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From Sustainable Energy without the Hot Air, Chapter 31, Pages 240--

First, the energy requirements for carbon capture from thin air are so enormous,
it seems almost absurd to talk about it (and there’s the worry that raising
the possibility of fixing climate change by this sort of geoengineering might
promote inaction today). But second, I do think we should talk about it,
contemplate how best to do it, and fund research into how to do it better,
because capturing carbon from thin air may turn out to be our last line
of defense, if climate change is as bad as the climate scientists say, and if
humanity fails to take the cheaper and more sensible options that may still
be available today.

I imagine a practical system will be somewhat similar to the techique they use to safeguard currency. In case people aren't aware of this, I put a couple links below. The basic idea is that embedded in the design of modern currency is a robust signature (created by Digimarc) which is steganographically hidden in the data.

In the case of currency, when you scan in something, programs (like Adobe Photoshop) run some code that looks for steganographic the currency signature in the image and if it finds it, then refuses to let process it. It is estimated, but not known, how this works, but empirically, a crop as small as 10% of the image a banknote can currency contains enough information to trigger the detection of the currency signature.

I imagine something could be done similarly with 3d printers. The carrot that will make the manufacturers of printers put this in will probably be legislation that shields them from legal reprecussions (sort of a safe harbor against enabling copyright infringement). As an example, color photocopiers have been convinced to include yellow ID dot codes...

http://en.wikipedia.org/wiki/Central_Bank_Counterfeit_Deterrence_Group
http://www.cl.cam.ac.uk/~sjm217/projects/currency/

I'd simply point out that UK high schools have surpassed their intro course and ask them at what point they plan to give you a better education in computers than a foreign government can give its kids.

If you really wanted to go the extra mile and spend a little bit of money on this "letter" you could buy a small SD flash card and spend $25 on a Raspberry Pi and work through this tutorial as you work through your intro course. Then when you're done you can get the Raspberry Pi to start and have the sole purpose be to display your letter to the staff. Just mail them the Raspberry Pi, the flash card, a USB to USB Micro cord and a short HDMI cable. Just write instructions to plug it into a USB port and monitor then in the letter explain how you used the GNU Toolchain and wrote the rest of this code yourself. It might be too much for some of the other students but it was cheaper than the textbook. If you can do it then your once great alma mater is selling its students short.

A letter can be crumpled up and thrown away. A Raspberry Pi can as well but I guarantee it's going to hurt like hell ;-)

muhula writes: The scary part of this chip and pin vulnerability is that banks have a history of blaming the consumer and not issuing refunds ... banks systematically suppress information about known vulnerabilities, with the result that fraud victims continue to be denied refunds Ross Anderson heads the Cambridge group that found this attack and the earlier man-in-the-middle attack (a gadget between card & reader that makes all PIN verifications succeed no matter what number you enter). He's been writing about bank vulnerabilities for years. A famous older paper: "Why cryptosystems fail" http://www.cl.cam.ac.uk/~rja14/Papers/wcf.html Problems with PIN numbers: http://bits.blogs.nytimes.com/2012/02/20/security-of-self-selected-pins-is-lacking/

The device is called the "broadband phone"

http://www.cl.cam.ac.uk/research/dtg/attarchive/bphone/apps.html

http://www.xorl.org/people/njh/bpstory/index.html

Check out this tutorial for OS development on the Pi : http://www.cl.cam.ac.uk/freshers/raspberrypi/tutorials/os/

Sorry, but elastic modulus usually isn't a big consideration, unless the structure has to be extremely rigid for some reason. Otherwise, you might as well let them flap in the breeze like airplane wings.

The best way to compare materials is a plot of density vs. tensile strength.(Java warning!) In this plot, the materials in the upper left corner are ideal. TFA states the material's density as 1.6g/cc (or 1600kg/m^3) and the tensile strength of 7.5GPa (or 7500 MPa) which would make it the best material on the graph.

I like this. We can start this cut-off with the the academics.

Also your example of 85% in and 90% out seems a bit messed up since .85*.90 is about 76.5% which compares favorably to your pneumatic air storage system.

Pumped-storage hydroelectricity "reported energy efficiency varies in practice between 70% and 80%, with some claiming up to 87%" The book Sustainable energy without the hot air suggests that 90% efficiency is probably achievable with some small technology increases.

Compressed air energy storage "The theoretical efficiency of adiabatic storage approaches 100% with perfect insulation, but in practice round trip efficiency is expected to be 70%."

http://www.hpc.cam.ac.uk/ might be a good place to start.

The Cambridge Diploma in Computer Science, which ran from 1953 to 2008, was the world's first taught course in computing

-Source

Iris scanning actually works in a way similar to a hash. You take the iris picture and find a 2048-bit number, the "IrisCode" or wherever you wanna call it. If you want to make a comparison, then you find the IrisCode for the other picture, and compute the Hamming distance between two. The threshold for match or no-match is actually a function of the database size. (I read the paper a while ago and I'm probably made a few mistakes describing it, but it works along those lines). John Daugman site has more details.

