Lightning is a sudden electrostatic discharge that occurs typically during a thunderstorm. This discharge occurs between regions of a cloud(called intra-cloud lightning or IC), between two clouds (CC lightning), or between a cloud and the ground (CG lightning).
The charged regions in the atmosphere temporarily equalize themselves through this discharge referred to as a flash. A lightning flash can also be a strike if it involves an object on the ground. It creates light in the form of black body radiation from the very hot plasma created by the electron flow, and sound in the form of thunder. It may be seen and not heard when it occurs at a distance too great for the sound to carry as far as the light from the strike or flash.
Lightning is a flow of electricity, and as such cannot be stored. But it may eventually be possible to store the huge amount of electric charge that comes down during lightning discharges. No one as yet has perfected the technology for that.
To capture each and every lightning strike (land strikes only) we would most likely have to put extremely tall towers (think Eiffel tower) around a mile apart in a grid formation covering the entire globe. Yes, the entire globe as many strikes occurs over the oceans and seas. That is one tower for each of the almost 200,000,000 square miles of the earth’s surface.
Although in comparison, one hour of sunlight has the same amount of energy that we use in a year! We have much more power available from the sun and we only need our rooftops to accumulate all we need. Especially with the advances and improvements being made with solar panel efficiency.
Most places receive lightning very infrequently but have a steady demand for electrical energy. The smaller the area you look at the fewer the lightning strikes will hit within that area per unit time. If you build some kind of device it has to be big enough to get hit by enough lightning strikes to supply the desired energy. If it gets hit once every ten years or so, you could be waiting a long time for a return on your investment. Bulky devices cost more.
Lightning has a high voltage but not a huge amount of current. Controlled sources of electrical energy typically want the other way around — lots of current at lower voltages. 120V AC is what consumers can use, and they want a steady supply of it. Voltage and phase should not drift over time. Lightning can give you tens of thousands of volts over a few milliseconds and then be gone for the rest of the day. The lightning strike may damage the equipment, and still not have as much energy as we’d like to use. The problem is that the energy is deposited all at once, instead of spreading out over time.
Much of the energy of the lightning discharge goes into heating up the air and making it glow. The available energy at the ground is just the amount of energy required to get the electrons into or off of the ground surface.
Though there are some things you might do to harvest energy from atmospheric electricity that does not involve attracting lightning strikes. A tall lightning rod with a sharp tip will have a small current flowing from its tip, and a bigger one during a storm. Since air is a not-too-bad insulator when it’s not undergoing electrical breakdown, it is hard to make a complete circuit from which you can extract energy. A conducting object (like a person, or a skyscraper) easily modifies the electric field in its vicinity.
In 2007, a company called Alternative Energy Holdings tried to make it happen, with a design that involved a tower, grounding wires and a capacitor but failed to ensure success in terms of high efficiency.