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Next Big Future

"Next Big Future" - 9 new articles

  1. Spent Fuel Cooling Pools Should not be a problem
  2. Status of the Japanese reactors
  3. Current Japan Earthquake damage costs range from 35 to 171 billion
  4. What happened at Fukushima and the Levels of Containment of a Boiler Water Reactor
  5. Radiation and risks
  6. Other energy issues and nuclear power over reactions
  7. Researcher Hod Lipson discusses adaptive robots
  8. Sheparding Asteroids into desired formations and large space Igloo structures
  9. Deaths per TWH by energy source
  10. More Recent Articles
  11. Search Next Big Future
  12. Prior Mailing Archive

Spent Fuel Cooling Pools Should not be a problem

Some news sources and internet sources(Christian Science Monitor) are trying to make an issue of spent fuel cooling pools now that the Japanese reactors are on the way to cold shutdown.





DOE source David Mohre - Emergency Management Specialist at U.S. Department of Energy indicates - Multiple tests have been run with spent fuel cooling turned off. Temperatures do not reach boiling, not even close. Evaporation rates go up, and that requires daily makeup of gallons of water, not thousands of gallons.



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Status of the Japanese reactors

The status of the Japanese reactors







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Current Japan Earthquake damage costs range from 35 to 171 billion







Japan's earthquake damage costs are ranging from $35 billion to $171 billion

estimates from different companies saying the losses could be about a $171 billion in total in the earthquake zone alone. That's not just for the clean up, but the economic losses too. Other people saying, probably much lower -- about $35 billion. But that would still make it one of the most expensive disasters ever. Second only, in fact, when you take inflation into account, to Hurricane Katrina.

Here are some more photos of the damage of the earthquake in Japan.




The Largest Earthquakes

Wikipedia lists of earthquakes by magnitude

Rank Date          Location              Name                           Magnitude


1    May 22, 1960  Valdivia, Chile  1960 Valdivia earthquake               9.5
2    Mar 27, 1964  Prince William Sound,Alaska, USA 1964 Alaska earthquake 9.2
3    Dec 26, 2004  Sumatra, Indonesia   2004 Indian Ocean earthquake       9.1
4    Nov 4, 1952   Kamchatka, Russia    1952 Kamchatka earthquakes         9.0
5    Mar 11, 2011  Sendai, Japan  2011 Sendai earthquake                   9.0
6    Nov 25, 1833  Sumatra, Indonesia   1833 Sumatra earthquake            8.8–9.2 (est.)
     Jan 31, 1906  Ecuador – Colombia   1906 Ecuador-Colombia earthquake   8.8
     Feb 27, 2010  Maule, Chile         2010 Chile earthquake              8.8
9    Jan 26, 1700  Pacific Ocean, USA/Canada 1700 Cascadia earthquake      8.7–9.2 (est.)
     July 8, 1730  Valparaiso, Chile     1730 Valparaiso earthquake        8.7–9.0 (est.)
     Nov 1, 1755   Lisbon, Portugal      1755 Lisbon earthquake            9.0 (est.)
     Feb 4, 1965   Rat Islands, Alaska   1965 Rat Islands earthquake       8.7
13   Aug 15, 1950  Assam, India, China   1950 Medog earthquake             8.6
     Mar 9, 1957   Andreanof Islands,Al  1957 Andreanof Islands earthquake 8.6
     Mar 28, 2005  Sumatra, Indonesia    2005 Sumatra earthquake           8.6

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What happened at Fukushima and the Levels of Containment of a Boiler Water Reactor

Brave New Climate has a description of what happened at Fukushima

The earthquake that hit Japan was 7 times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; the difference between the 8.2 that the plants were built for and the 8.9 that happened is 7 times, not 0.7). So the first hooray for Japanese engineering, everything held up.

When the earthquake hit with 8.9, the nuclear reactors all went into automatic shutdown. Within seconds after the earthquake started, the control rods had been inserted into the core and nuclear chain reaction of the uranium stopped. Now, the cooling system has to carry away the residual heat. The residual heat load is about 3% of the heat load under normal operating conditions.

The earthquake destroyed the external power supply of the nuclear reactor. That is one of the most serious accidents for a nuclear power plant, and accordingly, a “plant black out” receives a lot of attention when designing backup systems. The power is needed to keep the coolant pumps working. Since the power plant had been shut down, it cannot produce any electricity by itself any more.

Things were going well for an hour. One set of multiple sets of emergency Diesel power generators kicked in and provided the electricity that was needed. Then the Tsunami came, much bigger than people had expected when building the power plant (see above, factor 7). The tsunami took out all multiple sets of backup Diesel generators.



When designing a nuclear power plant, engineers follow a philosophy called “Defense of Depth”. That means that you first build everything to withstand the worst catastrophe you can imagine, and then design the plant in such a way that it can still handle one system failure (that you thought could never happen) after the other. A tsunami taking out all backup power in one swift strike is such a scenario. The last line of defense is putting everything into the third containment (see above), that will keep everything, whatever the mess, control rods in our out, core molten or not, inside the reactor.

When the diesel generators were gone, the reactor operators switched to emergency battery power. The batteries were designed as one of the backups to the backups, to provide power for cooling the core for 8 hours. And they did.

