Our general tour is oriented to the guest who is visiting the park for the first time and takes approximately one and a half hours to complete.
The Solar Park presents the Sun, and the central role it plays to all life on Earth. Most of us take for granted the natural phenomena that surround us in our day to day lives. We wake every morning and do not wonder that the Sun is shining. We experience the cycle of the seasons, without thinking why winter comes, followed by spring, summer and fall. We do not ask why plants grow or how rain is formed. Most of us are not aware of the cycling of carbon and water in nature or the source of the oxygen that we breathe. Despite the current publicity of pollution and global warming, we do not ask what renewable energy is and how it can help reduce the damage to our environment.
Here in the Solar Park we discuss some of these questions and focus on the major issues of the phenomena mentioned above: The Sun!
The Sun is the hearth and engine of the Earth. It drives most of its systems - the climate, the water cycle, the carbon cycle- and provides most of its energy. Without it, there is no life. On the other hand, especially in this desert region, we struggle with the Sun on a daily basis: high heat, aridity, water shortage and drought. However, by means of science, technology and initiative, we can harness the energy of the Sun and make use of our local natural resources to live in peace with our otherwise harsh environment. Using a simple, hands-on approach, we will observe some of this technology.
Dear visitors: Please step into the Solar Park, embark upon a journey of discovery and adventure, a journey in the tracks of the Sun!
Cluster #1: Ecological Desert Systems
Evaporative Cooling Tower
In the desert, we live in a hot, dry environment and expend enormous amounts of energy cooling our homes and work places. How can we cool our inner spaces without using the high amounts of energy typical of conventional air-conditioning? This exhibit shows how to cool a large space, based on the principles of natural ventilation, evaporative cooling and solar power.
How does it work?
We see before us a 15 meter (50 feet) tall tower. The upper opening points in direction of the prevailing winds of this region (northwest), and allow that wind to be channeled into the tower. A large fan provides a backup for times when there is no wind. The hot, dry air passes through 2 rings of misting sprinklers that spray tiny droplets of water into the air. The evaporation of these droplets absorbs the heat contained within the air and lowers its temperature and raises its humidity. The cool, damp, heavy air sinks towards the bottom of the tower; hot air is drawn in its path through the upper opening, in effect maintaining an even air flow through the system.
The source of the water for this system is the Nubian Sandstone aquifer which spreads across the Sinai and the desert of the Negev. Because this water is salty and potentially harmful to the system, the tower includes a reverse-osmosis desalination unit that purifies the water used in the cooling system.
All of the energy demands of the tower for operating the fan, pumping the water to the sprayers and running the desalination unit, are supplied by the array of photovoltaic cells installed on the southern side of the tower, with a total output of 1.8 kW. A continually charged battery bank at the base of the tower provides backup power. The cooling tower works independently off the grid, using only locally available natural resources.
Come inside the tower and feel the temperature and humidity differences between the inside and outside. Outside the air is between is 30-40 C, inside the air is comfortably cool and moist at around is 20-25 C.
The Dew and Fog Collectors
The lack of fresh water is one of the main challenges of life on earth, especially in the desert. How do living creatures in nature extract water from the desert environment? Some plants and animals subsist solely on water from dew and fog. Fog and dew in the desert? If you sleep overnight in the desert, you will notice that in the morning your tent is cold and damp, and the windshield of your car covered with drops of water. Can we produce water from the air? These exhibits display how to exploit this hidden source of water.
How does it work?
The climate of the Negev is characterized by hot days and cool nights: ideal conditions for the creation of dew. During the day, water evaporates and the hot air absorbs the water vapor. During the night, the air cools and its capacity to hold water vapor decreases, until it reaches the dew point. At this point, the water begins to condense on surfaces such as leaves, grass, glass, coated metal sheets and plastic. Such surfaces cool (via infrared radiation) at a greater rate than they absorb heat. The dew collector is made up of two elliptical sheets of hard plastic, connected in a form resembling the wings of a beetle that lives in the local sand dunes. As with the beetle, at night dew forms on the "wings" of the collector, and drains along the seam of the wings into the "mouth" of the collector, where the water accumulates in a glass vessel. We have between 200-250 nights of dew per year, with an accumulation of 100-500 milliliter per square meter of surface area per night. If someone converted the roof of a modest 120 square meter home into to a dew collector, one could potentially produce between 1500-2400 liters of water a year- from air!
