Golden Gate Going Green


ZEB Frequently Asked Questions (FAQs)


What is hydrogen?

  • Hydrogen is the most common element in the universe; over 90% of the universe is made of hydrogen. Here on earth, hydrogen combines easily with other elements. When hydrogen combines with oxygen, it makes water that covers 70% of our planet.
  • Hydrogen promises a host of benefits. Since hydrogen does not occur on its own in nature, it must be produced by unlocking the molecular bonds in water or organic compounds, such as the methane in natural gas. Hydrogen can be produced from a wide variety of feedstocks and has the potential to help diversify the U.S. energy supply.

What is a fuel cell? How does it work?

  • When hydrogen (H2) combines with oxygen (O), it produces water (H2O) and electricity. In a fuel cell, hydrogen protons pass through a membrane to combine with oxygen on the other side. The electrons from the hydrogen are not allowed to pass through the membrane and leave the cell in the form of enough electric current to power a bus.

What are the environmental benefits of hydrogen fuel cells?

  • Fuel cells do not burn the fuel they use. Instead, they combine hydrogen with oxygen from the air to produce water and electricity. The only emission the fuel cell generates is water vapor. Using hydrogen instead of burning fossil fuels makes our air cleaner, diversifies our energy supply and potentially reduces global warming.

Why is hydrogen safe?

  • Like any fuel, hydrogen requires proper handling and a safe system design for production, storage and usage. In general, hydrogen, if properly handled, is as safe as gasoline, diesel or natural gas and, in some instances, safer. For decades, hydrogen has been shipped and used safely in the U.S. for use in everything from welding to hydrogenated peanut butter. Over 70 million gallons of hydrogen are transported on the country’s highways every year without any major problems. Hydrogen is the most common element in the universe, and it’s also the lightest – even lighter than helium. So if there’s a leak in a hydrogen tank, it dissipates quickly into the air without polluting.

Why are we doing this?

  • Hydrogen promises a host of benefits – from diversifying energy supply to improving the health of the environment. Putting zero emission buses on the streets has a direct impact on air quality and the health of local residents. If fuel cell technology proves to be feasible and economical, hydrogen could become an important part of the world’s energy mix. Testing the technology with centralized fueling and a transit fleet application is the logical first step.
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