Being the occasionally interesting ramblings of a major-league technophile.
As superstorm Sandy recently demonstrated, our modern world is not exempt from natural disasters. Throw in accidents, equipment failure, deliberate sabotage and who knows what else, and sometimes I marvel that things work as well and consistently as they do.
Anything which removes access to electrical utilities - including simple wilderness camping - also takes away the light those utilities can be used to produce. One of the more persistent efforts of humanity is to develop better and more convenient light sources. This isn't surprising when you consider how useful artificial illumination is to us. Lighting provides both practical and psychological benefits: It helps you see, it helps you be seen and it helps you be at ease.
From the time our ancestors first used fire, making light also meant making heat. Even many electric lights - including the incandescent bulb - create significant heat. (After incandescent bulbs were banned in one area, an imaginative entrepreneur tried importing them as "Ninety-seven percent efficient heaters." It didn't fly.) Incandescence is an easy way to make light; just heat something until it glows.
Incandescent bulbs work by heating a resistance to incandescence in a controlled manner. (Hence the name.) They have to be hot. Fluorescents are nearly the same age as incandescents, but until very recently their greater efficiency didn't compensate for their initial expense. Fluorescent lights function through a different mechanism, using electricity to excite a rarefied gas into producing ultraviolet light. This, in turn, excites a phosphor coating on the inside of the bulb, which glows in response. The process requires high voltage, both to start and to continue. Part of the breakthrough making compact fluorescent lights an economical replacement for incandescent bulbs is modern electronics. These greatly reduced the size, weight and cost of the circuitry needed to start and run the compact fluorescents.
Just as compact fluorescent bulbs began having their heyday, though, other technologies started moving in to replace them. Now, besides LEDs there are things like gas discharge and electroluminescent lights. It should be noted that both fluorescents and LEDs - in fact, all commercially available sources of electrical light - still produce waste heat. Just far less than standard incandescent lamps, halogen bulbs or - an extreme example - arc lights.
Most people in developed nations have primary lights - those they normally use - which are connected to their electrical utility. Portable illumination sources are usually secondary for them; things used short term for convenience, or medium- or long-term for emergencies. These portable light sources have also benefited from recent technological advances. Today there is a large assortment of self-contained lighting devices to choose from. Of course, you should make your choice well before the power goes out or you need to find your dog at night or check in a dark corner, or you're likely to remain in the dark for the duration.
Fire is the obvious solution for producing self-contained light. Candles and lamps are reliable traditional methods for seeing in the dark. Just be certain there are no flammable fumes - such as natural gas - around before lighting up. Also, keep in mind that even a single candle can produce a great deal of heat. That can be an advantage in cold or cool weather, but if the power outage occurs on a warm Summer evening with no AC and no breeze...
Candles work well, as long as you keep their disadvantages in mind. The main one being that unless you have a candle lantern, you're dealing with a completely open flame. A slight gust can blow them out, and if knocked over they can start fires. You can even cook over them, to a very limited extent. If you acquire candles for emergency lighting be certain they are unscented. The last thing you need is to discover you're allergic to the scent used, or how annoying even a pleasant scent is to breathe in an enclosed space for hours on end.
Candles can be made from a variety of substances, from beef tallow to straight paraffin. Bayberries - also known as candleberries - are still used to make some candles, though the physical and chemical characteristics of the wax they produce make it less suitable than modern paraffin or paraffin-beeswax mixtures. Given that paraffin is a petroleum byproduct and can have desired characteristics designed in, it and the mixtures with beeswax are generally the most suitable for nearly every modern candle type. Beeswax by itself generally has too low a melting point for hot areas. However, blending some with paraffin improves the physical and chemical characteristics of the candle, and also provides a nice scent.
Chemically fueled lanterns and lamps of various types are more contained and easier to regulate than candles. Some even have a built-in sparker for ignition. Best of all, you can refill them. Just remember that these, too, generate more heat than light. I strongly recommend a good kerosene lamp, especially those with mantles. These have a thorium dioxide-impregnated mantle - an inverted bag on a wire frame - which is placed over the more familiar wick after that is lit. These act as afterburners, both allowing more of the fuel to be burned and reducing fumes. Also, heated thorium dioxide gives off a nice, white light.
Pressure lanterns give off more light, due to the fuel being forcibly injected through an orifice into the flame holder as a vapor or very fine mist. The majority of these also use thorium impregnated mantles. The most familiar types are the Coleman "white gas" (naphtha) lanterns, but there are other brands. Some pressure lamps run off automotive gasoline (much safer now that tetraethyl lead has been eliminated) and others use kerosene. A few pressure lanterns are multi-fuel capable.
A good kerosene lamp can run for many hours without refueling. Pressure lanterns generally don't provide light for as long as wick lanterns, but that's because they're burning fuel at a higher rate to produce a more intense light. Naturally, the determining factor on duration is the size of the fuel tank.
One drawback of all combustion light sources is that they use oxygen. They also produce carbon monoxide, though with modern designs CO and noxious fumes are minimized. (The curl of a candle's wick is deliberate; it increases the burning efficiency and reduces smoke and fumes.) However, besides combustion there are also other methods of generating light through chemical reactions, and some of those are much less hazardous than anything with a flame. This includes being safer to use where there might be natural gas or other flammables in the air.
Chemical light sticks are very handy, and come in a variety of colors and brightnesses. (Just remember, the brighter, the shorter the duration.) However, they are quite variable in their shelf life. The same type of light sticks bought at the same time from the same manufacturer should all last at least to the expiry date (though some makers don't put those on the package, giving the false impression that they store indefinitely). However, whether they'll work well much past the date marked is a roll of the dice. A year beyond and half may work fine and the other half not at all.
