Author Topic: The Hydrogen Economy: Beware The Political Spin Doctors  (Read 2159 times)

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Offline Alan Taylor

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The Hydrogen Economy: Beware The Political Spin Doctors
« on: April 12, 2015, 13:07:18 PM »
The Hydrogen Economy: Beware The Political Spin Doctors






Preamble

This is a piece I wrote back in 2006 re the hydrogen economy, in particular as a response to vehicle manufacturers extolling the non polluting nature of hydrogen as a fuel.. I hope you like it..

Regards
AT



Quote
Folks,

I have been sounding off on his forum concerning the "irrational
exuberance" of some environmentalist groups, news organizations, and
automobile manufacturers concerning their promotion and presentation
of hydrogen as a non polluting fuel where the only by-product is water.
This is far from the truth, however it does not negate hydrogen as an
important resource, or compromise plans to move to a hydrogen based
economy. The challenges that face the widespread introduction of
hydrogen fuelled vehicles can be generalized as follows.

* Production of hydrogen
* Distribution and storage
* Development of economic hydrogen vehicles

These are very broad points, however the critical issue that has to be
addressed is the production of hydrogen, and the impact this has on
the environment. Hydrogen is is most abundant element in the known
universe. However, here on earth it appears in conjunction with other
elements, primarily in water, and hydrocarbons. Hydrogen has to be
separated from these other elements, therefore hydrogen is a
manufactured fuel and is no different in this respect to gasoline and
diesel oil. As is the case with both gasoline and diesel fuel, CO2 is
released to atmosphere during the processing of hydrogen
for use as a fuel.

In the United States 95% of hydrogen produced uses natural gas as the
feedstock (CH4) via the Steam Reforming of Methane. Globally, between
50% to 60% of hydrogen produced in this manner. In order to
understand where and how the production of hydrogen results in the
release of CO2 to atmosphere, we have to take a brief look at the
process of the steam reforming of methane.

Steam reforming of methane is endothermic in nature i.e.heat must be
supplied to the process for the reaction to take place and be maintained.

The process consists of essentially two steps.

Stage 1. (CH4 + H2O -> CO + 3H2 )The natural gas feedstock (about
92% CH4 depending upon source) requires methane reacting with high
pressure superheated steam at about 1340 - 1480 deg.F to produce what
is referred to as a synthesis gas (syngas), the composition of which
is primarily hydrogen (H2) and carbon monoxide (CO).

Stage 2. (CO + H2O -> CO2 + H2) This second stage is referred to
as water gas shift (WGS) reaction, where the carbon monoxide (CO)
produced during stage 1 of the process is reacted with steam over a
nickel catalyst to form hydrogen and CO2. The WGS process occurs in
two distinct stages, a high temperature shift at about 664 deg. F and
a low temperature shift occurring between about 375 - 415 Deg. F.

The separated hydrogen is stored in high pressure tanks at the point
of manufacture.


CO2 Issues

==========

The release of CO2 to atmosphere occurs during the first stage of the
reaction where either, natural gas, fuel oil, or coal can be used to
fire high pressure steam boilers to produce superheated steam. The
burning of these fuels releases CO2 into the atmosphere. During the
second stage of the reaction, CO2 is a direct byproduct of the
reaction, and it is vented to atmosphere.

By far the largest CO2 component is associated with the first stage
reaction, and currently, using natural gas as the feedstock for both
the SMR shift process, AND as the fuel stock for the high pressure
steam boiler plant, the current CO2 impact is 2.5 lbs of CO2 for every
pound of hydrogen (H2) produced.

CO2 Mitigation

==============

Currently the USA produces about 9 million tons of hydrogen per year
95% of which is from the SMR process, about 8.55 million tons. The CO2
released for this level of SMR production would be approximately 21.4
million tons. This is approximately the CO2 impact of our current
"hydrogen economy". The way ahead is to integrate SMR hydrogen
production plants with nuclear power plants, where the high pressure
steam would be provided by the nuclear reactor, and almost eliminate
the CO2 released to atmosphere during the SMR process. In this manner
hydrogen powered vehicles would manage to live up to the current hype.

Until then hydrogen powered vehicles as an answer to the ecologists
dream..... Well folks its all just smoke and mirrors..
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AT