Energy & Green Tech

Green roofs are worth the cost for urban residents

Plant-covered roofs have become a regular sight in Portland, Oregon. The city is a leader in incorporating green infrastructure for stormwater management, including free street trees, rebates for small residential housing ...

Energy & Green Tech

In Iceland, CO2 sucked from the air is turned to rock

At the foot of an Icelandic volcano, a newly-opened plant is sucking carbon dioxide from the air and turning it to rock, locking away the main culprit behind global warming.

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

These solar panels pull in water vapor to grow crops in the desert

Using a unique hydrogel, scientists in Saudi Arabia created a solar-driven system that successfully grows spinach by using water drawn from the air while producing electricity. The proof-of-concept design, described March ...

Engineering

Next-gen heat pump could cut energy bills and carbon emissions

Researchers from the University of Glasgow have developed a new type of heat pump, a flexible heat pump technology, which could help households save on their energy bills and contribute towards net-zero emissions goals.

page 1 from 40

Water

Water is a ubiquitous chemical substance, composed of hydrogen and oxygen, that is essential for the survival of many known forms of life. In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71% of the Earth's surface. On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Saltwater oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured products. Other water is trapped in ice caps, glaciers, aquifers, or in lakes, sometimes providing fresh water for life on land.

Water moves continually through a cycle of evaporation or transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea. Over land, evaporation and transpiration contribute to the precipitation over land.

Clean, fresh drinking water is essential to human and other lifeforms. Access to safe drinking water has improved steadily and substantially over the last decades in almost every part of the world. There is a clear correlation between access to safe water and GDP per capita. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70 percent of freshwater is consumed by agriculture.

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