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Environmental Science
Life After Fossil Fuels
The Energy Transition
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Life after fossil fuels means replacing coal, oil, and natural gas with energy systems that emit little or no carbon dioxide during operation. This transition matters because fossil fuel combustion is the main driver of human-caused climate change and also creates air pollution that harms health. A clean-energy society uses renewable power, nuclear energy, storage, efficient buildings, and electrified transportation to provide the same services with much lower emissions. The goal is not only to produce cleaner electricity, but to redesign the whole energy system.
Key Facts
- Carbon dioxide emissions from fuel use can be estimated by CO2 = fuel burned × emission factor.
- Electrical power is energy transfer per time: P = E/t.
- Renewable energy sources include solar, wind, hydro, geothermal, and sustainably managed bioenergy.
- Electrification reduces emissions most when the electricity grid is low carbon.
- Energy storage helps balance supply and demand: stored energy = power × time.
- Green hydrogen is made by electrolysis using low-carbon electricity: 2H2O -> 2H2 + O2.
Vocabulary
- Energy transition
- The large-scale shift from fossil fuel energy systems to low-carbon energy sources, technologies, and behaviors.
- Renewable energy
- Energy from sources that are naturally replenished on human timescales, such as sunlight, wind, flowing water, and geothermal heat.
- Grid storage
- Technology that stores electricity or energy for later use to help match power supply with demand.
- Electrification
- The replacement of fuel-burning devices with electric technologies, such as electric vehicles and heat pumps.
- Green hydrogen
- Hydrogen fuel produced by splitting water with electricity from low-carbon sources.
Common Mistakes to Avoid
- Assuming renewable energy always means zero environmental impact is wrong because solar farms, wind turbines, dams, mines, and transmission lines still require land, materials, and careful planning.
- Treating electricity and total energy as the same thing is wrong because transportation, heating, and industry often use fuels directly and must also be decarbonized.
- Ignoring energy storage and grid upgrades is wrong because solar and wind output vary with weather and time, so reliable clean power needs balancing systems.
- Calling hydrogen a primary energy source is wrong because hydrogen must be produced using another energy source, making it an energy carrier rather than a natural fuel supply.
Practice Questions
- 1 A town uses 600 MWh of electricity per day. If a solar farm produces an average of 50 MW for 6 hours per day, how many MWh does it produce daily, and what fraction of the town's daily electricity is that?
- 2 A battery can deliver 200 MW for 4 hours. Calculate its stored energy in MWh. If a city needs 800 MWh during an evening peak, is one battery enough?
- 3 Explain why electrifying cars and home heating reduces emissions more in a region with a clean electricity grid than in a region powered mostly by coal.