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Monthly Discussion
Our Need for Hydrogen
The
energy market is a niche where various primary energy sources coexist and
compete with each other. It was in 1975 when Marchetti first applied the
generalized substitution model and found surprisingly good description of
worldwide data over a historical window of more than one hundred years. His
updated results are reproduced in Exhibit 3 as published in PREDICTIONS.
During the last one hundred years,
wood, coal, natural gas, and nuclear energy are the main protagonists in
supplying the world with energy. More than one energy source is present at any
time, but the leading role passes from one to the other. Wind power and water
power have been left out because they command too small a market share.
Exhibit
3. Data, fits, and projections for the shares
of different primary energy sources consumed worldwide. For nuclear, the dotted
straight line is not a fit but a trajectory suggested by analogy. The
futuristic source labeled “Solfus” may involve solar energy and thermonuclear
fusion. The small circles show how things evolved since 1982 when this graph
was published in PREDICTIONS. *
In the early nineteenth century and before, most of the world's energy needs were satisfied through wood burning and to a lesser extent animal power not shown in the figure. Contrary to the popular image of coal-burning locomotives, wood remained the principal fuel for railroads in the United States up to the 1870s. The substitution process shows that the major energy source between 1870 and 1950 was coal. Oil became the dominant player from 1940 onward, as the automobile matured, together with petrochemical and other oil-based industries.
It becomes evident from this picture that
a century-long history of an energy source can be described quite well—smooth
lines—with only two constants, those required to define a straight line. (The
curved sections are calculated by subtracting the straight lines from 100
percent.) The destiny of an energy source, then, seems to be cast during its
early childhood, as soon as the two constants describing the straight line can
be determined.
There are other messages in Exhibit 3.
By looking more closely at the data we see that world-shaking events such as
wars, skyrocketing energy prices, and depression had little effect on the
overall trends. More visible may be the effect of strikes. In the coal
industry, for example, such actions result in short-term deviations, but the
previous trend is quickly resumed.
Another observation is that there is
no relationship between the utilization and the reserves of a primary energy
source. It seems that the market moves away from a certain primary energy
source long before it becomes exhausted, at least at the world level. And
vice-versa; despite the ominous predictions made in the 1950s that oil would
dry up in twenty years, oil use continued growing unhindered and more oil was
found as needed. Oil reserves will probably never be exhausted because of the
timely introduction of other energy sources. Well-established substitution
processes with long time constants are of a fundamental nature and cannot be
reversed by "lesser" reasons such as depletion of reserves.
Exhibit 3 also indicates that natural
gas will replace oil progressively to reach a zenith in the 2020s and become
more important worldwide than oil was in the 1970s. Supplying a major fraction
of the world's energy needs by gas will require much more gas than today's
proven reserves, but one need not worry about it; important natural gas fields
are likely to be found. Searches for "dry" gas have also started. Gas
is a more probable find than oil the deeper one goes underground, due to the
thermal gradient of the earth's crust. Ultimately, if during the gas era the
discovery of new gas fields does not keep up with demand, for whatever reason,
oil or coal may be artificially processed to produce the amount of gas lacking.
Synthetic gaseous fuels such as methanol could easily be used in cars.
But history since 1982 has proven the
gas takeover inaccurate. The small circles in Exhibit 3 show important
deviations from the projected trends for the shares of coal and natural gas.
While the trajectories for oil and nuclear energy consumption turned out as
predicted, the evolution of natural gas fell way below what had been expected,
and the share of coal remained high deviating progressively more and more from
the predicted course. How can these energy sources behave like species in
natural competition for almost one hundred years, and then suddenly fall in
disarray?
Cesare Marchetti argues that the
deviation is due to legislative intervention by some governments (for example,
U.K. and Germany) to keep coal production levels high. Such interventions can
be considered "unnatural" and should be corrected sooner or later.
