permaculture

["Lawrence F. London, Jr." <lflj@intrex.net>]

Helium-3 and clean(er) nuclear (fusion) power
http://en.wikipedia.org/wiki/Helium-3

Helium-3 (He-3) is a light, non-radioactive isotope of helium with two protons and one neutron, which is rare on Earth; 
it is sought after for use in nuclear fusion research. More abundant helium-3 is thought to exist on the Moon (embedded 
in the upper layer of regolith by the solar wind over billions of years) and the solar system's gas giants (left over 
from the original solar nebula), although still in low quantities (28 ppm of lunar regolith is helium-4 and 0.01 ppm is 
helium-3).[1] It is proposed to be used as a second-generation fusion power source.
Fusion Reactions
Some fusion processes produce highly energetic neutrons which render reactor components radioactive with their 
bombardment, and power generation must occur through thermal means. However, the appeal of helium-3 fusion stems from 
the nature of its reaction products. Helium-3 itself is non-radioactive. The lone high-energy proton produced can be 
contained using electric and magnetic fields, which results in direct electricity generation.[9]
However, since both reactants need to be mixed together to fuse, side reactions (21H + 21H and 32He+ 32He) will occur, 
the first of which is not aneutronic. Therefore in practice this reaction is unlikely to ever be completely 'clean', 
thus negating some of its attraction. Also, due to the higher Coulomb barrier, the temperatures required for 21H + 32He 
fusion are much higher than those of conventional 2H + 31H (deuterium + tritium) fusion.
The amounts of helium-3 needed as a replacement for conventional fuels should not be underestimated. The total amount of 
energy produced in the ³He + 21H+ reaction is 18.4 MeV, which corresponds to some 493 megawatt-hours (4.93x108 Wh) per 
three grams (one mole) of ³He. Even if that total amount of energy could be converted to electrical power with 100% 
efficiency (a physical impossibility), it would correspond to about 30 minutes of output of a thousand-megawatt 
electrical plant; a year's production by the same plant would require some 17.5 kilograms of helium-3.
The amount of fuel needed for large-scale applications can also be put in terms of total consumption: According to the 
US Energy Information Administration, "Electricity consumption by 107 million U.S. households in 2001 totaled 1,140 
billion kWh" (1.114x1015 Wh). Again assuming 100% conversion efficiency, 6.7 tonnes of helium-3 would be required just 
for that segment of one country's energy demand, 15 to 20 tonnes given a more realistic end-to-end conversion 
efficiency. [citation needed]


 China's ambitious plans in space
http://www.cnn.com/2007/TECH/space/11/26/china.space.race/index.html

According to Cheng, the Chinese are now embarking on a systematic space program the world has not seen since the 1960's 
and for the first time since the collapse of the Soviet Union, the United States is facing real competition. That may 
explain why the head of NASA, Michael Griffin, recently warned that "China will be back on the moon before we are . . .
But there could be a lot more at stake than just lunar boasting rights. It's unlikely the Chinese will land at 
Tranquility Base and pull down the Stars and Stripes. But the goal could be mining resources. One powerful, potential 
fuel source is helium-3. Helium-3 originated from the sun and was deposited in the moon's soil by the solar wind. It is 
estimated there are up to two million tons on the moon, and virtually none on Earth.
"If we can ever get helium-3 and helium-3 to fuse together it is what we call nuclear power without nuclear waste -- 
there is no radioactivity associated with that reactor," says Professor Gerald Kulcinski, an expert in helium from the 
University of Wisconsin.
The key though, says Kulcinski, will be developing a fusion reactor, which he says could be done within 15 to 20 years, 
in tandem with a program to establish a permanent human presence on the moon. Just four tons of helium-3 would be enough 
to supply all the power needs for the United States for a year, two shuttle payloads according to Kulcinski.
Analysts believe the lure of such potent resources is one of the reasons behind China's exploration of space. State 
media reported last month details of a new rocket with enough thrust to put a space station into orbit. When it's 
developed, the Long March 5 will have almost three times the power of existing rockets.
China has long wanted to be part of the international space station, but has always been denied, partly it's believed 
because of U.S. concerns. But that may not be a problem for the Chinese if they can send their own space station into 
orbit, reportedly by 2020. But again the Chinese are sending mixed messages, saying no firm date has been decided. More 
immediately, there are plans a for televised space walk by three taikonauts next year, according to the Shanghai Daily.