At least in one thing plants are a lot smarter than humans. Over billions of years, they developed perhaps the most efficient power supply in the world: photosynthesis, or the conversion of sunlight, carbon dioxide and water into usable fuel, emitting useful oxygen in the process. In the case of plants (as well as algae and some bacteria), "usable fuel" is carbohydrates, proteins and fats. Humans, on the other hand, are looking for another type of energy. For years, scientists have been trying to come up with a way to use the same energy system that plants do but with an altered end output.
The energy available in sunlight is an untapped resource we've only begun to really get a handle on. Current photovoltaic-cell technology, typically a semiconductor-based system, is expensive, not terribly efficient, and only does instant conversions from sunlight to electricity -- the energy output isn't stored for a rainy day. Fossil fuels are in short supply, and they're contributing to pollution and global warming.
Artificial photosynthesis, changing the way we power our world
An artificial processes that mimics what happens in plants could potentially create an endless, relatively inexpensive supply of all the clean "gas" and electricity we need to power our lives - and also in a storable form. But for an artificial system for human needs, the output has to change. Instead of releasing only oxygen at the end of the reaction, it would have to release a biogas, like liquid hydrogen (or perhaps methanol) as well.
That hydrogen could be used directly as liquid fuel or channeled into a fuel cell. Getting the process to produce hydrogen is not a problem, since it's already there in the water molecules. And capturing sunlight is not a problem - current solar-power systems do that.
There have been important advances in this area in the last five or ten years. Once perfected, these systems could change the way we power our world. Nowadays, while artificial photosynthesis works in the lab, it's not ready for mass consumption. Replicating what happens naturally in green plants is not a simple task. Source: http://goo.gl/LLEyCD