Transcript NUCLEAR ENERGY: FUSION

NUCLEAR ENERGY:
FUSION
Thermonuclear Reaction
E = mc2
Energy Comparison
http://fusedweb.pppl.gov/CPEP/Chart.html
Reaction
Starting
Material
Temp
needed
Energy
J/kg fuel
Chemical
Fission
Fusion
C+O2
CO2
coal
U-235
2
700 K
1000 K
UO2 ore
3.3E+7 or 2.1E+12
33 MegaJ or 2000
GigaJ
+ 21H 
3 He + 1 n
2
0
H-2, H-3
isotopes
1E+8 K
1H
3.4E+14 or
3400000
GigaJ
Nuclear Fusion (1)
• Nuclear reaction in which light nuclei
combine or fuse to produce a heavier
nucleus and a lot of energy.
• Example: Deuterium and/or Tritium fuse
• 21H + 21H  32He + 10n
• 21H + 31H  42He + 10n
Nuclear Fusion (2)
• Huge potential for meeting our energy needs: 1
g of H2 produces energy from burning 1 ton of
coal
• Deuterium is naturally occurring and is available
at 0.015% abundance. 21H in water could meet
energy needs for millions of years.
• Tritium is radioactive and must be produced via
fission of Li (abundant in earth’s crust).
• 63Li + 1n0  42He + 31H
Nuclear Fusion (3)
• For example, 10 grams of Deuterium
which can be extracted from 500 L (or 0.5
Mg) of water and 15g of Tritium produced
from 30g of Lithium would produce enough
fuel for the lifetime electricity needs of an
average person in an industrialized
country.
Nuclear Fusion (4)
• Produces minimal radioactive waste, but
risks exist with β emitting tritium.
• Produces no greenhouse gases or acid
rain.
• But requirements to carry out a controlled
fusion reaction and convert the energy
produced to industrial and household uses
is very difficult technologically and
financially.
Sustained Fusion Requirements
• Extremely high temperatures (100 – 200
million K) at which the hydrogen isotopes
are stripped of their electrons creating a
plasma of hot charged gases.
• Control of plasma to confine the energy
for 1-2 seconds.
• Extremely high pressure to force the
cations closer than 10-15 m to achieve
plasma density > 2E20 particles/m3
Sustained Fusion Requirements
• Safe handling of radioactive itopies.
• Technologies under development
– High magnetic fields to trap plasma of ions
(Tokamak)
– Fission rxn needed to produce neutrons for
tritium production  radioactive fallout
– “cold” fusion
– Creating high temperatures
Current Research to Control Fusion
Reaction for Energy Production
• Currently, fusion is not a feasible
alternative to fossil fuels but countries
have formed consortium to work on this
very difficult technological problems.
– ITER (collaboration of EU, Japan, US, S.
Korea, Russia, China, India) will achieve 500
MW of fusion power (10x more than existing
technology) and will be built in France to be
operational in 2015. June 2005 agreement
References
• JET: Joint European Torus, largest nuclear
fusion research facility located in the UK.
• www.jet.efda.org/pages/content/fusion1/ht
ml
• http://en.wikipedia.org/wiki/Nuclear_fusion
• http://news.xinhuanet.com/english/200603/02/content_4247782.htm
Thermonuclear Weapons
• Fusion of hydrogen bomb: heat and
explosion responsible for damage;
requires an atomic bomb to ignite.
– US and USSR tested H-bombs in early 1950’s
– Britain, China and France have the H-bomb
• Neutron bomb: small hydrogen bomb with
emission of high energy neutrons
responsible for the damage.
Solar Energy
• Energy from sun results from nuclear reactions
fusing hydrogen isotopes.
• This energy sustains life on earth
• Renewable until H isotopes are exhausted, but
other fusion rxns can occur.
• Huge energy capacity: 0.01% of the sun’s
energy can meet 100% of global energy needs
• But there are many challenges before it can be
harnased or captured.
Direct Solar Energy
• Solar Cells
– Photon + reactants  electricity via a
chemical rxn
• Solar Heating
– Capture IR component of sunlight to heat
water, space, etc
Indirect Solar Energy
Current/Pot.
Production
Hydroelectric 24/100 (EJ)
Wind
15/300 (EJ)
Biomass
55/ (EJ)
Tide, Wave
Xx/20 (EJ)
Problems
Creates flooded land,
CH4, Hg
Noise, disrupts
wildlife, needs land,
Aesthetics
Pollution, needs
land, processing
2 high tides/day