This essay is adapted from the keynote address to the Business Roundtable's National Summit on Technology and Climate Change, held August 31, 2000 in Washington DC. The author is grateful to Cesare Marchetti, Perrin Meyer, and Paul Waggoner for their help.
It was published in the Electricity Journal 14(1):24-33, 2001.
The figures are located at the end of this document for easier online reading.
PDF version: someways.pdf
Some Ways to Lessen Worries about Climate Change
Program for the Human Environment
The Rockefeller University, New York, NY.
ABSTRACT: Technology can make adapting to climate change, offsetting emissions, and preventing emissions cheap and effective. The trick is easing in the changes when the technologies turnover, operating at the point where old things are substituted anyway.
Hope is a better companion than fear. Science has effectively
alarmed many people about the chances human activities will harm Earth's
climate. More importantly, science and engineering can lessen worries about
climate change. My menu of ways lessens worries by positive means of providing
a needed service or product rather than the negative means of issuing scary
press releases and shutting down a plant.
Let me first briefly offer my premises about the climatic
outlook. All we firmly know is that human activities are changing the chemical
composition of the atmosphere, above all with additions of carbon dioxide.
Changing what’s in the air will very likely change the climate. We do not
know to what.
In fact, I believe the future climate is not unknown. Rather,
and more important, it remains unknowable. The complexity of the climate
system, the numerous factors that can vary and their interactions, forbids
reliable calculations beyond the broad generality about likely global warming.
My colleagues gulping research grants hate me for saying it, but I do not
believe more research will reduce uncertainty. Over the 23 years I have now
worked on the climate problem, the ten billion dollars or more spent on research
have not reduced uncertainty about the future climate or provided a convincing,
detailed picture. The spray of views is undiminished, and a new mystery arises
for every one apparently solved. Meanwhile, we have definitely added more than
100 billions tons of carbon dioxide (CO2) to the atmosphere and
notable amounts of other stuffs that also absorb and reflect radiation.
Because the future climate is unknowable, the operative
question is “How risk averse are we?” “We” may be a
country, a household, or a firm. In general, I consider myself risk accepting.
I bicycle hundreds of hours each year, an extremely dangerous use of time, and
usually pedal without a helmet. I often eat sushi, a frequent cause of food
poisoning. I choose to live in a neighborhood in New York City where during the
1980s most mornings on my doorstep I found crack vials. But, gambling with the
climate does not strike me as a good bet.
Of course, Earth now presents a climate horrible for humans
over much of the planet much of the year. Still, humanity has invested heavily
in adjusting to the recent climate. We are attached to the system of reservoirs
providing New York City’s tasty waster, vineyards in Bordeaux, and the
National Park designated around the precipitous waterfalls of Yosemite.
Moreover, there is some – unknowable – chance that our activities
will trigger a catastrophic change, say to a severe Ice Age.
So, I say, let us prepare, just in case. Purchase some
insurance. We routinely do. Insurance, in its literal form of policies in fine
print, is now about 2% of US GDP. Inspired spending, even against hypothetical
threats, can bring great and lasting achievements, such as Europe’s gothic
cathedrals. The sorts of insurance I shall propose, however, resemble building
a fire escape, storing fuel outside rather than in the stairwell, and using
diesel rather than 100-octane fuel.
Three forms of climate insurance exist. I will call them
adaptation, offsets, and prevention. Public and private entities should
research and invest in all three.
Let me begin with adaptation, which tends to get short
schrift. Many of our devices and strategies, from anti-freeze, air
conditioning, and corn futures markets to windshield wipers, radar, and domed
stadiums, already adapt for climate. Societies are always trying to
climate-proof themselves. According to Genesis, Joseph helped the Pharaoh
during the 7 fat years to insure against the stress of the 7 lean years to
To a considerable extent societies have now climate-proofed
themselves. In the summer of 1998 China
experienced one of the most extreme floods in its long recorded history,
affecting some 20 million hectares, or 80,000 square miles. Yet, compared to
1997, rice production reportedly fell only about 1% and total cereal production
increased slightly. Still, we can adapt more.
