Winter Ice Manufacture by Snowmaking:
A Novel Approach for Massive Ice Production
for a Variety of Industrial Applications

Moshe Alamaro
Harvard-MIT Division of Health Sciences & Technology
Massachusetts Institute of Technology

Summary: I propose that the same snowmaking that is used in ski resorts be used in the winter to manufacture ice, and that the ice be preserved for the summer to alleviate water shortages in New England and elsewhere. Massive ice piles that are produced in the vicinity of water reservoirs or lakes will be allowed to melt gradually in the spring and summer, making better economic use of scarce land. Large amounts of ice can also be used in the summer for providing chilled water for air-conditioning of commercial buildings and for the operation of new year-round ski resorts.

This concept is based on radical revision of existing snowmaking technologies, which have evolved through trial and error over the past 50 years. In all that time, no one has performed a comprehensive analysis to describe or optimize the snowmaking process. According to the theory behind the proposed new concept, which is based on three-phase fluid, and heat and mass transfer analyses, the accumulation and production rates of artificial snow or ice are proportional to the height from which water is sprayed. To achieve a high rate of ice accumulation, water should be sprayed from tall towers with a height of 200-300 feet. (Such towers may be constructed by bungee-jump recreational contractors, for example.)

Artistic rendering of the winter ice manufacture concept

Click on the image to see a larger version

The concept of winter ice manufacture (WIM) has been developed to:

• Address summer water shortages for communities in New England, the Great Plains and elsewhere.
• Provide an inexpensive alternative to reverse osmosis for desalination.
• Provide chilled water for assisting large air conditioning systems of commercial buildings.
• Create large ice and snow piles for commercial recreational activities such as summer ski resorts (as in Australia and Japan) and ice parks.

The concept calls for large masses of ice to be manufactured in the winter, close to existing water reservoirs, thereby increasing their effective capacity. During subfreezing atmospheric conditions, water will be sprayed into the air to produce ice, in a process similar to snowmaking. The pile of ice will be gradually melted during the spring and summer, providing a continuous supply of fresh water.

Current snowmaking technology uses machines to spray water into cold, dry air. Heat transfer and evaporation cool the water drops, as they fall. The existing process requires water to be atomized using high-pressure air and sprayed from a height of a few feet. This requires a high flow rate of high-pressure air both for fine atomization and initial spray cooling. In the proposed snowmaking process, however, the water is sprayed from a height of 200-300 feet, leading to an increase of about two orders of magnitude of the ice production rate compared to conventional snowmaking. The new method also eliminates the need for the compressed air.

Conventional snowmaking requires enormous amounts of energy for air compression used for water atomization. In the proposed process, spraying the water from high altitudes increases the free fall time of the drop. This enables increasing the water drop mass by two orders of magnitude compared to the mass of the drops in conventional snowmaking. Therefore, the new process allows spraying the water through inexpensive hydraulic nozzles, instead of using atomizers and energy-intensive compressed air.

Economic Development and Commercial potential: The entire system can be made either static or site–specific; alternatively mobile or portable systems can be constructed, requiring neither dedicated on-site equipment nor permanent construction. A company that owns the equipment can dispatch mobile systems to various municipalities under short-term contracts. Water authorities would pay a day rate or a fee based on the amount of ice produced. The mobile system approach increases the utilization rate of capital equipment, especially the high-head water pumps. Equipment could be relocated during the winter to areas with favorable weather conditions and the need for water or ice storage.

Inland locations such as in Minnesota would be an ideal location for pilot development and testing, due to favorable winter weather conditions. Also, hardware and facilities at existing ski areas might be accessed to minimize initial demonstration program costs. Target markets for operation will include Northern US states such as New England, Midwest and other areas where the system will be used for alleviating water storage, the creation of new year-round ski resorts and for cooling for a variety of industrial applications. Large scale farming in the Great Plains is a second market with potential longer-term impact. Small systems may also be used in gulf courses to store water from winter to summer. Draw down of the water table for irrigation is a continuing problem, and ice storage using winter precipitation may supplement the current pumped supply.

Engineering: This technology can be implemented using available and established hardware technologies. Performance and cost can be improved by addressing refinements in droplet freezing mechanisms. These refinements include new nucleation techniques to enhance and initiate the freezing process of super cooled water drops. Potential techniques for the production of ice crystals may include electro-freezing and/or the expansion of a dedicated small amount of compressed humid air.

The engineering development and refinement program will include the development of new insulation methods to prevent premature melt of the ice. It will also include new spraying techniques and the development of new control software to address successful operation during the ever-changing winter weather conditions. New de-icing and fog prevention techniques will also be developed.

Development Plan, Timetable and Budget: A demonstration development for eight months is planned for next winter. We seek now $600,000 for project initiation to start with the demonstration development. The demonstration will concentrate on two key technological milestone issues. The first is the dependency of the mass production rate of ice on the height from which water is sprayed. This demonstration can be accomplished using cranes to elevate the spraying nozzles as high as possible. The spraying can use simple inexpensive hydraulic nozzles instead of expensive atomizers since this concept allows for spraying relatively large water drops.

The second key issue for the initial phase of development is the production of ice crystals, which are required for the nucleation of supercooled water drops. This will be accomplished initially by expanding cold humid air through a variety of nozzle configurations (including existing snowgun hardware technologies). This development maybe done outdoors and/or in a climate room. The development will use borrowed equipment from ski resorts that expressed their willingness to collaborate and provide in-kind support.

The second phase of development will require both in-kind and cash investment. The in-kind will include contributions from partner companies, municipalities, suppliers and government agencies. The required cash investment for the second phase is estimated as $0.6- $1.0 million, depending on the level of in-kind contribution. In the second phase that will take 12 months, all other issues for development are in the category of system integration that do not pose technological risk. They include the development of an insulation quilt to prevent premature melting of ice, the prevention of icing on the spraying tower, the integration of weather data with operational control and the development of energy and recreational applications for the ice. Total development time for this program is estimated as 24 months. The total required cash and in-kind investment is estimated as $1.5-2.0 million

The program goal after 18-24 months is to transfer and franchise the commercial use of the technology to one or several companies with the technology becoming self-sustaining at that point.

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