Within the 8 hours, another power source had to be found and connected to the power plant. The power grid was down due to the earthquake. The diesel generators were destroyed by the tsunami. So mobile diesel generators were trucked in.

This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more.

At this point the plant operators begin to follow emergency procedures that are in place for a “loss of cooling event”. It is again a step along the “Depth of Defense” lines. The power to the cooling systems should never have failed completely, but it did, so they “retreat” to the next line of defense. All of this, however shocking it seems to us, is part of the day-to-day training you go through as an operator, right through to managing a core meltdown.

It was at this stage that people started to talk about core meltdown. Because at the end of the day, if cooling cannot be restored, the core will eventually melt (after hours or days), and the last line of defense, the core catcher and third containment, would come into play.

But the goal at this stage was to manage the core while it was heating up, and ensure that the first containment (the Zircaloy tubes that contains the nuclear fuel), as well as the second containment (our pressure cooker) remain intact and operational for as long as possible, to give the engineers time to fix the cooling systems.

Because cooling the core is such a big deal, the reactor has a number of cooling systems, each in multiple versions (the reactor water cleanup system, the decay heat removal, the reactor core isolating cooling, the standby liquid cooling system, and the emergency core cooling system). Which one failed when or did not fail is not clear at this point in time.

So imagine our pressure cooker on the stove, heat on low, but on. The operators use whatever cooling system capacity they have to get rid of as much heat as possible, but the pressure starts building up. The priority now is to maintain integrity of the first containment (keep temperature of the fuel rods below 2200°C), as well as the second containment, the pressure cooker. In order to maintain integrity of the pressure cooker (the second containment), the pressure has to be released from time to time. Because the ability to do that in an emergency is so important, the reactor has 11 pressure release valves. The operators now started venting steam from time to time to control the pressure. The temperature at this stage was about 550°C.

This is when the reports about “radiation leakage” starting coming in. I believe I explained above why venting the steam is theoretically the same as releasing radiation into the environment, but why it was and is not dangerous. The radioactive nitrogen as well as the noble gases do not pose a threat to human health.

At some stage during this venting, the explosion occurred. The explosion took place outside of the third containment (our “last line of defense”), and the reactor building. Remember that the reactor building has no function in keeping the radioactivity contained. It is not entirely clear yet what has happened, but this is the likely scenario: The operators decided to vent the steam from the pressure vessel not directly into the environment, but into the space between the third containment and the reactor building (to give the radioactivity in the steam more time to subside). The problem is that at the high temperatures that the core had reached at this stage, water molecules can “disassociate” into oxygen and hydrogen – an explosive mixture. And it did explode, outside the third containment, damaging the reactor building around. It was that sort of explosion, but inside the pressure vessel (because it was badly designed and not managed properly by the operators) that lead to the explosion of Chernobyl. This was never a risk at Fukushima. The problem of hydrogen-oxygen formation is one of the biggies when you design a power plant (if you are not Soviet, that is), so the reactor is build and operated in a way it cannot happen inside the containment. It happened outside, which was not intended but a possible scenario and OK, because it did not pose a risk for the containment.

So the pressure was under control, as steam was vented. Now, if you keep boiling your pot, the problem is that the water level will keep falling and falling. The core is covered by several meters of water in order to allow for some time to pass (hours, days) before it gets exposed. Once the rods start to be exposed at the top, the exposed parts will reach the critical temperature of 2200 °C after about 45 minutes. This is when the first containment, the Zircaloy tube, would fail.

And this started to happen. The cooling could not be restored before there was some (very limited, but still) damage to the casing of some of the fuel. The nuclear material itself was still intact, but the surrounding Zircaloy shell had started melting. What happened now is that some of the byproducts of the uranium decay – radioactive Cesium and Iodine – started to mix with the steam. The big problem, uranium, was still under control, because the uranium oxide rods were good until 3000 °C. It is confirmed that a very small amount of Cesium and Iodine was measured in the steam that was released into the atmosphere.

It seems this was the “go signal” for a major plan B. The small amounts of Cesium that were measured told the operators that the first containment on one of the rods somewhere was about to give. The Plan A had been to restore one of the regular cooling systems to the core. Why that failed is unclear. One plausible explanation is that the tsunami also took away / polluted all the clean water needed for the regular cooling systems.

The water used in the cooling system is very clean, demineralized (like distilled) water. The reason to use pure water is the above mentioned activation by the neutrons from the Uranium: Pure water does not get activated much, so stays practically radioactive-free. Dirt or salt in the water will absorb the neutrons quicker, becoming more radioactive. This has no effect whatsoever on the core – it does not care what it is cooled by. But it makes life more difficult for the operators and mechanics when they have to deal with activated (i.e. slightly radioactive) water.

But Plan A had failed – cooling systems down or additional clean water unavailable – so Plan B came into effect. This is what it looks like happened:

In order to prevent a core meltdown, the operators started to use sea water to cool the core. I am not quite sure if they flooded our pressure cooker with it (the second containment), or if they flooded the third containment, immersing the pressure cooker. But that is not relevant for us.

