Michael, Some quite thoughtful material, with agreement across much of what you say. And, by the way, if anything, Michael's words might understate the challenges in the water arena, which are quite fearsome in many parts of the world, with the acquifer challenges (read Ogallala Blue (http://www.prairiefirenewspaper.com/2007/08/book-review-ogallala- blue) for example) occurring also in the face of coming challenges due to glacier melts and disruptions in rainfall patterns with climate change. (In this vein, I've been surprised that I haven't seen discussions of trying to capture melting Greenland ice as fresh water for the desert along the lines of towing ice bergs for Saudi as seemed to be a rage of discussion 30 years ago ...)
In any event, I want to challenge on one item: "I suspect a huge push toward nuclear power is the only plausible escape route given the limitations on other sources of energy." There are some quite serious inherent limitations on what can be done in the nuclear energy field, not least of which is the timeline required for ramping up the infrastructure (engineers, industrial, uranium mining & processing) that has atrophied across much of the world. While I see nuclear energy as quite probably part of the equation, I think an expansion of nuclear power from 20% to 30% (e.g, an over 50% increase if we assume demand growth) in the United States by 2025 is just on the edge of the possible (think of trying to get plants through regulatory processes, financed, constructed, etc ...). In the face of the challenges due to climate change, this elimination of perhaps 20% of coal-fired electricity in the US just isn't enough to be meaningful, unless there are other tremendous changes. The challenges for renewables are, imo, less than your note suggests. If we move (US) to a smart(er) grid, with PHEVs and V2G (vehicle-to- grid) penetration, the amount of renewables that can peentrate the market will skyrocket as there will be many paths to deal with intermittency. And, of course, one benefit of Solar (PV or CSP), Wind, Ocean, small hydro, distributed biomass, etc is that the power can be introduced incrementally. A 500 megawatt wind farm might add production to the grid with each wind turbine. Even if the "farm" takes five years to build, the first non-GHG power might be on the grid in year one. Large-scale nuclear & hydro, it is a zero/one situation, with no reduction in GHG footprint of electricity production until the whole system is done. And, of course, efficiency ... In other words, imo, the only path forward is a holistic one, that considers the entire energy triad (end use / desired output, efficiency of systems using power, and power source). A Siegel Energy Smart http://energysmart.wordpress.com On Apr 6, 8:04 pm, "Michael Tobis" <[EMAIL PROTECTED]> wrote: > On Sun, Apr 6, 2008 at 6:38 PM, David B. Benson <[EMAIL PROTECTED]> > wrote: > > > > > On Apr 6, 1:54 pm, "Michael Tobis" <[EMAIL PROTECTED]> wrote: > > > ... > > > Food is largely provided through extractive use of ground water. > > World-wide? I doubt this. Data? > > The magnitude of the aquifer depletion problem has only recently become > evident. Although comprehensive data do not exist, it is believed that > global groundwater over-pumping (i.e., beyond the rate at which groundwater > is recharged) totals at least 160 billion cubic meters a year, equal to > twice the annual flow of the Nile rivers. For example, the rate at which > groundwater is extracted in India is more than twice the rate of recharge, > with some water tables now falling by one to three meters per year. As a > result, India could lose 25% or more of its current crop production during > the next 25 years due to unsustainable aquifer usage rates. Similarly, > Mexico is depleting ground water reserves in some agriculturally important > regions at rates exceeding 3 meters per year. The implications for global food > security<http://www.usaid.gov/our_work/environment/water/food_security.html>are > enormous. It is estimated that nearly 10% of the global food supply > (160 > million tons of grain) is currently based on the unsustainable practice of > depleting groundwater. > > http://www.usaid.gov/our_work/environment/water/groundwater_mgmt.html > > mt --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/globalchange -~----------~----~----~----~------~----~------~--~---
