At Saudi Arabia's University of Petroleum and Minerals, solar energy experts at the adjacent but autonomous Research Institute are investigating several phases of solar energy: photovoltaic cells, the effects of surface dust on collectors (which is a major problem affecting efficiency), and - an especially interesting aspect-collection of energy in what they're calling a "solar pond."

A "solar pond" is an attempt to solve one of the more difficult problems associated with solar energy: how to collect it. Though sunshine falls on the peninsula in massive quantities, no one has yet perfected a way of conserving it efficiently, and the Research Institute hopes that what they call a "salt gradient" solar pond, may provide a solution.

Essentially, a solar pond is, in the words of the solar program's acting director Bruce Nimmo, "just water, salt, a hole and a liner." The hole is scooped out of "sabkhas," the salt flats which abound the eastern coastal region of Saudi Arabia, then lined with plastic and filled with salt water, found, usually just below the surface.

What happens then, however, isn't at all as simple. Based on certain principles concerning the loss of heat from liquids and gasses, the water in a solar pond gets hotter and hotter and can be stored without loss of the heat.

Normally, in ponds, lakes or seas, the water, when it is heated by the sun, loses the heat at the surface through convection - roughly defined as movement in the water caused by temperature, density and gravity factors. But if the water is heavily salted, the movement of the heated water at the bottom of the pond or lake is restricted by the high density caused by the high salinity. As a result, the convection principle - i.e. the loss of heat at the surface caused by movement - no longer operates effectively; to the contrary, the water in the bottom half of the pond gets hotter and hotter; in the solar pond temperatures can go as high as 212 degrees F, enough to boil an egg or, more practically, provide hot water for dishwashers, showers, and washing machines in homes.

For researchers interested in that principle, Saudi Arabia's "sabkhas" are perfect; they are exposed to enormous quantities of sunlight and they usually have a bountiful supply of salt water a meter or two beneath the surface.

Solar ponds are also cheap to establish. Instead of constructing elaborate structures of metal and glass, the Research Institute can simply dig into a "sabkha" with a bulldozer, line it, wait until it fills up or fill it and, in some cases, increase the salt content.

So far, the institute's modest experiments - with a prototype pond built at the institute's solar lab last fall - have been successful; a meter and a half deep (five feet) and saturated with salt in its bottom half, the pond, built above ground, registered a temperature of 129 degrees F in its "lower convecting zone" or salt-saturated region just two weeks after start-up. In sufficient volume, water at that temperature could be pumped out of the pond's lower half and piped to homes and buildings for heat, or to factories, for such industrial purposes as washing bottles in a bottling plant.

The Research Institute, however, has more ambitious goals. Its scientists want to use solar ponds to generate electricity - by heating water to about 200 degrees F in the pond - pumping it out and transferring the heat in the water to a fluid with a lower boiling temperature (a Freon, for example) which, as it vaporizes, could drive a turbine.

For now, though, the institute's program is focused on simply generating enough electricity to light up a nearby laboratory at night. The power supplied by the hot water from a single test pond should, according to researchers, be enough to light 15 one hundred-watt bulbs 24 hours a day and three ponds-totalling 2,000 square meters (21,528 square feet) - are to be built in 1982 on a beach near UPM, two of them in "sabkhas."

In their research, the institute team is not neglecting the element of cost. They say, for example, that the cost of a solar pond built in a "sabkha" is about $ 10 a square meter - about 10 to 20 percent of the cost of conventional solar thermal collectors (in which water is heated as it circulates through pipes beneath glass in the sunshine). And although conventional solar thermal collectors make about 35 percent of sunlight that falls on them available as heat- compared to 25 percent from solar ponds - the ponds offer other advantages.

Most thermal solar collectors, for example, require separate storage areas to hold heated water for use when the sun is not shining, whereas a solar pond has built-in hot water storage, down in the high-salinity layers. A solar pond, moreover, is not affected by dust which, accumulating on other types of solar collectors, cuts efficiency. The dust simply sinks into the ponds.

Last, there is the fact that the price per BTU (British Thermal Unit-a measure of thermal energy) receive from a solar pond is now close to the price per BTU of a barrel of oil delivered to a user, according to Dr. Nimmo. That fact, undoubtedly, is spurring solar pond research.