The point is that the nuclear fuel has now been cooled down. Because the chain reaction has been stopped a long time ago, there is only very little residual heat being produced now. The large amount of cooling water that has been used is sufficient to take up that heat. Because it is a lot of water, the core does not produce sufficient heat any more to produce any significant pressure. Also, boric acid has been added to the seawater. Boric acid is “liquid control rod”. Whatever decay is still going on, the Boron will capture the neutrons and further speed up the cooling down of the core.

The plant came close to a core meltdown. Here is the worst-case scenario that was avoided: If the seawater could not have been used for treatment, the operators would have continued to vent the water steam to avoid pressure buildup. The third containment would then have been completely sealed to allow the core meltdown to happen without releasing radioactive material. After the meltdown, there would have been a waiting period for the intermediate radioactive materials to decay inside the reactor, and all radioactive particles to settle on a surface inside the containment. The cooling system would have been restored eventually, and the molten core cooled to a manageable temperature. The containment would have been cleaned up on the inside. Then a messy job of removing the molten core from the containment would have begun, packing the (now solid again) fuel bit by bit into transportation containers to be shipped to processing plants. Depending on the damage, the block of the plant would then either be repaired or dismantled.

Now, where does that leave us?

* The plant is safe now and will stay safe.
* Japan is looking at an INES Level 4 Accident: Nuclear accident with local consequences. That is bad for the company that owns the plant, but not for anyone else.
* Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). A very small amount of Cesium was released, as well as Iodine. If you were sitting on top of the plants’ chimney when they were venting, you should probably give up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.
* There was some limited damage to the first containment. That means that some amounts of radioactive Cesium and Iodine will also be released into the cooling water, but no Uranium or other nasty stuff (the Uranium oxide does not “dissolve” in the water). There are facilities for treating the cooling water inside the third containment. The radioactive Cesium and Iodine will be removed there and eventually stored as radioactive waste in terminal storage.

* The safety systems on all Japanese plants will be upgraded to withstand a 9.0 earthquake and tsunami (or worse)

* I believe the most significant problem will be a prolonged power shortage. About half of Japan’s nuclear reactors will probably have to be inspected, reducing the nation’s power generating capacity by 15%. This will probably be covered by running gas power plants that are usually only used for peak loads to cover some of the base load as well. That will increase your electricity bill, as well as lead to potential power shortages during peak demand, in Japan.

Further Reading

More technical information on Fukushima at Brave New Climate

March 14 updates

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Radiation and risks

Goatguy adjusted the scale of the EPA radiation chart. Original chart is below.

EPA radiation facts

The average person in the United States receives about 360 mrem every year whole body equivalent dose At low doses, such as what we receive every day from background radiation, the cells repair the damage rapidly. At higher doses (up to 100 rem), the cells might not be able to repair the damage, and the cells may either be changed permanently or die. At even higher doses, the cells cannot be replaced fast enough and tissues fail to function. An example of this would be "radiation sickness." This is a condition that results after high doses to the whole body (over 100 rem), where the intestinal lining is damaged to the point that it cannot perform its functions of intake of water and nutrients, and protecting the body against infection. This leads to nausea, diarrhea and general weakness. With higher whole body doses (over 300 rem), the body's immune system is damaged and cannot fight off infection and disease. At whole body doses near 400 rem, if no medical attention is given, about 50% of the people are expected to die within 60 days of the exposure, due mostly from infections.



Health Risk Est. life expectancy lost

Smoking 20 cigs a day                   6 years
Overweight (15%)                        2 years
Alcohol (US Ave)                        1 year
All Accidents                           207 days
All Natural Hazards                     7 days
Occupational dose (300 mrem/yr)         15 days
Occupational dose (1 rem/yr)            51 days
You can also use the same approach to looking at risks on the job:

Industry type Est. life expectancy lost

All Industries                          60 days
Agriculture                             320 days
Construction                            227 days
Mining and quarrying                    167 days
Manufacturing                           40 days
Occupational dose (300 mrem/yr)         15 days
Occupational dose (1 rem/yr)            51 days


Sievert metric radiation unit at wikipedia

* 1 Sv (Sievert) = 100 rem
    * 1 mSv = 100 mrem = 0.1 rem
    * 1 μSv = 0.1 mrem
    * 1 rem = 0.01 Sv = 10 mSv
    * 1 mrem = 0.00001 Sv = 0.01 mSv = 10 μSv

Counts per minute at wikipedia

* One becquerel (Bq) is equal to one disintegration per second, or 60 dpm.
* One curie (Ci) is equal to 3.7 x 10 10 Bq or dps, which is equal to 2.22 x 10^12 dpm.

The becquerel (symbol Bq) is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second.

The curie (Ci) is an older, non-SI unit of radioactivity equal to the activity of 1 gram of radium-226.

The conversion factors are:
1 Ci = 3.7×1010 Bq
    1 Ci = 37 GBq
    1 μCi = 37,000 Bq
    1 Bq = 2.70×10−11 Ci
    1 Bq = 2.70×10−5 μCi
    1 GBq = 0.0270 Ci 

The original EPA chart


Radiation health effects

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Other energy issues and nuclear power over reactions

5 oil refineries in Japan are shutdown and two of them are on fire.

