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This creates a limit to the amount of heat energy that can do work in a cyclic process, a limit called the available energy. Mechanical and other forms of energy can be transformed in the other direction into thermal energy without such limitations. [14] The total energy of a system can be calculated by adding up all forms of energy in the system.
As an energy source, biomass can either be used directly via combustion to produce heat, or converted to a more energy-dense biofuel like ethanol. Wood is the most significant biomass energy source as of 2012 [ 103 ] and is usually sourced from a trees cleared for silvicultural reasons or fire prevention .
An energy transition is a broad shift in technologies and behaviours that are needed to replace one source of energy with another. [14]: 202–203 A prime example is the change from a pre-industrial system relying on traditional biomass, wind, water and muscle power to an industrial system characterized by pervasive mechanization, steam power and the use of coal.
GCSE Bitesize was launched in January 1998, covering seven subjects. For each subject, a one- or two-hour long TV programme would be broadcast overnight in the BBC Learning Zone block, and supporting material was available in books and on the BBC website. At the time, only around 9% of UK households had access to the internet at home.
The molar heat capacity is the heat capacity per unit amount (SI unit: mole) of a pure substance, and the specific heat capacity, often called simply specific heat, is the heat capacity per unit mass of a material. Heat capacity is a physical property of a substance, which means that it depends on the state and properties of the substance under ...
The BBC Learning Zone (previously The Learning Zone) was an educational strand run by the BBC as an overnight service on BBC Two. It broadcast programming aimed at students in Primary, Secondary and Higher Education as well as to adult learners.
In the winter of 2011–12, the benefit cost the UK Government £2.1 billion and was paid out to 12.7 million people. [17] It was criticised by Paul Burstow (former care services minister) in 2013 for its lack of targeting, Burstow saying that "80% of older people do not require [the benefit]" and proposing that it be only given to pensioners ...
At the heat source of a system of natural circulation, the heated fluid becomes lighter than the fluid surrounding it, and thus rises. At the heat sink, the nearby fluid becomes denser as it cools, and is drawn downward by gravity. Together, these effects create a flow of fluid from the heat source to the heat sink and back again.