Limiting atmospheric carbon dioxide emissions to minimize "dangerous anthropogenic interference" with climate as the human economy continues its historical growth will require a revolutionary change of the world energy system. For example, holding global warming below "only" 2 degrees Celsius -- an amount which could itself create serious adverse impacts -- implies adding the equivalent of one large power plant per day emitting no CO2; or comparable reductions in demand in the sense of Lovins' "negawatts " by improvements in energy efficiency and/or energy-conserving behavior. Massive emission cuts increasing with time relative to those that would be produced if carbon intensity (C/E) remained constant will be needed, with emissions declining to near zero by the century's end.
Civilization today is energized overwhelmingly by fossil fuels, increasingly we predict by high-carbon-emitting coal, as oil and gas production will likely peak in coming decades, and energy demand continues to rise. Beyond the screen of obfuscation and denial of global warming by "skeptics" and special interests are emerging policy questions: Can "existing" energy technology simultaneously run the world economy and stabilize the fossil fuel greenhouse? Or, as I will argue, is an aggressive R & D effort led by the US urgently needed to develop new high-technology energy sources in parallel with implementation of existing emission-limiting measures? Holding that "technology exists" is the IPCC Third Assessment Report mitigation working group who in their Summary for Policymakers said "known technological options could achieve a broad range of atmospheric CO2 stabilization levels, such as 550 ppm, 450 ppm, or below over the next 100 years," defining "known technological options" as already existing in operation or in pilot plants. This definition excludes carbon capture and sequestration (CCS) plants -- perhaps the most "market ready" technology -- because first pilot plant won't exist until 2010 at best. Likewise, Pacala and Socolow claim that "Humanity already possesses the fundamental scientific, technical, and industrial know-how to solve the climate problem for the next half century." This might be the case in the sense that humanity had the know-how to build nuclear weapons in the late 30s or go to the Moon in the 50s. But it took the Manhattan and Apollo programs to make it so.
Stabilizing climate change is a hard problem. I will argue that although technologies capable of slowing global warming cost and otherwise effectively over the next fifty years don't exist in an operational sense, they can be developed, and deployed in time to matter, if broad-spectrum research, development and demonstration were initiated now, preferably with the urgency of World War II mobilization. This is justified by the threat of global warming, but is no excuse for not deploying emission-limiting measures that can be implemented today.
An assessment is presented of fossil fuel (with CCS), nuclear and renewable energy technologies options, and of enabling transmission and storage technologies, to supply the required amounts of emission-free power at the required times. In light of the 10-100 year time scale -- roughly 60 years separate the Wright brothers from Neil Armstrong's walk on Moon -- emphasis is placed on innovative opportunities from recent discoveries in material science (high-temperature superconductivity, carbon nanotubes); the geophysics of available energy fluxes in space (solar power satellites, lunar power systems), at Earth's surface (Massive offshore wind farms, PV panels in the US southwest and the Sahara), tropospheric jet streams (tethered high-altitude autogyros) and in ocean boundary currents (seawater uranium harvesting) and geothermal heat flows (hot rock drilling & mining for heat); and electric grid and storage systems supportive of renewable energy (direct current, superconducting and smart grids, distributed generation, hydro, flywheel and inductive electrical storage); and approaches to replacing liquid hydrocarbons derived from fossil fuels (hydrogen, CO2 removal from the atmosphere, biofuels, microwave beaming to cars and aircraft).
As with biological evolution, technology evolution requires mutations. Most mutations are unsuccessful. But without them evolution stops. Some who characterize advanced energy technologies to reduce carbon emissions as "blue sky" might have said the same of flying machines and radio a hundred years ago, when innovations like computers and nuclear reactors would have been to most pundits unimaginable. History suggests we avoid such dismissals. Particularly telling is the recent 911 Commission finding that the greatest failure by intelligence organizations in anticipating fundamental challenges to our civilization like 911 was "failure of imagination."
Global warming in the last millenium
Very rapidly we've entered uncharted climatic territory - the anthropocene. Over the 20th century, human population quadrupled and energy consumption increased sixteenfold. Near the end of the last century, a critical threshold was crossed, and warming from the fossil fuel greenhouse became a dominant factor in climate change. Hemispheric mean surface temperature is higher today than at any time in the last millennium -- the so-called Mann et al. "hockey stick." Temperatures are likely to go "off the scale" in the 21st century.
Ken Caldeira, Atul Jain, and Martin Hoffert published on "Climate Sensitivity Uncertainty and the Need for Energy Without CO2 Emission", in the March 28, 2003 issue of science:
The UN Framework Convention on Climate Change calls for "stabilization of greenhouse gas concentrations at a level that would prevent dangerous anthropogenic interference with the climate system." Even if we could determine a "safe" level of interference in the climate system, the sensitivity of global mean temperature to increasing CO2 is known perhaps only to a factor of three or less. Here we show how a factor of three uncertainty in climate sensitivity introduces even greater uncertainty in allowable increases in atmospheric CO2 concentration and allowable CO2 emissions. Nevertheless, unless climate sensitivity is low and acceptable amounts of climate change are high, climate stabilization will require a massive transition to CO2 emission-free energy technologies.
Figure 3: Mean rate of increase in installed capacity in carbon-emission-free primary power required over the period from year 2000 to year 2050 to stabilize climate, shown as a function of climate sensitivity to a carbon dioxide doubling and equilibrium global warming for the GDP and energy demand growth assumptions of the IPCC IS92a scenario. To hold global warming below 2oC with a climate sensitivity of 2.5 degrees C/CO2 doubling requires adding the equivalent of one 1000 MW (thermal) emission-free power plant every day for the next 50 years.