A "HUMAN_IRIS" is just a 2048 bits field. Read about IrisCode (pdf warning) some time. It's a really elegant solution.

I've occasionally daydreamed a fun academic paper would be to collect sets of password hashes, rub them up against a rainbow table, and make graphs and correlations and wild assumptions about the correlation coeff of IQ and rate of easily cracked pwd vs site etc etc. Sounds like fun so its probably been done before.

Yes, it's been done on 70 million passwords. See http://www.cl.cam.ac.uk/~jcb82/doc/B12-IEEESP-analyzing_70M_anonymized_passwords.pdf

As usual.

The original paper is located here. From the conclusion:

"The most troubling finding of our study is how little password distributions seem to vary, with all populations of users we were able to isolate producing similar skewed distributions with effective security varying by no more than a few bits."

And yet in TFA this gets transformed into "old people use strong passwords and young people use weak ones!" and everyone starts wondering what could account for this. It also makes the study sound as though it specifically focused on user age, or that user age was the most interesting result, when in fact there were several other significant (yet still small) variations in different groups in the study, e.g. Indonesian users tended to use much weaker passwords than German or Korean users. They also found that users who tend to log in from multiple locations also tend to use stronger passwords.

So why is the old people/young people thing the single takeaway that gets headlined and reported? It's not like what I just wrote would have been particularly difficult to outline or explain, even in a brief news article. I blame laziness on the part of the reporter.

The methodology is explained in the paper "The science of guessing: analyzing an anonymized corpus of 70 million passwords" available at http://www.cl.cam.ac.uk/~jcb82/doc/B12-IEEESP-analyzing_70M_anonymized_passwords.pdf Plain text passwords were captured at login time in coöperation with Yahoo! under ethics and legal-approved rules. The experimental design contains technical measures to ensure that user IDs were not associated with passwords and further measures to protect against passwords that might be used in more than one place.

The original paper includes even more details. Yahoo set up a server in the middle of its login process to record login attempts which hashed passwords with a salt, then produced a histogram of the hashes for demographic subgroups. The researcher did his analysis on the histograms, not the hashes themselves.

I came here to say "Ok, so they discovered the JTAG port." Seems that blog was already on it.

Now, the researchers claim demonstrate that, via the JTAG port, they can subvert one form of Actel's AES security (but not all--see below) on someone's design to allow reverse-engineering a circuit design loaded into the FPGA. That's fairly interesting. I know that there's a fair bit of business in claiming an FPGA is invulnerable to such snooping, so that vendor A can ship a prototype design to customer B without worrying that customer B might rip off vendor A's design. For example, vendor A might ship an FPGA-based version of a chip they're designing to customer B, so they can design/debug their system while vendor A finishes the design, so both A and B can ramp their products more closely together.

Here's Actel's pitch on design security. The hack claims to expose the AES key for at least one of their encrypted modes, which implies that that particuler security feature is busted, and the guarantees against counterfeiting, reverse engineering and overbuilding it provides are also busted. According to the (occasionally somewhat breathless) claims in this draft paper, that is indeed what they've accomplished. Even then, they didn't break everything:

There are several security protection levels in the PA3 devices according to the manufacturer's datasheet [14]. The Passkey offers the highest level of reversible protection mechanism. Various DPA techniques were attempted to extract the Passkey, however, we were unable to get even a single bit in two weeks time using our off-the-shelf DPA equipment (oscilloscope with differential probe and PC with MatLab). The Passkey hardware security had robust countermeasures that proved to be DPA resistant. In addition to the unstable internal clock and high noise from other parts of the circuit, the Passkey access verification had its side-channel leakage reduced by a factor of 100. Only noise can be observed in the power traces without any characteristic peaks in the frequency domain. This was likely to be achieved through using a well compensated silicon design together with ultra-low-power transistors instead of standard CMOS library components. In addition, the useful leakage signal has a spread spectrum with no characteristic peaks in frequency domain, thus making narrow band filtering useless.

It'll be interesting to see how Actel responds.

As for "ZOMG, the Chinese can infect all our nukes! RUN!" that seems unlikely. To perform this analysis, you need to be able to isolate the FPGA and its bitstream in a circuit where you can observe all the pieces functioning together. This is trivial in the "vendor A / customer B" scenario above. It's not so easy to do without a specimen of the system you're trying to hack, though.

The chip is the ProASIC3 from Microsemi/Actel. The "backdoor" is part of the JTAG, the debugging framework for the chip. The backdoor was implemented by Acatel (see the original paper) for debugging purposes. China is not really involved in any of this.

https://www.cl.cam.ac.uk/~sps32/sec_news.html#Assurance

it's also written black on white (err greyish background) there
in the abstact of the paper ! No need to guess :-)

"Abstract. This paper is a short summary of a real world AES key extraction performed on a military grade FPGA marketed as 'virtually unbreakable' and 'highly secure'. We demonstrated that it is possible to extract the AES key from the Actel/Microsemi ProASIC3 chip in a time of 0.01 seconds using a new side-channel analysis technique called Pipeline Emission Analysis (PEA)."

  that's indeed extremely fast ...