Water is paramount. Technologies for tunneling and pumping
can ease the creation of new supply. Numerous technologies can also moderate
demand, for example, by spying and stopping leaks and waste. Prosperous
societies can also afford large-scale coastal protection, as the Thames Barrage
and the Netherlands Rhine Delta scheme show. Because populations are imploding
into cities, making cities habitable in unwelcoming climates helps a lot. We
already do in Phoenix and Edmonton. Cheap, efficient, and environmentally
benign refrigeration will win ever-larger markets. So will means to lift
moisture-use efficiency in agriculture. Everyone concerned with changing
climate can benefit from better weather forecasts, because eventually the
climate becomes the weather of the next few days, and a forecast of rain can
save water that would have been sprinkled on a lawn or pumped on a crop. Some
adaptations, like carrying an umbrella, need finally be implemented only when
the front nears
As hinted, adaptation comes through both hardware and
software, through both markets and regulation. Markets allow us to average over
larger spaces and longer times, lessening the consequence, for example, of a
poor crop in Kansas with a bumper crop in Australia. Regulation, such as wise
zoning, can lessen the amount that societies build in hazard-prone settings. A
strategy such as making available fresh water from one basin in another benefits
from both markets aimed to encourage high valued uses and regulation to assure
protection of poor consumers.
Adaptation makes sense because, even if humans do not change
the climate, nature will.
My second strategy, offsets, recognizes that some greenhouse
gases will surely be emitted and seeks to capture or otherwise offset those
emissions. The scope of effort needed to close the carbon cycle is huge.
Globally, humans now average emission of a ton of carbon per year. An American
emits about 5 tons per year or 14 kg per day. The volume of material involved
in carbon waste management contrasts with that of another element useful for
energy, uranium, where we deal in grams per capita per year.
Still, engineers, ecologists, and others have proposed many
schemes for offsets. At this stage, most merit more study for their benefits
and risks, and some are ready for demonstration and implementation. I will
mention a few schemes.
One is to fertilize parts of the surface of the open ocean,
basically with iron, setting in motion enhanced growth of marine plants and
animals, which will eventually sink to the ocean floor with their captured
carbon and thus encourage the surface ocean to absorb more carbon from the air.
Rough calculations make ocean fertilization look cheap.
Foresters and farmers can also sequester carbon. My
colleagues and I have shown that a widespread reversal of the deforestation that
has prevailed for centuries is now underway, and that humanity can achieve a
great restoration of the world’s forests over the next 50 to 100
years. We might, for example, set a goal of a
10% increase in the world’s forest estate over the next 50 years. This
could compensate for about 5 years of present emissions.
The catch is that forests also darken the planet, and thus
tend to make it warmer, lowering the so-called albedo or reflectivity of
Earth’s surface and thus increasing energy absorption. After all, the
basic problem is not CO2 but energy balances. Fearless engineers may
prove that creating deserts, which like the ice have high albedo, will counter
warming more than planting forests. So, let's breed and plant light-colored
Farmers can also grow more food while storing more carbon.
Unconsciously, Washington and Brussels may be storing carbon by paying farmers
to idle land and thus increase the stash of soil organic matter. Washington and
Brussels ought consciously to start paying farmers to plant trees instead of
paying them not to grow more food.
Noting that some of the so-called aerosols or particles in the
atmosphere tend to cool Earth’s surface, like clouds, some geoengineers
have proposed offsetting increased greenhouse gases with distribution of shady
particles. As mentioned, energy balance not CO2 is the basic
problem. Indeed, the CO2 itself, if not the other greenhouse gases,
provides raw material for photosynthesis in the biosphere.
Many conferences and now some grants from the US Department
of Energy address how CO2 might be stripped from power plant
smokestacks and pumped back under the land or sea.