Figure 5: Per Capita Carbon Emissions Versus Per Capita GDP of 100 Nations
Note that carbon intensity is defined as the ratio of carbon emissions to GDP (gross domestic product). It can be broken down as the product of energy intensity E/GDP and the carbon emission factor, C/E
What does the SRES emission uncertainty range mean?
(Editor's note: SRES = IPCC Special Report on Emissions Scenarios)
Figure 6: Global carbon dioxide emssions related to energy and industry from 1900 to 1990 and for 40 SRES scenarios from 1990 to 2100, shown as an index (1900 = 1). Colored lines are individual SRES scenarios. The area shaded in blue is the range of scenarios in the literature documented in the SRES database.
Fossil Fuel Emissions and Stabilization Triangles
ExxonMobil Energy Projections
Milestones in predicting the probable evolution of societies
Many Worlds? A popular hypothesis of cosmology and quantum mechanics is that universe is continually split into infinite parallel versions, with outcomes covering every possible situation. Their probabilities are described by wavefunctions, much as an electron's position is. If we only knew them for the 40 SRES scenarios. . .
Will civilization crash this century? Plots are the "standard world model" run from Meadow's (1974) "Limits to Growth" sponsored by the Club of Rome which assumed no major change in physical, economic or social relationships that have historically governed the devlopment of the world system. All variables follow historical values from 1900 to 1970. Food, industrial output, and population grow exponentially until the rapidly diminishing resource base forces a slowdown in industrial growth. Because of natural delays in the system, both population and pollution continue to increase for some time after the peak of industrialization. Population growth is finally halted by a rise in the death rate due to decreased food and medical services.
That resource scarcity limits economic growth as embodied in this model is fundamentally opposed by the boundless growth paradigm of market economics embodied in IPCC SRES scenarios.
Fossil fuel electricity from steam turbine cycles:
Fossil fuel CO2 sequestration and burial
rates to generate 10 TW emission-free:
Mass-produced widely distributed PV
arrays and wind turbines may eventually
generate 10-30 TW emission-free:
(LEFT) The conventional light water reactor (LWR) employs water as both coolant and working fluid. (RIGHT) The helium-cooled, graphite-moderated, pebble bed, modular nuclear fission reactor is theoretically immune to loss of coolant (TMI) and criticality (Chernobyl) accidents.
Pathway to Stabilization of Atmospheric Emissions
Physics offers both opportunities and limits on new technologies; but predicting winners can be hazardous. For example:
There has been a great deal said about a 3,000 mile high angle rocket. In my opinion such a thing is impossible for many years. The people who have been writing these things that annoy me, have been talking about a 3,000 mile highangle rocket shot from one continent to another, carrying an atomic bomb and so directed as to be a precise weapon which would land exactly on a certain target, such as a city. I say, technically, I dont think anyone in the world knows how to do such a thing, and I feel confident that it will not be done for a very long period of time to come . . . I wish the American Public would leave that out of their thinking.Vannevar Bush, Head of US scientific WW II effort (in 1945)
Arthur C. Clarke's Laws of Technological Prophecy
"Bucky" Fuller's global electrical grid:
- proposed in the 1970s augmented with computerized load management and high-temperature superconducting (HTS) cables could transmit electricity from day to night locations and foster low-loss distribution from remote, episodic or dangerous power sources. The resistivity of copper oxide HTS wires vanishes below the 77 K boiling point of liquid N2 available from air. Could HTS nanotubes do the job someday?
Capturing and controlling space solar power:
Figure 18: (Left) Wireless power from space could enable developing nations to avoid fossil-fuel-based industrialization. Ultralight large SPS aperture antennas and other components could be fostered by nanotechnology. (Right) Deflecting sunlight with a 2000 km flat lens at the L1 Lagrange point or intentional aerosol injections to the stratosphere are potential "worst case" mitigators of global warming.
The most successful approach to fusion so far has been has been confining a D-T plasma (in purple) with complex magnetic fields in a "bagel"-shaped chamber (a tokamak). "Breakeven" requires that the plasma triple product (= number density X confinement time X temperature) attain a critical value; as it has nearly done in recent experiments. A fusion-fission hybrid breeder based on tokamak research may be feasible prior to a fully fusion power reactor. Experiments on advanced fusion fuel cycles and simpler designs are also needed -- like the levitated dipole experiment at MIT shown above.
Energy Applications of Carbon Nanotubes
Figure 20: CG image of carbon nanotube.
Hydrogen Storage: High H2 sorption may result from polarization inside tubes enhanced by dopants
Figure 21: Superconducting nanotubes inside zeolite pores (inset), against backdrop of zeolite crystals. COURTESY OF PING SHENG AND NING WANG.
Superconductivity: So far, electron-hole doped fullerenes superconduct at temps < 52 K
Nanotube-Enabled Space Elevators
Climbing into space on ultrastrong tethers -- possibly carbon nanotubes -- a space elevator could provide cheap access to orbit someday. This visualization appeared in an article by T. Ferris in the NY Times Magazine 28 Nov. 1999, where the price of carbon nanotubes was estimated at ~ $1000/gm. Cost breakthroughs could enable this technology, as well as large aperture microwave antennae and solar polar satellites even sooner.
History of US Federal Government R&D
deja vu: The double-finned beast on a microwave tower in the middle right of the collage at left is the Lebost Wind Turbine (LWT). The top is an image from an interview Jane Pauley of the NBC Today show did with me live from the Barney Building roof in the summer of '79 shortly after the LWT went up. The winning architectural design for the WTC reconstruction, the Freedom Tower by Daniel Liebeskin and David Child, is projected to contain wind turbines inside its open cabletensioned upper structure, sufficient to generate 20% of the building's electricity -- the first wind turbine in lower Manhattan since we built the NYU LWT during the "Energy Crisis" of the 1970's.
We don't have 25 years to wait for the next ones.
Research and Demonstrations