Solar Energy

A possible substitute for oil

Solar Energy may profitably be utilized for the production of Oxygen and Hydrogen by electrolysis of water

All countries throughout the world receive solar radiations in variable amounts. In south east Asia, especially in Pakistan, plenty of sunshine is available around the year. This energy is presently not being utilized, as it should be.

It is the earnest duty of our scientific community to sit together and evolve a strategy for economic utilization of this energy, particularly in our socio-economic scenario. The traditional methods of solar energy utilization, most commonly practiced elsewhere such as electrical energy generation through photovoltaic conversion, may not be appropriate in our local environment.

The only economically feasible and practice ways for utilization of solar energy abundantly available are as under:

1-Distillation of saline water for special uses, such as in drinking water in remote areas, pharmaceutics, boilers, medicinal herbs growth etc.

2-Cooling of buildings to replace / supplement the existing cooling systems.

3-Generation of oxygen in hospitals for life saving and hydrogen as a fuel through water electrolysis.

These subjects are dealt in detail in the following sections:

1-The use of saline / brackish water with high TDS is injurious for health, specially for the young and infants. This water is often, locally termed salty, contains excess salts / Minerals / Dissolved solids, chiefly Sodium, Calcium, Magnesium, Chlorides, Sulfates, Bicarbonates, while Nitrates , Fluorides and Potassium etc., are found in small amounts. Civic authorities try their utmost to avoid the distribution of such water in municipal supplies. A significant amount of underground water locally available is highly mineralized / brackish. Such water, if used on regular basis may cause serious health problems including blood and kidney diseases, calcium deposition problems etc. The only solution is to get rid off these excessive minerals / salts, through distillation / purification.

In the light of existing energy problems, and plenty of sunshine, with scarcity of good quality water, the only solution seems to be the use of solar energy for distillation of saline water. It not only provides pure water for use in medicines etc. but it is also free of bacterial contaminations.

(A common type of solar still is shown in Figure.)

The specialized companies have developed the systems to improve the efficiency, yield, and quality.

The plant economy (cost / litre of fresh water) will however be the prime factor. In addition, the capital cost will have to be kept at a minimum, so that pay back time be as less as possible.

2- The solar energy may be utilized for the space cooling or space heating of a building. In our tropical environment the previous one seems to be more attractive. It will significantly reduce load on the existing air conditioning systems if any. Consequently the payback will be in terms of energy saving.

The space cooling in buildings like educational institutions, community centers, hospitals etc. may be achieved by insulating the sun load of three main portions of a building like roof, windows and walls by suitable means.

These ideas will have to be practiced with the objective of energy saving and without sacrificing the aesthetical beauty of the building. Efforts should be made to adopt means and methods to beautify the building.

3- Solar Energy may profitably be utilized for the production of Oxygen and Hydrogen by electrolysis of water. In local environmental conditions, which are degrading day by day , patients of respiratory disorders / diseases like asthma, bronchitis, sinusitis etc. are ever increasing. The only solution for the relief of such patients is the supply of purified air, richer in oxygen. Presently, in hospitals and polyclinics, oxygen is mainly supplied through cylinders via nabulizers. The oxygen, can be supplied / provided through a centralized system in a room / ward housing patients , having respiratory disorders and breathing difficulties.

Hydrogen, available as a by product, may be used as a fuel or vent off in the atmosphere. This idea, if practiced, may provide a cheaper source of oxygen for health institutions. Although once, capital cost will be involved, but in the following periods, the overheads in terms of decentralized oxygen supply by means of cylinders etc. will be saved. The pay back time of the capital cost incurred can further be minimized if hydrogen is utilized-either in any industrial use or in burning, specially at a remote place.

In addition to above systems, solar energy may profitably be utilized for provision of hot water in canteens, hostels, etc. by means of solar heaters. These heaters may be installed at a fairly low cost and payback will be in terms of energy expenditures. Moreover, these heaters are rather maintenance-free.

The farm products may be multiplied manifold by the use of hot and demineralized water for irrigation. The requirement of such water is comparatively lesser, and it helps in reclamation of land by soil salts management. This water is quite conducive in growth of special herbs used in medicines etc.

The water of such quality may be obtained at a competitive / feasible cost by the use of solar evaporators. The output of such evaporators may be cycled in horticulture, green house, and other possible outlets, apart from production of high quality drinking water for patients.

The undue losses of certain crops / herbs due to excessive moisture content may be avoided by the use / installation of solar dryers.

If the owner of a hotel / cafeteria / canteen of a large institution serving one thousand peoples per day, wants to have his own mineral water plant of about 1000 litres / day along with provisions of building cooling system, and hot water supply for washing and laundry requirements, then he should seriously consider to install a solar energy utilization plant instead of conventional cooling / heating systems. The solar energy distillation plant may also use brackish / saline water as a feed.

The added advantage in the plants for materialization of above ideas / concepts is that, moving components are minimum, so the maintenance costs are negligible. Moreover, one system may easily be tied up with other without at all disturbing the existing operation / system of the organization.

In the light of current economic crunch and environment, it is advisable to adopt / practice only those means for solar energy utilization, which are practical, feasible in terms of investment pay back time etc.