While farming and domestication was primarily intended to supply a steady source of food for cultures previously living off of the land, the fact is that these practices have probably saved numerous species and environments. Case in point: the buffalo of the American West. Imagine what would have happened if all of the settlers moving into the West had depended on the buffalo for sustenance instead of creating cattle ranches. While sport hunting did deplete the buffalo's numbers, mass consumption may have wiped them out completely.
Other than geothermal power and power derived from radioactive elements, almost all energy on Earth originated at some point from the sun. The sun is Earth's powerplant, constantly bathing the planet in the energy required for photosynthesis and life as we know it. Photovoltaic cells can capture the sun's energy directly and convert it into powering electrical currents. This reduces our use of fossil fuels that pollute the environment.
Corn ethanol was a step in the right direction for biofuels, but cellulosic ethanol stands to change the world energy paradigm as we know is. Cellulosic ethanol can be produced from almost any kind of plant, including the weed-like switchgrass that grows throughout the American prairies. While cellulosic ethanol does require an additional step to convert the plant cellulose to a useable material, ultimately, it will end up costing far less than corn ethanol while remaining almost infinitely sustainable. Better yet, the plants that work best for this process are dry, stick-like flora that contain very little water. As such, the American fuel market won't have to trade hundreds of gallons of irrigation water to supply relatively little fuel.
Recently used to help clean the Gulf oil spill, these devices are fantastically efficient at removing oil from water. Consisting of a large, spinning drum, centrifugal oil separators effectively accelerate gravity separation by drastically increasing the G forces acting upon the water. This forces water -- which is denser -- to the outside of the drum, where it gets pushed out and ejected back into the ocean. The separated oil stays in the middle and flows down into a reclamation tank. One benefit to this approach is that centrifugal separators can run almost continuously, requiring very little down-time or energy input.