Daniel

From TFA:

Today we released the drafts of our full papers on QVL technology due to accidental publicity, because someone put the link to our very old drafts of abstracts on Reddit.

This is a security guy I would trust, yessir.

Either the claims will be backed up by independently reproduced tests or they won't. But, given his apparent track record in this area and the obvious scrutiny this would bring, Skorobogatov must have been sure of his results before announcing this.

Here's his publications list from his University home page, FWIW:
http://www.cl.cam.ac.uk/~sps32/#Publications

The original article is here.
It refers to an Actel ProAsic3 chip, which is an FPGA with internal EEPROM to store the configuration.

What kind of storage system can work over seasonal timescales?

Pumped hydro storage for electricity, Ground source heat pumps for heating. The ground source can be heated in summer via solar or air conditioning, and the pumps can be driven by generated electricity in winter (an average heat pump has an efficiency of 400%, 660% efficient pumps are available in Japan):

Heat pumps are superior in efficiency to condensing boilers, even if the heat pumps are powered by electricity from a power station burning natural gas. If you want to heat lots of buildings using natural gas, you could install condensing boilers, which are “90% efficient,” or you could send the same gas to a new gas power station making electricity and install electricity-powered heat pumps in all the buildings; the second solution’s efficiency would be somewhere between 140% and 185%.

heat pumps with a coefficient of performance of 6.6 have been available in Japan since 2006. The performance of heat pumps in Japan improved from 3 to 6 within a decade thanks to government regulations.

So if we switch to ground-source heat pumps, we should plan to include substantial summer heat-dumping in the design, so as to refill the ground with heat for use in the winter. This summer heat-dumping could use heat from air-conditioning, or heat from roof-mounted solar water-heating panels. (Summer solar heat is stored in the ground for subsequent use in winter by Drake Landing Solar Com- munity in Canada [www.dlsc.ca].) Alternatively, we should expect to need to use some air-source heat pumps too, and then we’ll be able to get all the heat we want – as long as we have the electricity to pump it.

What kind of storage system can work over seasonal timescales?

Pumped hydro storage for electricity, Ground source heat pumps for heating. The ground source can be heated in summer via solar or air conditioning, and the pumps can be driven by generated electricity in winter (an average heat pump has an efficiency of 400%, 660% efficient pumps are available in Japan):

Heat pumps are superior in efficiency to condensing boilers, even if the heat pumps are powered by electricity from a power station burning natural gas. If you want to heat lots of buildings using natural gas, you could install condensing boilers, which are “90% efficient,” or you could send the same gas to a new gas power station making electricity and install electricity-powered heat pumps in all the buildings; the second solution’s efficiency would be somewhere between 140% and 185%.

heat pumps with a coefficient of performance of 6.6 have been available in Japan since 2006. The performance of heat pumps in Japan improved from 3 to 6 within a decade thanks to government regulations.

So if we switch to ground-source heat pumps, we should plan to include substantial summer heat-dumping in the design, so as to refill the ground with heat for use in the winter. This summer heat-dumping could use heat from air-conditioning, or heat from roof-mounted solar water-heating panels. (Summer solar heat is stored in the ground for subsequent use in winter by Drake Landing Solar Com- munity in Canada [www.dlsc.ca].) Alternatively, we should expect to need to use some air-source heat pumps too, and then we’ll be able to get all the heat we want – as long as we have the electricity to pump it.

We could have gotten 100% of Europe's electricity

He didn't say 100% of Europe's electricity - he was referring to Germany's (nuclear generated?) electricity. 203.7 billion Euros ($255 billion) would buy a lot of solar panels. I don't know if that would be enough to match whatever German electricity production figure the OP was referring to, perhaps someone will work it out.

shipped it with a 50% loss across half the globe

No, 15%:

An organization called DESERTEC [www.desertec.org] is promoting a plan to use concentrating solar power in sunny Mediterranean countries, and high-voltage direct-current (HVDC) transmission lines (figure 25.7) to deliver the power to cloudier northern parts. HVDC technology has been in use since 1954 to transmit power both through overhead lines and through submarine cables (such as the interconnector between France and England). It is already used to transmit electricity over 1000-km distances in South Africa, China, America, Canada, Brazil, and Congo. A typical 500 kV line can transmit a power of 2 GW. A pair of HVDC lines in Brazil transmits 6.3 GW.

HVDC is preferred over traditional high-voltage AC lines because less physical hardware is needed, less land area is needed, and the power losses of HVDC are smaller. The power losses on a 3500 km-long HVDC line, including conversion from AC to DC and back, would be about 15%. A further advantage of HVDC systems is that they help stabilize the electricity networks to which they are connected.

When you see others posting and saying, "Oh but what happens when the sun isn't shining." quite a few of them are intelligent people.

The problem with your assertion is the "solar is useless because the sun does not shine 24 hours a day" argument assumes that a) sustainable energy proponents have not already thought of this (they have), and b) there are no possible solutions. Intelligent people who are actually interested in investigating and learning about the issues, rather than scoring some cheap political points, would have discovered that both of these assumptions are false, and hence wouldn't repeat that particular argument in the first place.

