Hey there Rana Hadi Al-Shammari! Great questions! So, when it comes to biohydrogen production by algae, it's a bit of a science extravaganza. Let's dive in.

1. Key factors influencing efficiency:

a. **Strain Selection**: Different algae species have different potentials. It's like assembling your superhero team—pick the right members for the job.

b. **Cultivation Conditions**: Think of it as creating the perfect environment. Temperature, pH, and light intensity play a crucial role. Algae are picky, you Rana Hadi Al-Shammari know?

c. **Nutrient Availability**: Just like us, algae need their vitamins. Nitrogen and phosphorous are their superfoods for efficient biohydrogen production.

2. Metabolic pathway and limitations:

a. **Photosynthesis Magic**: Algae are the solar panels of the bio world. They use photosynthesis to convert light into energy, and this energy can be redirected for hydrogen production.

b. **Dark Fermentation**: When the lights go out, algae switch to dark fermentation. This metabolic pathway kicks in, producing biohydrogen without the need for sunlight.

Now, for limitations:

- **Oxygen Sensitivity**: Like any superhero, algae have a weakness—oxygen. High oxygen levels can stunt biohydrogen production. They need an oxygen-free environment to truly shine.

- **Enzyme Bottlenecks**: Sometimes, the enzymes responsible for hydrogen production are the bottleneck. Imagine a traffic jam, but on a microscopic scale.

Some interesting articles:

Patent Development of sustainable environment by utilizing energy e...

Chapter Using Microalgae for Treating Wastewater

Technical Report Algae Strain Identification for Wastewater Treatment

Poster Reaction Energy: Fueling tomorrow

Technical Report Sustainable Future With Green Technolgy

Working on this topic is still on my wish list.

In a nutshell, biohydrogen production by algae is like conducting a symphony—you Rana Hadi Al-Shammari need the right players, the perfect environment, and a conductor who knows the score. Nailing these factors ensures optimal biohydrogen production. Cheers to the algae maestros! 🌱💡