1. Chapter 16:
Future Climate
Part 3—Economics
and energy policy

2. Reminder (point also made in An Inconvenient Truth):
Stabilizing atmospheric CO2 is extremely difficult! It requires huge cuts in emissions 

3. Target goals for atmospheric CO2 and associated emission scenarios
2013
1990
The Earth System (2010), Fig. 16-8
We need to cut CO2 emissions in half (3 Gt C/yr) just to limit ourselves to
750 ppmv of CO2
Stabilizing at today’s CO2 level would require negative emissions, i.e., net
CO2 uptake

4. Cost-Benefit Analysis
When evaluating whether or not a particular project, e.g. building a dam, makes sense economically, economists often employ cost-benefit analysis
Evaluate the economic costs of the project
Weigh these against the economic benefits
This same type of analysis can be applied to global warming

5. The “DICE” Model DICE model = Dynamic Integrated Climate-Economy model
Developed by William Nordhaus at Yale University
Weighs the projected economic damages from global warming against the costs of mitigation

6. (spending power)

7. DICE model results
2CO2
W. D. Nordhaus, Science 258, 1315, 1992

8. The discount rate, , is a key factor
Nordhaus assumes a discount rate of 3%/yr

10. Recently, the issue of discounting, and of global warming policy in general, has been revisited in a British study called the Stern Review
These authors recommended using much lower discount rates
Consequently, they suggested that we should cut back much more sharply on CO2 emissions 

11. Projected CO2 emissions and concentrations for different strategies
Business
as usual
Business
as usual
Kyoto
Nordhaus
Nordhaus
Stern
Stern
Gore
Carbon emissions
CO2 concentrations
The Challenge of Global Warming: Economic Models and Environmental Policy,
William Nordhaus, July 24, 2007
(See Figures and in The Earth System, ed. 3)

12. Practical carbon policy implications
Nordhaus
$30/ton of carbon, rising to $200/ton in 200 yrs. The initial tax is equivalent to
9¢/gal on gas
1¢/kWh on electricity (~10% of current price)
Stern
$100/ton initially, rising to $950/ton in 100 yrs
Stern
Nordhaus
Optimal carbon tax
(Fig a in The Earth System, ed. 3)
The Challenge of Global Warming: Economic Models and Environmental Policy,
William Nordhaus, July, 2007

13. Moral of this story:
How one decides to discount future costs and damages is very important to the decision making process. Considerations of intergenerational equity suggest that the discount rate should be low

14. Strategies for coping with global warming
Reduce greenhouse gas emissions, especially CO2
Energy conservation can help
Requires development of alternative energy sources (solar, wind, nuclear, geothermal, etc.)
Scrub the CO2 out of the atmosphere, or out of smokestack emissions, and bury it somewhere (carbon sequestration)
Direct geoengineering of the climate

15. Energy-efficient cars
Toyota Prius
Should we pass regulations, e.g., the CAFÉ (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?

16. Wind power Wind is one form of alternative, and renewable, energy for
producing electricity
T. Boone Pickens

17. Ground-based solar power plant
Two distinctly different types of plants:
Photovoltaic
Solar thermal power
/Image9.jpg

18. 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 birds
Solar_Power_Facility

19. 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]

20. “War of Currents” (late 1880’s)
Tesla
Thomas Edison favored a system
designed around direct current
Westinghouse
George Westinghouse and Nikola Tesla
favored a system based on alternating
current. They obviously won..

21. Existing and planned HVDC links
Xiangjiaba Dam to Shanghai
(2000 km, in operation)
Amazonas region to Sao Paulo
(2500 km, starting in 2015)

22. Ryan Switts NPRE 498 December 6, 2010
Three Gorges Dam
Ryan Switts
NPRE 498
December 6, 2010
-- Located on the Yangtze River in central China
-- Three different HVDC links are already in
operation between this site and various cities
in China

23. 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)

24. Lunar solar power
power-tower-beams-energy-to-earth/
Solar energy could be collected on the Moon’s 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

25. 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 235U are limited  need breeder reactors if you want this to last a long time. (Breeders convert 238U to fissionable 239Pu, i.e., plutonium)
The Susquehanna Steam Electric
Station (image from Wikipedia)

26. 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 of the four
damaged reactor buildings at Fukushima,
Japan
[Image from Wikipedia]

27. “Passively safe” reactors
Westinghouse’s 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

28. 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]

29. Carbon sequestration
Klaus Lackner at Columbia University is a pioneer in this field
One strategy: React coal with steam and produce hydrogen
CH2O + H2O  CO2 + 2 H2
Then sequester the CO2 in deep underground aquifers, the deep ocean, or possibly in subglacial Antarctic lakes

30. Geoengineering solutions
Alternatively, we may wish to forget about the CO2 and simply try to compensate for the expected climate change
Need to worry about ocean pH!
Different ideas for doing this 

31. 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

32. Seawater spray solution
Fleets of seawater sprayers could create additional tropospheric
aerosol particles that could cool the Earth by increasing its albedo

33. 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.)

34. 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 CO2 doubling would require deflecting about 2% of the incident sunlight
uanews.org (Univ. of Arizona)

35. Your professor’s opinions
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 CO2 emissions, i.e. a carbon tax