Sustainable Energy Mix

Renewables can help dairies offset rising costs

India has around 75 million dairy farms, more than anywhere else in the world. These dairies have capacities ranging from 1,000 litres per day (LPD) to 2 million LPD, in both the cooperative and private sectors. They are engaged in the processing of milk and the production of downstream products. The dairy network has around 165,000 village-level dairy cooperatives, 218 district/regional/ taluka unions and 24 state dairy federations/apex milk unions. Around 15 million milk producers are affiliated to this network, which has a total of 72 million LPD (MLPD) of processing capacity, 18 MLPD of chilling capacity and 38 MLPD of village-level bulk milk cooling capacity.

Due to fluctuations in the availability and collection of milk, as well as fierce competition from dairy products from other states, particularly Gujarat and Uttar Pradesh (the largest milk producing state in India with around 17 per cent share in the total milk production), the dairies in states such as Rajasthan, Madhya Pradesh, Andhra Pradesh, Maharashtra, Tamil Nadu and Bihar need to cut costs to remain competitive.

Dairies are major energy consumers and normally purchase grid electricity. They also generate the required process steam by purchasing and firing coal or biomass. Their annual energy bills account for 20-30 per cent of the value addition at their plants. Therefore, the potential for saving steam and minimising power consumption at these dairy plants is quite high. Under these circumstances, the dairies have no other option but to reduce their energy consumption as well as the cost of operation.

It is also essential for them to optimise their energy mix by implementing other renewable energy projects such as captive/grid-connected cogeneration power plants, biogas/bio-CNG generation plants using dairy waste, as well as rooftop and ground-mounted solar power plants by utilising the available space on their premises. This will help them increase their revenues and overcome the current financial stress.

While some of the progressive dairies have taken a series of measures for reducing their energy costs, a few have implemented captive cogeneration and solar power projects. However, these efforts need to be undertaken on a larger scale. For example, in 2016, Kaira District Cooperative Milk Producers Union Limited became a pioneer in the Indian food sector by starting a fully automated bio-CNG generating and bottling plant using the waste generated at the dairy, as part of its green initiatives. Popularly known as Amul Dairy, the cooperative invested Rs 17.5 million to implement this biogas purification/compression technology.

Before introducing the new technology, Amul Dairy used to burn the biogas, producing harmful carbon dioxide and hydrogen sulphide. Also, on an average, one litre of water is used for chemical cleaning of the plant and machinery for every litre of milk processed. This water contains residual milk solids and emits 2,500 cubic metres of methane daily with 60-65 per cent purity. But ever since the bio-CNG generation plant became functional, the methane content in the purified gas has gone up to 93 per cent, which makes it as good as CNG. Therefore, it can be used as transport fuel.

Following suit, Surat District Co-operative Milk Producers’ Union Limited (SUMUL) set up a “dung bank” in the district for collecting all the animal dung at one place. It is using this dung for producing biogas and distributing it at uniform pressure through pipelines to around 121 beneficiaries in the city. The dung slurry remaining after this process is used for composting. The central and state governments have rewarded these efforts. SUMUL is extending this programme to other districts as well. Through this initiative, an additional income of Rs 1.5 million will be available to members annually, leading to clean villages and improved environment.

Earlier, milk producers used the cow dung as fertiliser rather than as fuel. But now, time is saved as the food cooks faster with biogas than dung, costly gas cylinders can be avoided, and methane gas is not emitted directly into the atmosphere but collected in tanks and used in the kitchen as biofuel. SUMUL has activated about 700 family-size biogas plants in the past seven years, with about 320 being set up during the past year alone. In addition to government assistance, the union has set aside Rs 1,000 to encourage every milk producer to support this activity in his/her village.

Policy initiatives

The central government is considering a unique solar plan for the dairy sector, according to Dilip Rath, chairman, National Dairy Development Board (NDDB). He mentioned this during a recent workshop on Solar Energy for Dairy Farmers. According to him, the NDDB has already started deploying concentrating solar thermal (CST) technology in dairy processing plants to partly reduce the reliance on thermal energy. “CST can improve the annual heat demand of a processing plant from 5 per cent to 15 per cent. With the help of capital subsidy from the Ministry of New and Renewable Energy (MNRE) and the United Nations Development Programme, the NDDB has completed over 15 CST installations at the processing plants of dairy cooperatives across the four states of Maharashtra, Punjab, Gujarat and Karnataka. The total installed collector area at these locations is over 8,000 square metres of aperture area,” he said.

