Modern society, which depends on fossil fuels, faces two major challenges: resource depletion and environmental problems. We will learn about the role of chemistry in creating a sustainable society.
Basic Knowledge
The main energy sources today are fossil fuels (coal, petroleum, and natural gas), which emit CO2 when burned. Fossil fuels are finite, and their estimated years of recoverable reserves are approximately
・Petroleum: about 50 years, coal: about 130 years, natural gas: about 55 years (estimated)
.
Renewable energy includes solar, wind, hydroelectric, geothermal, and biomass energy. These are clean energy sources with low CO2 emissions. Nuclear power emits very little CO2, but the treatment of radioactive waste is an issue.
Improving energy-conversion efficiency and saving energy = energy conservation; reusing waste = recycling. Both are keys to a sustainable society.
Fossil fuels (coal, petroleum, and natural gas. Finite resources that emit CO2 when burned)
Renewable energy (solar, wind, hydroelectric, geothermal, and biomass energy. Does not run out)
Biomass (organic resources derived from plants and animals. Carbon-neutral because burning them does not increase CO2)
3Rs (Reduce = decrease, Reuse = use again, Recycle = recover and use again)
Hydrogen energy (uses H2 as fuel through combustion or fuel cells. The only emission is water)
Sustainable Development Goals (SDGs) (17 goals adopted in 2015, including energy, the environment, and poverty)
Further Study
The hydrogen society is attracting attention as a next-generation energy system. If H2 is produced by electrolyzing water using renewable energy (green hydrogen) and then converted into electricity in a fuel cell, no CO2 is emitted at all. Fuel-cell vehicles (FCVs), such as Toyota's MIRAI, are one example.
In the field of energy-saving materials, LED lighting (with more than 10 times the energy efficiency of incandescent bulbs), lithium-ion batteries (for electric vehicles and energy storage), and thermoelectric conversion materials (which convert waste heat into electricity) have been put into practical use. Progress in chemical decomposition and resynthesis technologies is essential for building a circular society.
- Fossil fuels = coal, petroleum, and natural gas. Burning them emits CO2
- Renewable energy = solar, wind, hydroelectric, geothermal, and biomass energy
- Hydrogen energy → fuel cell → the only emission is water
- 3Rs: Reduce, Reuse, Recycle
- Biomass remains within the carbon cycle even when burned
- SDG 7: Affordable and clean energy for all
- Green hydrogen = produced by electrolyzing water with renewable energy
Points to Note
① Nuclear power does not emit CO2, but it is not “renewable energy” (uranium fuel is finite). ② Biomass produces CO2 when burned, but it is considered carbon-neutral because it only re-releases the CO2 absorbed by plants during growth. ③ The priority order of the 3Rs is Reduce (prevent generation) ＞ Reuse (use again) ＞ Recycle (recover as resources).
Practice
- Explain all three 3Rs and arrange them in order of priority.
- Explain chemically why hydrogen energy is called “clean.”
- Explain why biomass is considered carbon-neutral.