Business

Study shows regulators are allowing utilities higher returns

For many years, all electric utilities in the U.S. were regulated monopolies. Although some states deregulated electricity generation over the past 20 years, electric utility companies in other states today remain monopolies. ...

Energy & Green Tech

Calcium batteries: New electrolytes, enhanced properties

Calcium-based batteries promise to reach a high energy density at low manufacturing costs. This lab-scale technology has the potential for replacing lithium-ion technology in future energy storage systems. Using the electrolytes ...

Energy & Green Tech

Chilled electricity

It should be possible to generate electricity and refrigerate simultaneously using low-grade waste heat from industry, according to research published in Progress in Industrial Ecology, An International Journal. The key is ...

Energy & Green Tech

Three challenges to wind energy potential

Wind energy researchers from the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) are among a team of authors inviting the scientific community to address three challenges that will drive the innovation ...

Engineering

Mobile phone signals provide occupancy numbers for buildings

Buildings currently consume about 40 percent of all the electricity used in the United States, most of them located in urban areas that are growing rapidly. Because electricity generation is the largest source of greenhouse ...

Energy & Green Tech

Li-ion batteries: Science 'directly into your hand'

They are omnipresent and essential to navigating modern life. Small, light, rechargeable: lithium ion batteries have revolutionised our world in less than three decades.

Robotics

Deep-learning method to design fly-like robots

"Just think about what a fly can do," says Professor Pavan Ramdya, whose lab at EPFL's Brain Mind Institute, with the lab of Professor Pascal Fua in EPFL's Institute for Computer Science, led the study. "A fly can climb across ...

Energy & Green Tech

A new water-splitting technique to generate clean hydrogen

Electrolytic hydrogen production entails the generation of hydrogen from water using electrical power, which should ideally come from renewable power sources such as sunlight and wind. Although this method of producing hydrogen ...

Energy & Green Tech

Wind power from the sky

Anyone who has ever steered a child's kite knows the feeling: The wind grips the kite and pulls the string. The string is quickly tensioned, the spindle rotates between the fingers and is difficult to control. The question ...

page 1 from 23

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.

This text uses material from Wikipedia, licensed under CC BY-SA