# Dairy Waste and Potential of Small-Scale Biogas Digester for Rural Energy in India
###### Abstract  
In order to reduce emissions of greenhouse gases, related global warming and dependency on fossil fuels, it is crucial to promote the uses of renewable energy, and conversion of biomass and organic waste into energy sources. In many parts of the world, a substantial increase in efforts for the conversion of waste into energy is currently being observed. Specifically, biogas technology has been emphasized for the conversion of animal waste into biomethane/biogas because livestock waste is considered to be a substantial source of ambient greenhouse gases, causing climate change. While biogas technology, an aerobic process to convert livestock waste into biogas, is promoted in both developed and developing countries, this review article is focused on improving our existing understanding of small-scale biogas technology and relevance of this technology in rural environment of India. A thorough review research has been performed to gather the information on livestock population, manure production, and potential of biogas technology in India to provide a wholistic information. A summary of the financial supports facilitated by various agencies, the cost of biogas plants, potential uses, and potential challenges in the dissemination of biogas technology in India has been discussed in this study. We anticipate that the data and interpretation provided here will help in understanding the scope of biogas technology in India and will help in formulating the policies which will support the implementation of biogas technologies in developing countries. biogas technology; rural environment; renewable energy; livestock; greenhouse gases +
Footnote †: Dairy Waste and Potential of Small-Scale Biogas**  
Footnote †: Dairy Waste and Potential of Small-Scale Biogas Digester for Rural Energy in India**
2011 Census Report of Government of India, currently 800 million people live in around 600,000 villages [4]. According to a World Bank Report, more than 40% India's workforce is engaged in Agriculture [5]. The average Indian household consisted of 5.4 people in rural areas and 5.2 people in urban areas [6]. India had 192 million households in 2001 [6]. A United Nations report described that economic growth over past several decades in India led to significant declines in poverty, and also resulted in increased economic inequality [7]. For the top 5 most populous countries, Gross Domestic Product (GDP)/capita in 2020 was 10,500 USD, 1900 USD, 63,543 USD, 3869 USD, and 6796 USD for China, India, USA, Indonesia, and Brazil, respectively [8]. Dairy is the top-ranking commodity in India, and based on Food and Agriculture Organization (FAO) report, India has transformed from a country with shortage of milk to a leading milk producer [9]. An Economic Survey Report estimated that approximately 198.4 million tonnes of milk were produced in India in 2019-2020 [10]. FAO reported that per capita milk availability in India was 130 g/day in 1950-51, which increased to 374 g/day in 2017-18 [11]. Dairy animals are a regular source of income and cash in India and women often play a crucial role in milk production in rural areas [12]. In general, milk is produced by smallholders in India, and milk production is crucial for household livelihoods, food security, and nutrition. According to FAO, India is the world's largest milk producer, with 22% of global production followed by the United States of America and China [9]. While New Zealand and United States of America are the highest milk surplus countries, FAO outlined that China, Italy, the Russian-Federation, Mexico, Indonesia are the countries with the highest milk deficit [9]. While milk production is crucial for the economy and food security in developing countries as well in developed countries, it also produces livestock waste such as manure. Livestock affects environment, and for sustainable development in agriculture, it is crucial to understand the linkages between livestock industry and environment, and adopt best practices to reduce livestock's environmental impact [13].