Sustainable energy sources fluctuate, but there are already solutions to this problem. In particular, pumped storage is already used in Britain to store 30 GWh of excess energy produced in the night, for release during the day with only 30 seconds delay for a whole hydro station to come online. The efficiency of this pumped storage system is 75% (it is estimated that newer facilities could achieve 85%). There are people proposing building a 1km drop pumped storage system beneath London.

Anyone who is intelligent and educated and who still claims that "solar power can't work at night" or "wind power can't work when it's not windy" is being deceptive, by deliberately ignoring the fact that energy can be stored. This is not a fantasy, it is a system that already exists and is in real use.

When you see others posting and saying, "Oh but what happens when the sun isn't shining." quite a few of them are intelligent people.

The problem with your assertion is the "solar is useless because the sun does not shine 24 hours a day" argument assumes that a) sustainable energy proponents have not already thought of this (they have), and b) there are no possible solutions. Intelligent people who are actually interested in investigating and learning about the issues, rather than scoring some cheap political points, would have discovered that both of these assumptions are false, and hence wouldn't repeat that particular argument in the first place.

Sustainable energy sources fluctuate, but there are already solutions to this problem. In particular, pumped storage is already used in Britain to store 30 GWh of excess energy produced in the night, for release during the day with only 30 seconds delay for a whole hydro station to come online. The efficiency of this pumped storage system is 75% (it is estimated that newer facilities could achieve 85%). There are people proposing building a 1km drop pumped storage system beneath London.

Anyone who is intelligent and educated and who still claims that "solar power can't work at night" or "wind power can't work when it's not windy" is being deceptive, by deliberately ignoring the fact that energy can be stored. This is not a fantasy, it is a system that already exists and is in real use.

When you see others posting and saying, "Oh but what happens when the sun isn't shining." quite a few of them are intelligent people.

The problem with your assertion is the "solar is useless because the sun does not shine 24 hours a day" argument assumes that a) sustainable energy proponents have not already thought of this (they have), and b) there are no possible solutions. Intelligent people who are actually interested in investigating and learning about the issues, rather than scoring some cheap political points, would have discovered that both of these assumptions are false, and hence wouldn't repeat that particular argument in the first place.

Sustainable energy sources fluctuate, but there are already solutions to this problem. In particular, pumped storage is already used in Britain to store 30 GWh of excess energy produced in the night, for release during the day with only 30 seconds delay for a whole hydro station to come online. The efficiency of this pumped storage system is 75% (it is estimated that newer facilities could achieve 85%). There are people proposing building a 1km drop pumped storage system beneath London.

Anyone who is intelligent and educated and who still claims that "solar power can't work at night" or "wind power can't work when it's not windy" is being deceptive, by deliberately ignoring the fact that energy can be stored. This is not a fantasy, it is a system that already exists and is in real use.

> You seem to mostly know what you are talking about, but this is just FUD. Tor works and is open-source. That e-mail references the source to a modified version of TorButton that apparently had a trojan that ran anon's LOIC DDOS tool. It has nothing to do with the security of Tor or TorButton.

Thanks, that answers some of my questions.

I really don't feel safe using Tor, in part because it was invented by the Naval Research Laboratory and one of its creators has clarified USG interest in the project, so I'll just leave it at this, which is a paper presented on some of its weaknesses. Perhaps some of these weaknesses have been resolved by now; perhaps not.

I don't claim to be an expert, I just think that anyone who really believes that Tor is secure might want to consider whether they have underestimated the capabilities of the government. The USG is really amazing when it wants to be.

Consider two possible worlds: one where we build thousands of nuclear plants. Another where instead we equip the whole world with solar.

The difference is that we already have the technology to build nuclear power plants on a scale to power the world. We do not have the technology to build photovoltaic farms to power the world. This situation might change, if the technology develops to a point where solar becomes viable, but it would require some huge technological leaps - perhaps photovoltaic plastics. Providing only 1/4 of UK's energy consumption (pop. 62M) would require more than 100 times all the photovoltaics that exist in the entire world right now. Another quote:

Fantasy time: solar farming

If a breakthrough of solar technology occurs and the cost of photovoltaics came down enough that we could deploy panels all over the countryside, what is the maximum conceivable production? ...

How audacious is this plan? The solar power capacity required to deliver this 50 kWh per day per person in the UK is more than 100 times all the photovoltaics in the whole world. So should I include the PV farm in my sustainable production stack? I’m in two minds. At the start of this book I said I wanted to explore what the laws of physics say about the limits of sustainable energy, assuming money is no object. On those grounds, I should certainly go ahead, industrialize the countryside, and push the PV farm onto the stack. At the same time, I want to help people figure out what we should be doing between now and 2050. And today, electricity from solar farms would be four times as expensive as the market rate. So I feel a bit irresponsible as I include this estimate in the sustainable production stack in figure 6.9 – paving 5% of the UK with solar panels seems beyond the bounds of plausibility in so many ways. If we seriously contemplated doing such a thing, it would quite probably be better to put the panels in a two-fold sunnier country and send some of the energy home by power lines. We’ll return to this idea in Chapter 25.

