Renewable Energy

Wind and solar are powering a clean energy revolution.
Renewable power is booming, as innovation brings down costs and starts to deliver on the promise of a clean energy future. American solar and wind generation are breaking records and being integrated into the national electricity grid without compromising reliability.

This means that renewables are increasingly displacing “dirty” fossil fuels in the power sector, offering the benefit of lower emissions of carbon and other types of pollution. But not all sources of energy marketed as “renewable” are beneficial to the environment. Biomass and large hydroelectric dams create difficult tradeoffs when considering the impact on wildlife, climate change, and other issues. Here’s what you should know about the different types of renewable energy sources—and how you can use these emerging technologies at your own home.

What Is Renewable Energy?
Renewable energy, often referred to as clean energy, comes from natural sources or processes that are constantly replenished. For example, sunlight or wind keep shining and blowing, even if their availability depends on time and weather.

While renewable energy is often thought of as a new technology, harnessing nature’s power has long been used for heating, transportation, lighting, and more. Wind has powered boats to sail the seas and windmills to grind grain. The sun has provided warmth during the day and helped kindle fires to last into the evening. But over the past 500 years or so, humans increasingly turned to cheaper, dirtier energy sources such as coal and fracked gas.

Now that we have increasingly innovative and less-expensive ways to capture and retain wind and solar energy, renewables are becoming a more important power source, accounting for more than one-eighth of U.S. generation. The expansion in renewables is also happening at scales large and small, from rooftop solar panels on homes that can sell power back to the grid to giant offshore wind farms. Even some entire rural communities rely on renewable energy for heating and lighting.

As renewable use continues to grow, a key goal will be to modernize  electricity grid, making it smarter, more secure, and better integrated across regions.

Die "Blaue Stunde"

Der Begriff blaue Stunde bezieht sich auf die besondere Färbung des Himmels während der Zeit der Dämmerung nach Sonnenuntergang und vor Eintritt der nächtlichen Dunkelheit. Besonders geprägt wurde der Begriff von Schriftstellern und Dichtern, die ihn häufig mit melancholischen Gefühlen assoziieren.Dieselbe Färbung ist auch während der Morgendämmerung zu sehen, allerdings wird der Begriff in diesem Zusammenhang seltener verwendet. Das Blau des Himmels hat eine andere spektrale Zusammensetzung, da es auf eine andere physikalische Ursache als bei Tage zurückzuführen ist. Während der blauen Stunde besitzt dieser tiefblaue Himmel etwa dieselbe Helligkeit wie das künstliche Licht von Gebäude- und Straßenbeleuchtungen.