What do ethanol and hydrogen powered cars emit?

Question

What do ethanol and hydrogen powered cars emit?

Answer 1

CO2 and H2O for ethanol

H2O for Hydrogen

Answer 2

Hydrogen cars emit water.  Ethanol is a hydrocarbon so cars powered by ethanol emit carbon dioxide and water.  But ethanol is derived from plants, so they absorbed the carbon dioxide from the atmosphere and using the ethanol puts it back.  So there is no increase in carbon dioxide.  However, using land to grow plants to produce ethanol is reducing habitats for wild animals, so it's not all good.

Answer 3

Ethanol fueled cars also emit CO, NOx and various aldehydes.  Hydrogen powered cars emit NOx

Answer 4

It's a little more complicated than that.

Burning ethanol releases water and CO2, and the CO2 was absorbed from the atmosphere by the plants, so it's part of the natural carbon cycle.  However, you still need to burn energy to produce the ethanol (growing it, transporting it, etc.), and ethanol contains less energy per volume than gasoline, so overall you're not releasing much less CO2 than burning gasoline.

When you burn hydrogen the only biproduct is water (hydrogen combining with oxygen in the air).  However, you have to get the hydrogen from somewhere in the first place.  The only efficient way we have of getting hydrogen right now is from natural gas, but when you get hydrogen from natural gas you release carbon dioxide.  As much as burning gasoline, in fact.

Theoretically if you could get hydrogen from water, the only inputs and outputs would be water and it would be a totally clean process.  In reality it takes a ton of energy to break the atomic bonds in water, and that energy has to come from somewhere.  If you're getting the energy from the power grid, then you're also releasing the emissions from the power plants in the process.

Answer 5

Heat -

H2 burns to release water as steam

ethanol ( CH3CH2OH, C2H5OH ) release CO2, CO and impurities

it's better drunk than burnt

unless U use ethanol to extract, transport and store it (coolers) then u will have burnt non renewable fuel and so there is a net increase in CO2.  Ethanol from plant extraction is extremely inefficient when the entire distribution chain is considered. It's a waste of food crops and land that could have been used for forest - most likely was until some ethanol producing firm burnt down 200year old rainforest growth.