Figure 1. Biogas Plant in Asy-Syafa’at Ranch (top), Biogas and Bioslurry System (down).
As one of the pioneer NGOs which introduces Biogas application in Indonesia, Yayasan Rumah Energi, collaborated with PYC to improve the development of Biogas as a cooking fuel. There are about sixteen million potential biogas users in Indonesia, but as the first step, biogas was targeted to be installed in one million users. However, in the nine years of development, the expansion was considered slow with only 23,000 biogas unit in ten provinces were able to be installed. One of the problems is the high installation cost which required about 10 to 15 million rupiahs, which its cost depends on (1) the storage capacity and (2) the material price to build a biogas plant. The least possible capacity of the biogas is around 2m3 which needs about two cows or 300 chickens to fill the waste storage every day. This smallest capacity produces approximately 0.7 m3 biogas or about 1-1.5 hours of cooking in one stove. With biogas could fill around 1/3 of the maximum storage capacity, then the bigger the storage capacity, the more biogas will produce.
On December 12, 2018, PYC research team accompanied by Yayasan Rumah Energi team visited Asy-Syafa’at Ranch in Sawangan, Depok which has applied biogas for their daily activities. The biogas was granted by the local government in 2004, and the ranch has used it as the cooking fuel. Since the ranch could accommodate approximately 60 cows, the government built around 12m3 biogas capacity. It takes about two tons of cow’s waste to fill the biogas storage for the first attempt; then it should be added with 75 kg of cow’s waste daily. It is essential to keep at least ten cows in the ranch to fill the biogas storage so the storage would stay in the maximum capacity. The lack of waste supply will dry the storage and damage the whole biogas system. One time the storage was not filled for about two weeks causing the biogas to run out, so the owner had to repeat the installation process from the storage draining and filled the empty storage with two tons of cow’s waste. Another vital aspect to be concerned is the ratio between the water and the waste; it is necessary to understand the right ratio because the lack of water would lead the cow’s waste to solidify and too hard to be processed.
Cooking with biogas requires a specific stove due to the different gas pressure of LPG. A few years ago, the biogas stove price was almost four times higher than the regular one since the manufacturer was located in East Java and only produce limited quantity. However, today, the innovation was made by modifying the regular stove so that it could be used as the biogas stove. The biogas is distributed in a PVC pipeline to the stove location which could safely reach up to 200 meters for one stove usage. Another method is to use the storage balloon or tire inner tube to keep the biogas inside so that it could be easily stored or carried around.
Another biogas processing advantage is the utilization of the biogas process residue known as bioslurry. The waste in the biogas storage would produce methane (CH4) gas and sludge through the anaerobic digestion. The methane gas or the biogas is then distributed along the pipeline as the cooking fuel while the sludge which called bioslurry could be used as the fertilizer. The bioslurry contains nutrients which benefit the plants and are proven to affect the plant growth better than the unprocessed animal waste fertilizer. Since Asy-Syafa’at Ranch located in the urban area, most of the fertilizers were sold to the decorative plant sellers rather than to farmers. Still, the bioslurry gives more added value to the animal waste.
The ranch workers admitted that they doubt and worried about producing the biogas at first, but the constant learning and experience made them realized that the biogas had brought great benefit to the ranch. They no longer care about the LPG price and availability, since biogas could substitute LPG as the cooking fuel. Also, the bioslurry sale could make additional revenue. Although the biogas in this ranch was provided by the government, the owner actually planned to build one himself before the government offered the grant. The workers argued that even though the owner built the biogas himself without the government support, the initial cost required to build the biogas is worth with all the benefits and they recommended every ranch to build one.