We do need Hydrogen as an Energy Source and for Storage..
1. We should produce H2 from sunlight and completely recycle the cathalyts.
2. We should enforce decentralized production.
3. We shoud carfully exploit heat and power decentralized in fuelcells.
4. And we should use H2 for lokal storage of energy, as an add to batteries in an ultrasmart electric grid.
But we must be sure that the endproduct is water and not greenhousegases, Oxygen-depletion could not happen, if Hydrogen is exclusively produced by splitting water. And the risks are far below the use of nuclear-power. Energy is mass x speed of light x speed of light proved to be inadequat for men.
Hydrogen is an energy-carrier (corpuscular, chemist) rather than a primary source, and should be used like electricity (wave, physics) .
We actually HOPE that most questions here are from "non-scientists", and I am gratified that you understand the need to understand some of the "basics" related to the political/social claims of environmental issues. Just like an investment portfolio for personal financial security, energy sustainability requires a portfolio of sources and mechanisms. There is no single "best" power source. However, trying to apply a single source to ALL energy applications will always result in waste, inefficiency and pollution. To address your specific questions about hydrogen I offer the following:
1. Most sources of Hydrogen are dirty. There are relatively few actual 'sources' of hydrogen. Any derived from organic molecules (which I believe is what you have reference to, particularly in the refining industries) will necessarily produce carbon dioxide as a by-product, and thus are less efficient from an energy perspective than burning the hydrocarbon fuel directly. The bulk of hydrogen production today is for use in chemical synthesis where pure hydrogen is required, NOT for energy production.
2. It's difficult to compress and therefore transport. Technologically, it is not really more "difficult", it just requires more energy (from somewhere) that does decrease the "lifecycle" value of the energy generated eventually by the hydrogen.
3. It does release powerful greenhouse gases when burned. That is incorrect, as the combustion of hydrogen with oxygen produces water only.
4. And finally there is some analysis that using hydrogen results in oxygen depletion (see link for example). Any combustion process will use up oxygen. Whether hydrogen consumes more or less than other fuels depends on your basis. For energy production the baseline should probably be moles of oxygen consumed per moles of fuel per kJ of heat produced.
Before the knives come out, I am not anti hydrogen - just trying to understand what solutions we hope it gives us, I am also a non-scientist so please be gentle with me!
So starting from the top: Do we really need hydrogen, what are we hoping that hydrogen as an energy source would give us? Yes, I think that hydrogen is a very promising portable fuel - IF it is produced only by solar energy from WATER.
Process Systems Consulting