The best way is to sequester the emissions in caverns
underground, where the coal, oil, and gas came from. On a small scale,
CO2 already profitably helps tertiary recovery of oil. As I will
explain later, I support the idea of hydrogen (H2) refineries,
extracting H2 from methane (CH4) or other hydrocarbons and
producing CO2. Located near exploited oil fields, the refineries
would find a market for their emitted CO2 to recover oil.
Oil and gas are preserved in natural geological traps that
only occasionally contain them, so one can extend the storage to the traps that
lack oil and gas that prospectors routinely find.
Aquifers in silicate beds could be used to move the waste
CO2 to the silicates where “weathering" would make carbonates
and silica, an offset good for millions of years.
The key to offsets is to determine how much carbon we need to
sequester and when. For example, if humanity sets a goal of stabilizing
CO2 at 450 parts per million (ppm) by volume in the atmosphere,
industries might need to sequester about 50 ppm, before the evolution of the
energy system eliminates the emissions of CO2 anyway. Among the
several strategies available, offsetting for 50 ppm should certainly be
Offsets benefits from a system organized to collect
CO2 and move it to the disposal points. Because the energy industry
is quite concentrated and the materials flow through a few large pipelines and
refineries, there I propose we concentrate the task of offsets.
Before sharing my thoughts on my third insurance, prevention
of emissions, allow me to offer some necessary premises. The most fundamental
is that evolution is a series of replacements. We experience these replacements
daily. For example, compact discs replaced cassettes, which replaced
long-playing records, which replaced 78-rpm records (Figure 1). A new
generations of computer chips replaces the old every 2-3 years, as if programmed
by robots in Silicon Valley. Importantly, the superior performance of the
technology fits a larger market (Figure 2).
Replacements also mark the evolution of the energy system.
Between about 1910 and 1930 cars replaced horses in the United States. Earlier
steam engines had replaced water wheels and later electric drives replaced steam
engines. Each of these replacements required about 50 years in the marketplace.
It required about the same amount of time for railways to replace canals as the
lead mode of the US transport infrastructure and longer for roads to overtake
railways and for air to overtake roads (Figure 3). Considering primary sources
of energy, we find that coal replaced wood and hay, and oil in turn beat coal
for the lead position in the power game. Now natural gas is overtaking oil.
The so-called oil companies know it and invest accordingly. In turn, I believe,
nuclear will beat the hydrocarbons.
The driving force in evolution of the energy system is the
increasing spatial density of energy consumption at the level of the end user.
At very high spatial density of consumption, finally only electricity and
hydrogen will meet consumers' stringent requirements for versatility,
cleanliness, and other attributes. Hydrogen of course produces only water vapor
when burned, effectively zero emissions. So, hydrogen must replace carbon in
the energy system, and in fact it is. This replacement, called decarbonization,
is the most profound finding of 25 years of energy
research. It implies that ultimately primary
fuels that easily supply H2 and electricity will win, too.
The stable dynamics of the energy system permit reliable
forecasts. Globally we are destined to use about 100 million tons more
coal. This is about half what humans have
mined in all our earlier history, and 30-40 years at present levels of
production, so all the participants in the coal industry have a generation or
two in which to remodel themselves. They can concentrate on extracting methane
from coal seams and sink CO2 there, staying in business without coal
extraction. Using CO2 to displace CH4 adsorbed in coal
beds provides a two for one bargain.
Coal’s market has progressively shrunk compared to
electric power generation and steel making. We need still to invent better
alternatives for the latter. Iron ores can be reduced with hydrogen and the
metallurgical treatment done in arc furnaces.
Tunneling, by the way, matters immensely for future human
well being, so the coal industry has a valuable skill to sell. A good use of
unemployed miners would be climate adaptation: digging tunnels under the cities
to ease traffic and expand badly needed, and energetically superior, metro
networks as well as water supply and sewer systems.
