Energy & Green Tech

Low-cost catalyst boosts hydrogen production from water

A future powered by carbon-free fuel depends on our ability to harness and store energy from renewable but intermittent sources, such as solar and wind. Now, a new catalyst developed at University of Toronto Engineering gives ...

Energy & Green Tech

'Sun in a box' would store renewable energy for the grid

MIT engineers have come up with a conceptual design for a system to store renewable energy, such as solar and wind power, and deliver that energy back into an electric grid on demand. The system may be designed to power a ...

Energy & Green Tech

Best hope yet for aluminium-ion batteries

UNSW Sydney's Dr. Dong Jun Kim has led a team of researchers to show rechargeable aluminium-ion batteries are a possibility with a future in renewable energy storage.

Energy & Green Tech

Why aren't there electric airplanes yet?

As electric cars and trucks appear increasingly on U.S. highways, it raises the question: When will commercially viable electric vehicles take to the skies? There are a number of ambitious efforts to build electric-powered ...

Energy & Green Tech

Coordinated development could help wind farms be better neighbors

As onshore and offshore wind energy farms have proliferated globally in recent years, new research led by the University of Colorado Boulder highlights a previously underexplored consequence: a wake effect from upwind wind ...

Energy & Green Tech

Real-time feedback makes hotel guests slash shower power

Providing hotel guests real-time feedback on the power they use in the shower sharply curbs the amount of energy consumed even though they do not pay for it, according to new research released Monday.

Energy & Green Tech

Explaining the plummeting cost of solar power

The dramatic drop in the cost of solar photovoltaic (PV) modules, which has fallen by 99 percent over the last four decades, is often touted as a major success story for renewable energy technology. But one question has never ...

Energy & Green Tech

Brick by brick, a solution seeking to topple energy storage roadblock

A nagging question as the year gets closer to the very end. The wind is there. The water is there. The sun is there. How is it that we are still so far off in fossil-fuel land? Farms, plants, rigs later, those in the renewables ...

Energy & Green Tech

Mining bitcoin uses more energy than Denmark: study

Extracting a dollar's worth of cryptocurrency such as bitcoin from the deep Web consumes three times more energy than digging up a dollar's worth of gold, researchers said Monday.

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Energy

In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working") is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law. Different forms of energy include kinetic, potential, thermal, gravitational, sound, light, elastic, and electromagnetic energy. The forms of energy are often named after a related force.

Any form of energy can be transformed into another form, but the total energy always remains the same. This principle, the conservation of energy, was first postulated in the early 19th century, and applies to any isolated system. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.

Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy relative to the Earth.

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