It doesn't matter how much grass and scrubby plants cows need to eat to produce a kilo of beef, because it won't do us a bit of good if they don't.

In modern farming, what percentage of cows do you think are fed using only scrubby grass land as a food source? We're talking here about land that is so useless that it can't be used to grow any human consumable crops like rice, wheat, potatoes etc. I would bet that the vast majority of "green grass" cow farms in the U.S. and Western Europe would be just as capable of growing potatoes as grass.

Do these calculations give an argument in favour of vegetarianism, on the grounds of lower energy consumption? It depends on where the animals feed. Take the steep hills and mountains of Wales, for example. Could the land be used for anything other than grazing? Either these rocky pasturelands are used to sustain sheep, or they are not used to help feed humans. You can think of these natural green slopes as maintenance-free biofuel plantations, and the sheep as automated self-replicating biofuel-harvesting machines. The energy losses between sunlight and mutton are substantial, but there is probably no better way of capturing solar power in such places. (I’m not sure whether this argument for sheep-farming in Wales actually adds up: during the worst weather, Welsh sheep are moved to lower fields where their diet is supplemented with soya feed and other food grown with the help of energy-intensive fertilizers; what’s the true energy cost? I don’t know.) Similar arguments can be made in favour of carnivory for places such as the scrublands of Africa and the grasslands of Australia; and in favour of dairy consumption in India, where millions of cows are fed on by-products of rice and maize farming.

On the other hand, where animals are reared in cages and fed grain that humans could have eaten, there’s no question that it would be more energy-efficient to cut out the middlehen or middlesow, and feed the grain directly to humans. - source

Depending on how you account for these factors, you reach very different answers about who should pay for carbon emissions.

The obvious answer to the question "who should pay for emissions?" is "the people who did it". You are, for some reason, attempting to lump in lots of other environmental issues to the one of CO2 emissions. When we regulated SO2 emissions, we just did it - we didn't wait until we had figured out how to handle deforestation or population growth in Africa, or how to somehow "correct" the effects of colonialism or emigration in Europe thousands of years ago.

If you don't think that the emitter should pay, then who should? The rich? The poor? Everyone pay an equal share? If so, how do you account for different salary rates in different nations - should everyone pay an equal proportion of their income? It is ridiculous to suggest that, say, Africans with their average income of $315 a year should have the same responsibility towards paying this cost as Westerners who earn many times more, especially when it was the Western nations who contributed most to the increase in co2 levels:

The major countries with the biggest per-capita emissions are Australia, the USA, and Canada. European countries, Japan, and South Africa are notable runners up. Among European countries, the United Kingdom is resolutely average. What about China, that naughty “out of control” country? Yes, the area of China’s rectangle is about the same as the USA’s, but the fact is that their per-capita emissions are below the world average. India’s per-capita emissions are less than half the world average. Moreover, it’s worth bearing in mind that much of the industrial emissions of China and India are associated with the manufacture of stuff for rich countries.

So, assuming that “something needs to be done” to reduce greenhouse gas emissions, who has a special responsibility to do something? As I said, that’s an ethical question. But I find it hard to imagine any system of ethics that denies that the responsibility falls especially on the countries to the left hand side of this diagram – the countries whose emissions are two, three, or four times the world average. Countries that are most able to pay. Countries like Britain and the USA, for example.

Historical responsibility for climate impact

If we assume that the climate has been damaged by human activity, and that someone needs to x it, who should pay? Some people say “the polluter should pay.” The preceding pictures showed who’s doing the polluting today. But it isn’t the rate of CO2 pollution that matters, it’s the cumulative total emissions; much of the emitted carbon dioxide (about one third of it) will hang around in the atmosphere for at least 50 or 100 years. If we accept the ethical idea that “the polluter should pay” then we should ask how big is each country’s historical footprint. The next picture shows each country’s cumulative emissions of CO2, expressed as an average emission rate over the period 1880–2004. Average pollution rate

Congratulations, Britain! The UK has made it onto the winners’ podium. We may be only an average European country today, but in the table of historical emitters, per capita, we are second only to the USA.

It takes 15 Terawatts to power the world [wikipedia.org] and each fission reactor apparently provides about 1 gigawatt [euronuclear.org], so to furnish 50% of the world's energy needs of today with nuclear, we'd need to build 1 billion nuclear fission reactors.

Your math is wrong. 15*10^12 / 1*10^9 = 15000 reactors. The estimate I've read is lower, 3000 new reactors over 60 years, i.e. 50 new reactors a year globally, which might be acheivable. See Sustainable energy without the hot air, chapter 24: Nuclear: Mythconceptions

I heard that nuclear power can’t be built at a sufficient rate to make a useful contribution.

