A Fresnel lens can be characterized as the "flat screen" version of a magnifying glass, and has the ability to project focused light. A conventional magnifying glass design can do the same thing, of course, but at the scale of a lighthouse, a gigantic conventional lens would be somewhat costly and unwieldy. A Fresnel lens is far lighter and cheaper to produce and install than a conventional lens of similar magnification power. Such lenses do have the drawback, though, that they distort the image that they project. This would be bad if you were trying to use a Fresnel lens in an application where image correctness was critical. However, if the "image" you are projecting is merely a bunch of bright white light, then scrambling it up a bit will have no practical effect on the outcome.
Now, a crazy, way-outside-the-box solution to storage of energy for later use is to simply project the energy through time to the time in which it is needed. Well, maybe not "simply", and not using a Fresnel lens, of course. But, as with the innacuracy of the Fresnel lens, if we consider that the projection - through time - of energy or matter may have limitations in accuracy or resolution with early technologies, then it becomes apparent that an early application of such fledgling technologies might be the projection of amorphous volumes of energy (or matter) - where a certain predictable level of "jumbling" is acceptable and will not diminish the value of the outcome and the practical usefulness of the technology.
Projecting light with the Fresnel lens, the lighthouse is effective if it is designed and placed so that the beam of light is not obstructed by cliffs and rocks in its path, allowing the light to reach its destination, so that the lighthouse is visible to ships and, therefore, useful. Similarly, when projecting energy through time, it would be useful if that energy were not to be obstructed at any point as it "traveled" in the fourth dimension. This might be best accomplished if the device containing the energy creates a safe enclosure around the energy, not merely to contain it in the present, but also to enclose a safe region in space through which the energy can travel in time - without risk of obstruction. A device that projects energy through time provides an enclosure that encapsulates and safeguards that energy as it travels, but also acts as the means to tap the traveling energy at its destination time, - so, effectively, a portal that provides an entry point and an exit point for energy to travel from one time to another.
Ironically, it sounds almost as though one is describing a battery here. It's an enclosure into which energy can be input, and out of which energy can be tapped at some time in the future, when that energy is needed. Storage of water for future use is done in a reservior or dam. Storage of electrical energy for future use is done using a battery, or by the capturing of potential energy in a stable form of matter - through a process that consumes energy to transform a material, which transformed material can then be stored in a reservior - for future transformation back to its original state with an accompanying release of the captured potential energy.
In practical terms, a "time battery" may appear to behave much like a chemical battery, ultracapacitor, fuel cell, etc. At some level, it's just a black box. However, a subtle difference might be the need to choose - at the source time - a target time for the release of the energy. This then would be less of an on-demand access model, and more of an estimated/anticipated demand model. In other words, it might not be possible for the target time to control how much energy is projected to it. An estimate would be made - at a source time - of the amount of energy that should be transmitted to a target time. This estimate may be accurate enough to be practically useful, but more or less energy than what the target time actually needs might be available to it, and a shortfall would need to be supplemented for. Inaccuracies of demand prediction over time could be smoothed over with other, more conventional storage and recovery technologies.
One of the challenges with renewable energy technologies - such as wind and solar - is providing consistent supply to users when there is not consistent capturing from the energy source. One really wants to store the excess energy being captured from sunlight during the day, so that it can be used in the evening when there is no supply from the source. But what if we think of this problem differently - not one of storage, but one of projection of the energy to when it is needed. Will breakthroughs in our understanding of physics make it possible to temporally project energy, rather than storing it? Or is this just stating the same thing in different terms?
This is the stuff of science fiction, but fun to think about. When we think of time travel, we may be misled by romanticized notions of people leapfrogging from one period in human history to another. But, were technologies to become viable, their immediate practical applications might be much less sophisticated, involving relatively crude applications - such as the transfer of energy to anticipated times of demand, or primitive, morse code like communication. The sun acts like a giant, cosmic lighthouse - projecting energy to Earth that feeds plant life and the solar panels on our roofs. We might someday be able to establish beacons for the projection of energy from one time to another.