This is supported by personal experience. I made a bulk buy of some standard eight hour light sticks several years ago. (By the way, the duration rating is arbitrary. The sticks will gradually dim after activation, but continue giving off some light for much longer than the rating. The value given is likely to some point of intensity.) A couple of years back - long after their expiration date - I decided to test those remaining from that batch, after I tried to use one and it was completely dead. Some worked fine; some were completely dead; some glowed but dimly. I'm not sure of the mechanism by which lightsticks fail, but they do have a limited shelf life.
Lightsticks are a good choice for power outages of a few hours, especially if extra heat is not desired. However, they can't be recharged of refilled, which makes them costly for extensive use. They come in claimed durations ranging from five minutes to twelve hours. They also come in a variety of colors, including white (and even infrared). Just be sure to buy good quality ones and pay attention to the expiration dates.
Until the invention of white LEDs (all LEDs are actually monochromatic, giving off light in a very narrow band of frequencies; the "white" ones are actually ultraviolet LEDs in a phosphor coated capsule, the same method used in fluorescent lights) flashlights were a very poor choice for more than short-term lighting. Today, we have a vast assortment of LED flashlights and lanterns which produce plenty of light for long periods on one charge of battery. They emit little heat, they are generally inexpensive and are very reliable.
Moreover, modern flashlights come with a huge assortment of potential features. Variable focus, variable light levels, variable flash rates - including automatic SOS signaling - solar charging panels, and on and on. Some made for police and security use have a special rapid strobing feature which can render someone helpless through disorientation and nausea. These are popular with prison guards. Modern aluminum alloys and polymers mean today's flashlights are lightweight, handy and very, very rugged.
Even good flashlights are poor choices for lighting a large room or campsite. A few - like the Maglights - can be converted to modest lamps by such measures as unscrewing the head. LED lanterns are a better choice for this function. Again, these have a wide variety of features available, including charging ports for cell phones.
One type of non-electric lighting not often seen today is the gas mantle wall fixture. These can use propane or butane from self-contained or household tanks, or even natural gas from a utility line. As with the mantle lamps mentioned above, they have a thorium-impregnated bag around the nozzle, and give off a clean, white light. Many are rated for indoor use, and can be switched between fuel types by changing an orifice. They are most commonly used for isolated cabins or permanent camps, where hauling in propane tanks is easier and more efficient than fueling a generator.
Besides choosing which light source to acquire (having more than one type is a good idea, too) you need to decide whether to go with something strictly for emergencies or a more general light source which can also function well in a power outage. Having an assortment of types on hand is useful. These can include a general, handy light source for short term use (including looking to see what just knocked over your trash cans) and medium and long-term types for extended loss of utilities.
As mentioned above, some flashlights can function as lanterns. If power outages are rare in your area and you need a good flashlight anyway, two or three those could carry you through. This is especially true if you keep a supply of batteries for them on hand, or have a way to recharge them. Most people would be better off choosing one or two good quality, general-purpose flashlights - plus a few cheap ones to keep in handy places around the house - and another light source to illuminate whole rooms during outages. If you live in a location with frequent, extended blackouts, you should consider getting a generator... or maybe moving. :-)
Something which sees regular use is probably more rugged than something intended only for emergencies. Of course, the purely emergency equipment is likely simpler to use and more reliable than regular equipment, if only because it isn't used until an emergency.
Some more unusual light sources include radioactive isotopes in phosphor-lined capsules. The radiation source is usually tritium, which has a half life of twelve and a third years. This application is not as exotic as it sounds. The technology behind this is rugged and safe, and has been used for decades to provide illumination for firearm night sights, watches and many other items. However, these lights are expensive, and not really appropriate for area illumination.
Of course, some isotopes glow on their own, a few purely from the heat they release. The safest of the latter is plutonium 238. Decaying plutonium primarily gives off alpha particles, which are stopped by a few inches of air or the layer of dead cells on the outside of your skin. That's right; you can hold a chunk of plutonium in your hand with little danger from ionizing radiation. From that cause, plutonium only becomes a serious health risk when it comes in direct contact with living tissue. Of course, with Plutonium 238 there is another risk. This is so active it glows a dull red from the heat of its decay. While such a lump could be used directly to create illumination, far more common is to use that heat to generate electricity. That is then used to produce light or perform whatever other task is needed.
This leads us to the very exotic realm of radio thermal generators, or RTGs. These have had some terrestrial use, but their most common application by a huge margin is for space probes going places where photovoltaic panels aren't practical. The New Horizons probe to Pluto is a prime example. These units are simple heat engines, and not nuclear reactors. They contain a radioactive heat source - usually plutonium 238 - and that natural heat is used to generate electricity. Pu 238 has a half life of 87.7 years, so is not the limiting factor on service life. (The Voyager probes' RTGs have gradually deteriorated in output, but that is mostly due to other factors.
Hand-cranked flashlights have been around for decades, but most have not been very functional. Today, with better rechargeable batteries, high-rating capacitors and high-efficiency superultrabright white LEDs the better quality ones are quite practical for short-term illumination needs. Many can also be charged by other means - such as a photovoltaic panel or a variety of plugs. Once charged (however you do it) they can even be used to charge a cell phone or other device.
Given the huge variety of various types of good quality, affordable illumination available today, there's no excuse not to have something on hand when needed. Or, better, several somethings.
This document is Copyright 2014 Rodford Edmiston Smith. Anyone wishing to repost it must have permission from the author, who can be reached at: firstname.lastname@example.org