The difficulty of building nuclear power fast has been exaggerated with the help of a misleading presentation technique I call “the magic playing field.” In this technique, two things appear to be compared, but the basis of the comparison is switched halfway through. The Guardian’s environment editor, summarizing a report from the Oxford Research Group, wrote “For nuclear power to make any significant contribution to a reduction in global carbon emissions in the next two generations, the industry would have to construct nearly 3000 new reactors – or about one a week for 60 years. A civil nuclear construction and supply programme on this scale is a pipe dream, and completely unfeasible. The highest historic rate is 3.4 new reactors a year.” 3000 sounds much bigger than 3.4, doesn’t it! In this application of the “magic playing field” technique, there is a switch not only of timescale but also of region. While the first figure (3000 new reactors over 60 years) is the number required for the whole planet, the second figure (3.4 new reactors per year) is the maximum rate of building by a single country (France)!

A more honest presentation would have kept the comparison on a per- planet basis. France has 59 of the world’s 429 operating nuclear reactors, so it’s plausible that the highest rate of reactor building for the whole planet was something like ten times France’s, that is, 34 new reactors per year. And the required rate (3000 new reactors over 60 years) is 50 new reactors per year. So the assertion that “civil nuclear construction on this scale is a pipe dream, and completely unfeasible” is poppycock. Yes, it’s a big construction rate, but it’s in the same ballpark as historical construction rates.

How reasonable is my assertion that the world’s maximum historical construction rate must have been about 34 new nuclear reactors per year? Let’s look at the data. Figure 24.14 shows the power of the world’s nuclear fleet as a function of time, showing only the power stations still operational in 2007. The rate of new build was biggest in 1984, and had a value of (drum-roll please...) about 30 GW per year – about 30 1-GW reactors. So there!

Typically a "green" produced by GaN is fairly easy to manufacture and fairly efficient, but it is physically a very *hard* material. In contrast, the "blue-green" produced by InGaN (an alloy of a little bit of InN and base of GaN) isn't as efficient as it tends to have lots crystal defects and these defect cause brittle-ness and results in some electron-hole recombinations to be non-radiative (generating heat and not band-gap light emissions).

Regardless of this manufacturability issue, many white LEDs use an InGaN band-gap devices and create the "warmer" parts of the spectrum using phosphors. This makes most of the output light more blue-ish, but only the phosphor re-radiated (stoke's shifted) part in the warmer part of the spectrum where you pay the efficiency cost. For "cool" devices, less of the output is down-converted, so you have less efficiency loss. For "warmer" devices, more of the light is down converted and you pay for more conversion efficiency loss. Some warm devices actually have multiple LEDs (say a red, green, and blue), but color stability is generally hard to maintain over time and temperature, so these devices are generally less efficient and more expensive.

In any case, the effect that was described is that the currently "cheap" way of growing GaN base crystals for LEDs results in a polar orientation which is bad for high-current operation as it tends to generate a back field. This is described in more detail in this other site:

Most of the commercial GaN devices are grown along the [0001] direction, so-called “polar” or “c-plane” structures. However, there is an internal electric field perpendicular to the active regions in the c-plane devices as the c-axis is polar. This will result in band bending and a poor overlap of electron and hole wave-functions (the Quantum confined Stark effect, or QCSE), which reduces the radiative recombination efficiency and affects the device performance. In order to avoid (or reduce the effects of) the QCSE, GaN can be grown in “non-polar”, or “semi-polar”, orientations, in which there is no, or much less, internal polarization fields along the growth direction. In theory, this should increase the efficiency of light emitting structures. The high density of structural defects (such as basal plane stacking faults and partial dislocations) in heteroepitaxially grown non-polar and semi-polar GaN results in low internal quantum efficiency and output power of the devices, as reported in the literature.

Of course the answer is to just grow low-defect GaN in a non-polar or semi-polar orientation, but that's currently hard to do. These UCSB researchers aren't the only group working on this problem, but they apparently have done some cooperation with people doing actual manufacturing (Mitsubishi Chemical).

The reason is that many nations like China will take advantage of this to build up their own economy

Worse, EU and liberals here fall for the trap of emissions PER CAPITA. It is the WORST IDEA EVER. China has not had a changing population, yet, their emissions went up nearly 10 fold over something like a 20 year period

If emissions went up, and population was constant, then per capita emissions also went up. Why are you implying that per capita is therefore not a useful measure? It should also be noted that China's emissions have gone up because it is now manufacturing the majority of the world's stuff. If you want to control emissions based on manufacturing and economic output, then China is going to be given a huge share.

Anyway, the belief that everyone should have an equal share (per capita) is an ethical and moral issue. Some people believe that everyone should be entitled to an equal share. Some people believe that people of their own nationality or ethnicity should have a greater share of pollution rights than people who don't share a nationality or ethnicity. Climate change without the hot air - great book for people interested in the actual numbers - has this insight:

assuming that “something needs to be done” to reduce greenhouse gas emissions, who has a special responsibility to do something? As I said, that’s an ethical question. But I find it hard to imagine any system of ethics that denies that the responsibility falls especially on the countries ... whose emissions are two, three, or four times the world average. Countries that are most able to pay. Countries like Britain and the USA, for example.

It's a good point. It is not easy to construct a moral argument as to why people of one nationality or ethnicity should be allowed to pollute more than others. And since you can trade credits, the argument that it should be about GDP is invalid, because the high GDP nations can easily buy more credits from the low GDP nations.