To conclude about coal, we should squeeze the maximum
electricity from the black rocks with the minimum fallout of nasties, but coal
is not our primary concern because its use will fade anyway.
Amazingly, oil is also not our prime concern. Globally,
drivers and others will consume about 300 million tons more oil, before the
fleet runs entirely on H2 separated from methane or water. This
amount is roughly double the petroleum that has so far been extracted, so oil
companies can choose to play business as usual for a while. But the entry
under the car’s hood of fuel cells or other motors fueled by H2
dooms oil, over the decades required for the turnover of the fleet, and makes a
huge niche for the easy ways to make the needed hydrogen fuel.
Preaching the advent of the Methane Age 20 years ago I felt
myself a daring prophet but now this prophecy is like invoking the sunrise.
Between its uses to fuel turbines to make electric power and for fuel cells for
transport, gas will dominate the primary energy picture for the next five or six
decades. I expect methane to provide perhaps 70% of primary energy around the
year 2030 and to reach a peak absolute use of 30 x 1012 m3
of natural gas in 2060. Although simply substituting gas for coal or oil
reduces CO2 emissions by a third to a half, the peak use would
correspond to 2 to 3 times today's carbon emission to dispose annually. Even in
2020, we could already need to dispose carbon from gas alone equal to half
today's emission from all fuel and later it would cause about 75% of total
CO2 emissions. So prevention – and offsets -- must focus on
Our plan must be to give the final consumer, whether the
operator of a power plant or a car, a fuel that produces zero emissions, namely
hydrogen. Several paths reach hydrogen. In principle, we could start from
heavy oil and end in hydrogen and CO2. Refiners have done it since
the 1960s. Refiners can more easily transform methane into hydrogen and
CO2. The methods now come from chemistry like that used to make
ammonia, but the energy companies could whip the imaginations of the
petrochemists to make more efficient processes suitable for plants two orders of
magnitude larger than present fertilizer plants but with less requirement for
Helpfully, so-called "city gas," basically impure hydrogen,
was the fuel gas of much of Europe until World War II. In a neat reversal, the
easiest market for hydrogen now to conquer is the household in Europe and North
America, where most residences already connect to the gas net. Sometimes the
change back requires merely enlarging the nozzles of the burners.
Hydrogen-electric cars still have barriers to overcome,
particularly a high accelerating capacity. I say begin with buses and trucks
and leave final victory with cars for a little later.
Airplanes consume ever more fuel. Although hydrogen attracts
because of its light weight and combustion properties precious for high
performance, compact, safe storage of liquid H2 still offers barriers
for the engineers and scientists of the air and space carriers to overcome. The
prizes will include the markets for the new Super Jumbos and the commercial
hypersonics. To speed the ever more numerous climate negotiators cleanly to
their next meeting.
Nuclear fission probably, or possibly some other non-carbon
alternative, will eventually close the hydrocarbon fuel era. Nuclear plants can
economically make electricity by day and hydrogen by night, when electricity
demand falls. After TMI and especially Chernobyl, the pundits said such
accidents would be common. The world has now experienced 5000 reactor years of
operation since Chernobyl without a significant nuclear power plant accident.
That is, more than 400 plants have operated safely for 14 years each. Nuclear
power technology works, and punditry about the China Syndrome did not. Now is
the time to promote actively the development of high temperature gas-cooled
reactors and other plant designs especially well-suited for the joint production
of electricity and hydrogen.
In the interim before nuclear, however, can we find technology
consistent with the evolution of the energy system to economically and
conveniently dispose the carbon from making kilowatts? The practical means to
dispose the carbon from generating electricity consistent with the future
context is what I and my associates call ZEPPs, Zero Emission Power
The first step on the road to ZEPPs is focusing on natural gas
simply because within a couple of decades half of CO2 emissions will
come from natural gas. A criterion for ZEPPs is working on a big scale. One
reason is the information economy. Even with efficiency increasing, the
information economy demands huge amounts of electricity. Observe the recent
rapid growth of demand in a college dormitory, or in the State of California and
especially Silicon Valley. Chips could well go into 1000 objects per capita, or
10 trillion objects, as China and India log into the game.
