Renewable and non-renewable energy resources

Energy resources can be classified into two main categories: renewable and non-renewable.

Renewable energy resources

• Can be replenished naturally within a relatively short timeframe.
• Examples include resources that harness the Earth's heat or motion, such as geothermal, wind, and tidal power, as well as those that rely on the Sun's radiation, like solar power and biomass.

Non-renewable energy resources

• Have a finite supply and take millions of years to form.
• Cannot be easily replaced once depleted, making them unsustainable in the long term.
• Examples include fossil fuels, such as coal, oil, and natural gas.

Producing biofuels via photosynthesis and fermentation

Biofuels are a type of renewable energy resource derived from organic compounds produced through biological carbon fixation, a process that converts atmospheric carbon dioxide into organic compounds. In the case of biofuels, this process occurs through photosynthesis in green plants.

During photosynthesis, plants use light energy absorbed by chlorophyll molecules to drive a series of complex reactions that convert carbon dioxide and water into glucose (C_6_H_12_O_6_) and oxygen:

6CO_2(g) + 6H₂O_(l) ➔ C₆H₁₂O_6(aq) + 6O_2(g)

The glucose produced through photosynthesis stores chemical energy within its bonds and can be further processed to create biofuels. One common method is through fermentation, which involves microorganisms, such as yeast or bacteria, that convert glucose into ethanol (C_2_H_5_OH), a biofuel:

C₆H₁₂O_6(aq) ➔ 2C₂H₅OH_(aq) + 2CO_2(g)

Although fermentation releases carbon dioxide, a greenhouse gas, the amount released is offset by the carbon dioxide absorbed during photosynthesis, making biofuels a more carbon-neutral energy source compared to fossil fuels.

Advantages and disadvantages of biofuels

As the demand for renewable energy sources grows, biofuels present several advantages and disadvantages that are outlined in the table below.