With the successful experimentation of installing grid-connected solar photovoltaic (PV) systems with storage (if required) at the village level, dairy cooperatives/milk collection centres, the NDDB has started the propagation of solar energy-run village cooperatives across the country. Prime Minister Narendra Modi had personally inaugurated the NDDB-promoted Saur Urja Utpadak Sahakari Mandali Limited at Mujkuva village near Anand in Gujarat on September 30, 2018. Some 11 farmers have surrendered their access to the state-subsidised electricity, and have opted for solar energy. They are also supplying surplus electricity to the grid.

State initiatives

There are over 260 dairies in Maharashtra, where the Maharashtra Energy Development Agency (MEDA) has an ongoing energy conservation programme. In order to comprehensively sensitise the dairies in the state about the above opportunities, MITCON Consultancy & Engineering Services Limited (MITCON) and MEDA organised a business meet on “Energy Cost Reduction and Mix Optimisation in Dairies”, in Pune in January 2020. The event was supported by various technology/equipment providers in the sector. As per S.C. Natu, senior vice-president, MITCON, the outcomes from this business meet included the evolution of a supportive policy and regulatory framework, required financial models and technical support, and an action plan for the dairies to improve their energy efficiency and optimise their energy mix for higher revenues.

Multiplication effect

These initiatives are snowballing. Jaipur Zila Dugdh Utpadak Sahakari Sangh Limited has opened a tender for the supply and commissioning of a 1.5 MW roof-mounted captive solar plant. As per the tender document, successful bidders will have to maintain the rooftop solar plant for a period of 15 years, beyond the one-year warranty period. The estimated value of the contract is Rs 50 million.

In September 2019, Rajasthan Cooperative Dairy Federation Limited, in Hanumangarh, Rajasthan, issued a renewable energy service company (RESCO)  tender for a 600 kW solar power plant.

Raichur, Bellary & Koppal Districts Cooperative Milk Union Limited, through the NDDB, has implemented a compound parabolic concentrator (CPC)-based CST project for crate washing and cleaning in-place (CIP) sections, and for the pasteurisation process. The project provides hot water at 95° C as boiler feed. The roof-mounted solar thermal solution was designed with high efficiency CPC with a collector area of 354 m2. The project was completed at a total cost of around Rs 3.99 million and with MNRE support of Rs 1,197,984.

The system comprises a primary circuit with an array of CPC modules, a secondary circuit with storage tanks to store the heat, and a process integration circuit. The heat transfer liquid (water treated by reverse osmosis) circulating in the closed-loop primary circuit is heated in the CPC modules, and then exchanges its heat with softened water in the secondary circuit. This hot water in the secondary circuit is stored in stainless steel tanks. When the temperature of the water in the tanks exceeds a threshold value, process pumps transfer the hot water to the applications. The entire system is designed for reliable and automated operation including start-up and shutdown. In addition, a remote monitoring solution permits instantaneous, daily and monthly performance to be viewed at a glance. On an average, the systems deliver pressurised hot water at the rate of 900,000 kCal per day, saving approximately 113 kg of furnace oil per day. This is equivalent to a saving of about Rs 3,400 per day.

Conclusion

Being energy-intensive plants, dairies will soon join the category of designated consumers under the forthcoming Perform-Achieve Trade cycles of the Bureau of Energy Efficiency (BEE), Ministry of Power. This will mandate the dairies to undertake energy audits and achieve the targets to be set by the BEE, on the basis of baseline studies.

Dairies are already realising the importance of the right energy mix and have gone ahead with implementation. As per IIT Delhi, the current potential of producing biogas from dairy waste is 80.1 million cubic metres per year and for compressed biogas, it is 36.05 million kg per year. Given this huge potential, a uniform policy framework with suitable grant support can help improve the energy mix of the entire village-level dairy operations in India, thereby reducing energy costs. These decentralised energy options would also take a huge load off the national grid.

By Anita Khuller

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