# Dairy Waste and Potential of Small-Scale Biogas Digester for Rural Energy in India
## 6 Future Perspective for Biogas Technology in India  
Considering the livestock population in India and growing demand for milk production, technologies which help treating animal waste and converting animal waste into renewable energy have substantial scope for development and implementation, and biogas technology is one of them. One of the major advantages in using biogas technology fortreating animal waste is that it is relatively simple to develop, easily scalable, and produces a source of energy, and demand for energy in India is consistently increasing. Research showed that biogas potential in India ranges from 310-655 billion m\({}^{3}\) per year by 2040 [64]. Reports indicate that India may require more than 5000 compressed biogas plants (CPG) by 2023 [65]. Currently, the limited infrastructure of building large-scale biogas plants and compressing of biogas exist in India. The primary purpose of the planned CPG biogas plants is to increase the availability and affordability of renewable transport fuels and identify sustainable alternative energy source [65]. Approximately 600 million tons of biowaste is produced in India, which has the potential to increase compressed natural gas (CNG) production by 25 times and replace 50% of the total fuel imports [66]. In India, 3 different sizes of biogas plants are installed: (1) small size biogas plants; (2) medium size biogas plants; (3) large-scale (i.e., industrial size biogas plants. The current trend of dairy farms in India showed that dairy farm structure is evolving, and medium-size dairy (up to 50 cows) farm numbers are increasing, while smaller size (conventional) dairy farms with 1-5 milking animals are decreasing [67]. In many regions, the growth in medium-size dairy farms is about 30% per year [67,68]. Often when sizes of dairy farms increase, it requires improved manure management, and anaerobic digesters/biogas plants can play a crucial role in improving the manure management. The number of dairy farms in India is more than 75 million, which are more than any other countries in the world [69,70]. Based on a report by FAO, South Asia (including India) and European Union (EU)-25 are the largest dairy regions accounting for more than 44% global milk production [70,71]. The largest population of bovine in the world live in India, which accounts for 22% global milk production [70,71], and the production of animal waste in the dairy industry is unavoidable. A recent 19 th Livestock Census reported that livestock population in India is about 512 million, which potentially produces 1095 million metric tons (MT) manure per year [71,72]. When manure management in the livestock environment is poor, it negatively affects livestock health, milk production, and poses risk to public and animal health [73,74]. In many developing countries such as India, substantial improvement in manure management is needed to enhance livestock living conditions and reduce the negative impacts of manure in environment and mitigate the public and animal health risk, and anaerobic digester/biogas plant technology can assist in improving the manure management and reducing the adverse impacts of manure in environment [74,75]. To disseminate biogas technology for conversion of animal waste, food waste, and biomass/organic waste into biogas (a renewable energy source), the availability of technologies can be considered sufficient. A range of technologies for converting biogas into electricity and transportation fuels are currently available. Challenges, however, in the adaptation of biogas technology include the required investment, operational cost, and economic benefits of biogas production. The use of biogas as a transportation fuel is relatively new and yet to be adapted at a large scale, however, it is an attractive alternative [76] to improve the biogas market and consumptions, which can provide a better financial return compared to the use of biogas as a source of heat.