Reporting from Haiti: On the Road to Developing a Wicked Biodigester

I come to you from Cap Haitien, Haiti where we are at work on AIDG- Haiti’s first biodigester. The majority of the biodigesters construction techniques have been developed in Guatemala but are being tried out here to make the technology more appropriate for Haiti.

Right before coming to Haiti, however, I was in Pachalum, Guatemala (Department of Quiche) working on the first of three biodigesters that AIDG is building in the community. AIDG and the municipality of Pachalum have entered into a unique project relationship. AIDG, Pachalum, and the families who will be receiving biodigesters are equally shouldering the costs associated with the project. The owners of the first digester, Don Ramiro and his family, will begin filling it with animal waste created from their pig farm. The Ramiros don’t currently have electricity and are looking forward to the benefits that their biodigester will bring. They are also excited to have one of the first biodigesters in the area.

The pigs on the Ramiro farm are used in the family restaurant, “La Casa de los Chicharonnes”, making the biodigester site long-term stable. A problem that we’ve observed with single family biodigesters is that the owners’ tend to sell off the animals that feed the digester in times of need. Once there is no waste to put in the digester, the system will stop producing gas after about a month. Undigested waste will settle to the bottom of the tank. The loads of settled out waste have to be removed before the digester could be put back on line.

Don Ramiro is less likely to reduce the number of animals he has unless his business closes down. So, we’ll be recommending “La Casa de Los Chicharonnes” to everyone to make sure that it doesn’t close!

Completed Biodigester at Don Ramiro's
Completed Biodigester at Don Ramiro’s

I’m using many of the techniques that were developed in Pachalum here in Haiti as we construct the biodigester. The system is being built at Project Pierre Toussaint, a center for Cap Haitien’s street boys. The center takes in street boys of all ages and shelters them, feeds them and gives them a hands-on practical education. It’s a very inspiring place to work.

After the digester is complete here, I will return to AIDG- Guatemala to finish up the project in Pachalum and build a biodigester for AIDG’s new educational center in Xela. We hope to use some new ideas for this installation that incorporate aspects from both the floating dome and fixed dome designs.

We’ve made multiple improvements to the design over the course of the technology development in Guatemala and Haiti:

  • We are now using a removable wood form for the construction of the concrete biodigester tank. The use of reusable forms is dropping the overall cost of the system and allowing it to be constructed more quickly and with much greater consistency in the shape of the tank. The removable wood form, when assembled looks like a giant wine aging barrel.
  • We are now encapsulating the fiberglass/sheet metal dome in a PVC frame that acts as part of the guide system to ensure the dome floats directly up and down as gas is produced and consumed. The PVC capsule carries all the structural forces so this is also a step in the direction of removing the sheet metal core from the dome. Removing the sheet metal/flat iron core would greatly reduce the overall cost of the system and also remove the potential of problems arising from zinc galvanization leaching into the digester and disrupting the process.
Interior Wood Form being used to Construct the Digester Tank
Interior Wood Form being used to Construct the Digester Tank
The wood form wrapped in HDPE, ready for the exterior form to be placed around it.
The wood form wrapped in HDPE, ready for the exterior form to be placed around it.
Making the concrete digester tank at Project Pierre Toussaint
Making the concrete digester tank at Project Pierre Toussaint