What a learner can do afterwards
- Lists at least four renewable and three non-renewable energy resources
- Explains what makes a resource renewable or non-renewable
- Compares the environmental impact of at least two different energy sources (e.g. wind vs coal)
- Discusses trade-offs between cost, reliability, and environmental impact in choosing energy resources
1 · Read
Renewable resources are renewed by natural processes on human timescales. Examples are solar, wind, hydroelectric, tidal, geothermal and biomass. Biomass supplies must be replaced as they are used. Coal, oil and natural gas formed over millions of years and are not replaced quickly enough for our use. Uranium is a finite mined nuclear fuel, so it is non-renewable too. Nuclear plants release energy by splitting nuclei, not by burning uranium.
Weather processes keep producing wind; uneven heating helps drive them. Renewable does not mean available everywhere or at every moment. Wood supplies shrink if trees are cut faster than they regrow. Geothermal sites also need management to avoid removing useful heat faster than it is replenished.
Coal and gas burning release CO2, adding to climate change. Wind and solar generation burn no fuel, but making their equipment has impacts. Wind farms can affect wildlife; dams change river habitats. Biomass burning releases CO2 and air pollutants. Nuclear generation has low CO2 emissions but produces radioactive waste. Each resource needs its own environmental comparison.
A town compares wind alone with the same wind farm plus gas backup. Adding backup costs more to build. If enough fuel and backup capacity are available, gas can cover calm-day shortfalls, but releases CO2 when used. Weigh the added building cost against the improved supply and emissions when gas runs. A plan must state what covers demand when wind output falls.
Solar output depends on sunlight and stops at night. Wind output depends on wind speed. Suitable geothermal plants can provide steady output, while tidal timing is predictable. All plants need maintenance. Storage or another available supply can cover shortfalls. For all-day demand, subtract hours fully covered by solar from 24. If solar covers 9 hours and there is no stored energy, another supply is needed for 24 - 9 = 15 hours.
Renewable describes natural renewal, not zero impact or constant output. Compare cost, reliability and environmental effects, including resource management and supplies for shortfalls.
Readings and flashcards written for this dataset.
More to read
What the renewable label tells you
A resource's renewable classification concerns its natural renewal. It does not describe every effect of the equipment using it. Sunlight, moving air, water movement and tides supply energy without consuming a finite fuel deposit. Biomass supplies need replacement, and geothermal sites need management.
Coal, oil and natural gas are fossil fuels. Their formation is much too slow to replace what people use on human timescales. Uranium is also non-renewable, but it is not a fossil fuel. Nuclear plants release energy by splitting nuclei.
A low-CO2 supply need not be renewable. Nuclear generation has low CO2 emissions but produces radioactive waste. Renewable biomass can release CO2 and air pollutants when burned. Classification is one part of an environmental comparison.
Planning for windy and calm days
A wind turbine takes energy from moving air. Its blades drive a generator. Generation burns no fuel, but producing and installing the equipment uses materials and energy.
A supply plan compares wind output with electricity demand. If the whole site has little wind, adding turbines may still leave a shortfall. Storage, other generators or connections to other regions can help when they have enough available capacity. A plan needs to say which of these will supply electricity during calm weather.
Location matters too. Turbines can make noise and affect birds and bats. Planners consider nearby homes, habitats, wind conditions and construction costs. A renewable resource does not make every proposed site suitable.
Using solar electricity when it is available
Solar panels convert sunlight to electricity without a rotating generator. Output changes with sunlight, so clouds, season and time of day affect the supply. There is no sunlight-powered generation at night.
A home can use electricity while its panels produce it. A battery can supply stored energy later, but has limited capacity and adds cost. A grid connection or another available source may cover remaining shortfalls.
Roof panels use an existing surface rather than a separate field. Their manufacture, installation and disposal still have environmental impacts. Comparing plans means checking how much electricity is supplied, when it is needed and what covers periods of low output. Costs depend on the location and the whole system.
A geothermal resource depends on its site
Geothermal systems use heat from underground. Some supply heating directly. At suitable hotter sites, hot water or steam can provide energy for a turbine and generator.
A suitable plant can supply steady electricity without relying on that day's sunshine or wind. It still needs maintenance. Accessible heat, drilling conditions and development costs limit where geothermal electricity is practical.
The local resource needs management. Removing useful heat or fluids faster than they are replenished can reduce output. Emissions and local environmental effects depend on the site and equipment. Geothermal generation therefore has different supply conditions from wind and solar, but is not an unlimited source at every location.
Why finite fuel still matters when energy is conserved
Energy is conserved, but a transfer may spread energy into the surroundings as heating. That energy is harder to use again for the same task. A finite fuel supply can therefore be used up even though total energy has not disappeared.
Insulation can reduce the energy needed to heat a room. An efficient appliance can provide a service using less electricity. These measures reduce demand; efficiency is not another energy resource.
Electricity is only part of total energy use. Transport and heating can use fuels without first generating electricity. To interpret an energy-share percentage, check its date, source and measure. A share of electricity cannot be treated as a share of all energy use.
2 · Watch
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Where it sits
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Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.