Solar energy sustains life on our planet. It provides us warmth, grows our food and powers our water cycles in addition to the light it provides. It helps our body produce vitamin D. In tracking down the origin of various forms of energy that we come across, it shouldn’t be surprising to find that all signs point to the sun. Be it wind, wave or even biomass energy, all are driven by the sun. It is the closet fusion reactor we have albeit 93 million miles away. It is the most natural form of energy that we utilize and it is the most abundant. Every hour the earth receives more energy from the sun than what the whole world consumes in a year.
Thus in apocalyptic times, harnessing solar power can be the means to survival as it is the form of energy that we don’t only need as a species but also as a civilization.
Solar Survival Kit
Back in 2010, when the earthquake hit Haiti and the floods that followed the same year in Pakistan, millions of people lost their livelihoods. More recently we saw a devastating earthquake in Nepal (April, 2015). In such situations access to basic necessities becomes the key to survival. This includes clean water, sanitation and food and need to communicate for rescue. Even if a country has a robust emergency response mechanism, it is not always possible to reach all of the effected. Utilization of indigenous energy can be the key to survival, till rescue arrives.
In many developing countries bulk of the population is not urbanized. Due to the remote nature of the dispersed populace, grid connections are not feasible particularly in mountainous terrain. Even if there is electricity grid or communication lines, chances of them collapsing after floods, avalanches, mudslides, earthquakes or tsunamis are high. Even in the case of heavy snow or torrential rains, pylons have been reported to have folded. In such cases, tapping of solar energy is a feasible and effective option because:
- Simplicity of use and low cost
- Omnipresent and abundant
- Reliable nature of gadgets (no moving parts)
This article looks how solar energy can be utilized to survive disasters and emergencies. It is not claimed that the solutions presented herein are the best possible and the most feasible. The best possible solutions vary from location to location and situation to situation. The main advantage of solar energy is its versatility. It can be used in a variety of emergency situations both on land and in the sea.
1. Water Purification
Access to pure water is the first and foremost requirement for survival. If water source is present, it needs to have excessive dissolved salts removed and purified of biological contaminants. Both of these can be achieved through solar energy.
Salty water is not only bad for health but can also be dangerous for consumption, particularly when the salt quantity is high because it can disturb the body’s electrolyte balance. To get an idea, listed below are salt levels in various sources of water.
|Type||PPM of Salt|
|Supply Mains Water (US)||500|
|Irrigation water limit||2000|
|Mild Brackish Water||1000-5000|
|Moderate Brackish Water||5000-15000|
|Heavy Brackish Water||15000-35000|
As can be observed from the table, water with lesser than 100 ppm of salt is normally consumed for drinking, whereas sea water contains 300 times the salt compared to drinkable water.
Solar desalination is a tried and tested method that can reduce the dissolved salts to very low levels. In fact a solar desalination plant designed by Akhtar Iqbal Zuberi in Pakistan was able to reduce sea water to only 16 ppm of dissolved salts. However because of the huge dimensions of this system, it cannot be classified as portable.
There are two types of Solar Desalination systems in the market that are portable. One uses PV electricity and other that uses solar thermal energy. The PV device has been designed by the MIT. MIT’s prototype can reportedly produce 80 gallons of drinking water per day, depending on weather conditions. This is not being mass produced and therefore at present is unavailable in the market. When the product will be launched able in the near future due to its complex construction, high price is anticipated.
The more low cost and established option is that which uses solar thermal energy. This system is called a Solar Still. It is part and parcel of modern day life boats.
The Solar Still is simply a basin of water that is covered with a transparent plastic sheet. Salty water stored in the basin gets evaporated leaving salt behind. The water vapours condense on the transparent cover and drip into a container. Solar stills can be purchased readily with prices starting from £100. At a much cheaper cost however, one can make a similar apparatus using black garbage bags and Perspex / clear plastic sheet. Details of these DIY stills are widely available on the internet.
Solar Water Disinfection (SODIS)
Occasionally water may have pathogenic substances (e.g. bacteria, viruses, protozoa and worms) but may not have a salinity problem. In such cases a simple SODIS (Solar Water Disinfection) can help. The idea is to store water in a transparent vessel and expose it to sunlight. A PET bottle can be used for this purpose. The exposure to UV sun rays eradicates most of the biological contaminants.
On a sunny day, 6 hours of exposure to sunlight is enough. If the light intensity is poor, as in cloudy days, than up to 2 days of exposure would be needed. To ensure a constant supply of water, multiple bottles would therefore be needed for batch consumption. Two PET bottles in an emergency kit would serve the purpose. It should be noted that SODIS does not remove toxins or contaminants that are non-biological. Separate purification for that would be required. An Alum crystal can be used to remove turbidity of water.
Solar PV with Connector
Solar PV panels are now available in many sizes. Many portables ones can be purchased directly from your local electronics store. It should be noted that the size of the panel doesn’t necessarily depict the power output. Amorphous silicon panels for instance are poor in efficiency compared to a mono crystalline and for a same size, produce significantly less power. The power rating of the panel rather than the size should be looked at before acquisition. 40 Watt foldable solar panels are available and can be stored in a small space. Flexible thin film panels are also available that be rolled. They can serve a dual purpose, provide shelter and electricity.
By producing electricity through the PV panels and attaching them to the right power connector, cell phones can be charged. In fact in many third world countries, PV powered kiosks are already being used to charge cell phones in areas not connected to the grid. It should be noted that PV panels only require light and do not require direct sunlight to work. A working phone can be vital to send distress signal. A piece of mirror can also be used to signal using reflection of light.
Solar LED Lights
During the night time, for visibility and to fend of predators, light is important. It gives you a safety cover and provides awareness of the surrounding. Not only that, it serves as a locating signal for a search party. LED lights are much more efficient than tungsten filament and even florescent lamps.
Solar garden lights use LED lights in conjunction with a small PV modules and a battery. These can also be used in the solar emergency kit. The energy by the PV is stored during the day and when it gets dark, a sensor switches on the LEDs. Another low cost option is LED torches that have a windup mechanism.
Solar Shower Bags
Solar shower bags can be handy as they produce warm water that can help with cleansing and sanitation. These bags are used by campers and are normally hung on a tree branch. Water temperatures can reach very high levels. The warm water can also act as a hot water bottle to provide relief to muscle ache or other injuries sustained or used for heat storage in a cold environment. If insulation is wrapped around the shower bag, heat could be stored for longer duration.
3. Food Preparation
Solar cookers have been used for decades. In many places particularly in Africa, they provide women an alternative to fire based cooking for which they have collect dry wood. Because of smoke free cooking mechanism, their usage has health benefits. There are several designs that have emerged. Some of them are big enough to cook for the whole village with tracking system to make them efficient. Other designs are more passive and are left alone in the sun to mostly cook food over a longer period of time. Solar ovens are also used successfully in sub Saharan region. It should be noted that unlike PV based gadgets, solar cookers do require direct solar radiation to work.
Higher heat produced by these cookers eliminates many contaminants and breaks down the raw food into a more digestible diet. For the emergency kit “The Bread Box” solar cooker can be used. In fact it can be used as a box to store all the other items. It has a simple construction and it can be easily made at home from even a shoebox. It should be noted that the vessel containing the food that will be placed inside the cooker must have an outer coating of black paint.
|Solar Still||£100 (DIY £15)|
|Two empty PET bottles||£2|
|40 W Solar PV with connectors||£ 50|
|Solar LED lights||£3 each|
|Solar Shower bags||£3|
|Bread box Collector||DIY £15|
I hadn’t thought about solar power and survival before. Interesting point and some good food for thought.