The oil extracted through these methods is referred to as "green crude" and it's not ready to be used as fuel until it undergoes another process called transesterification. This step adds more substances to the mix, including alcohol and a chemical catalyst that causes the alcohol to react with the oil. This reaction creates a mix of biodiesel and glycerol. The final step in processing separates the glycerol from the mixture and leaves a biodiesel that's ready to be used as fuel. Maybe one day it really will be easy being green.
You can read more about it here https://auto.howstuffworks.com/fuel-efficiency/biofuels/convert-algae-to-biofuel.htm
Grasses, shrubs, cacti, and gourd plants.
1. The cell wall has lignin (hard substance): to prevent the xylem vessel from collapsing and withstand high pressure.
2. The absence of protoplasm (nucleus + cytoplasm) and cross wall: to allow water to move through the lumen easily.
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