I am fascinated by the ever growing ways of harvesting energy. Let me give you two examples.
We got used to wind turbines, they are becoming more and more part of the landscape in windy areas, they are huge and sometimes they upset people leaving nearby for their noise. Their output is in the (single digit) MW and they often come in cluster (wind farms). They work best with wind speed in the order of 8-10m/s and their "blades" speed is amazingly fast, up to 320km per hour (you may not realise that but this is actually the speed reached by the tip of the blade.
Technology is now making possibile to create much smaller wind turbine, like the ones proposed by the French company NewWind. As you can see in the photos and in the video clip they are proposing an "artificial" tree whose leaves are mini turbines. They are effective with wind speed of just 2m/s (4-5 times lighter than the one needed for their giant siblings) and a "tree" can produce 4 kW (300-1,000 times less than the big wind turbine). Each tree has 72 "aeroleaves" and the current cost for a "planted" tree is slightly less than 30,000€, but the price is expected to decrease significantly as sale volume increases.
With 4kW you can power a home in Italy. Just imaging living in an area where you normally have breeze (like most places by the seashore in Italy or in mountain valleys) and you can "plant" one of these trees in your courtyard mingling inconspicuously among the other trees already there. You may not meet all your energy needs (the breeze sometimes is not there) but probably most of them.
So far there are very few trees installed, mostly because of their price, but I like this idea of producing electrical power with something that can become part of our landscape without "intruding" into it.
Another example is technology that can transform our windows into power generators like the one provided by SolarWindow.
There are actually a variety of different technologies that can transform a surface into an electricity generator by converting the sunlight. Photovoltaic is clearly an example but what interest me most are technologies that can piggy back on existing surfaces without being perceived, like the one shown in the video clip: a transparent layer that can be overlaid on windows panes, including the Windows that run under your laptop screen (and it is clearly OS independent so, yes, you can use it on OS X too!). Solar Wind claims that the investment will pay back in just a year for an installation of film covering a skyscraper.
Indeed the solar energy we are receiving on our planet every day from the Sun is thousands of times bigger than the one we use for all our energy needs. And even if we have converter with an efficiency of just 10% (only 10% of the energy present in Sun light hitting the surface is converted into usable energy) and we use just 1% of our Planet surface we would have much more energy available than what we need.
The catch is actually the cost: it is not competitive with the cost of energy derived from fossil fuel (and storing electrical energy is way more complicated, and costly, than storing fossil fuel energy).
Hence, no silver bullet. Yet, the idea that we can produce power through our windows is quite interesting to me.