Big total energy use means big individual ZEPPs because the
size of generating plants grows even faster than use, though in spurts. Plants
grow because large is cheap if technology can cope. Although the last wave of
power station construction reached about 1.5 gigawatts (GW), growth of
electricity use for the next 50 years can reasonably raise plant size to about 5
GW (Figure 4). For reference, the New York metropolitan area now draws above 12
GW on a peak summer day.
Bigness has a hidden plus for controlling emission. Although
one big plant emits no more than many small plants, emission from one is easier
to collect. Society cannot close the carbon cycle if we need to collect
emissions from millions of microturbines.
Big ZEPPs means transmitting immense mechanical power from
larger and larger generators through a large steel axle as fast as 3,000
revolutions per minute (RPM). The way around the limits of mechanical power
transmission may be shrinking the machinery. Begin with a very high pressure
CO2 gas turbine where fuel burns with oxygen. Needed pressure ranges
from 40 to 1000 Atm, where CO2 would be recirculated as a liquid.
The liquid combustion products would be bled out.
Fortunately for transmitting mechanical power, the high
pressures shrink the machinery in a revolutionary way and so permits the turbine
to rotate very fast. The generator could then also turn very fast, operating at
high frequency, with appropriate power electronics to slow the generated
electricity to 60 cycles.
Our envisioned hot temperature of 1500 degrees C will probably
require using new ceramics now being engineered for aviation. Problems of
stress corrosion and cracking will arise at the high temperatures and pressures
and need to be solved. Power electronics to slow the cycles of the alternating
current also raises big questions. What we envision is beyond the state of the
art, but power electronics is still young, meaning expensive and unreliable, and
we are thinking of the year 2020 and beyond.
The requisite oxygen for a 5 GW ZEPP also exceeds present
capacity but could be made by cryoseparation. Moreover, the cryogenic plant may
introduce a further benefit. Superconductors fit well with a cryogenic plant
nearby. Superconducting generators are one of the sweetest cherries of
One criterion of great interest for ZEPPs is their overall
projected plant efficiency. Colleagues at Tokyo Electric Power calculate the
efficiency could be 70%, well above the 50-55% peak performance of today.
With a ZEPP fueled by natural gas transmitting immense power
at 60 cycles, the next step is sequestering the waste carbon. At the high
pressure, the waste carbon is, of course, already liquid carbon dioxide and thus
easily-handled. Opportunity for storing CO2 will join access to
customers and fuel in determining plant locations. Because most natural gas
travels far through a few large pipelines, these pipelines are the logical sites
In short, the vision is a supercompact (1-2 m diameter),
superpowerful (potentially 10 GW or double the expected maximum demand),
superfast (30,000 RPM) turbine putting out electricity at 60 cycles plus
CO2 that can be sequestered. ZEPPs the size of a locomotive or even
an automobile, attached to gas pipelines, might replace the fleet of carbon
emitting monsters now cluttering our landscape.
We propose starting introduction of ZEPPs in 2020, leading to
a fleet of 500 5 GW ZEPPs by 2050. This does not seem an impossible feat for a
world that built today’s worldwide fleet of some 430 nuclear power plants
in about 30 years. Combined with other offset strategies, ZEPPs, together with
another generation of nuclear power plants in various configurations, can stop
CO2 increase in the atmosphere near 2050 AD in the range 450-500 ppm
without sacrificing energy consumption.
ZEPPs merit tens of billions in research and development
(R&D), because the plants will form a profitable industry worth much more to
those who can capture the expertise to design, build, and operate them.
