OSC Recycling & Sustainability Service Group

A reflective blog exploring recycling & sustainability initiatives at the Overseas School of Colombo

Catching a Flame: Biogas Explorations Part II

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Biogas_Temp_Measurement_4(MR)(04_19)

First flame: burning biogas and heating a liter of water. One of the first trials by the Class of 2020 ES&S class.

Sri Lanka is experiencing significant challenges with a power deficit in the last month and the outlook does not look good into the foreseeable future. There are now scheduled blackouts of about 4-5 hours in most parts of Sri Lanka every working day (see article below for analysis on cause and consequences). Meanwhile at OSC we are making slow progress with our school biogas plant. This system was installed in October it has taken a while to be fully functioning. In the first month of April 2019 we made the first successful trials of heating water using a stove and gas from the tank.

Though the system was installed in October 2018, it took several months to get the anaerobic bacteria charged inside the digester. To enable this, we fed the system with fresh cow dung every 2-3 days.  Team from OSC’s maintenance department was put in charge of feeding it regularly. Unfortunately, the biogas plant was unintentionally neglected over the winter holidays and we had to start all over again in January. It is a reminder of the importance of maintaining and being consistent with the inputs int the system.

The problem that we have had at the beginning stages of the biogas plant was controlling the CO2 levels. The inputs were almost all cow dung (with no food waste) but our outputs were high in CO2 and relatively low in methane (CH4). We attempted to measure samples of the gas with the Vernier CO2 gas sensor/probe. However, every attempt to monitor the CO2 showed very high readings that were off the charts (@ 10,022 ppm). After many failed attempts we were advised by Sunil to keep giving it cow dung.

We finally got a flame at the end of March. At, first after putting a match to the burner, we were unaware that the gas was lit. However, we tried putting some paper over the burner and it lit (see linked video)! The gas has an odor but when burnt this goes away. Since the first firing we have been heating up a liter of water and recording data every 2-3 days. It takes the biogas tank about 72 hours to digest and produce enough gas. At this stage the inputs are being controlled by maintenance and we need to get better data on their additions (both in quantity and quality and frequency). We will start adding food waste to the system after returning from our April break.

 

FIRST BURN_ HEATING A LITER OF WATER WITH BIOGAS (TEMPERATURE CHANGE AND FLOAT HEIGHT) (2)

Data recorded on first run of the OSC biogas plant on 1 April 2019. Data recorded and processed by the OSC ES&S Class of 2020 (Nehe & Shivani) with input from their teacher.

REFERENCES & FURTHER READING

Lanka Biogas. Web.

Written by ianlockwood

2019-04-09 at 2:36 PM

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