Reply #54: A minor contribution from nuclear woud require a new Yucca Mtn every 2 years. [View All]

[kristopher]

From a presentation by John Holdren.

The nuclear option: size of the challenges

• If world electricity demand grows 2% /year until 2050 and nuclear share of electricity supply is to rise from 1/6 to 1/3...
–nuclear capacity would have to grow from 350 GWe in 2000 to 1700 GWe in 2050;
– this means 1,700 reactors of 1,000 MWe each.

• If these were light-water reactors on the once-through fuel cycle...
---–enrichment of their fuel will require ~250 million Separative Work Units (SWU);
---–diversion of 0.1% of this enrichment to production of HEU from natural uranium would make ~20 gun-type or ~80 implosion-type bombs.

• If half the reactors were recycling their plutonium...
---–the associated flow of separated, directly weapon - usable plutonium would be 170,000 kg per year;
---–diversion of 0.1% of this quantity would make ~30 implosion-type bombs.

• Spent-fuel production in the once-through case would be...
---–34,000 tonnes/yr, a Yucca Mountain every two years.

Expanding nuclear enough to take a modest bite out of the climate problem is conceivable, *but* doing so will depend on greatly increased seriousness in addressing the waste-management & proliferation challenges.


Mitigation of Human-Caused Climate Change
John P. Holdren

Repeating that conclusion: Expanding nuclear enough to take a modest bite out of the climate problem is conceivable, *but* doing so will depend on greatly increased seriousness in addressing the waste-management & proliferation challenges.

What does he say about renewables?

The renewable option: Is it real?

SUNLIGHT: 100,000 TW reaches Earth’s surface (100,000 TWy/year = 3.15 million EJ/yr), 30% on land.
Thus 1% of the land area receives 300 TWy/yr, so converting this to usable forms at 10% efficiency would yield 30 TWy/yr, about twice civilization’s rate of energy use in 2004.

WIND: Solar energy flowing into the wind is ~2,000 TW.
Wind power estimated to be harvestable from windy sites covering 2% of Earth’s land surface is about twice world electricity generation in 2004.

BIOMASS: Solar energy is stored by photosynthesis on land at a rate of about 60 TW.
Energy crops at twice the average terrestrial photosynthetic yield would give 12 TW from 10% of land area (equal to what’s now used for agriculture).
Converted to liquid biofuels at 50% efficiency, this would be 6 TWy/yr, more than world oil use in 2004.

Renewable energy potential is immense. Questions are what it will cost & how much society wants to pay for environmental & security advantages.

Mitigation of Human-Caused Climate Change
John P. Holdren

John P. Holdren is advisor to President Barack Obama for Science and Technology,
Director of the White House Office of Science and Technology Policy, and
Co-Chair of the President’s Council of Advisors on Science and Technology...

Holdren was previously the Teresa and John Heinz Professor of Environmental Policy at the Kennedy School of Government at Harvard University,
director of the Science, Technology, and Public Policy Program at the School's Belfer Center for Science and International Affairs, and
Director of the Woods Hole Research Center.<2>

http://en.wikipedia.org/wiki/John_Holdren