The process of fog formation works on the same principle of dew formation, only that with fog, water condenses on "cloud formation nuclei" suspended in the air- such as tiny specks of dust and salts. The fog collector contains a nylon net stretched on an elliptical frame, perpendicular to the prevailing breeze. On a foggy night, tiny drops of fog water are trapped on the strands of the net; the droplets condense, grow heavy and fall into the container at the bottom of the collector. In the Nitzana area, we have up to 50 nights of fog per year with the ability to collect up to 1500 milliliters of water per square meter of net per night.
In Israel we are blessed with an advanced water infrastructure, and will probably never depend on such methods for water supply. However, there are places in the world, such as the deserts of Africa, the mountains of South America and the Indian sub-continent that these methods supply the water demands of entire villages.
Cluster #2: Sun as a Source of Heat
Here in the Negev, we have access to plentiful groundwater resources but the water is salty. How can we use this water? Desalination is the process of turning salt water into fresh water. Conventional desalination methods -such as distillation and membrane technologies - require much energy; typically the source of this energy is petroleum and coal. Can we use the energy of the Sun, which is clean and readily available, instead of expensive, polluting fossil fuels? This exhibit shows how.
How does it work?
The solar still consists of a glass pyramid with a basin at its base, which is filled with salty water. The black surface of basin absorbs solar radiation and heats up. The "greenhouse effect"-caused by the entrapment of infrared radiation by the glass walls further increases the heat. The water in the basin heats up and evaporates, leaving the solid salts behind in the basin. The vapors rise, hits the glass walls and condense into water drops. The water, which is now fresh, trickles down the glass into the gutter surrounding the basin and drains into the jar at the bottom of the still.
Visitors may sample the water from the basin using the tap located at the bottom center of the pyramid and note that the water is hot and salty. Now sample the water from the collection jar- it is fresh, clean and not salty! With only the clean, free energy of the Sun, such an apparatus can distill 10 liters of water, per square meter, per day.
How do we transfer heat energy in heating or cooling processes? This exhibit displays methods of heating and cooling water with the Sun and air, and presents the three basic principles of heat exchange- radiation, conduction and convection.
How does it work?
The exhibit consists of a solar collector and a radiator that are connected to each other in a closed loop. The solar collector is a panel that is typical of solar water heaters, as found on the roof of almost every house in Israel. The solar collector is made up of a thin, black-coated sheet of metal behind a glass pane. The Sun heats the black metal sheet by radiation. The "greenhouse effect", caused by the glass trapping the infrared radiation emitted from the metal, further heats the collector. Heat passes through the sheet into tiny copper tubes embedded in the sheet by conduction. Water, flowing in the copper tubes, heats to temperatures of 80-100 C. The hot water rises to the top of the collector and up to the radiator. The radiator consists of a long, convoluted copper tube, which works much like the radiator of your car. Air flowing around the surface of the exposed tubing carries off the heat by convection. The water in the radiator tubing cools to near ambient temperatures- 30-40 C- and flows down through the tubing back to the entrance into the solar collector. The water continues to flow in a convective current through the closed loop.
Note the two thermometers - one on top, where the hot water enters the radiator, and one at the bottom, where the cooled water enters the collector. The collector is covered by six white shutters. Open all the shutters, thus exposing the panel to the Sun, and within moments the temperature shown on the top thermometer begins to rise (the length of time depending on time of day and cloudiness). Yet the bottom thermometer stabilizes at approximately the surrounding temperature. Try closing some of the shutters in order to control the rate of heating and temperature level.
In this region, the Sun strikes the Earth with an equivalent power output of approximately 400 watts per square meter of surface area. Most of the radiation simply heats the earth or is reflected back into the atmosphere. Is it possible to "harvest" this energy- to concentrate the radiation from a wide area into a single point and to use it, when and where it is needed? This exhibit presents advanced technology for the concentration of solar radiation and various applications of its energy.
How does it work?
The solar concentrator is made up of an array of 61 hexagonal mirrors arranged in the form of a dish with a diameter of 3.4 meters (11 feet). The mirrors are configured such that they reflect the suns rays towards a target mounted on the tower facing the array. All of the radiated energy intercepted by the "dish" is concentrated onto the tiny target. The temperature at this point can reach 800-1000 C. The array is mounted on a pedestal which tracks the position of the Sun. The controller of the positioning system is programmed to calculate the angles of the Sun every 20 seconds of the day, for every day of the year, and in turn calculates the appropriate angle of the dish to focus the suns rays onto the target. The original purpose of this particular concentrator was to produce a laser beam for scientific and industrial applications. In principle, one could also use this type of technology to produce steam for the generation of electricity.
