Chapter 16: Future Climate Part 2Possible Solutions to the Global Warming Problem Strategies for coping with global warming Reduce greenhouse gas emissions, especially CO 2 Energy conservation can help Requires development of alternative energy sources (solar, wind, nuclear, geothermal, etc.) Scrub the CO 2 out of the atmosphere, or out of smokestack emissions, and bury it somewhere (carbon sequestration) Direct geoengineering of the climate Energy-efficient cars Toyota Prius Should we pass regulations, e.g., the CAF (Corporate Automobile Fleet Efficiency) standards, requiring cars to get better gas mileage? Alternatively, should we impose a stiff gas tax, or better yet, a carbon tax, to encourage car buyers to purchase fuel-efficient vehicles? Wind power T. Boone Pickens Wind is one form of alternative, and renewable, energy for producing electricity Solar photovoltaic power plant Photovoltaic cells convert sunlight directly into electricity These are the types of solar panels found on some houses and on spacecraft Efficient at relatively low light intensity levels The 25.7 MW Lauingen Energy Park in Bavarian Swabia, Germanypower_station Solar thermal power plant The Ivanpah solar thermal power plant in southern California has an installed capacity of ~130 MW per tower ( 3 towers) 400 MW This is about half that of a conventional nuclear reactor (~1 GW per unit) These power plants are most efficient at high light intensities, and so are well suited for desert areas like the American Southwest Environmental concerns include the effect on desert tortoises and birdsSolar_Power_Facility High-voltage direct current (HVDC) For either wind or solar power, the best sources of power are often located far from where the power is needed HVDC is the best way to transmit power over long distances Losses: ~3%/1000 km Hence, transmission from Arizona to New York (~2000 mi. or 3000 km) would involve losses of only ~10% Long distance HVDC lines carrying hydroelectricity from Canada's Nelson river to this station where it is converted to AC for use in Winnipeg's local grid [Image and caption from Wikipedia] War of Currents (late 1880s) Thomas Edison favored a system designed around direct current Westinghouse Tesla George Westinghouse and Nikola Tesla favored a system based on alternating current. They obviously won.. Existing and planned HVDC links Xiangjiaba Dam to Shanghai (2000 km, in operation) -- Part of the Three Gorges hydropower project Amazonas region to Sao Paulo (2500 km, starting in 2015) Ryan Switts NPRE 498 December 6, Located on the Yangtze River in central China -- Three different HVDC links are already in operation between this site and various cities in China Satellite solar power Image from Wikipedia Satellites could be placed in geosynchronous orbit One might also be able to do this from the Moon (David Criswell, University of Houston) Lunar solar powerpower-tower-beams-energy-to-earth/Solar energy could be collected on the Moons surface using giant collectors like the one shown at the left The energy could then be beamed back to Earth using either microwaves or lasers Nuclear power plant Nuclear power is a known, but potentially dangerous means of producing electricity Waste disposal is an issue, if not a problem Reserves of fissionable 235 U are limited need breeder reactors if you want this to last a long time. (Breeders convert 238 U to fissionable 239 Pu, i.e., plutonium) The Susquehanna Steam Electric Station (image from Wikipedia) Nuclear accidents Public acceptance of nuclear power is a big issue Accidents like those at Chernobyl (Ukraine), Three-Mile Island (Pennsylvania), and Fukushima (Japan) do little to increase confidence Are the dangers acceptable, or, alternatively, can they be minimized? Satellite image on 16 March (2011) of the four damaged reactor buildings at Fukushima, Japan [Image from Wikipedia] Passively safe reactors Westinghouses AP1000 nuclear reactor is an example of a so- called passively safe design In the event of an accident, the reactor chamber could be flooded with water from a tank located directly above it Nuclear waste disposal Disposing of nuclear waste is also a huge issue Currently, all of our spent nuclear fuel is stored on-site at power plants in ponds Opening of the nuclear waste repository at Yucca Mountain, Nevada, ~100 mi. north of Las Vegas, has been postponed indefinitely Funding was terminated in 2009 by the Obama administration, for political (not technical) reasons Picture of Yucca Mountain [From Wikipedia] Carbon sequestration Klaus Lackner at Columbia University is a pioneer in this field One strategy: React coal with steam and produce hydrogen CH 2 O + H 2 O CO H 2 Then sequester the CO 2 in deep underground aquifers, the deep ocean, or possibly in subglacial Antarctic lakes Subglacial lakes Lake type--subglacial rift lake Max length--250 km Max width--50 km Surface area--15,690 km Average depth--344 m Max depth--1,000 m Water volume--5,400 km Residence time (of lake water)-- 1,000,000 yrs Lake Vostok circled in red Image and information from Wikipedia Diagram of Lake VostokLiquified CO 2 would be pumped down into the lake CO 2 would form a clathrate, which would remain stable as long as the ice remained above it Possible subglacial lake systemLake Vostok is one of as many as 50 subglacial lakes lying beneath the Antarctic ice cap Lake Vostok alone has the volume of Lake Michigan Geoengineering solutions Alternatively, we may wish to forget about the CO 2 and simply try to compensate for the expected climate change Need to worry about ocean pH! Different ideas for doing this Stratospheric aerosol injection One geoengineering strategy is to intentionally inject sulfate aerosols into the stratosphere, mimicking a large volcanic eruption But, the resulting uneven distribution of particles could result in massive weather disruption Mt. Pinatubo, Philippines, 1991 Seawater spray solutionFleets of seawater sprayers could create additional tropospheric aerosol particles that could cool the Earth by increasing its albedo The solar shield: Lagrange points in the Earth-Sun system It is theoretically possible to build a solar shield at the (unstable) L1 Lagrange point. (One has to actively adjust its position because this is an unstable saddle point in the gravitational potential field.) The solar shield Rather than building a single large mirror, it is more practical to fly about one trillion smaller (2-ft. diameter) lenses (Roger Angel, PNAS, 2006) Technically, this is called a Fresnel lens Offsetting one CO 2 doubling would require deflecting about 2% of the incident sunlight uanews.org (Univ. of Arizona) In my opinion, none of the geoengineering solutions are advisable, although we may need to resort to them if other measures fail Energy conservation and renewable energy sources (including biomass fuels) must be part of the solution Nuclear energy should not be ruled out as an option The best way to make all this happen is to impose a gradually increasing tax on CO 2 emissions, i.e. a carbon tax Your professors opinions