The management of organic waste can be a challenge in large countries such as India, where, with 1.3 billion inhabitants and 5,000 cities, 160,000 tons of municipal solid waste and over 60,000 million litres of liquid waste are generated per day, mainly in the form of sewage and wastewater. However, waste can also be considered a business opportunity if used for energy production through biogas technology. UNIDO (United Nations Industrial Development Organisation) is promoting the production of biogas in India. How? We asked NP Singh, Senior Technical Advisor of the UNIDO India Sustainability Cities Programme.