At least five refineries, with a combined oil-processing capacity of 1.2 million barrels a day, shut down automatically when they sensed the earthquake. This is roughly a quarter of Japan's total refining capacity. A fire broke out around storage tanks of the Sendai and Chiba refineries, but neither has been damaged.

Nuclear Overreactions written up at Slate.com



Less than a year ago, a drilling rig exploded off the coast of the United States, killing 11 workers and pouring 4 million barrels of oil into the Gulf of Mexico. No natural disaster caused this tragedy. It was entirely man-made. President Obama halted deep-water drilling but lifted the moratorium less than six months later. On Friday, while fielding questions about Japan's nuclear reactors, he proudly noted that his administration, under new, stricter rules, had "approved more than 35 new offshore drilling permits."

That's how we deal with tragedies in the oil business. Accidents happen. People die. Pollution spreads. We don't abandon oil. We study what went wrong, try to fix it, and move on.

Contrast this with the panic over Japan's reactors. For 40 years, they've quietly done their work. Three days ago, they were hit almost simultaneously by Japan's worst earthquake and one of its worst tsunamis. Not one reactor container has failed. The only employee who has died at a Japanese nuclear facility since the quake was killed by a crane. Despite this, voices are rising in Europe and the United States to abandon nuclear power. Industry analysts predict that the Japan scare, like Chernobyl, will freeze plant construction.

Let's cool this panic before it becomes a political meltdown.

Fossil fuel deaths from 1969 to 2000
This is a count of the accidents and not the air pollution deaths or deaths from other pollution caused by fossil fuels




Jerome a Paris is a wind farm investor Here are a few of his non-obvious facts about the incidents of the past few days:

* earthquake kills people, nuke power plants don't kill people. Despite being hit by a very large natural event, damage seems limited to the nuclear plants themselves, with no real material consequences outside the plants. Even with an accumulation of adverse events (earthquake + tsunami), the overall safety design seems to have, ultimately, functioned;

* earthquakes is what costs money. Overall, the damage to the nuclear plants seems less than to much of the infrastructure which was hit by the earthquake+tsunami, and it's not obvious that the damage to the nuclear plants will cost more than a small fraction of the overall damage; an immediate question is thus whether the damage to these plants should be included in the cost of electricity or in the cost of earthquake insurance;

* centralised power plants have a cost. Nuclear power plants are large single points of failure - an immediate cost for consumers will be felt as the large nuclear capacity now offline will need to be replaced by more expensive gas-fired power (fueled, in Japans's case, by LNG imports), if available, and tensions in the power network may lead to rolling blackouts or other form of unreliability - or use of even more expensive oil-fuelled backups; This means that the nuclear industry needs to include such catastrophic events in the pricing of its energy - especially in an earthquake-prone place like Japan, via the incorporation of (i) a lowish, but not far from nil, probability of full loss of large chunks of generating capacity and (ii) the ongoing cost of the availability of a larger permanent reserve capacity to cope with temporary or permanent losses of capacity at large power plants;

* energy policy is the government's job. All of this underlines that the overall design of the power system hinges on the rules established by public authorities - from the mostly technical stuff on how much backup the system should have, to the allocation of the cost of insurance for large catastrophes, to the safety margins to take into account (ie what threshold of frequency for catastrophic events that you have to deal with, and how big a disruption should be factored in) and to the cost of funding the plants themselves as well as whatever additional safety features you impose on them.



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Researcher Hod Lipson discusses adaptive robots

In an interview with Sander Olson, Cornell engineer and researcher Hod Lipson discusses adaptive, evolving robots. Lipson's robots compete and learn, and acquire new skills in movement. Lipson uses simulators to co-evolve both simulators and robots. Lipson's has already demonstrated a robot that can compensate for losing a limb by modifying its movement.

Hod Lipson
Question: You have recently created a "robotic scientist". What do you mean by that?

Answer: The robotic scientist is a program that can discern the mathematical laws behind the data and derive an hypothesis. This machine isn't really a robot, it is more of an algorithm, and its effectiveness is determined by the quality of the data and the amount of computing power used. It is essentially a data mining tool for scientists, and it should accelerate scientific discovery.



Question: How does the automated scientist work?

Answer: The machine tries to find invariants in the data, and those invariants are key to finding the underlying physics. we are confident that it can substantially speed up the pace of scientific research in many fields.

Question: Your robots learn by evolutionary techniques. How do they accomplish this?

Answer: The vast majority of robots today operate by programming rather than by learnt behavior. Self-modeling robotics involves having a robot internally create models of its operation based on its experience, and compare the efficacy of those models. We have already demonstrated a legged robot that can compensate for losing a limb by altering its movements.


Question: How quickly can your evolvable robots adapt their behavior?

Answer: The robots we demonstrated took a few days to generate their self-model. In general, it depends largely on how fast their CPUs are and how complex the experiences to be modeled are. Given the combination of faster machines and increasingly efficient algorithms, robots should be able to able to adapt to their surroundings and circumstances even faster in the future.


Question: Your research lab at Cornell has done has created printable ornithopters. What can these insectoid robots do?

