Ethanol is flammable and care must be used to avoid accidental fire. Even a small amount of methanol can make you very sick or even kill you. Methanol is flammable and care must be used to avoid accidental fire. Accidentally releasing that pressure can be dangerous. Natural gas is flammable and care must be used to avoid accidental fire.
Electricity can electrocute people if they touch live wires.
Compressed hydrogen is under high pressure, and, as with compressed natural gas, care must be taken to avoid accidental release. Liquefied hydrogen is very cold and can injure by freezing. Hydrogen is flammable and care must be used to avoid accidental fire. Natural gas is flammable and care must be used to avoid accidental fire. Accidentally releasing that pressure can be dangerous.