OSC Recycling & Sustainability Service Group

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

Archive for the ‘Energy Matters’ Category

2019-20 School Year Beginnings

leave a comment »

The 2019-20 Recycling & Sustainability service group.

The 2019-20 is well under way and we have a new group of enthusiastic students in the service activity this year. For the first time in 15 years we have student leadership provided by Grade 9 (MYP4) students. Lexie and Darja have both been committed members for several semester of R&S and this year they are the student leaders. Diviyanshu is  playing an important role as a business advisor. He is also working on a website for the group as part of his CAS Project.

Our activities this year have fouced on paper collection but we are also spending time promoting the use of our biogas plant as a place for students and staff to put waste food. In late October and early November Lexie and Darja started collecting waste food from the canteen at the end of lunch. We cooked the first batch of popcorn using the plant in November. Sharing it around has helped draw attention to the efforts of seeing waste as a resource.

Steps in using the biogas plant to make popcorn.



Fonseka, Reka Tharangani and Priyantha Wickramarachchi. Sunday Times. “Food, waste and poverty.” 20 October 2019. Web.

Saheed, Zulfath. “Dirty Talk: Trash Woes Persist.”  LMD: The Voice of Business. ND. Web.  



Written by ianlockwood

2019-11-07 at 2:21 PM

Catching a Flame: Biogas Explorations Part II

leave a comment »


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.



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.


Lanka Biogas. Web.

Written by ianlockwood

2019-04-09 at 2:36 PM

Small Steps: Efforts to Reduce Electricity Consumption at OSC

with one comment

Simple graph illustrating electricity consumption patterns between 2010 and 12 compared to the 2013 values. The gap between the red and blue lines signifies a drop in units consumed.

Simple graph illustrating electricity consumption patterns between 2010 and 12 compared to the 2013 values. The gap between the red and blue lines signifies a drop in units consumed.

In early 2013 electricity prices in Colombo rose dramatically causing much unhappiness amongst consumers but also forcing people and organizations to look at innovative ways to make cuts. At OSC, electricity is a major monthly cost to the school, mainly as a result of air conditioning usage and we too came up with a response. At the beginning of the 2013-14 school year the administration asked teachers to refrain from using air conditioners during the first period of the day (7:40-9:00) in an effort to reduce our electricity use. For the OSC Environmental Systems & Societies (ES&S) class, the school’s experiment in acting on a real world problem offered a unique teachable moment. Now after an analysis of electricity bills from the last 8 months the class has the data to show that a seemingly small initiative can have an impact on reducing consumption.

Electricity in Sri Lanka

Electricity in Sri Lanka is produced using a variety of sources including hydroelectric generators and thermal plants burning heavy diesel and coal. Depending on the time of year, Sri Lanka generates about 49% of its electricity from hydroelectricity (Sri Lanka energy). When it’s raining and the reservoirs in the Central Highlands are full, more power can be generated this way. When it is dry (as it is now) the country has to rely on thermal sources burning fossil fuels. In the last decade there have been calls to increase electricity production to keep up with the growing demand. This is mostly being addressed by building large-scale (300+ MW)  thermal plants. The relatively new coal-burning thermal plant in Norochcholai has been in the news because of its frequent breakdowns and concern about environmental impact from its SO2 and CO2-laden emissions.

ES&S Power Consumption Study

The students of the ES&S DP II class including Yo Kubota, Harshini Karunaratna, Jesse Doige, Sarah Ibrahim and Shabirullah Majeed conducted a study of OSC’s electricity consumption as part of a unit of global energy resources (IB ES&S Syllabus component 3.3). They looked through past copies of electricity bills (going back at least four years) and assessed what patterns could be deduced from the data. The electricity bills are complicated to analyze: There are two meters on the campus and each meter has two different reading in Units (kWh). Each of these meters has a normal 3 phase meter and a full sized transformer that reads in kVa. The two monthly  bill report on the costs and these are broken down into peak and non-peak hours. Costs, of course, have changed over the last several years as per unit prices of power have climbed. To simplify the analysis, the class looked at unites (kWh+kVa). This has its disadvantages but allowed us to compare data across the time period with the units as a fixed variable. The students looked at different aspects of the data with some of them focusing on events. I was interested in the data after August 203 when the new “no AC before 9:00” rule came into effect. The rule was enforced on a voluntary basis and some important spaces (computer labs, library, business office) did not put it into effect.

According to our data the consumption of electricity units in the main meter declined significantly between August 2013 and December 2013. Compared to the average monthly power reading on the same meter, the August 2013 to December 2013 show anywhere from -3% to -28% less in the same time period. Although there are other factors that affect monthly unit readings the data shows a clear declining trend. For example in September 2013 the unit consumption was 40,688 units (kWh) whereas the average for September had been 40,688 units with a high in 2012 of 50,560 units! This adds up to a -18% decrease in units consumed for this meter. The graphs above and table help to illustrate the findings.

Table of raw data from OSC Main Meter 2010-13

Table of raw data from OSC Main Meter 2010-13

When analyzing the data several factors need to be considered.

  • The timing of the school calendar has an impact on consumption. If the school year lets out in early June (as it did in 2013) than the monthly consumption is lower than normal (in fact June 2013 was 43% lower than the 2010-13 average). On years when the school year ended in mid-June the consumption levels show up as being higher. Number of holidays can also have an impact of monthly readings.
  • In 2013 the school replaced ACs with newer, more efficient models and it is quite likely that these changes had an impact on readings.
  • The data presented here only looks at the main school meter. The auditorium meter also accounts for a significant amount of power consumption at OSC. This has its own peaks and troughs depending on large events, numbers of assemblies etc.
  • The destination between the two sub-meters (kWa and kVa) of the main school meter needs separate analysis.

Conclusion & Epilogue

The electricity data from the OSC campus that the ES&S class has analyzed suggests that simple voluntary actions by individuals can have an impact on the overall electricity consumption of a medium sized institution like our school. Though there are several factors at play the effort of teachers and students to turn off ACs seems to have had a clear impact as seen in the decline in power consumed. This is significant as we look to take small, but meaningful steps to address our use of fossil fuels and the production of greenhouse gases. Though we didn’t look at the 2014 data, January suggests that we should not be complacent and that the “no AC before 9:00” rule needs to be further supported.

Article © Ian Lockwood with statistical verification courtesy of Britton Riehm and the OSC Math Department.

Further Links 

David, Anthony. “Country in for a shock”. Sunday Times. 4 September 2011. Print & Web.

David, Anthony. “Norochcholai adds to CEB’s losses.” Sunday Times. 4 March 2012. Web.

Fazlulhaq, Nadia and Harish Murali. “Out of the dark for the moment.” Sunday Times. 29 July 2012. Web

How your electricity bill is calculated. Web.

Sri Lanka Energy Forum. Web.

Sri Lanka Energy Profile. Web.

“Sri Lanka Energy Sector Overview.” South Asia Initiative for Energy Integration. ND. Web.

Written by recycling1011

2014-03-16 at 4:17 PM