Answer: We have created usable ornithopters using 3-d printing techniques. We recently published a paper that describes these printed ornithopters. The main advantage of crafting these devices from 3-d printing techniques is that we can quickly construct and analyze a wide variety of performance parameters in order to determine optimal design. These ornithopters currently can stay up for 80 seconds. These ornithopters are powered by lithium-polymer batteries, and we hope to have them fly for several minutes within a few years.


Question: You have also discussed "evolving simulators". What do you mean by that?

Answer: Much of the exploratory evolution of our machines occurs in a simulator, sometimes through hundreds of iterations. But the simulators themselves aren't completely accurate, so we need the simulators themselves to improve. As these simulators evolve they become increasingly accurate and specific, able to predict machine behavior with increasing accuracy.


Question: Do your robot learning algorithms reach a point of diminishing returns?

Answer: The learning rate for the machines asymptotically slows down after a while. But there is much that can be done to improve the algorithms, and that is what our lab is focusing on with our research.


Question: Is Cornell engaging in any pure AI research?

Answer: Yes, Cornell has active AI programs underway. The AI researchers at Cornell are working on both robotics and non-robotics applications.


Question: What is the first commercial application you see for your robots?

Answer: Within the next several years, we could see commercial applications emerge that use our learning algorithms - mostly in the area of fault tolerance.


Question: Your are an expert in the nascent field of 3-d printing. How does this work?

Answer: The technology for 3-d printing has actually been around for a while. The scheme involves using an inkjet printer to deposit layer after layer of a material to create 3-d objects. This technique can be used to construct a wide variety of structural shapes. Non-structural components, such as batteries, wires, and motors, are considerably more difficult. That is where we are focusing our research.


Question: How much progress do you anticipate in the field of robotics in the next decade?

Answer: The fields of robotics and 3-d printing are both embryonic, but are experiencing exponential growth. This progress should continue for the next decade, leading both to a plethora of consumer products and to scientific advances.


Question: What about 20 years?

Answer: I see my research in terms of both the body - 3-d printing - and the brain - evolvable robots. In the next 20 years, we will see 3-d printing move from being a niche technology to the main method of manufacture for many products. 3-d printing is inherently more versatile and could be more cost-effective than traditional fabrication methods for "long tail" products. 20 years from now, robots will be using machine learning techniques to model the world and to learn on their own.






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Sheparding Asteroids into desired formations and large space Igloo structures

There have been papers written about having spacecraft near asteroids to generate a gravitational tow.

There was the Asterants proposal to use solar sails to retrieve 500 kilogram asteroids.

There may be as any as one million asteroids that are 1000 meters across or larger.

There are over a quadrillion space rocks beyond the orbit of Neptune in the solar system

In space it is relatively easy to move quite large space rocks using solar sails, ion drives and other means. There are a lot of space rocks and a survey could be done to select the rocks that would have to be moved with the least amount of effort.



Then once each asteroid is moved into place they would be locked into place.

It could be easier to gather asteroids to make desired shapes instead of digging out a larger asteroid. Different sized asteroids could be used from 500 kg, to tons up to asteroids that are 100 to 1000 meters across.

Six large asteroids 9 (4 walls and a roof and a ceiling) could be brought together to enclose a very large cube like void.

Pushing asteroids together easier than excavating a large asteroid

There have been various imagined asteroid colonies in space art where a large asteroid has a colony inside it.


It is far easier to push very large objects in space. Tiny ion engines or plasma rockets that can accelerate for years can move huge mountain size objects while digging out an asteroid is not much easier than digging out a very large hole on earth.

It is far more near term to look at assembling asteroids into structures than it is to create or bring heavy construction equipment out to the asteroids.

I had the idea for this when I was on a snow weekend in Tahoe and other people had created the base of snowmen and we pushed them together to create the beginnings of a wall for a larger fort. We also tunneled into the snow. Pushing things together gave a quick start to the effort.

Holding the asteroids in place

The engines that moved the asteroids might be left in place, or some other form of space cement or binding needs to be created.

As noted smaller asteroids of 500 kilogram or less could be used as ready made bricks. The smaller asteroids could be used inside the voids where larger asteroids have been brought together. The smaller asteroids could be formed into walls and floors.


How an Igloo is built


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Deaths per TWH by energy source







Comparing deaths/TWh for all energy sources

I wrote this back in 2008 and with one new death that is somewhat nuclear energy related (a death at one of the japanese nuclear plants following the 8.9 earthquake) the statistics are not changed. Japan should have had sealed backup diesel generators or updated some of their designs. However, nuclear still compares very, very well to the other energy sources.

Energy Source              Death Rate (deaths per TWh)

Coal – world average               161 (26% of world energy, 50% of electricity)
Coal – China                       278
Coal – USA                         15
Oil                                36  (36% of world energy)
Natural Gas                         4  (21% of world energy)
Biofuel/Biomass                    12
Peat                               12
Solar (rooftop)                     0.44 (less than 0.1% of world energy)
Wind                                0.15 (less than 1% of world energy)
Hydro                               0.10 (europe death rate, 2.2% of world energy)
Hydro - world including Banqiao)    1.4 (about 2500 TWh/yr and 171,000 Banqiao dead)
Nuclear                             0.04 (5.9% of world energy)


Update: A superior form of solar power would be the Coolearth concentrated solar power system which would be installed on the ground or wires over a ground installation.



