The economic impact of the dairy industry is significant in almost every region of the United States. In several states, the dairy industry is actually the main economic driver. There are approximately 9.4 million dairy cows in America, collectively producing about 217 billion pounds of milk per year. This total represents 23,000 pounds of milk per cow each year. With growth forecasted for the year ahead, the industry is on solid footing for investing in production while reducing production costs.
Fluid milk processing is energy-intensive all along the production line and supply chain. Worldwide, the dairy industry has set an overarching goal of reducing greenhouse gas (GHG) emissions and the other environmental impacts associated with milk processing. Although the major GHG emissions associated with milk production occur on the farm, most energy usage related to milk processing occurs at the milk processing plant and afterward, during refrigerated storage (a key requirement for the transportation, retail, and consumption of most milk products).
Sustainable alternatives and designs for the dairy processing plants of the future are now being actively explored by the global dairy industry as it seeks to improve efficiency, reduce costs, and comply with corporate social and environmental responsibilities.
The U.S. dairy processing industry consumes around $1.5 billion of purchased fuels and electricity per year. Energy-efficiency improvements are an ideal way for plants to reduce these costs, lower emissions of energy-related pollutants, and reduce susceptibility to volatile energy prices.
Solar Thermal Solutions for the Dairy Industry
Integrating a high-temperature solar thermal solution can provide energy-efficiency opportunities for steam systems, refrigeration systems, accelerated anaerobic digesters, and key unit operations in the production of processed dairy products. Together, these end uses account for the majority of thermal and electrical energy used in the U.S. dairy processing industry.
By employing drop-on-site, “plug-and-play” hybrid solar/gas absorption chillers, advanced solar thermal technologies take an innovative approach to reducing the temperature of milk from the parlor at 101 °F to 36 °F for shipping to processors. Utilizing solar energy, biogas from farm digesters, and/or natural gas as the backup, these systems allow for significant savings in electricity costs for refrigeration, and can replace the existing electric vapor compressor systems widely used today.
Hybrid solar/gas chillers employ a high-efficiency, solar-driven double-effect absorption chiller, integrating high-temperature, nontracking concentrating collector technology and a supplemental heater using digester biogas or natural gas to deliver high-efficiency, on-demand refrigeration/cooling and heating on a 24/7 basis.
This advanced-technology, hybrid solar/gas dairy milking parlor cooling/refrigeration product is market-ready and available in the United States. The advanced solar thermal technology of today achieves temperatures in excess of 230 °C at 45% efficiency, even under diffused or hazy conditions. Today, a 6.6-ton double-effect chiller is being tested at the University of California Solar Lab.
Solar cooling is well understood, and there are many solar absorption HVAC systems in use both domestically and abroad. When advanced solar thermal technology is packaged with a 30-to-50-ton double-effect chiller, the improved technology reduces lifecycle cooling costs. Statistics show a three-to-five-year payback in many applications, and even less if the system is run with farm-generated biogas after sunset or through the night.
As referenced above, the “plug-and-play” solar heating and cooling solutions for dairies will provide significant energy and production cost savings. Plus, additional savings can be achieved by capturing the heat on the condenser side of the chiller for water heating used for sanitation. Combining the savings of the chiller and hot water generation can have a great impact on overall dairy energy costs.
Looking Ahead
The value of the milking parlor chiller cannot be overstated. It’s important to understand that the hybrid solar chiller is installed between the precooler and the existing electric vapor compressor chillers; this means that there is redundancy, and the existing chillers can be used as a backup to the solar chiller.
Most of today’s suppliers have complete confidence in the ability of the solar hybrid chiller to carry the full load. However, any new technology must be always thoroughly tested and analyzed until long-term performance data is available to the consumer.
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