On Mon, 08 Mar 2021 15:10:08 -0800, Mark Mocho wrote:

On Monday, March 8, 2021 at 1:42:45 PM UTC-7, Eric Greenwell wrote:
Mark Mocho wrote on 3/8/2021 11:34 AM:
And I seem to remember hearing that water vapor is more of a
"greenhouse gas" than carbon dioxide.
Not so much when it comes to climate change, because as water vapor
increases (primarily due to global warming), it forms more clouds,
which reflect the heat, tending to reduce global warming - all part of
a natural cycle that's be going on since the earth began. CO2 does not
condense, and we are adding it to the atmosphere at a far higher rate
than natural carbon sinks can remove it.
--
However, using hydrogen as an alternative fuel WILL add to the amount of
water vapor in the atmosphere. Note the following statement:

"...water vapor is the largest contributor to the Earth’s greenhouse
effect...However, water vapor does not control the Earth’s temperature,
but is instead controlled by the temperature...If there had been no
increase in the amounts of non-condensable greenhouse gases (like carbon
dioxide), the amount of water vapor in the atmosphere would not have
changed with all other variables remaining the same." (from the American
Chemical Society's ACS Climate Science Toolkit)

The key phrase is the last one: "with all other variables remaining the
same." Imagine that instead of seeing "normal" contrails behind a high
flying airliner, there is a huge plume of water vapor that results from
burning hydrogen. That definitely adds to atmospheric water vapor,
independent of the natural evaporation/condensation cycle that forms
clouds.

Of course, the "Chemtrails" paranoids will get a corresponding boost in
popularity.

If H2 was to replace hydrocarbons as the main fuel type, where would it
come from? Electrolysis of water? Stripping carbon out of hydrocarbons?
ow would the cost compare with other power sources once transport to the
point of use is included in the price?

It appears that the last two are the current favourites in the form of
steam reforming of natural gas, partial oxidation of methane, and coal
gasification, with extraction from carbon compounds providing 96% and are
not particularly green because they all produce a lot of carbon oxides as
a waste product - and we don't have a good way of using them or keeping
them out of the atmosphere.

Bottom line: hydrogen has good energy capacity per kilogram, but this
tends not to look so good once you consider the cost of carrying it
around in compact, multi-kilogram quantities. Pipes should be fine,
provided somebody manages to invent a reasonably light pipe material that
H2 can't leak through, but you can't power road/rail vehicles or aircraft
with piped hydrogen!


--
Martin | martin at
Gregorie | gregorie dot org