Also, see this diagram of cumulative emissions.

If we assume that the climate has been damaged by human activity, and that someone needs to x it, who should pay? Some people say “the polluter should pay.” The preceding pictures showed who’s doing the polluting today. But it isn’t the rate of CO2 pollution that matters, it’s the cumulative total emissions; much of the emitted carbon dioxide (about one third of it) will hang around in the atmosphere for at least 50 or 100 years. If we accept the ethical idea that “the polluter should pay” then we should ask how big is each country’s historical footprint.

So, in terms of CO2 in the air right now, the USA, Western Europe and Russia are responsible for the vast majority of historic emissions because we have been digging up, drilling, and burning fossil fuels for longer.

Consider this thought experiment: residents of your city got into the habit of dumping rubbish in the city. The wealthy people dumped far more than the poor. Over time all this rubbish has accumulated and now someone needs to pay to have it cleaned up. Who should pay? Should all residents pay an equal amount, regardless of who actually dumped the rubbish? Should the poor pay? The rich? Should the people who actually dumped the rubbish be the ones that pay to clean it up? What about the people who are still dumping huge amounts of rubbish? Should they be paying more than the ones who dump very little?

The reason is that many nations like China will take advantage of this to build up their own economy

Worse, EU and liberals here fall for the trap of emissions PER CAPITA. It is the WORST IDEA EVER. China has not had a changing population, yet, their emissions went up nearly 10 fold over something like a 20 year period

If emissions went up, and population was constant, then per capita emissions also went up. Why are you implying that per capita is therefore not a useful measure? It should also be noted that China's emissions have gone up because it is now manufacturing the majority of the world's stuff. If you want to control emissions based on manufacturing and economic output, then China is going to be given a huge share.

Anyway, the belief that everyone should have an equal share (per capita) is an ethical and moral issue. Some people believe that everyone should be entitled to an equal share. Some people believe that people of their own nationality or ethnicity should have a greater share of pollution rights than people who don't share a nationality or ethnicity. Climate change without the hot air - great book for people interested in the actual numbers - has this insight:

assuming that “something needs to be done” to reduce greenhouse gas emissions, who has a special responsibility to do something? As I said, that’s an ethical question. But I find it hard to imagine any system of ethics that denies that the responsibility falls especially on the countries ... whose emissions are two, three, or four times the world average. Countries that are most able to pay. Countries like Britain and the USA, for example.

It's a good point. It is not easy to construct a moral argument as to why people of one nationality or ethnicity should be allowed to pollute more than others. And since you can trade credits, the argument that it should be about GDP is invalid, because the high GDP nations can easily buy more credits from the low GDP nations.

Also, see this diagram of cumulative emissions.

If we assume that the climate has been damaged by human activity, and that someone needs to x it, who should pay? Some people say “the polluter should pay.” The preceding pictures showed who’s doing the polluting today. But it isn’t the rate of CO2 pollution that matters, it’s the cumulative total emissions; much of the emitted carbon dioxide (about one third of it) will hang around in the atmosphere for at least 50 or 100 years. If we accept the ethical idea that “the polluter should pay” then we should ask how big is each country’s historical footprint.

So, in terms of CO2 in the air right now, the USA, Western Europe and Russia are responsible for the vast majority of historic emissions because we have been digging up, drilling, and burning fossil fuels for longer.

Consider this thought experiment: residents of your city got into the habit of dumping rubbish in the city. The wealthy people dumped far more than the poor. Over time all this rubbish has accumulated and now someone needs to pay to have it cleaned up. Who should pay? Should all residents pay an equal amount, regardless of who actually dumped the rubbish? Should the poor pay? The rich? Should the people who actually dumped the rubbish be the ones that pay to clean it up? What about the people who are still dumping huge amounts of rubbish? Should they be paying more than the ones who dump very little?

Another unexpected nding was the relationship between risk and security investment. One might expect that as US banks are liable for fraudulent transac- tions, they would spend more on security than British banks do; but our research showed that precisely the reverse is the case: while UK banks and building soci- eties now use hardware security modules to manage PINs, most US banks just encrypt PINs in software. Thus we conclude that the real function of these hardware security modules is due diligence rather than security. British bankers want to be able to point to their security modules when ghting customer claims, while US bankers, who can only get the advertised security benet from these devices, generally do not see any point in buying them. Given that the British strategy did not work - no-one has yet been able to construct systems which bear hostile examination - it is quite unclear that these devices add any real value at all.

Actually there are some decent introductions like ANSI C for Programmers on UNIX Systems that are short and focused enough to be useful. Combining that with something like python (which is quite well supported on Ubuntu and has abundance of online resources, including online consoles with training exercises) should get one quite far, for relatively minor effort on the student's part.

That article doesn't tell the whole story, though. It leaves out the cost of actually producing the vegetables that you eat

No it doesn't. The whole point of that particular chapter of the book is to show the overall cost of producing the various food types, including the cost of oil, fertiliser etc.

Read the book if you are actually interested in this stuff - it provides a very good "physicists perspective" of energy usage, with all of the figures cited to actual published research.

