Suranti served fried sweet potatoes when welcoming the arrival of the media crew at her house last July. Fried sweet potatoes as usual, the difference is, the cooking energy uses a two-burner gas stove with a fire source from cow dung. This renewable energy was created thanks to the persistence of her husband, Sudarman, in the past year.
About 100 meters behind the house of this husband and wife in Mukti Sari Village, Tapung District, Kampar Regency, Riau, there is a stable with nine cows—two belonging to the Bhina Mukti Sari Group led by Sudarman. Next to it, installed several installations and connected to each other..
He was originally a palm oil farmer. When he had the opportunity to attend an agricultural school sponsored by the Kampar government, he chose to focus on studying cattle husbandry.
After school, he immediately bought two cows. Gradually, the children became 17.
Every day—if he’s not tired after his main job as a farmer—Sudarman, takes 70-80 kilograms of cow dung from the pen and puts it into the inlet . It is a kind of container for mixing cow manure with a rotating iron rod in the middle. Cow dung mixed with water at a rate of one to one. If 80 kilograms of cow dung, you need 80 liters of water.
Mixing time is about five minutes. The softer the dirt forms, the better the fermentation process. If there are still a lot of lumps, the methane gas produced will be slightly reduced.
After the cow dung has turned into mush, then it flows through the small hole below the inlet to the biodigester . This, two meters deep well with a circumference of about three meters. Can accommodate eight cubic cow dung. In the soil chamber decomposition without air takes place, seven to 15 days, to produce methane gas.
Irpan, Supervisor of the Rumah Energi Foundation (YRE), said that weather conditions play a significant role and determine the time span for the fermentation of cow dung to produce biogas.
If the temperature is too cold, the process can take longer than the average temperature above 23 degrees. In fact, during the rainy season it can last up to a month. One example, their experience in Pengalengan, Bandung, West Java, with temperatures below 18 degrees.
Based on the results so far, a supply of 80 kilograms of cow dung mixed with 80 liters of water can produce zero point a certain amount of methane gas. Or, eight cubic feet of fermented cow dung in a biodigester can produce 2.4 cubic meters of methane gas.
The inlet and biodigester are about one meter apart, connected by a four-inch pipe in a 60 degree slope. On top of the biodigester a small dome is built to control the flow of gas which is equipped with an opening and closing tap and main pipe.
It is from here that the methane gas is supplied to the Suramti stove, using a half inch piping installation which is also embedded more than 15 centimeters in the ground.
Even though the gas pipe faucet is closed, there is no need to worry. Because there is a gas exhaust channel as a safety point in the form of a small 60 centimeter box.
According to Irpan, the habit of opening and closing gas pipe faucets is one way to anticipate installation maintenance so that it lasts longer. If the tap is opened, the gas pressure in the installation automatically tightens, if it is closed the pressure decreases.
“It’s better if the tap is closed when finished cooking. The average community continues to open. Because at home there is a manometer to control gas conditions,” said Irpan who assisted the construction and maintenance of the biogas reactor in Mukti Sari.
He did not recommend methane gas from fermented cow manure be filled into canisters, such as LPG packages produced by the government. Because methane gas very quickly causes porous metal and is worried that at high pressure it will leak and explode.
Cooking, lighting and fertilizer
Every day, without a shortage of gas supply, Suramti can meet household needs. He can also save and reduce monthly expenses. If the price of 3 kilograms of LPG is IDR 25,000 per cylinder, you can save IDR 75,000 per month.
“I usually buy melon gas (3 kilograms of LPG), so I don’t buy it. In fact, gas cylinders were lent to neighbors. Used to be economical to cook, now I don’t. There is no difference in the quality of biogas with LPG. The fires are just as beautiful. Blue. In fact, the power of biogas is not too high. Cooking is endless. What is important there (the reactor) is filled, “said Suramti.
In fact, he said, he sometimes doesn’t even use one LPG cylinder. “Only for backup and in case there is damage to the biogas installation,” continued Sudarman.
On the wall near Suramti’s cooking stove, on a daily basis, two controls are installed. First , water drain, to accommodate dew water flowing in the biogas installation. Installation at the lowest point between the main gas pipe and the stove.
Second , a manometer , in the form of a clear hose filled with colored water, as an indicator of whether or not there is gas pressure in the pipeline and biodigester installation . Also to detect leaks.
The size of the biodigester , which can accommodate eight cubic feet of processed cow dung, can actually supply the needs of two households. It’s just that, at this time, Sudarman and Suramti are still fleeing to their own homes, aka not to their neighbors. He said, there are still people who do not believe.
On Sudarman’s kitchen wall, two biogas pipelines are also attached . Apart from being connected to the stove, one more pipe is used to distribute gas to the petromax lamp that hangs on the terrace of the house. This lamp is a mainstay when there is a power outage in Mukti Sari Village.
When the residents’ houses are dark, Sudarman’s residence remains bright.
Sudarman, haven’t fully used the petromax lamp from biogas. He just took advantage of the emergency situation. According to Irpan, trials in one place, for one month, using petromax biogas from dusk to dawn, managed to save 15% of electricity usage costs. In fact, even though they still use the stove for cooking, every day, there is never a shortage of biogas supply. With a routine record of filling cow dung in the inlet .
Feces do not only become biogas. Dregs of cow feces for liquid fertilizer. This is a derivative from the fermentation of manure in a biodigester where methane levels have been reduced.
The processing of cow manure into fertilizer is still an integral part of the process of fermenting feces into biogas, using one installation. The methane gas that has accumulated in the biodigester will automatically push the cow dung—especially if the gas pipe is closed—out and channel it to the outlet , the cow dung dregs holding tank. At the end of the outlet there is a hole or overflow to the slurry pit . This is the final part of the cow manure processing plant which collects the dregs to be used as fertilizer.
The liquid fertilizer produced by processed cow dung belonging to Sudarman has practically become ‘nutrition’ for the plants of Mukti Sari residents as well as a new economic source.
He sells liquid fertilizer for IDR 1,000 for a five liter jerry can. The buyer gets the fertilizer from the slurry pit . This organic fertilizer has been used in oil palm, vegetables, chilies and papayas.
“Get additional income from the sale of fertilizers. A month can be 1,000 liters. Just buy rice. This year, I also never bought chemical fertilizers. It’s quite a money saver.” Money can also be allocated for children’s college fees and buying vehicle oil to find grass for cows.
Sudarman hopes that the people in his village will turn to this energy. He still convinces his neighbors that cow dung is not always dirty. Currently, only members of the Bhina Mukti Sari Group, especially those who raise cattle, have biogas installations to supply energy in their respective homes.
Energy is independent
Sudarman’s energy independence is part of Pertamina Hulu Rokan’s (PHR) social and environmental responsibility program. PHR has built eight biogas reactors in Mukti Sari to become an Independent Energy Village.
“Previously this village had intervened for the local group’s cattle cultivation program. Based on internal studies, indeed there must be a supply of biogas reactors that can be donated on an ongoing basis,” said Delly Paramita, Senior Analyst CSR PHR, some time ago.
The results of PHR calculations in collaboration with the Rumah Energi Foundation (YRE), meanwhile, at least of the eight biogas reactors installed, are able to manage 20 tons of CO2 equivalent to methane gas for the beneficiaries’ daily cooking needs.
Mukti Sari, adjacent to the main PHR facilities. You could say ring one Pertamina’s operations. Therefore, at the end of this year, PHR will add another 12 biogas reactors, as Pertamina Group’s flagship program to encourage energy independence in their operating areas.
Waryono, Head of Mukti Sari Village, supports this biogas development program.