Rooftop solar is several times more dangerous than nuclear power and wind power. It is still much safer than coal and oil, because those have a lot of air pollution deaths.

Rooftop solar can be safer [0.44 up to 0.83 death per twh each year). If the rooftop solar is part of the shingle so you do not put the roof up more than once and do not increase maintenance then that is ok too. Or if you had a robotic system of installation.

World average for coal is about 161 deaths per TWh.
In the USA about 30,000 deaths/year from coal pollution from 2000 TWh.
15 deaths per TWh.
In China about 500,000 deaths/year from coal pollution from 1800 TWh.
278 deaths per TWh.



Air pollution deaths from coal, oil and natural gas are from the analysis of the impact of particulate matter (10 micron and 2.5 micron). Other air pollutants also cause health impacts but the scientific cause and effect is the most clear with particulates.

Ground level ozone and other pollutants also have health effects

Here is an article with some pictures related to air pollution.

Besides replacing coal burners with nuclear power, there are particulate control technology costs about $20 million to 50 million per 1 gigawatt coal plant to achieve 99-99.5% reduction in particulates. (electrostatic precipitators) A total of about $400 million for the more effective air pollution technologies for Sulfur dioxide, nitrogen oxides and particulates.

So it is perfectly feasible and economic to retrofit existing coal plants to prevent most of the air pollution and the damage that they cause. The costs is far less than what is required to deal with carbon dioxide (pipes to capture and put it all into large places underground). China has about 650 GWe of coal power installed in 2011. It would probably be cheaper for China to do the particulate retrofits (say $30 million per GWe). Therefore $20 billion would enable a 99.5% reduction in particulates. The United States has 315 GWe of coal power installed in 2011. It would cost about $16 billion for electrostatic precipitators on all coal plants in the United States.

Controlling all particulates from coal plants, oil plants, natural gas plants, certain industrial facilities and retrofitting better control technology on cars and trucks would save 800,000 to 1.2 million lives per year. The cost would be in the range of $300 billion to $1 trillion (If phased in over ten years would be $30-100 billion per year worldwide.) The cost would be more than offset by improved health and lower medical costs.

Calculated deaths per Terawatt hour

Wind power proponent and author Paul Gipe estimated in Wind Energy Comes of Age that the mortality rate for wind power from 1980–1994 was 0.4 deaths per terawatt-hour. Paul Gipe's estimate as of end 2000 was 0.15 deaths per TWh, a decline attributed to greater total cumulative generation.

Hydroelectric power was found to to have a fatality rate of 0.10 per TWh (883 fatalities for every TW·yr) in the period 1969–1996

Nuclear power is about 0.04 deaths/TWh.

The ExternE calculation of death/TWh from different energy sources (not including global warming effects and is the average for European nations).











This draws on data from 4290 energy-related accidents, 1943 of them classified as severe, and compares different energy sources. It considers over 15,000 fatalities related to oil, over 8000 related to coal and 5000 from hydro.


Deaths statistics from the fuel chain for coal and nuclear

Higher level of deaths from coal in public health would be related to the increased deaths from particulates. The deaths totals are more from coal occupation are mining.

The World Health Organization and other sources attribute about 1 million deaths/year to coal air pollution. Coal generates about 6200 TWh out of the world total of 15500 TWh of electricity. This would be 161 deaths per TWh.
In the USA about 30,000 deaths/year from coal pollution from 2000 TWh. 15 deaths per TWh.
In China about 500,000 deaths/year from coal pollution from 1800 TWh. 278 deaths per TWh.

The construction of existing 1970-vintage U.S. nuclear power plants required 40 metric tons (MT) of steel and 190 cubic meters (m3) of concrete per average megawatt of electricity (MW(e)) generating capacity. For comparison, a typical wind energy system operating with 6.5 meters-per-second average wind speed requires construction inputs of 460 MT of steel and 870 m**3 of concrete per average MW(e). Coal uses 98 MT of steel and 160 m**3 of concrete per average MW(e); & natural-gas combined cycle plants use 3.3 MT steel and 27 m**3 concrete.

Wind power generation was 95 GW at the end of 2007.
1 MW produces 3,066 MWh if 35% efficient.
20 GW in Germany generated 30 TWh in 2006.
95GW would be generating about 150TWh.
95000GW would have taken 43.7 million tons of steel and 82.7 million tons of concrete. 3% of one year of global steel production. 4% of one year of the world’s concrete production. Half of one year’s production in the US for steel. About 15 deaths if corresponded to half of one years metal/nonmetal mining fatalities. 0.1 deaths per TWh. If the metal and concrete had come from China about 2700 metal/nonmetal mining deaths per year for 5 times the amount of steel. 270 deaths to get the metal for the wind turbines. 1.9 deaths per TWh. These construction related deaths are amortized over the life of the wind turbines of 30 years. Other wind power deaths need to factor in dangers associated with working with very tall structures (50 stories tall) and with deep water work associated with building and anchoring offshore.

