Renewable energy in High Cold Deserts

Ladakh is the northernmost region in the Jammu & Kashmir State of India. It can be called a 'Trans-Himalayan high altitude desert' with minimum temperature in winters -20°C to -35° and hardly any rainfall. Leh, the capital, is at 11,500 feet (3500m).

The cold climate of Ladakh generates a high demand for heating. But lack of rainfall makes trees and firewood scarce. However, its average of 300 days of sunshine per year makes this region especially suited for solar energy.

Since 1994 SECMOL has developed solar heated buildings and other forms of solar energy to make its campus at Phey self-reliant.

SOLAR POWER ON PHEY CAMPUS

Our campus outside Leh at Phey, established in 1994, is almost completely solar powered. We use solar electricity for all our electrical and pumping needs. The campus has two solar cookers and a low tech water heater for bathing. Most noteworthy are the campus buildings, which depend on passive solar heating to keep warm even in the coldest months of winter.

Solar panels

Four arrays of 16-24 panels each generate electricity for lighting, computers and TVs. On sunny days we can even use carpentry and soldering tools. These also power pumps to lift water from the Indus for irrigation of fields and trees. Nothing grows here in Ladakh without irrigation, and the nearby spring is only enough for the kitchen and bathing, not enough for our trees and gardens.

The power is stored in 16 solar batteries, and stores enough to run for three days of cloudy weather.

 

Solar cookers

In our campus community kitchen we use two concentrating reflector-type solar cookers to cook most of our food directly on the sun's rays. They were assembled in 1997 by a group including SECMOL students at a workshop at LEDeG under Swiss direction.

This cooker is a large parabolic reflector made of household mirrors, that focuses the rays of the sun to a secondary reflector under big pots inside the kitchen. This very efficient design gives energy equal to a large gas burner, and saves a lot of money while preserving the environment.

Solar cooker.

SECMOL solar water heater

For bathing we have designed a very low cost solar water heater from basic materials easily available. The cost of one 100 litre solar heater is Rs 3,500, whereas commercial ones cost Rs 25,000 per 100 litre.

A great advantage of this design over expensive commercial models is that it has no pipes inside that can freeze and break, so it can be used all winter without draining. Since it is basically a large shallow tray, if it freezes overnight, nothing breaks, and in the sunny morning it simply melts and starts warming up again.

 

Materials:
a. Aluminium sheet painted black, or black plastic.
b. Greenhouse plastic to cover it.
c. Frame made of mud bricks or wood.
d. A common toilet-tank valve if desired

The bottom is a black tray that can hold two inches (5 cm) of water. It must be black to absorb the sun's light and convert it to heat, and can be made either of sheet metal bent up at the sides to form a tray, or commercial black pond-liner plastic (tough and UV resistant) and formed around a frame of bricks. We have also made one of cement and black tiles to preheat cooking water in the kitchen (because we were concerned about consuming water heated on black paint or plastic.)

We find that 3 feet (1 m) is a good maximum width to allow maintenance without walking on the base, and the tray can be as long as you have space and materials. Our are about 18 feet (5 m) long.

It is covered with a small plastic greenhouse. In the winter the one on the bathroom roof is inside an additional plastic greenhouse.

We fill it with water in the morning, and by 12 noon it makes 100 litres of 45°C water. Shallower will get hotter faster. A common toilet tank valve on the inlet pipe prevents overflow by automatically letting cold water in when warm water is drawn out, and cutting the supply when the water level reaches the desired height.

SECMOL buildings and passive solar design

SECMOL buildings are completely independent of conventional heating methods such as firewood stoves or gas or electric heaters. They are designed to absorb heat from the sun and to store it for as long as possible. This method is called 'passive solar design,' as disticnt from active designs which use circulating water pipes, air blowers, or other moving parts. our method has indeed proved very effective. Because of its passive solar design the SECMOL buildings have stayed warm and have not needed any external heating in the last 10 years — even when the minimum outside temperatures falls down to -25°C.

Running solely on passive solar heating, the temperature in the main building at SECMOL Campus has been:

Average evening temperature in winter: +14°C
Minimum in a normal winter: +10°C
Minimum observed in 11 years: +8°C

In the main building at Phey Campus the stair wells have geranium and other plants blooming and flourishing even in January when the minimum outside temperature is -25°C.