Research on ZEPPs could occupy legions of academic researchers, and restore an
authentic mission to the National Laboratories of the US Department of Energy
(US DOE), working on development in conjunction with private companies. ZEPPs
need champions, and I hope they will be found among the readers of the
To summarize, I have searched for technologies that handle the
separation and sequestration of amounts of carbon matching future fuel use. Like
the jumbo jets that carry the majority of passenger kilometers, compact ultra
powerful ZEPPs could be the workhorses of the energy system in the middle of the
Remarks and Conclusions
Let me offer a few brief remarks about popular aspects of the
climate debate and then conclude.
Conventionally, I would now make the usual warm and very fuzzy
remarks about so-called solar and renewable sources. The reality is that each
is dirty in its own way: hydro kills rivers, biomass gobbles habitat that could
be wilderness, windmills kill birds (and could easily become still relics if the
winds change), fields of photovoltaics are Earth painted black, and so on.
After 20 years and more than $12 billion in R&D from the US DOE, and
friendly words from consumers, solar and new renewables do not provide the US
with a single new quad of the more than 90 quadrillion BTUs the US consumed in
the year 2000.
Most important, no one has figured out how to achieve
economies of scale with these energy sources. When increasing spatial density
of energy consumption drives the system, we must match it with economies of
scale in production. We need B-747s as the backbone of the energy system, not
2-seater Piper Cubs. Of course, the little planes play crucial roles in the
capillary ends of the system and in providing back-up and flexibility. But they
will not prevent greenhouse gas build-up.
And what about efficiency? The opportunity appears huge,
because the efficiency of most aspects of the energy system -- extraction of
resources, generation and transmission of power, and especially the devices used
finally by consumers -- is a small fraction of what it could be. Alas,
historically, inefficiency tends to lessen at an implicit, steady, gradual rate.
The rate appears the outcome of a complex of factors including how consumers
spend their money and time, and the ability to maintain and service products.
Rates of efficiency gain do not seem persistently altered by so-called
Better efficiency, by the way, is not particularly driven by
prices. For example, the prize for more efficient aircraft engines has been
range. Fuel economy enabled the Airbus 340 to fly nonstop from Frankfurt to
Honolulu and thus gain a new market. Reducing the fuel bill was not the game.
The prizes for more efficient electronics are often time and portability.
Spartan electronics extend the operational time of a cell phone and reduce the
weight of its batteries. Consumers cheerfully pay for these benefits, unlike
for energy efficiency per se.
More generally I doubt fiddling with prices has much long run
effect on the energy system. Carbon taxes are just more taxes, with a smell of
morality. Carbon taxes will have negligible impact on transport fuel
consumption in particular. The usual car owner with a constant travel money
budget saves money by continuing to drive the old car and offsetting higher fuel
prices by lowering capital or amortization costs. As we saw during the
so-called Oil Crisis, the behavior spreads havoc through the auto industry
without benefiting the environment.
Although emission trading might in principle lower the cost of
decarbonizing, I doubt whether societies can solve the hardest problem of a
trading system: the allocation of permits worth about a trillion
If solar and renewables, efficiency, taxes, and emission
trading all count for little, what adaptation, offsets, and prevention shall we
Since the 19th century, Earth has had a 30%
increase in CO2 from about 280 to about 360 ppm with no discernible
harm. We probably cannot avoid about as much again, say a 25% increase to 450
ppm. So, we should invest in adaptation to live with likely change.
We should choose long-term solutions for emissions compatible
with the evolution of the energy system. This means shift to methane, focus
offsets on the carbon in methane, prepare the hydrogen economy, and anticipate
the nuclear millennium that will follow our Methane Age.
