Energy and ecology
Energy is a body’s ability to do work; it changes from one form to another but is neither lost nor created from nothing. Thermal power stations burn coal, natural gas or fuel oil: the heat turns water to steam, the steam spins a turbine and the turbine spins a generator. This releases carbon dioxide and sulphur and nitrogen oxides: carbon dioxide adds to global warming and climate change, while sulphur and nitrogen oxides cause acid rain. Energy sources are of two kinds: non-renewable (oil, natural gas, coal) – the supply runs out; and renewable (solar, wind, water energy) – constantly renewed in nature and hardly polluting the air. Solar panels convert light directly to electricity; hydroelectric stations use the energy of flowing water. The textbook says that in 2022 a large solar plant was being built in Samarkand; today several large solar and wind plants operate in Uzbekistan. The textbook gives 62.8 billion kW·h generated in 2018 and 71.3 billion kW·h in 2021, i.e. an increase of 8.5 billion kW·h in 3 years.
Debate table: draw a two-column table (wind and solar energy). For each write pros and cons (for example needs a windy place, gives little on a cloudy day, takes up land, does not pollute air). Discuss in class. Safety: during outside observation do not stare at the Sun and watch out for traffic.