For many people, it's difficult to imagine what an electromagnetic pulse (EMP) event could do to modern society. People are, after all, dependent on electronics and power grids to supply them with energy.
Electronic devices are likely to let you down after an EMP event, so you're going to have to go old-school.
Battery-powered flashlights. It is unlikely for an EMP event to damage older flashlights or discharge batteries, as long as they are not installed. What this means is that having flashlights on standby as well as a supply of batteries to fuel them should be good for preppers, as it remains to be the handiest light source in the wake of such an event. However, it is important to note that these should be a traditional, incandescent bulb flashlight, as LED flashlights, being small circuits, may not survive an EMP event.
Liquid-fueled lanterns. Lanterns are easy to carry and are reliable for almost any lighting purpose. There are different kinds of lanterns that use different kinds of fuel, however, modern lanterns rely upon white gas or "camp fuel." Kerosene lanterns are also popular but are not always easy to come by. Instead, use butane, which is an affordable and stable alternative. Remember that you have to be careful with liquid-fueled lanterns because they prove to be extreme fire hazards.
Candles. Used by kings and paupers alike, we can enjoy plenty of candles today for ambiance and practicality. You should be able to buy different sorts of candles in great abundance in any grocery or department store. However, not all candles are created equal, and it is important that your emergency candles can provide you with an excellent return while minimizing indoor pollution. The biggest problem with candles is that it presents an open flame, which makes it a fire hazard, but also, it easily gets put out by drafts of wind. Instead of relying on candles fully, you may want to limit their use to small bathrooms and rely on other lighting materials for larger areas of the home.
Torches. The humble torch is still relevant to use, especially for EMP scenarios. Just a stick with a wad of combustible material affixed at the top end, torches have been lighting our way. Despite being a primitive piece of technology, improvements were made to the torch over the years. Torches can be prepared ahead of time, or they can be improvised easily using anything that is close at hand. With a basic understanding of torch construction and illumination, you can fashion one that can burn for some time.
Flares. These pyrotechnic devices can produce extremely bright, vivid light for fifteen minutes to half an hour. This is good for emergency signaling, especially in highway safety situations, as well as for indicating distress at sea. However, there are some drawbacks to using them in terms of personal illumination. Flares are fairly easy to come by and are long-lasting, making them great to use for EMP events.
In case of an EMP event that can completely knock out the power grid, the most traditional lighting solutions prove to be the most useful during this potential catastrophe.
Mankind has relied on different lighting tools for years and we can rely on them once more when the situation calls for it.