What all that means, say researchers, is that solar ponds could add enormously to the already impressive potential for solar energy in Saudi Arabia. Though there are no plans now for a large-scale effort, Dr. Nimmo says the institute experiments suggest that solar ponds could provide five percent of Saudi Arabia's energy needs by the end of the century.

At a formal ceremony last year, Saudi Arabia i proved decisively that its commitment to solar energy is real: government officials dedicated, and opened, the largest solar heated complex in the world - the King 'Abd al-'Aziz training school in Tabuk.

The choice of Tabuk for the experiment - one of several now under way in Saudi Arabia -was anything but arbitrary. The site was chosen because Tabuk, in the northwest corner of Saudi Arabia, is perfect for solar energy: the sky is almost always clear and blue, and the prevailing breezes quickly sweep away dust that, in some areas, accumulate on solar collectors and reduces efficiency.

The Tabuk area, in fact, has the highest solar heating potential in the world - a persuasive factor when the Saudi Arabian Ministry of Defense and Aviation was weighing the pros and cons of a solar energy system in planning its new physical training school for the kingdom's Air Force.

Beautiful and ultra-modern, the new school, built by the U.S. Corps of Engineers, will depend on the sun to provide 70 percent of its total heat load, including 40 percent of the building heat and 100 percent of the domestic hot water needs - 36,000 gallons a day, enough to supply about 400 American homes.

In designing the school, Sverdrup and Parcel Associates, Inc. of St. Louis, Missouri, included in the 14 buildings a number of features known as "passive" solar energy, i.e. features that make it easier to heat- or cool - a given structure. To help minimize heat loss in winter, for example, but also to help cool the buildings from May to November - when peak temperatures have climbed to 117 degrees F - the lower levels of some of the buildings were built below the ground.

In addition, glass has been kept to a minimum, all windows are recessed and double paned - with a highly reflective bronze glazing - all large windows face north, and built-in heat exchangers expel excess heat. Because it can also get pretty cold in the desert - between December and March temperatures can go down to freezing - the designers also provided extras affecting the heating; extra insulation was added to the roofs and walls of the buildings - as well as to water storage tanks and heat exchangers. They also installed added protection for the collector plates; when temperatures drop a pump circulates hot water to the collector circuits.

The heart of the system, however, consists of the solar collector plates installed on the roof of the Field House; they cover an area about the size of three football fields and are attached to 12 roof panels. These plates trap the heat of the sun and transfer it to a liquid flowing through them - much the way a garden hose left lying in the sun for an afternoon will produce warm water at the end of the day.

From the rooftop, a piping system - well insulated - distributes the hot water, along with a heated solution of water and ethylene glycol, through a unique system of upright steel tanks in the support columns of the Field House. This design, according to Sverdrup and Parcel Associates, provides flexibility; collected energy can be transferred to where it is needed most and the temperatures can be controlled to provide maximum capacity. Furthermore, they say, simplicity of design and the use of conventional components guarantee easy maintenance, fuel conservation and efficient functioning for an estimated 35 years. Including the replacement of parts, the system is expected to pay for itself in 20 years.

The calculations are complicated, but what they boil down to is a decision to enlist the sun in Aramco's endless war against corrosion - through photovoltaic cells, the tiny devices developed for the space program which convert sunlight directly into electricity.

In effect, corrosion is an electro-chemical cancer that attacks buried petroleum pipelines and well casings, eventually, riddling them with microscopic holes or weakening their resistance to the high pressures of flowing petroleum. An enormous problem in industrial societies, corrosion is the movement of metal ions - electrically charged atoms - from one point on a pipeline, or a well casing, to another point.

What happens, engineers say, is that an electric current is set up when two dissimilar metals - or two areas of the same metal - come in contact via a bridge, or path, like soil or water; moving from a negatively charged area the anode - the current carries ions away from the anode and flows to the cathode. In streaming from the anode the ions dissolve and corrosion results. Because steel alloys in well casings and pipelines contain enough dissimilarities, such "galvanic cells" are easily activated and corrosion - occurring at an anode, the point where the pipeline loses ions eventually eats a hole through the metal pipe or casing, in weaker areas of the metal, and a leak results.

