Dairy Industry Exemplary to Exploit Solar Process Heat

At 176.4 million tonnes annually, India is the global milk and milk products producer. There are over 1,200 large, medium & small dairy industries. The dairy industry is dominated by the co-operative sector with 60% of the installed processing capacity in this sector. Milk processing in India constitutes around 35% of total milk production, of which the organised dairy industry accounts for 13% of the milk produced while the rest of the milk is either consumed at farm level or sold as fresh.

Energy plays a major role in processing milk and milk products. In a dairy, primary energy sources such as furnace oil, etc. are used in boiler for generating steam which in turn is used for heating applications like pasteurization, evaporation, drying of milk. Nearly 30% of overall manufacturing cost is spent on purchase of furnace oil, electricity, which is substantial. Typical dairy plants derive about 70% of their energy requirements in the form of thermal energy and the remaining 30% is consumed in the form electricity.

As a part of the Indo-German cooperation project “Solar Payback” for accelerating Solar Heat for Industrial Process (SHIP) the study undertaken by Solar Thermal Federation of India has identified Dairy processing as topmost potential sector as shown in Fig. 1.

Identified potential industries for industrial process heat

Figure 1 : Identified potential industries for industrial process heat

Thermal Energy Consumption Break Down

The total amount of heat energy generated by boiler is divided into various processes as per requirement. The process wise thermal energy consumption is represented in Fig. 2 below. Maximum amount of thermal energy generated is consumed for chilling and cold storage. Followed to this sterilization and spray drying consumes equal amount of energy. Chemical processes carried out at dairy requires smallest amount of energy of total energy generated. Solar thermal systems can enormously contribute to driving the various thermal processes in the dairy industry which demand water at temperatures <120 °C.

Process wise heat demand and share of energy consumption in the dairy industry

Figure 2: Process wise heat demand and share of energy consumption in the dairy industry

Table 1 shows the mapping of various diary processes with different solar technologies.

ProcessEnergy/Fuel being usedApplication mediaTemperature required OC
Washing and
furnace oil, gas
and agriculture
Hot water40-60
Electricity, gas
and diesel
< 5
PasteurisationFuels like
furnace oil,
coal, gas and
70 – 80
Ultra-PasteurisationFuels like
furnace oil,
coal, gas and
125 – 140
Fuels like
furnace oil,
coal, gas and
100 – 120
Spray dryingFuels like
and gas
Hot air100 – 140
Fuels like
furnace oil,
coal and gas
Hot air70 -110

Table1: Solar technology mapping in the dairy sector

There is however no latest study available on the estimated replacement potential of fuel oil/biomass using solar thermal energy. PricewaterhouseCoopers had undertaken an analysis on the percentage wise use of fuels in a typical dairy processing unit using Annual Survey of Industries database as shown in Figure 3.

Percentage-wise fuel consumption in a typical dairy processing industry

Figure 3: Percentage-wise fuel consumption in a typical dairy processing industry (Source: PwC analysis, based on ASI database 2007–08)

Figure 3 indicates that electricity drives most of the processes in the industry, followed by petroleum products and other fuels such as rice husk, firewood, etc.

The assumption is crucial for a conservative and pragmatic estimate of the energy replacement potential considering the Direct Normal Irradiance (DNI) available in different parts of the country. Fig. 4 below is the map of DNI over India.

National Dairy Development Board (NDDB), a national Institution to support policies for growth of farmers has already implemented 15 pilot SHIP projects in the country and are showing promising results. There have also been several learnings on the grey areas. Dilip Rath, Chairman NDDB said “solar thermal is idyllically win-win for a typical dairy processing in India. Mandatory heat demand supported with higher subsidies for renewable energy technologies will positively attract dairies. Close to 9GW of demand exists for chilling in all dairies in India where solar thermal can be useful.”

India is blessed with reasonable Direct Normal Irradiance, which makes ideal platform to explore solar heating optimally in the dairy processing industries. The ball can be set rolling to establish SHIP as the emerging renewable energy technology. In a volatile fuel oil pricing scenario investing in sustainable energy technologies assumes significance to improve cash flows and lowering overall production costs.

The project Solar Payback suggests a six-point action plan to further the development of SHIP in dairy processing

  • Formulate a committee involving NDDB, MNRE and STFI that will draft a policy paper specific to dairies to accelerate SHIP in dairies. Capital subsidy to be the driver but linked to performance.
DNI Map of India

Fig. 4.: DNI Map of India, source : Solargis s.r.o. https://solargis.info/

  • Mandate a certain percentage of solar heat energy generation hence create market demand.
  • Explore Viability Gap Funding to bring down the payback to three years to make it financially viable.
  • Analyse the Energy Service Company (ESCO) concept that will become less burden for dairies to invest up-front.
  • Investigate the multilateral agencies that can fund under Climate Change programmes for solar energy project development mitigating greenhouse gases
  • Undertake awareness workshops in locations with high concentration of dairies and at reasonably good DNI locations thus share the benefits of using SHIP.
Jaideep N. Malaviya
Secretary General & Chief Project Executor – Solar Payback, India
Jaideep N. Malaviya