Being able to create fire on demand is an essential part of any survival plan. Fire is used not only for heat, in some cases light, as a deterrent to insects and animals in outdoor situations, but also for cooking and water sterilisation. Heating food and water kills the great majority of parasites and diseases, renders food easier to eat, tastier and also arguably releases more accessible energy from food.
Creating a fire requires the obvious elements - a supply of fuel, air (for oxygen) and an ignition source. Whilst fires can be started using primitive techniques like steel and flint or fire-drill or other 'romantic' wilderness methods, in practice these are hard, uncertain and require considerable skill and practice (this author has tried most of them): you do not want them as your main approach.
By far the best way to light your fire is with a ready source of flame. The recommended source of flame is a disposable (or refillable) gas lighter, these things are ubiquitous, available in bulk packs and smaller, easier to use and less expensive even than matches which are susceptible to damp. The refillable 'turbo' or 'jet' (often described as windproof or cigar/pipe lighters) kind are slightly to be preferred over the very low cost disposable variety because they are much harder to blow out and you can direct the flame onto recalcitrant kindling. A stock of low-cost gas lighters is an essential component in any survival kit and thrift stores as well as Ebay or Amazon offer a vast range.
Get a stock of these now and distribute them about your person and property. Vendors often sell packs of five or ten for less than the cost of a takeaway coffee. There's no excuse for not having many more of them than you need. If you get the refillable kind, get a refill gas canister or two at the same time. If you plan to carry them when hiking or outdoors, put them in a resealable plastic bag to keep water out. Unless there's a reason not to (airport security frowns on them) make sure that it's hard for you to go out without one. They are so cheap you can distribute them liberally.
Preparing for emergencies should aim above the hiking camp-fire kind of cooking, which we'll come to later. You may wish to ensure you have several options open to you and should consider several of the following:
Whichever type of cooker you choose, keep a stock of fuel, of course.
Camping-style stoves are available in a range of fuel types as follows:
Both Kerosene and Diesel find use in oil-fired heating  . If you already use oil heating, your tank is a valuable source of fuel and it would make sense to have fallback cooking options which also use it. In the UK at least, most heating oil is Kerosene, though some is the heavier variety almost identical to Diesel (except dyed to prevent its use as road fuel). If your cooker uses the same fuel as your transport then your fuel stores potentially become dual purpose.
UK readers may be interested to know that Weights and Measures legislation prohibits delivery of quantities less than 500 litres to customer tanks.
Being prepared means not just having the equipment but also being familiar with using it. Scheduling one meal a month, or taking reasonably regular camping/hiking expeditions where you use the equipment in practical situations is highly advisable. You learn, for example, just how important windbreaks are if you are cooking outdoors. Cooking indoors might be your solution but warning charcoal fires in particular are deadly indoors or even in an enclosed tent. Cooking with any of these devices should never be done in enclosed spaces.
At some point you may find that you need to resort to camp-fire style cooking, burning wood scavenged from whichever source you can manage.
Although it's not a difficult skill to learn there is nonetheless a considerable art to building a suitable fire, in particular having it light first time in damp or wet conditions. It's not a subject we propose to cover here yet but this is a topic you should inform yourself about.
To be suitable for cooking your fire needs to get over the early stages of burning and to produce a bed of embers which glow red. This is the useful stage of a fire and is in practice the same as a charcoal barbecue, since the wood has become charcoal by this stage. This stage is typically half an hour or so after lighting the fire so a camp fire from collected wood is not usually a quick solution to making a hot drink or meal.
If you can't carry a gas lighter or dry matches (but why bother with matches?) you may have to revert to more difficult techniques. These come in a range of desirabilities which we'll cover in roughly descending order.
For all of these you are likely to need tinder and kindling. The distinction between the two is broad and not absolute.
Tinder is very dry, typically fine material, often charred or semi-charred cloth, friable wood, plant fibres or similar. The key thing about tinder is that it will take the smallest spark and start to glow - it forms an ember, not a flame.
