Biomass energy is not related to

Options

A. photosynthesis
B. fermentation
C. anaerobic digestion
D. geothermal energy

Explanation

To determine which option is not related to biomass energy, we need to analyze each of the given options: photosynthesis, fermentation, anaerobic digestion, and geothermal energy.

### Step-by-Step Solution:

1. **Understanding Biomass Energy**:
- Biomass energy refers to energy derived from organic materials, which include plant and animal matter. This energy is stored in the form of chemical energy in the biomass.

2. **Analyzing Photosynthesis**:
- Photosynthesis is the process by which green plants convert sunlight into chemical energy, storing it in the form of glucose. This process is fundamental to the formation of biomass, as it is how plants produce the organic matter that constitutes biomass.

3. **Analyzing Fermentation**:
- Fermentation is a metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen. It is a method used to convert biomass (like sugar from plants) into biofuels such as ethanol. Thus, fermentation is directly related to biomass energy.

4. **Analyzing Anaerobic Digestion**:
- Anaerobic digestion is a biological process that breaks down organic matter (biomass) in the absence of oxygen, producing biogas (methane) and digestate. This process is also closely related to biomass energy as it converts organic waste into usable energy.

5. **Analyzing Geothermal Energy**:
- Geothermal energy is the heat that comes from the sub-surface of the earth. It is derived from the natural heat of the earth's core and is not related to organic matter or biomass. It is a separate energy source that does not involve the conversion of biomass.

6. **Conclusion**:
- Among the options provided, photosynthesis, fermentation, and anaerobic digestion are all processes related to biomass energy. In contrast, geothermal energy does not relate to biomass energy. Therefore, the correct answer is **geothermal energy**.

### Final Answer:
**Geothermal energy** is not related to biomass energy.

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