The symbol "kWh" is commonly used in commercial, educational, scientific and media publications,4 and is the usual practice in electrical power engineering. Other abbreviations and symbols may be encountered: "kW h" is less commonly used.
The international standard for SI states that in forming a compound unit symbol, "Multiplication must be indicated by a space or a half-high (centered) dot (?), since otherwise some prefixes could be misinterpreted as a unit symbol" (i.e., kW h or kW?h).
This is supported by a voluntary standard6 issued jointly by an international (IEEE) and national (ASTM) organization.However, at least one major usage guide and the IEEE/ASTM standard allow "kWh" (but do not mention other multiples of the watt hour). One guide published by NIST specifically recommends avoiding "kWh" "to avoid possible confusion". The US official fuel-economy window sticker for electric vehicles uses the abbreviation "kW-hrs". Variations in capitalization are sometimes seen: KWh, KWH, kwh etc. "kW?h" is, like "kW h", preferred with SI standards, but it is very rarely used in practice. The notation "kW/h", as a symbol for kilowatt-hour, is not correct. Źródło: https://en.wikipedia.org/wiki/Kilowatt_hour
Although electricity had been known to be produced as a result of the chemical reactions that take place in an electrolytic cell since Alessandro Volta developed the voltaic pile in 1800, its production by this means was, and still is, expensive.In 1831, Michael Faraday devised a machine that generated electricity from rotary motion, but it took almost 50 years for the technology to reach a commercially viable stage.
In 1878, in the US, Thomas Edison developed and sold a commercially viable replacement for gas lighting and heating using locally generated and distributed direct current electricity. The world's first public electricity supply was provided in late 1881, when the streets of the Surrey town of Godalming in the UK were lit with electric light.This system was powered from a water wheel on the River Wey, which drove a Siemens alternator that supplied a number of arc lamps within the town.
The electric power industry is the generation, transmission, distribution and sale of electric power to the general public.The electrical industry started with introduction of electric lighting in 1882.
Throughout the 1880s and 1890s, growing economic and safety concerns lead to the regulation of the industry.Once an expensive novelty limited to the most densely populated areas, reliable and economical electric power has become a requirement for normal operation of all elements of developed economies. By the middle of the 20th century, electric power was seen as a "natural monopoly", only efficient if a restricted number of organizations participated in the market; in some areas, vertically-integrated companies provides all stages from generation to retail, and only governmental supervision regulated the rate of return and cost structure. Since the 1990s, many regions have opened up the generation and distribution of electric power to provide a more competitive electricity market.
However, transmission and distribution are harder problems since returns on investment are not as easy to find.Źródło: https://en.wikipedia.org/wiki/Electric_power_industry.