2.3 Flashcards
What is the current problem with energy
- huge and increasing amounts required
- mostly provided by combustion of fossil fuels - also release of CO2 into atmosphere and oceans with a probable contribution to global warming
What is the change in atmospheric levels of carbon dioxide over the last century
Increase of a third
What will happen to fossil fuels if we carry on with the current consumption without finding alternatives sources of energy?
- supply of fossil fuels will diminish
* their cost will increase
3 renewables energy sources that are being researched right now and what is their aim
- nuclear power, solar energy and biomass fuels
* to achieve carbon neutrality
What is carbon neutrality
The carbon dioxide generated in combustion of the biomass is compensated for by that absorbed during the photosynthetic growth of plants
Nuclear power
- non-renewable
- generates electricity directly
- can produce 20% of energy needed with a very small amount of uranium
- drawbacks with radioactive emissions and safe disposal of radioactive waste
Solar power
- renewable
- generates electricity directly
- captures energy from the sun and converts it into electricity
- availability of solar energy is in excess but high cost of collection, conversion and storage limits its use
Hydrogen combustion
- no carbon dioxide produced during its combustion
- doesn’t naturally occur on earth
- research to make it through the solar photolysis of water
What is the aim of green chemistry
Make chemicals and products that are essential to have as little impact on the environment as possible
Examples of green chemistry
- use as little energy possible
- using renewable resources as often as possible
- methods with high atom economy
- better catalysts
- avoid using solvents that are bad for the environment
- make biodegradable products
- avoid toxic materials
How does using as little energy possible and getting it from renewable resources contribute to green chemistry?
Generally increase energy efficiency
Why use methods with high atom economy for green chemistry
- High percentage of mass of reactants ends up in products
* little waste
How do better catalysts help green chemistry
- carry out reactions at lower temperatures and pressures
- save energy
- avoid constructing strong plants
Why should toxic materials be avoided
Ensure no undesirable co-products or by-products are released into environment
Prevent pollution
What is the major chemical reaction today to provide energy
Combustion of fossil fuels
In vehicles, homes and factories
Not to produce a product but to provide energy
