All clean energy is renewable, but not all renewable energy is perfectly clean.

Not all renewable energy sources are completely clean, although they are generally cleaner than fossil fuels. “Renewable” simply means the energy source naturally replenishes itself, while “clean” refers to how little pollution or environmental damage it causes. Some renewable sources still have environmental impacts. 

1. Solar Energy

 Solar power is one of the cleanest renewable energy sources. It produces electricity without emitting greenhouse gases during operation.

However:

Manufacturing solar panels uses chemicals and energy.

Large solar farms require significant land.

Disposal of old panels can create waste issues.

Overall, solar energy remains very low in pollution compared with coal or oil. 

2. Wind Energy

 Wind power is another very clean renewable energy source.

Possible impacts:

Turbines can affect birds and bats.

Noise or visual concerns for nearby communities.

Manufacturing turbines requires metals and energy.

Still, its carbon footprint is extremely low. 

3. Hydropower

 Hydropower is renewable but not always completely clean.

Environmental concerns include:

Flooding of large areas for reservoirs.

Displacement of communities.

Disruption of fish migration and river ecosystems.

Some reservoirs release methane from decaying vegetation.

So while hydropower produces low emissions, it can have significant ecological impacts. 

4. Biomass Energy

 Biomass energy (burning wood, crop waste, or organic materials) is renewable but not completely clean.

Issues include:

Burning biomass releases carbon dioxide and air pollutants.

Large-scale biomass production can lead to deforestation.

Inefficient biomass use can worsen indoor air pollution.

However, if managed sustainably, biomass can be carbon-neutral because new plants absorb the emitted CO₂. 

Renewable energy = energy that naturally replenishes.

Clean energy = energy that causes minimal pollution.

Some renewable sources like solar and wind are very clean, while others like hydropower and biomass have environmental trade-offs.