According to this thinking, pressure must be building up for corrective action,
which could take the form of miners' strike, social unrest, or other political
intervention. But there is another problem. The extraordinary gains of coal
depress the market share of natural gas instead of that of oil. In the
substitution model there should be no interaction between phasing-in and
phasing-out competitors; everyone competes against the frontrunner, in this
case oil, and yet in Exhibit 3 natural gas, a phasing-in competitor, loses
market share to coal, a phasing-out competitor. Oil, the competitor with the
dominant market share, that normally should feel the competitive squeeze,
behaves like a non-participating spectator of the coal-gas struggle. As if
natural gas had become vulnerable prematurely.
The explanation may lie with the
intimate relationship between energy source and means of transportation. We saw
earlier that there is a coupling between energy and transportation in the sense
that each type of transportation is associated with one principal fuel, even if
early and late version of it may use different fuels. Coal was the principal
fuel of railroads and oil that of automobiles. The principal fuel of the
airplane could well be some gas (natural gas in the beginning, hydrogen
eventually). But the corresponding airplane technology is still not there. With
airplanes not requiring gas as fuel, the lack of important demand for gas
translates to diminished competitiveness so that when coal persists in the
market, gas suffers (out of turn) before oil.
Environmentalists have been very vocal in their
support of natural gas. I wonder, however, what has really been their role in
the greening of natural gas. The importance of gas in the world market has been
growing steadily for the last ninety years, independent of latter-day
environmental concerns. The voice of environmentalists reminds me of Ralph
Nader's crusade in the 1960s for car safety, while the number of deaths from
car accidents had already been pinned around 23 annually per 100,000 population
since the 1930s!
Environmentalists had also taken a
vehement stand on the issue of nuclear energy. This primary energy source
entered the world market in the mid 1970s when it reached more than 1 percent
share. The rate of growth during the first decade was disproportionably rapid,
however, compared to the entry and exit slopes of wood, coal, oil and natural
gas, all of which conformed closely to a more gradual rate (see Exhibit 3). At
the same time, the opposition to nuclear energy was also out of proportion when
compared to other environmental issues. As a consequence of the intense
criticism, nuclear energy growth slowed down considerably, but did not stop.
The little circles in Exhibit 3 are steadily approaching the straight line
proposed by the model. One may ask what was the prime mover here—the
environmental concerns that succeeded in slowing the rate of growth or the
nuclear energy craze that forced environmentalists to react?
Exhibit 3 suggests that nuclear energy
has a long future. Its share should grow at a slower rate, with a trajectory
parallel to those of oil, coal, and natural gas. But there is no alternative in
sight. The next primary energy source—fusion and/or solar and/or other—is
projected to enter the picture by supplying 1 percent of the world's needs in
the 2020s. This projection is reasonable because such a technology, once shown
to be feasible, would require about a generation to be mastered industrially,
as was the case with nuclear energy.
Let us try to be optimistic and
suppose that progress gallops and a new clean energy source (possibly involving
several technologies) enters the world market during the first decade of the
twenty-first century. It will have to grow at the normal rate, the rate
at which other types of energy have entered and exited in the past. Therefore,
it will have an impact on nuclear energy similar to the way gas had an impact
on oil. That is, nuclear energy, and to a lesser extent gas, will saturate at
lower levels while the new energy will reach relatively higher shares. Still,
nuclear energy will have played a role at least as important as oil did in its
time.
When Will
Hydrogen Come?
One
of the most recent (and most vocal) concerns of environmentalists is CO2
(carbon dioxide) pollution, presumably responsible for global warming. Present
levels of CO2 in the atmosphere have reached record-high values
primarily due to coal burning worldwide and gas emissions from automobiles in
developed countries. However, the environmentalists are once again blowing the
whistle for a phenomenon that has been following a "wise"
natural-growth path for more than one hundred years.
