H. rolled them down the block to get them in the back gate.

Besides making use of readily available recycled materials to build the digesters, the idea behind the design is to create a household-scale digester that can operate in cold climates. The normal cylindrical water tanks we use in Egypt (and which ARTI uses in India) are not readily available in Europe and America. Special ordered they can cost up to $500, while these used food and chemical containers can be had for 5 to 10 times less.  So for low-cost systems these are the way to go.

The system Solar CITIES has designed is composed of three tanks. One, which is ground mounted, is the digester itself. Filled on the first day with about 40 kg of animal manure and 975 liters of water it is subsequently sealed. Because it is sealed, it can be insulated for outside use or placed indoors. The gas is piped to a second ground-mounted collection tank that is initially filled with 1000 liters of water to which ethylene glycol or some other anti-freeze additive can be added. This tank is sealed. As gas is created in the digester it builds up pressure, which forces it into the collection tank. As the sealed collection tank fills with gas, the gas displaces the water/anti-freeze mix via a looping tube into a 20 gallon sump. The sump is basically just a plastic trash can placed next to the collection tank. In the sump is a fractional horse-power garden pond pump and a float switch. When the sump fills about 3/4 full the sump pump goes on and pumps the water to an empty holding/pressure tank that is mounted above the collection tank and is open to atmospheric pressure via a small hole in the top. As gas fills the collection tank, the pressure tank fills with water. When one wants to use the gas in the kitchen or the barbecue one simply opens the valve to a 1 inch pipe that connects the two tanks. The water in the top tank then flows back into the bottom tank and forces the gas out the top through a tube to the stove.

With this design, the gas collection/water-displacement pressure part of the system can be kept outdoors in a safe location and remain uninsulated. The minimal energy requirements of the water pump can be handled by a solar-charged battery. In our case, we use an AC pump with an inverter but a DC pump can also be used directly.

Thus kitchen waste is directly turned into fossil fuel-free cooking gas and easily transportable liquid fertilizer. Smells, flies and rodents are also eliminated from the home and the other so-called “garbage” (paper, plastic, metal, glass) can be easily sorted and cleanly stored for recycling or sale.

Ironically the tanks shown below, which we purchased from a recycler in Santa Rosa we found on Craig’s List, had previously contained Kosher food-grade glycerin.  We are sure this makes the methanogenic bacteria very happy!

The feedstock for our biogas digester is just ordinary organic wastes from the kitchen, ground up into a slurry with water using a typical insinkerator waste disposal unit. At 460 Lucas we are also implementing a compost bin but only for cellulosic and lignocellulosic material (wood chips, leaves, grass clippings), paper, cardboard, newspaper, paper towels, shredded junk mail, tea bags and hard pits of fruit). The compost bin, as we learned from our friends in Africa, uses aerobic microbes to create a nice healthy soil from stuff most people burn or bury in landfills. We are also putting in a composting toilet, which we learned about in rainforest areas in Belize and Brunei and then found could be implemented in urban areas when visiting Johannesburg, South Africa.

Our Humble Beginnings in Essen, Germany

One of Culhane’s biodigesters (in the greenhouse behind him) feeding a 1000 liter Puxin biogas bag.

January 30, 2009

Home scale biogas at home. This is where it all began for Solar CITIES co-founder T.H. Culhane when he built his own household biodigester on the family porch in Essen after returning from his first visit to India in January of 2009 where he learned about the ARTI India system. Today, Culhane has three biodigesters on his porch—one ARTI style made from a 500 liter, a 300 liter water barrel, and two 1,000 liter IBC systems that Culhane innovated himself.