One of the very best tinders is charcloth - cotton or linen cloth (not synthetic material) that's been heated to charring point in an oxygen-free atmosphere. As its name suggests it's essentially cloth charcoal. It's easy to make by cutting an old cotton t-shirt into small squares, putting them into a tin can with a lid that's had a small hole punched in it to let gases out, then heating the tin and cloth to about red heat in a fire. Once cool, you have numerous squares of very fragile charcloth.
A small spark can be enough to create the glowing ember in your tinder. By carefully folding the tinder around the ember you can then gently blow on the ember and cause it to grow until the whole piece of tinder is glowing red to yellow-hot. A certain amount of skill and practice is required to get good at this. You will not usually get a flame from your tinder, that's the next phase.
Kindling is very dry plant material which lights easily. The fluffy seed-heads of flowers such as thistles are often good kindling as can be fine grass stalks, dried leaves and many other similar materials.
You will typically have already made a ball of kindling the size of a grapefruit (reasonably tightly packed), made a depression in it and then you transfer your glowing tinder ember into the depression, folding the kindling carefully around the ember. At this point you blow onto the ember to make it hotter, pause so the heat from the ember chars the kindling, then blow again. Several stages of this take place as the kindling first chars, then becomes an ember itself and then finally (you hope) bursts into flames. This is not a hard process to learn but there is skill in it nonetheless. Once you have flames, you transfer the flame to your fire - usually rapidly as you are by now holding the burning ball of kindling in your hand.
A handy kindling/firelighter combination to carry is cotton wool makeup-removal pads half-dipped in molten vaseline (or vaseline rubbed into half). They will easily light from a gas lighter or firesteel (see below) and the vaseline-dipped part burns like a barbecue lighter. These are highly recommended. They are messy but carry well in a resealable plastic bag. There's no such thing as too many.
In order of preference for lighting the tinder we suggest:
There are other primitive fire lighting techniques such as fire drill and fire plough which tend to be emphasised in bushcraft/survival guides and courses. It does no harm to learn all the techniques available if you have the time.
In emergency conditions heat is likely to be needed. Anyone who has used an open camp fire for heat will be familiar with the prodigious quantities of fuel needed to warm a group of people. Most of the heat goes into warming the atmosphere for little benefit. The closer you can get to the fire the more of its radiant heat you can absorb but the hot gases produced are essentially lost to the atmosphere.
Solid-fuel open fires in rooms with chimneys were traditionally used for heating for many years. These have a similar problem to outdoor fires in that much of the heat is lost up the chimney whereas in general enclosed fires designed for efficiency make better use of fuel. The combustion products from solid fuels mandate the use of a chimney or some similar way of venting smoke to the atmosphere, something which cannot be avoided. Whilst your property may use other methods as the main source of heating, being able to fall back to an efficient solid-fuel fire in emergencies is clearly a desirable option when combined with suitable stocks of fuel.
A useful backup to a solid fuel fire is one of the many portable kerosene fires which are available. Kerosene is the fuel of choice for these as gasoline is very hazardous for indoor use and diesel produces an unpleasant smell. Kerosene fires are designed to burn and vent into living space without the use of a chimney. They burn with little smell and low risk of harmful combustion by-products although safety advice should always be followed.
There is an obvious dual-fuel benefit to be obtained if kerosene fuel can be used for both heating and cooking purposes.
Fire also has the useful by product of light, which both helps lift the spirits and extend the productive day. Oil lamps date back into prehistoric times and candles somewhat later.
Candles can often be obtained at very reasonable prices, form an important part of an emergency plan and are easily stored. The larger ones in glass containers may also be improvised heat sources for cooking in extreme situations.
Kerosene-burning oil lamps with wicks remain available from specialist suppliers. They range from traditional 'cottage' style wick-based lamps through to pressurised vaporising types sometimes known as 'Tilley' or 'Petromax' lamps. These have remained popular in camping and off-grid environments.
The efficiency of modern LED lamps makes solar-charged, battery powered and wind-up torches/lanterns an essential component in the mix of emergency lighting provision. A drawback to lanterns and torches is that carrying them takes up one hand, a problem removed by the development of powerful LED based head-mounted torches. Provided care is taken to ensure that the batteries are kept up to date, head torches become an important component in the emergency kit.