Using the pulley installed on the target tower, you can raise different objects to the focal point for different applications- you can boil a kettle of water, you can burn a piece of wood or cardboard, or you can melt plastic or wax in a mold to make a sculpture.
Absorption and Reflection of Light
How do different objects heat up in the Sun? In the summer, why is it difficult to walk barefoot on the pavement, while it is much easier to stand on a wooden deck? This exhibit presents literally hands-on what is the composition of the suns rays, and what is the influence of the color and material of the object in the production of heat.
How does it work?
The exhibit is composed of three rows of disks, four disks to a row. The top row displays plastic disks of different colors. The middle row shows brown disks of different materials (wood, PVC, stone and copper). The bottom row includes disks of different types of glass (transparent, blue-tinted, mirror and fogged).
Light is composed of a spectrum of radiation of different wavelengths, or in simpler words, of different colors. When a light hits an object, the objects surface reflects all or part of the spectrum of the light, depending mostly on the objects color. We say that the wavelength that is not reflected is "absorbed" by the object. We see the reflected wavelength as the objects color. Black objects absorb nearly all the spectrum; white objects reflect nearly all the spectrum; red objects absorb all the light except for wavelengths in the red part of the spectrum. Absorption of light produces heat in the object. The level of heat depends upon the properties of the material of which the object is composed - such as density, thermal capacity and conductivity. Dense materials with high thermal capacity, such as most metals, heat rapidly and high. Materials with high thermal mass, such as stone, accumulate and store heat. Light materials with low thermal capacity, such as wood, heat less.
Turn the array so that the disks face the Sun, and let them warm up. Touch the discs and feel the temperature differences. For instance, place one hand on the black disc and the other on the white, and decide which color you would prefer to wear in the summer, and which in the winter. Why do pots and pans come equipped with wooden handles? Check this by placing one hand on the wood disc and the other on the copper. Now turn the discs away from the Sun and let them cool- which disk stays hotter the longest, and why?
Cluster #3: The Solar System
What causes the day and night and the change of the seasons? Most of us know that these are results of the Earths rotation on its axis, its revolution around the Sun. This globe helps examine these phenomena in real-time. We can check where in the world people are sleeping, what the time is in Fiji or New York, and in which hemisphere it is winter or summer.
How does it work?
The globe is oriented parallel to the axis of the Earth (pointing North at an angle complementary to the local latitude, about 31 ), such that the globe moves with the Earth, like a tiny twin, simulating its rotation with respect to the Sun, which causes day and night. It also allows us to see the angle of the Earths axis with respect to the Sun, which changes as it revolves the Sun, causing the change in seasons.
Stand about one to two meters behind the globe, in line with the axis. Note the spot of light projected on the globe by the Sun. Where the spot on the globe is brightest and warmest shows where in the real world it is solar noon (12-1 pm clock time). Where the globe is shaded, it is already night time in the world, and at the borders of the shadow it is either dusk or dawn.
Turn the time-scale ring until the current time lines up with our location (marked by a circle) - the scale shows the time it is in any part of the world. Does it correspond with the shadow? If you are visiting in the summer, note that the northern hemisphere (where we are) faces the Sun, the South Pole is continually dark and the North Pole is continually lit and warm. If you are here in the winter, the southern hemisphere faces the Sun, the North Pole is continually dark and the South Pole is continually lit and warm.
We invite our visitors to look through the solar telescope, which allows you to observe the Sun directly without harming your eyes. The telescope also functions as a sundial and calendar.
How does it work?
A strong filter fitted on the lens turns this regular telescope into a solar observation device. Because our angle relative to the Sun changes throughout the day and throughout the year, as long as the telescope points towards the Sun, it also indicates the hour of the day and the date of the year. Please note: Due to the eccentricity of the curvature of the Earth and its rotation about its axis, there will always be a deviation between "solar time" and "clock time". However the deviation is relatively small ( 25 minutes) and one may accurately calculate the correction for any time.
First you must find the Sun. There are two methods to aim the telescope towards the Sun. The first method uses the "finder" mounted on the telescope casing, comprised of a ring shaped aperture which projects the suns rays onto a solid metal disk. One simply moves the telescope until the "circle of light" is the centered on the disk.
The second method uses the hour and date scales installed on the axes of the telescope mount. One aligns the arrows of the scales with the current date and time.
