Energy & Green Tech

Answer to energy storage problem could be hydrogen

Hydrogen has the greatest potential among technologies for seasonal energy storage in the future, according to an analysis conducted by researchers at the National Renewable Energy Laboratory (NREL).

Energy & Green Tech

Water vapor in the atmosphere may be prime renewable energy source

The search for renewable energy sources, which include wind, solar, hydroelectric dams, geothermal, and biomass, has preoccupied scientists and policymakers alike, due to their enormous potential in the fight against climate ...

Computer Sciences

Engineers offer smart, timely ideas for AI bottlenecks

Rice University researchers have demonstrated methods for both designing innovative data-centric computing hardware and co-designing hardware with machine-learning algorithms that together can improve energy efficiency by ...

Energy & Green Tech

Dye-sensitized solar cells that adapt to different light conditions

Solar cells made of semi-transparent photovoltaic (PV) materials typically have a fixed optical transmission, which results in either high transparency or high efficiency, but rarely both. In order to perform optimally when ...

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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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