Wind power proponent and author Paul Gipe estimated in Wind Energy Comes of Age that the mortality rate for wind power from 1980–1994 was 0.4 deaths per terawatt-hour. Paul Gipe's estimate as of end 2000 was 0.15 deaths per TWh, a decline attributed to greater total cumulative generation. By comparison, hydroelectric power was found to to have a fatality rate of 0.10 per TWh (883 fatalities for every TW·yr) in the period 1969–1996. This includes the Banqiao Dam collapse in 1975 that killed thousands.



Metal/Nonmetal fatalities in the USA (iron and concrete components mainly)

(3.1 GWp generated 2TWh in Germany for solar)

Coal and fossil fuel deaths usually do not include deaths caused during transportation. The more trucking and rail transport is used then the more deaths there are. The transportation deaths are a larger component of the deaths in the USA than direct industry deaths. Moving 1.2 billion tons of coal takes up 40% of the freight rail traffic and a few percent of the trucking in the USA.

Uranium mining is a lot safer because insitu leaching (the main method of uranium mining) involves flushing acid down pipes. No workers are digging underground anymore. Only about 60,000 tons of uranium are needed each year so that is 200 times less material being moved than for coal plants.

But what about Chernobyl ?
The World Health Organization study in 2005 indicated that 50 people died to that point as a direct result of Chernobyl. 4000 people may eventually die earlier as a result of Chernobyl, but those deaths would be more than 20 years after the fact and the cause and effect becomes more tenuous.

He explains that there have been 4000 cases of thyroid cancer, mainly in children, but that except for nine deaths, all of them have recovered. "Otherwise, the team of international experts found no evidence for any increases in the incidence of leukemia and cancer among affected residents."


Averaging about 2100 TWh from 1985-2005 or a total of 42,000 TWh. So those 50 deaths would be 0.0012 deaths/TWh. If those possible 4000 deaths occur over the next 25 years, then with 2800 TWh being assumed average for 2005 through 2030, then it would be 4000 deaths over 112,000 TWh generated over 45 years or 0.037 deaths/TWh. There are no reactors in existence that are as unsafe as the Chernobyl reactor was. Even the eight of that type that exist have containment domes and operate with lower void co-efficients.

The safety issues with Rooftop solar installations
Those who talk about PV solar power (millions of roofs) need to consider roof worker safety. About 1000 construction fatalities per year in the US alone. 33% from working at heights.

Falls are the leading cause of fatalities in the construction industry. An average of 362 fatal falls occurred each year from 1995 to 1999, with the trend on the increase. 269 deaths (combined falls from ladders and roofs in 2002). UPDATE: Based on a more detailed analysis of the fatal fall statistic reports I would now estimate the fatal falls that would match the solar panel roof installations as 100-150. Only 30-40 are classified as being a professional roofer but deaths for laborer or general construction worker or a private individual count as deaths.

Roofing is the 6th most dangerous job. Roofers had a fatality rate in 2002 of 37 per 100,000 workers.

In 2001, there were 107 million homes in the United States; of those, 73.7 million were single-family homes. Roughly 5 million new homes are built each year and old roofs need to significant work or replacement every 20 years. So 9-10 million roofing jobs in the US alone. In 2007, Solar power was at 12.4 GW or about 12.6 TWh. The 2006 figure for Germany PV was only 1TWh from about 1.5GW from $4 billion/yr. The German rate of solar power generation would mean 12.4GW would generate 8TWh. 2.8GW generates 2 TWh for Germany, assuming other places are 50% sunnier on average, then the 9.6GW would generate 10.6 TWh.

$4 billion is about the cost of one of the new 1.5 GW nuclear power plants, which would generate 12 TWh/year. Nuclear power plants (104) rated at a total 100GW generated 800 Twh in 2007.

The world total was from about 1.5 million solar roofed homes. 30% of the solar power was from roof installed units. 1/6th of the 9 million roofing job accidents would be about 50 deaths from installing 1.5 million roofs if other countries had similar to US safety. The amount of roof installations is increasing as a percentage. 4 TWh from roofs PV. So 12.5 deaths per TWh from solar roof installations. Assuming 15 years as the average functional life or time until major maintenance or upgrade is required. The average yearly deaths from rooftop solar is 0.83/TWh. Those who want a lower bound estimate can double the life of the solar panels (0.44deaths/TWh). This is worse than the occupational safety issues associated with coal and nuclear power. (see table below). 12 to 25 times less safe than the projected upper bound end effect of Chernobyl (from WHO figures). The fifty actual deaths from roof installation accidents for 1.5 million roof installations is equal to the actual deaths experienced so far from Chernobyl. If all 80 million residential roofs in the USA had solar power installed then one would expect 9 times the annual roofing deaths of 300 people or 2700 people (roofers to die). This would generate about 240 TWh of power each year. (30% of the power generated from nuclear power in the USA). 90 people per year over an optimistic life of 30 years for the panels not including maintenance or any electrical shock incidents.

Maintenance and Functional life of solar panels

[Q26. Do they require any maintenance?
A26: Only an occasional wipe to ensure optimal performance of the solar panel.]