Technology can make adapting to climate change, offsetting
emissions, and preventing emissions cheap and effective. The companies that
provide the appropriate goods and services will profit. However, entering the
marketing too early can cost as much as entering too late. Society does not
want to risk being too late. Thus, cooperative efforts boosted publicly make
sense now, especially for momentous developments such as interbasin water
transfer or 5 GW ZEPPs that may cost dear and need widespread social
The trick is easing in the changes when the technologies
turnover, operating at the point where old things are substituted anyway. Even
a refinery is metabolized in a decade or two, that is, machinery is
substantially replaced due to wear and tear and obsolescence.
In contrast, beliefs, such as kosher dietary laws, can last
thousands of years. As a 19th century rabbi said, the loudest sound
in the world is a habit breaking. Infiltrating technology, we can avoid screams
while lessening worries about climate change.
Mechanisms such as the Electric Power Research Institute and
the Gas Research Institute, both now unintentionally endangered by the
re-regulation of their industries, have already played great roles in the US in
helping the timely evolution of climate friendly technologies, such as fuel
cells and superconducting materials. Adapting and expanding these
organizations, and making comparably valuable institutional innovations, also
make a worthy goal.
Great sins can elicit great cathedrals. In fact, the people
of medieval Europe were not more evil than those of other times and places, but
they channeled their guilt to glorious, enduring expression. Let us similarly
channel the diffuse anxiety that is environmentalism into immense
Figure 1. Successive replacements of recording media in the
U.S. ppmarket. Presumably digital video disks (DVDs) or some other new form of
recording will in turn replace CDs. The data are analyzed as a logistic
(S-shaped) growth process and plotted in the linear transform of the logistic
curve. F is the market share expressed as a fraction. Data source: Recording
Industry Association of America, Annual Report, Washington, D.C.,
Figure 2. Cumulative shipments of dynamic random access memory
(DRAM) chips in gigabytes by integrated circuit density of the chip type,
semi-logarithmic scale. Note that with each improved chip the market
effectively expanded by about 10 times. Data sources: Integrated Circuit
Engineering Corporation Status 1999; D. A. Irwin, P.J. Klenow, Learning-by-doing spillovers in the
semiconductor industry. Journal of Political Economy 102(6):1200-1227,
Figure 3. Shares of the actual total length of the US
transport infrastructure (squiggly lines) analyzed with the logistic
substitution model (smooth lines). Note the conjecture that magnetically
levitated trains (maglevs) will enter market; maglevs are a way for electricity
to penetrate the market for power for transport. Sources of data: A. Gruebler,
The Rise and Fall of Infrastructure: Dynamics of Evolution and Technological
Change in Transport (Heidelberg: Physica, 1990); US Department of
Transportation, National Transportation Statistics (Washington, DC: Bureau of
Transportation Statistics, 1999). Online at
Figure 4. The maximum size of power plants, US. Each line
represents an S-shaped (logistic) curve normalized to 100 percent, with
estimates for the midpoint of the process and saturation level indicated. So,
the pulse centered in 1929 quickly expanded power plants from a few tens of
megawatts (MW) to about 340. After a period in which plant size stagnated, the
pulse centered in 1965 quadrupled maximum plant size to almost 1400 MW. The
patterns for the world and a dozen other countries we have analyzed closely
resemble the USA. Note the projection for another spurt in plant size centered
around the year 2015, quadrupling the maximum again, to more than 5 GW. F is
fraction of the process completed. Source of data: World Electric Power Data
CDROM UDI-2454, Utility Data Institute, Washington DC,
1 J.H. Ausubel, Does Climate Still Matter? Nature
 See J.H. Ausubel,
Productivity, Electricity, Science: Powering a Green Future, Electricity Journal
9(3): 54-60, especially Figures 2 and 3.
 J. H. Ausubel, A. Gruebler,
and N. Nakicenovic, Carbon Dioxide Emissions in a Methane Economy, Climatic
Change 12:245-263, 1988.
 For more information on
ZEPPs, see J.H. Ausubel, Five Worthy Ways to Spend Large Amounts of Money for
Research on Environment and Resources, The Bridge 29(3):4-16, Fall