Advanced Technology Paths to Global Climate Stability: Energy for a Greenhouse Planet

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Science  01 Nov 2002:
Vol. 298, Issue 5595, pp. 981-987
DOI: 10.1126/science.1072357

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  • Regarding Advanced Technology Paths to Global Climate Stability: Energy for a Greenhouse Planet

    Although I agree with the article’s conclusion that worldwide efforts to develop the alternative energy production technologies needed to address greenhouse gas buildup in Earth’s atmosphere are sorely lacking, I am disappointed that the technology best able to deal with this impending catastrophe, solar thermal technology, was barely mentioned. Solar thermal electric technologies, including parabolic troughs, power towers,...

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    Competing Interests: None declared.
  • Slowing population growth

    In their comprehensive review of advanced technology paths to global climate stability, Hoffert (1) open with a clear statement of the origin of the problem: "In the 20th century, the human population [of the earth] quadrupled and primary power consumption increased 16-fold" (2). If these rates were to persist through the 21st century, Earth's population would be 16 times larger than in 1900, and the primary power...

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    Competing Interests: None declared.
  • Re: Hoffert et al.

    In their discussion of advanced energy technologies, Hoffert et al. state that “The main problem with fission for climate stabilization is fuel. Current estimates of [uranium] in proven reserves and (ultimately recoverable) resources are 3.4 and 17 million metric tons, respectively. This represents 60 to 300 TW-year of primary energy. At 10 TW, this would only last 6 to 30 years--hardly a basis for energy policy.” (1)....

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    Competing Interests: None declared.
  • Strategies for dealing with global warming

    The excellent article by Hoffert et. al. (Vol. 298 P. 981) has the unfortunate effect of misrepresenting the potential for near-term reductions in CO2 emission. Although energy efficiency is discussed in principle, the article inappropriately minimizes its immediate potential. DOE's "Clean Energy Future" report ( identifies the potential for eliminating over a third of all U.S...

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    Competing Interests: None declared.
  • The competitiveness of renewable energy

    In their article “Advanced Technology Paths to Global Climate Stability” (1 Nov., p. 982), Hoffert et al. argue that energy sources “that can produce 100 to 300% of present world power consumption without greenhouse emissions do not exist operationally or as pilot plants.” They also chide the Intergovernmental Panel on Climate Change for its “misperceptions of technological readiness.” Hence the authors conclude that in...

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    Competing Interests: None declared.
  • High-Temperature Solar-Thermal, a readily available solution

    Why haven't this extraordinary team of scientists and engineers mentioned readily available, fully-tested, DOE lab certified, solar-thermal technologies. These technologies include fixed parabolic troughs with tracking-thermal tubes that can produce electricity by powering Rankin Cycle engines with thermal transfer fluids heated to 750 degrees F (see Kramer Junction, CA/Gilbert Cohen/Luz/Duke Solar), and Dr. Roland Winst...

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    Competing Interests: None declared.
  • Life-cycle Assessment of Energy Technologies

    The article highlights several technologies that could lead the world to a sustainable development path; however, no discussion of global warming mitigation is complete without mentioning the life-cycle assessment (LCA) of the proposed technologies. Because greenhouse gases are emitted during the various phases of an energy generation process (manufacturing, construction, operation, and end of life), it is fundamental to...

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    Competing Interests: None declared.
  • Breeder reactors should be considered also

    Hoffert et al. dismiss the nuclear fission option as an answer to the world's long-term energy needs on the basis that there will not be enough uranium to fuel the number of current generation type of reactors needed to make a significant impact. Completely missing from their analysis is the potential role of breeder reactors, in which electricity is generated simultaneously with the production of more nuclear fuel th...

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    Competing Interests: None declared.
  • Ignores conservation

    A premise of this article is that energy demand will continue to climb, i.e., that people now driving SUV/Pickups will eventually be driving something larger and less efficient.

    I contend that various scenarios should be examined that identify various technologies that reduce energy demand beyond simple efficiency. For example, there exist today many homes and buildings that produce as much energy as they consu...

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    Competing Interests: None declared.

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