Renewable energy is energy from renewable resources that are naturally replenished on a human timescale. Renewable resources include sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy sources are sustainable, some are not. For example, some biomass sources are considered unsustainable at current rates of exploitation. Renewable energy is often used for electricity generation, heating and cooling.
Intermediate consumption (also called "intermediate expenditure") is an economic concept used in national accounts, such as the United Nations System of National Accounts (UNSNA), the US National Income and Product Accounts (NIPA) and the European System of Accounts (ESA). Conceptually, the aggregate "intermediate consumption" is equal to the amount of the difference between gross output (roughly, the total sales value) and net output (gross value added or GDP). In the US economy, total intermediate consumption represents about 45% of gross output.
Fumed silica (CAS number 112945-52-5), also known as pyrogenic silica because it is produced in a flame, consists of microscopic droplets of amorphous silica fused into branched, chainlike, three-dimensional secondary particles which then agglomerate into tertiary particles. The resulting powder has an extremely low bulk density and high surface area. Its three-dimensional structure results in viscosity-increasing, thixotropic behavior when used as a thickener or reinforcing filler.
Gross domestic product (GDP) is a monetary measure of the market value of all the final goods and services produced in a specific time period by a country or countries. GDP is most often used by the government of a single country to measure its economic health. Due to its complex and subjective nature, this measure is often revised before being considered a reliable indicator. GDP definitions are maintained by several national and international economic organizations.
Precipitated silica is an amorphous form of silica (silicon dioxide, SiO2); it is a white, powdery material. Precipitated silica is produced by precipitation from a solution containing silicate salts. The three main classes of amorphous silica are pyrogenic silica, precipitated silica and silica gel. Among them, precipitated silica has the greatest commercial significance. In 1999, more than one million tons were produced, half of it is used in tires and shoe soles.