The goal of the methane digester is to create an effective composting system for generating biogas from kitchen scraps to use for cooking, install a biogas stovetop, and install a composting toilet. This will require the following calculations: Theoretical Cooking Biogas Production and Theoretical Electrical Generation from Biogas Production. The timeline for the installation is one day and can be completed at any time after the siding is secured to the house, the kitchen countertops are installed, and the bathroom is finished.
Due to the electric draw of an electric stove and the non-renewable nature of propane, the goal is to design and implement a stove that can run off the biogas created by the compost.
The calculations are as follows:
(22,000,000J/m 3 of biogas)(0.2m 3of biogas/liter of food)(.35 avg ϵ of biogas turbine) (.00000028KWh/J) = .4312 KWh/liter of food waste
If a liter of food waste was generated each day the biogas turbine would can produce approximately 150KWh/year
The food will be placed into a chute that would lead to the outside where composting will take place and methane gases will be stored for the stove. This design is so that if there is ever a leak in the system, the house would not fill with methane gases. The chute is featured below in Figure 1.
Figure 1: Food chute connected to the outside composting system
The details of the chute are as follows:
The composting team is also responsible for obtaining a composting toilet that fits within the dimensions of the house. The toilet will need to be emptied every six months or so, but will result in all waste water to be considered grey water because there will be no sewage in it.
$60.00 for compost collection basin
$60.00 for system insulation
$30.00 for gas hose and gas line connections to biogas stovetop
$10.00 for PVC piping from interior of house to compost collection basin
$40.00 for biogas “tank” and weighted blanket
Total Budget: $200.00
$1200.00 to purchase one rather than build one
$325.16 Built in Gas Stove-Top
$79.99 5 Year Appliance Protection Plan
$ 40.00 Include hoses and fittings that will be used on the composting system
The system will be designed to generate biogas that can be used for up to 1.5 hours of cooking a day. The other benefit of this system will be that it can generate liquid fertilizer that can be used on the green wall of the tiny house. The design will also be mobile to fit with the trailer style of the home and can be completely disassembled from the tiny house at any time. It will be a simple, low cost and low maintenance system that will reduce the greenhouse gas emissions of the home by capturing the methane gas and burning it.
Objective: Mobile Garden that can travel with the home
Calculations Required: Porosity, Confirm the moisture barrier is not compromised
Timeline: 1 Day Installation, can be completed at anytime after the siding is secured to the house