15. How long will the panels last?
Generally, systems last 20-30 years since the waterproof seals on the panels tend to deteriorate over time.
16. If I move home, can I take the solar panels with me?
You could take your solar power system down and re-install it at your new house provided the roof of the new house is suitable. Or, you could include it in the selling price of your house. If your house is in a remote area and the solar power system is the sole source of power, the purchaser of your house would be wise to make sure the solar power system is included in the price, or they’ll be left without electricity.
[Generally hail resistant but a storm big enough to damage a regular roof would also damage a rooftop solar panel system.]

http://www.gepower.com/prod_serv/products/solar/en/faqs/resid_sys.htm#faq24
http://www.gepower.com/prod_serv/products/solar/en/faqs/resid_sys.htm#faq28http://www.heatmyhome.co.uk/pv-solar-panels.htm

The 10 most dangerous jobs
Occupation     Fatalities per 100,000 
Timber cutters              117.8
Fishers                       71.1
Pilots and navigators       69.8
Structural metal workers      58.2
Drivers-sales workers       37.9
Roofers                       37
Electrical power installers   32.5  [also, solar power related]
Farm occupations       28
Construction laborers       27.7
Truck drivers               25

Source: Bureau of Labor Statistics; survey of occupations with minimum 30 fatalities and 45,000 workers in 2002

Conclusion:
Nothing is perfectly safe. Chasing perfection can cause us to ignore just improving and trading worse for a lot better. Non-roof installations of solar is safer than roof installation. Nuclear, wind, non-roof solar and hydro are a lot safer than coal and oil. Natural gas is safer but not as much as nuclear and those others. The focus needs to be on getting rid of the most dangerous energy sources which are coal and oil first. Then after that decades long project is done to look at the other energy sources. Safety and improvements for all energy sources should be made as we go.

UPDATE:
Rooftop solar is still a hundred times safer than coal and oil power because of air pollution deaths. Other ways to make solar power safer:
1. Increase safety for all rooftop work (can reduce deaths by half or more)
2. Rooftop solar tiles installed on new buildings might not have any more incremental deaths as opposed to panels that are separate from the roof tiles or systems installed that replace roof tiles before they would normally be replaced.
3. Create some new installation system where people stay on the ground using some forklift or crane to raise and place a solar power system onto a roof. Have to ensure that the heavy machinery system is safer than the roofing process being replaced.

Some responders online are in denial that people who work on a roof can fall off regardless of the reason they went up there. If I go up there to replace roofing tiles or go up there to install solar panels, the risk of falling is pretty much the same especially when the number of times being compared heads to large numbers like millions of times for each. As I noted in the comments, statistics show that 70% of fatal construction falls occur at height of 3 stories or less.

Some have also claimed that someone who went up onto a roof to install a solar panel but then fell is not a death associated with solar power. Similarly then if someone is killed in a coal mine then that is not a coal power death because the coal was not in the power plant yet or they might have some other reason for being underground and would have been crushed anyway.

FURTHER READING
189 page pdf from the 1997 Externe analysis of energy sources and fuel cycles.

RELATED NEWS
Canada is increasing the planned number of nuclear reactors in Alberta to 4 plants generating 4 GW. The plan is to complete them by 2017.

Southern California Edison (SCE) plans to spend $875 million over the next five years putting solar panels onto commercial roofs to generate 250 megawatts of solar capacity. The panels will be on 65 million square feet of roof.

San Jose has a 15 year green vision to install 100,000 solar power roofs.

San Jose was chosen a Solar America City by the U.S. Department of Energy and will share $2.4 million in funding with 11 other cities. Other cities designated as Solar America Cities include Sacramento, Santa Rosa, Seattle, Wash.; Houston, Texas; Knoxville, Tenn.; Milwaukee, Wis.; Minneapolis & St. Paul, Minn.; Orlando, Fla.; Philadelphia, Penn.; and San Antonio, Texas.

Severin Borenstein, director of the U.C. Energy Institute and a professor at the University of California, Berkeley's business school, called existing technology "a loser" in a research paper. "We are throwing money away by installing the current solar PV technology," he said.

Borenstein calls for more state and federal money to be spent on research into better technology, rather than on subsidies for residential solar power systems. In his analysis, Borenstein found that a typical PV system costs between $86,000 and $91,000 to install, while the value of its power over its lifetime ranges from $19,000 to $51,000. Even assuming a 5 percent annual increase in electric costs and a 1 percent interest rate, the cost of a PV system is 80 percent greater than the value of the electricity it will produce. In his paper, Borenstein also factored in the value of greenhouse gas reductions into his calculations, and found that at current prices the PV technology still doesn't deliver.


California's Million Solar Roofs Plan, signed into law in 2006, which will provide 3,000 megawatts of additional clean energy and reduce the output of greenhouse gases by 3 million tons. The 2.9-billion-dollar incentive plan for homeowners and building owners who install solar electric systems will lead to 1 million solar roofs in California by the year 2018.

FURTHER READING
Sample solar power installation instructions

More rooftop solar panel installation instructions

Solar thermal panels for hot water heating are typically 36-75kg in weight per panel.

Solar PV panels are currently about 40-60 pounds (20-30kg).


US energy use by source

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