The important features to keep the buildings warm are:

• South facing windows, as the sun stays low in the southern sky in winter.
• A greenhouse attached the south side for the winter.
• The greenhouses are removed in springtime to prevent overheating.
• Skylights are covered with glass or clear plastic to trap warm air.
• Thick earthen walls and floors (thermal mass) to store collected heat.
• Insulation in ceilings, outer walls and under the floor.
• Low cost local materials like earth and rocks: cheap & best.
• Natural lighting so no electricity is needed for lighting in the daytime.

Glazing or plastic film to the south

In winter, huge plastic sheets come down and make a big greenhouse which works as a solar heat collector for the building. The plastic stays rolled up and tucked away in the summer to prevent overheating. This ultraviolet stabilised plastic is commonly used for agricultural greenhouses in Ladakh.

A bonus feature of the plastic covering is that they make excellent greenhouses to grow vegetables and flowers in the Ladakhi winter.

High thermal mass in the walls and floors

We build our buildings three feet below the ground level on the north side. The building benefits from the stability of earth’s temperature at that depth, which is relatively warm in winter and cool in summer. This also helps us get the building material — earth — right on site. The three feet of earth we dig out ultimately becomes the walls of the building.

The walls are build of rammed earth, a most eco-friendly method as the building material comes right from the site and is not transported hundreds of miles, and when construction is finished, there is no debris to be thrown away: no addition, no subtraction. Earth buildings are the warmest in winter and coolest in summer, and also moderate the humidity of the building.

The technique of rammed earth consists of casting huge bricks on site, in a frame made of planks. Sand and clay are mixed in the right amounts to get a very strong constitution. It is then filled in the frames and rammed with pounders.

The earth walls are very thick. They are not just structural (to take load) but also have an essential function as the heat bank (thermal mass). They absorb the excess solar heat during the day and release it to the room at night. The same properties also keep rammed earth buildings cool in summer.

Rammed earth is an ancient technique used for hundreds of monasteries, castles and forts around Ladakh. These structures have survived, unprotected and exposed to the elements, for hundreds of years.

While we resurrected this method in Ladakh, we were pleasantly surprised to learn that there is a resurgence of this technique in many western countries in Europe, North America, and especially in Australia.

Insulation in ceilings, outer walls and under the floor

Insulation is the key to retaining the heat that is collected during the day. But it does not need to be very expensive modern materials. The wood waste generated during the construction is filled in the ceiling to stop heat loss through the roof.

Insulation below the floor is also important. Layers of various sizes of rocks create insulating air-pockets between the rocks. A top layer of gravel and cement acts as a heat bank.

Sometimes the top layer of the floor is lined with slates from the nearby mountains. This reduces the use of cement, and the slates also become a thermal mass or heat bank as they are now cut off thermally from the cold ground.

This kind of floor absorbs the excess heat during the day and releases it during the night. Normally floors are an area of big heat loss.

The outer walls are insulated by a jacket wall outside the main structural wall. The six inch gap between the two walls is filled with low cost insulation: saw dust, wood shavings or sometimes paper and plastic garbage like bottles and bags from the city. Sometimes we have also used cow dung as an insulating plaster. Mixed with the right amount of earth and clay, it makes a strong and thermally effective plaster.

If comparing 'thermal conductivity' (insulation property) of common Ladakhi building materials, you find that mud is the best:

1 ft mud wall = 2 ft concrete = 4 ft stone = 1.5 inch of saw dust. = 1 inch of Thermocol, rockwool etc.

 

Natural lighting — the sun

Windows and skylights ensure that no place in the building needs electric lights in the day.

Sheyson Solar Earthworks

A commercial, income-generating section, Sheyson Solar Earthworks ran from 200 till 2008 to build solar buildings on turn-key contract for private homes, the government, NGOs, and the army. The profits from Shesyon Solar Earthworks supported educational reform, environmental awareness activities etc. Starting in 2009 Shesyon Solar Earthworks is on hold.

Sheyson projects

Sheyson completed many solar projects around Ladakh.

The Army Goodwill Headquarters in Leh, 2005:

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Contact Sheyson Solar Earthworks.