12 May 2011

What are the main applications of Solar Ponds? Describe briefly.

1. Heating and Cooling of Buildings:

          Because of the large heat storage capability in the lower convection zone of the solar pond, it has ideal use for heating even at high latitude stations and for several cloudy days. Many scientists have attempted and sized the solar pond for a particular required heating load for house heating. Calculations have shown that a solar pond with a 100m diameter and 1m deep lower convection zone is sufficient to drive either an absorption system or chillier capable of meeting 100 percent of typical cooling load of a 50 house community in Forthworth (USA).

2. Production of Power:

          A solar pond can be used to generate electricity by driving a thermo-electric device or an organic Rankine cycle engine - a turbine powered by evaporating an organic fluid with great promise in those areas where there is sufficient insolation and terrain, and soil conditions allow for construction and operation of large area solar ponds necessary to generate meaningful quantities of electrical energy. Even low temperatures heat that is obtained from solar pond can be converted into electric power. The conversion efficiency is limited due to its low operating temperatures (70-100ºC). Because of low temperature, the Solar pond power plant (SPPP) requires organic fluid which have low boiling points such as halo-carbons (like Freons) or hydrocarbons (such as propane).

3. Industrial Process Heat:

          Industrial process heat is the thermal energy used directly in the preparation and of treatment of materials and goods manufactured by industry. Several scientists have determined the economics of solar pond for supply of process heat in industries. According to them the solar pond can play a significant role supplying the process heat to industries thereby saving oil, natural gas, electricity, and coal. From the calculations it was concluded that for crop drying and for a paper industry, for which economics have been determined, the heat from solar pond is highly competitive with oils and natural gas.

4. Desalination:

          The low cost thermal energy can used to desalt or otherwise purify water for drinking or irrigation.

          Multi-flash desalination units along with a solar pond is an attractive proposition for getting distilled water because the multi-flash desalination plant below 100ºC which can well be achieved by a solar pond. This system will be suitable at places where portable water is in short supply and brackish water is available. It has been estimated that about 4700 m3/day distilled water can be obtained from a pond of 0.31km2 area with a multi-effort distillation unit. The cost of distilled water appears to be high for industrialized countries but can be used in developing countries where there is a shortage of potable water. Moreover this type of desalination plant produces five times more distilled water than the conventional basin type solar still.

5. Heating animal housing and drying crops on farms:

          Low grade heat can be used in many ways on farms, which have enough land for solar ponds. Several small demonstration ponds in Ohio, Iowa and Illinois have been used to heat green houses and hogbarns.

6. Heat for biomass conversion:

          Site built solar could provide heat to convert biomass to alcohol or methane. While no solar ponds have been used for this purpose, it is an ideal coupling of two renewable-energy technologies.