Once the telescope is aimed, peer through the eye piece. You can see the Sun as a white disk on a black background. You may see dark patches on the disk, which are called "Sun spots. Magnetic flux causes tornado like storms on the surface of the Sun, which inhibit the transfer of energy, resulting in regions that are cool (~4000 C) relative to the rest of the surface (~5500 C). These cool spots look dark in comparison. What looks to us like a tiny spot may be the size of the planet Earth or many times larger!
Centripetal Force (Force which propels a rotating body toward the center of rotation)
What causes the Earth to revolve around the Sun? Why does the Moon or a satellite revolve around the Earth? This exhibit demonstrates the mechanics of circular motion and what keeps the celestial bodies in their orbits.
How does it work?
The exhibit is composed of a small, green metal ball which revolves around a big, orange ball. The small ball is driven by a hand crank. The small ball is connected to the crank with a spring and slide mechanism, which extends or contracts according to the speed of the cranks rotation. How? The answer lies in Newton's first law; a body in motion will remain in motion, in a straight line, unless acted upon by some force. The force that causes the object to move in a circle is called "centripetal force" - or force that "seeks the center". The centripetal force acts on the object, to constantly change the direction of motion. In this exhibit, the centripetal force is the spring arm holding the small ball.
If we talk about the Earth moving around the Sun, or the Moon or satellite around the Earth, the centripetal force is the pull of gravity. If you speed up the hand-crank, you are actually accelerating the ball in a tangent to its orbit, increasing its tendency to move in a straight line out of the orbit. The spring resists and extends until it equalizes with the applied force. As a result, the ball continues to move in a circle, but at an orbit further from the big ball.
If we stop spinning the crank, the friction of air and of the gears slow the ball, allowing the spring to contract and pull it back towards the center. Perhaps you may ask why we on planet Earth do not eventually crash into the Sun. Fortunately, there is no friction is space, and the momentum of the Earth is enormous.
Turn the crank and make the small ball revolve around the big ball. The faster you spin and the more force you apply, the further the ball extends from the center. Imagine that the small ball is a spacecraft orbiting the Earth, and the force you apply on the crank is the force of the spacecrafts engine. You are trying to get further away from the Earth. Can you overcome the centripetal force, break out of the orbit, and fly into space?
Relative Sizes and Distances in the Solar System
We know that the Sun is big, but how big? How much bigger is it than the Earth? What are the relative sizes of the planets? The distances between the planets and the Sun are also huge. How close are we to Mars? How much further is Pluto from the Sun than the Earth? It is difficult to appreciate sizes and distances on an astronomical scale. In this exhibit, the sizes and distances have been scaled down many million times in order to help us understand the relative sizes and distances in our Solar System.
How it works
The first part of the exhibit presents the relative sizes of the Sun and planets of the Solar System (including Pluto, which is not actually a planet but a "dwarf planet"). The sizes have been scaled down about 400 million times, such that we see the Sun as a disk of 3.5 meters (11.5 feet), while our planet Earth is a mere 32 millimeters (1.3 inches). We could fit over 1.3 million planet Earths into the sphere of the Sun!
The second part of the exhibit demonstrates the relative distances of those celestial bodies. The exhibit includes ten cylindrical sights that are pointed at different objects in the desert landscape. Each object represents the position of a different celestial body in the Solar System, in order, starting with the Sun to the far left.
Peer through a sight and observe the object representing a particular planet or the Sun, then peer through the next sight to see the relative distance to the next object in the "desert" of space. For instance, the big white building in Moshav Kemehin represents the Sun. The fourth house in the first row represents the relative position of the Earth, about 105 meters (345 feet) in our modest "model" or 150 million kilometers (93 million miles) in reality. Our most distant neighbor, Pluto, is represented by the water tower in Ketziot, about 4.1 kilometers (2.5 miles) from our Sun in the "model", or 5900 million kilometers (3666 million miles) in reality.
In order to further appreciate the vastness of the distances, in this "model" our planet Earth would be the size of a small marble about 8.9 millimeters (about 1/3 inches) in diameter!
We hope that you have enjoyed your tour through the Nitzana Solar Park. We welcome your comments and suggestions.
Visits are possible everyday of the week from 9:00 a.m.- 4:00 p.m., by advance arrangement.
To arrange your visit, please contact:
Nitzana Hostel: 08-6561314 or 052-3927084
Nitzana Secretariat: 08-6561411
Cost: 10 NIS per visitor
How to get to Nitzana from Beer Sheva
The Solar Park of Nitzana is a participatory initiative of the Jewish Agency, the Sacta-Rashi Foundation and the Madarom Project.