As we moved from one energy source to the next in
Exhibit 3 the hydrogen content of the fuel increases. Wood is rich in carbon
but natural gas is rich in hydrogen. When hydrogen burns it gives water as
exhaust; when carbon burns it gives CO2 as exhaust. When wood burns
very little hydrogen becomes oxidized to give water. Most of the energy comes
from the carbon that oxidizes to give CO2. On the contrary, when
natural gas burns lots of hydrogen become water and very little carbon becomes
CO2. The molar ratio hydrogen/carbon for wood is about 0.1, for coal
about 1, for oil about 2, and for natural gas (e.g., methane) about 4. For a
fuel like hydrogen this ration becomes infinite and the CO2
emissions to the atmosphere null.*
The energy substitution described in
Exhibit 3 took place in such a way that fuels rich in hydrogen progressively
replaced fuels rich in carbon, and all that happened in a natural way
(i.e., following an S-shaped pattern). We moved from one energy source to the
next primarily in order to enhance the energy content of our fuel. One pound of
coal has more energy in it than one pound of wood. Similarly, one pound of oil
has more energy in it than one pound of coal. Still, one pound of natural gas
has more energy in it than one pound of oil. In each substitution we are
abandoning an energy source with less hydrogen atoms in it for an energy source
richer in hydrogen. The end of this sequence will be when we finally use pure
hydrogen as is actually done in rocket technology.
The combination of energy sources according to the
shares shown in Exhibit 3 yields a hydrogen content that increases along an
S-curve (see Exhibit 4). Society followed this S-curve on a global scale
without the conscious intervention of governments or other influential decision
makers. Bottom-up forces have safeguarded for one hundred and fifty years a
smooth transition to energies that are more performing and less polluting.
The black dots in Exhibit 4 represent the mix of
only fossil-based energy sources (there is no hydrogen involved in nuclear
energy). As a consequence, a deviation from the S-shaped pattern becomes
evident around year 2000 and becomes progressively more pronounced toward year
2050. The gray area in the figure represents the "missing" hydrogen
content. This amount of hydrogen could be contributed by nuclear energy, if we
want to continue the well-established natural course.
Nuclear energy can indeed do that in a number of
different ways. For example seawater can be split into hydrogen and oxygen via
electrolysis or by direct use of nuclear heat. It must be noted that nuclear
energy is not indispensable for the natural path to be maintained. There is
enough hydrogen in the fossil-based energies, so it suffices to simply adjust
the mix differently. At the end, the ceiling of the S-curve in Exhibit 4 being
around 80 percent could be achieved by using only natural gas and nothing else.
Alternatively, nuclear energy could be replaced by solar, wind, hydroelectric
or a combination thereof, but these technologies are still responsible for
insignificant contribution to the energy picture worldwide. Moreover such
scenarios would introduce important deviations from the natural paths in the
evolution of the market shares of Exhibit 3. In fact, the deviations from
model-substitution trends discussed earlier go the wrong way by aggravating the
missing-hydrogen problem, one more factor contributing to the pressure that is
slowly building up from the delay of hydrogen's introduction.
Hydrogen Content of the Primary-Energy Mix
Exhibit 4. The black dots indicate the evolution of the hydrogen-content
percentage according to the energy mix of Exhibit 3. The thick gray line is an
S-curve fit to the black dots over the period 1860-2008. The gray area reflects
the amount of hydrogen that needs to be provided from non-fossil types of
energy.
Interestingly, there is all ready a herald of the
approaching hydrogen era: fuel cells. This technology is rapidly picking up
momentum and is often mistaken for a solution to the energy question. But fuel
cells need hydrogen to run. If hydrogen were readily available, we could just
as easily put it in our cars. They would run faster and would produce no
undesirable emissions whatsoever.
Another important recent development is catalytic
hydrogen production, see project HYDROSOL, which permits extracting
hydrogen from water at relatively low temperatures. This technique is of
particular interest to countries with sunshine because a modest sun furnace can
do the job.3.