To fight corrosion, engineers long ago worked out a process called "cathodic protection" under which another source of metal - such as magnesium - is buried near the pipeline or well casing; it's a sort of sacrificial lamb used as a source of current sent to the pipeline rather than drawn from it. To put it another way, the pipeline, or casing becomes the cathode, and the sacrificial metal becomes the anode - thus giving rise to the "sacrificial mode" of cathodic protection.

In another mode, called "impressed currency," the key to cathodic protection is a reliable source of electricity. This mode requires a steady current flowing from an anode placed in the ground - usually graphite or high silicon iron which corrode slowly-to the cathode. Until recently this electricity was provided by power lines or generators. Now, however, Aramco has decided to use solar energy as a source of electricity for what is to bean expanded cathodic protection program.

According to Ahmad Abu Isa, superintendent of the Cathodic Protection Operations Division of Aramco Pipelines Department in Dhahran, Saudi Arabia, plans to use photovoltaic cells to provide power for numerous cathodic protection systems are based on the fact that photovoltaic equipment is virtually "maintenance free."

In addition, the cost of solar cells has plummeted in the past two years, while the cost of electricity from conventional sources has risen. With the company preparing to "electrify" some 1,330 well casings - about a third using solar power via photovoltaic cells -the savings could be important. The company also plans to install 14 photovoltaic units to protect some 250 kilometers (155 miles) of crude oil pipeline between Qatif and Qaisuma, the first leg of the Trans Arabian Pipeline - Tapline.

Aramco engineers have high hopes for the photovoltaic system - and solid reasons for their optimism. For two years, says Abu Isa, Aramco has been experimenting with a photovoltaic system set up to protect 5.6 kilometers of crude oil pipeline near Abqaiq (three and a half miles), the headquarters of Aramco's Southern Area Oil Operation. And so far, he says, there have been no problems at all.

A four-solar-panel "array," containing the photovoltaic cells and a battery that stores up to 200 hours of electrical power - to supply power at night or on overcast days - the Abqaiq unit produces 60 watts of power, enough to light a single average light bulb. Furthermore, engineers say, the unit is efficient. Because of the inland site, the dust that clings to the panels in other places - thus cutting the efficiency of the solar cells - is less of a problem; lacking the high humidity of the Gulf coast, thick dust does not accumulate.

A second photovoltaic system, Abu Isa says, has been working since October, 1980 providing cathodic protection for some 10.4 kilometers (six and a half miles) of crude oil pipeline north of Dhahran, and is still functioning smoothly. This system produces 108 watts of power.

According to Troy Stilley, senior project engineer with the Cathodic Protection Unit of Aramco's Central Area Project Design and Construction Department, a typical Aramco well casing requires 240 watts of power to protect it-enough to run two portable color television sets. But since power is also required whether the sky is overcast, or night has fallen, a panel capacity of some 1,500 watts must be built into the system.

Engineers say the price of a typical photovoltaic cathodic protection power supply is approximately $50,000 including the photovoltaic cells, the panel packaging, the unit's storage batteries and a regulator. Two years ago, that same typical photovoltaic power supply would have cost about $80,000

A complete system, including anode, fencing, platform and installation, runs to about $250,000. This may seem expensive for a few hundred watts of power but with each mile of power line strung to such outlying areas costing $100,000, plus fuel for the plant, solar energy, streaming freely down from the sky every day, offers cost advantages that are obvious.

Arthur Clark is a writer for Aramco Public Relations Department in Dhahran Saudi Arabia.

Nestled against the west wall of the Wadi Hanifa, 45 kilometers north of Riyadh (28 miles), the tiny villages of al-Jubaila and al-'Uyaina lie dreaming in the hot bright light of the Saudi Arabian sun, their 3,000 or so residents largely unaware that a new system of power generation is about to catapult them into the forefront of the solar age: a $16.5 million effort to provide the two villages with electricity through direct conversion of sunlight into electricity by using the world's largest photovoltaic collector system.

The villagers know, of course, that a major project is under way-and some can't wait. In al-'Uyaina, for example, 'Abd al-'Aziz, the 14-year-old son of shopkeeper Muhammad 'Abd Allah, is eagerly awaiting completion of the construction he can see on the escarpment above the palm-thatched porch of his father's shop where the men of the village gather to sip cool drinks and talk. Though 'Abd al-'Aziz is too young to realize the full import of what is happening, he is certainly confident that it is going to happen; on the gate of his house, next door to the shop, his father has installed two overhead light fixtures in anticipation of the day when solar energy will replace the generators chugging away in the wadi.

The experiment in al-Jubaila and al-'Uyaina is but one of several projects being carried out under the ambitious program called SOLERAS (Solar Energy Research American Saudi). Ajoint Saudi Arab-United States venture in bilateral cooperation, SOLERAS is a five-year endeavor to which the U.S. Department of Energy and the Saudi Arab National Center for Science and Technology (SANCST) have each committed $50 million, and for which the Solar Energy Research Institute (SER1) in Golden, Colorado is responsible.

The project at al-Jubaila and al-'Uyaina, however, is by far the largest of those projects. Indeed, it is the largest venture of its kind ever undertaken anywhere: installation of a solar energy system capable of delivering one megawatt - i.e. a million watts - of power.

Cost, of course, is a factor in solar energy, as it is in all forms of energy, and the cost of electricity produced directly from the sun has been dropping dramatically in recent years. Since the photovoltaic cell was first used in an American space satellite, prices overall have decreased 20 times.

And the future, leading solar experts believe, is even more promising. They say that five years of mass production could reduce prices substantially - conceivably to as low as 70 cents a peak watt, roughly competitive with oil.

At al-Jubaila and al-'Uyaina, the electricity will be produced - up on the escarpment's edge - by arrays of photovoltaic modules mounted on giant arms. Each module uses four fresnel lenses to concentrate the sunlight on four high-intensity silicon solar cells. These are bonded to an aluminum arm and a passive heat dissipator, with four such cells enclosed in a common housing.

The principle at work here is a fairly simple one: when sunlight hits the semi-conducting silicon material the cell, it knocks some of the electrons loose and - as they flow in between the layers of silicon - creates a current of electricity. With 64 such modules mounted on a horizontal tube that rotates about both axes in pursuit of the sun, and a total of 160 arrays, the photovoltaic field, under peak conditions, is expected to produce a million watts - one megawatt.

One question about Saudi Arabia's solar energy program that surfaces constantly is "why?" Why is Saudi Arabia, with its massive resources of petroleum, spending so much on experiments?

Part of the answer, says Dr. Bakr Khoshaim, the Saudi Arabian program director for SOLERAS, is that solar technology can speed up the kingdom's modernization. "Our aim is notto become the solar energy exporting nation of the world," he says in his dry, smiling way, "but to use this new technology to make life better for our people all over the kingdom. It may take 10 years for a power grid to reach some of our villages. They could have solar power in three."

Economist Cecil Thompson, director of the Solar Energy Research Institute (SER1) office in Riyadh, definitely agrees. "While it is true that this country has enormous fossil fuel reserves," he says, "and while this is fine for large energy generating facilities, you still must distribute this energy. This country has many villages waiting to be hooked up to an energy grid and this will take a lot of time and money. The trade-off then gets to be between urbanization - moving people closer to the centers of production and perhaps disrupting their lives-or finding another way of generating and distributing electricity to them. This is the context within which such things as solar-powered heating and air-conditioning, water desalination and solar controlled environment greenhouses become feasible here."

The solar village experiment, it is true, has already confirmed the existence of obstacles: dust, for instance, which daily coats the lenses and thus hinders the development of power. Nonetheless, the logic of solar energy is inarguable: two weeks of sunshine provide as much potential energy as all known global reserves of fossil fuels. Furthermore, solar energy is pollution free and - a vital factor - it is inexhaustible.

Even so, solar energy development by Saudi Arabia, a country that controls 25 percent of the world's petroleum resources, arouses curiosity. Skeptics wonder why Saudi Arabia is investing vast sums in projects like SOLERAS? Isn't solar power irrelevant in, and to, Saudi Arabia? Isn't there a danger that Saudi Arabia might become dependent on U.S. solar technology?

No, says Dr. Khoshaim, that's not the case. "SOLERAS is structured so as to serve the best interests of both Saudi Arabia and the U.S." SOLERAS, he goes on, is "a model of cooperation between two nations in pursuit of a technology which will benefltthem both."

SOLERAS, in fact, is a unique concept. It is not only jointly funded by two governments, but requires that each country relinquish a degree of sovereignty - with a board of directors from both countries deciding all matters. Which, says Cecil Thompson, precludes SOLERAS from taking on any project which is not in the best interests of either the United States or Saudi Arabia. "Saudi Arabia is not buying our technology; we are developing a solar technology together."

It is, in fact, a rare example of national foresight, say such spokesmen as Dr. Khoshaim, Faisal al-Bashir, the Saudi Arabian Deputy Minister of Planning and the University of Riyadh's Hammad Safrata, "Solar technology. certainly faces a host of major obstacles," says Dr. Safrata, "but it has come a long way in a few short years and there is every indication its growth is likely to be even more dramatic than in the past. Solar is a new child - and yet we're already asking about its cost of growing up!"

As to the possibility that Arabs might become dependent on western solar technology. Dr. Khoshaim says philosophically, "When you come right down to it, all countries are one country, aren't they? Nothing we develop is ours alone. It's for the world."

Saudi Arabia, furthermore, is developing its own solar potential - by participating in projects that SOLERAS is researching and developing in the U.S., as well as in the kingdom. In the U.S., for example, $3.8 million in engineering field tests of commercial solar cooling systems are being undertaken by three American companies: Carrier Corporation of Syracuse, New York, United Technology Research Center of Hartford, Connecticut, and Honeywell, Inc. of Minneapolis, Minnesota, each of them working to reduce the cost and improve the efficiency of air cooling systems.

Also under way in the U.S. is a $4 million project to design large-scale solar-powered desalination systems. The first phase of this program calls for a conceptual design of desalination systems capable of producing a million or more gallons of fresh water per day.

The second and third phases involve the construction of pilot plants, one in the U.S. and one in Yanbu, the new industrial center and oil port just dedicated on Saudi Arabia's west coast. Contracts have been signed with Boeing, Chicago Bridge and Iron, Donovan, Hamester and Rattien, Catatlytic and Exxon Engineeriing Research to construct the pilot plants by 1982.

Compared with Jiddah's three existing desalination plants - the smallest of which can produce 22.5 million gallons a day - these pilot plants may seem insignificant, yet some experts agree that the use of solar energy may be the most economical way to produce water for small communities in remote areas, because solar desalination can be applied on a small scale more easily than conventional desalination methods and obviates the need to transport fuel.

In Saudi Arabia, three other SOLERAS activities are already well advanced. Workshops on solar cooling have been held, research grants have been made to the kingdom's four main universities, and a solar data collection station has been established. In addition, two solar-controlled greenhouse systems will be completed this year: one in Saudi Arabia for a hot-arid climate, the other in the U.S. fora hot-humid climate. These will advance the technology of controlled environment agriculture in areas not already serviced by an electric power grid.

Since it extends the reach of solar experiments, the $8 million university grant program is particularly important. Managed by SANCST, which is headed by Dr. Rida 'Ubaid, the grant program involves the establishment of solar cooling labs, each to be equipped to conduct design, analysis, system integration. and experimentation on new and advanced cooling concepts. King Faisal University in Dammam, King 'Abd al-'Aziz University in Jiddah, the University of Petroleum and Minerals in Dhahran and the University of Riyadh have signed agreements to cover the first phase of the three phase effort.

To develop technicians to run the new solar programs, the program also schedules workshops in the kingdom and tours to the U.S. solar energy labs. In the last several years three such tours have been conducted for Saudi Arabian and U.S. students; participants visited the Solar Energy Applications Lab at Colorado State University, the Sandia Lab in Alburquerque, New Mexico, the Jet Propulsion Laboratory and the Applied Solar Research Company in Pasadena, California, and the Rocky Flats Wind Turbine test facility in Rocky Flats, Montana.

Such areas may seem a long way from Saudi Arabia's solar villages and from 14 year-old 'Abd al-'Aziz in Wadi Hanifa, but in the future-the foreseeable future - all those places will be playing a role in the development of energy straight from the sun.