Arguably vegans can be worse in this regard

Scientists have actually studied the energy cost of producing various diets, and the research shows that the vegan diet is the lowest. The energy cost of growing plants and feeding them to animals and then eating the animals exceeds the energy cost of growing and eating plants alone. There is a loss of efficiency for each stage of the path. btw, Shipping has a low energy cost in contrast to other freight transport.

Sustainable Energy - without the hot air , Chapter 13 Food and farming, David JC MacKay

The vegan has the smallest footprint: 3 kWh per day of energy from the plants he eats. A typical dairy diet adds 1.5 kWh/d to that. Meat adds 8 kWh/d. Include eggs 1 kWh/d. The total comes to 12 kWh per day, so the typical person chooses a diet that requires four times more energy to produce than the typical vegan diet.

Since vegans aren't all dead, I'm going to assume that a vegan diet would be survivable for most people.

I think a better metric is the number of fatalities.

This ignores the amount of power generated per fatality. A better metric is "deaths per GWy (gigawatt-year)." There's a graph that compares by this metric, nuclear comes out well, oil is the worst.

The problem with nuclear isn't really the technology itself, it's the irresponsible people that run the plants. Here's a quote from that link:

The THORP reprocessing facility at Sellafield, built in 1994 at a cost of £1.8 billion, had a growing leak from a broken pipe from August 2004 to April 2005. Over eight months, the leak let 85 000 litres of uranium-rich fluid flow into a sump which was equipped with safety systems that were designed to detect immediately any leak of as little as 15 litres. But the leak went undetected because the operators hadn’t completed the checks that ensured the safety systems were working; and the operators were in the habit of ignoring safety alarms anyway.

The safety system came with belt and braces. Independent of the failed safety alarms, routine safety-measurements of fluids in the sump should have detected the abnormal presence of uranium within one month of the start of the leak; but the operators often didn’t bother taking these routine measurements, because they felt too busy; and when they did take mea- surements that detected the abnormal presence of uranium in the sump (on 28 August 2004, 26 November 2004, and 24 February 2005), no action was taken.

By April 2005, 22 tons of uranium had leaked, but still none of the leak-detection systems detected the leak. The leak was finally detected by accountancy, when the bean-counters noticed that they were getting 10% less uranium out than their clients claimed they’d put in! Thank goodness this private company had a profit motive, hey? The criticism from theChief Inspector of Nuclear Installations was withering: “The Plant was operated in a culture that seemed to allow instruments to operate in alarm mode rather than questioning the alarm and rectifying the relevant fault.”

If we let private companies build new reactors, how can we ensure that higher safety standards are adhered to? I don’t know.

Price could still be an issue; there's more up-front cost, and the need to replace the batteries every 10-15 years

Which isn't really the issue that people make it out to be. The "replacement rate" for cars is about 15 years anyway, and the embodied cost of making a new car every 15 years works out at 14 kWh per day (link) And if you do it right, then electric cars also solve the energy demand management problem. And electric vehicles are much more energy efficient than other vehicles, comparative graph

Price could still be an issue; there's more up-front cost, and the need to replace the batteries every 10-15 years

Which isn't really the issue that people make it out to be. The "replacement rate" for cars is about 15 years anyway, and the embodied cost of making a new car every 15 years works out at 14 kWh per day (link) And if you do it right, then electric cars also solve the energy demand management problem. And electric vehicles are much more energy efficient than other vehicles, comparative graph

Price could still be an issue; there's more up-front cost, and the need to replace the batteries every 10-15 years

Which isn't really the issue that people make it out to be. The "replacement rate" for cars is about 15 years anyway, and the embodied cost of making a new car every 15 years works out at 14 kWh per day (link) And if you do it right, then electric cars also solve the energy demand management problem. And electric vehicles are much more energy efficient than other vehicles, comparative graph

I put this out to provoke discussion only. I does not represent our views, which take no stand on the questions raised below...

Nearly every book you read, every song you sing, every poem, thesis, play, movie, dance, audio recording, painting, drawing, sculpture, photograph, radio and television broadcast, and even the software on your computer "belongs" to somebody. All our academic knowledge is locked behind paywalls. Your entire culture has been commercialized and sold to the highest bidder. Did anybody ask you if this is what you wanted?

While copyrights may have been a workable notion at one time "To promote the Progress of ... the useful Arts", the interpretation of that has broadened to encompass almost all forms of expression written or recorded on some physical medium, utilitarian or not. This has produced a vast artificial economy that seeks to grow and perpetuate itself at the expense of the potential of modern technologies. The whole idea of parceling up the creative commons and granting monopolies on the fragments of our culture to individuals and corporations needs to be rethought.

We have lost our way. The institutionalized Ferengi culture imposed by copyright legislation has created a hideous distortion of human values. It is an anathema to genuine human culture, which is at its base freely shared experience and expression. We must renounce this mercantile obsession with profit and trade and find our way back to innocence and truth.

If copyrights were dismantled tomorrow, would people suddenly stop singing, writing books, or quit participating in the multitude of forms of cultural expression available? Do we need to provide financial incentives to grow our own culture? Is it heresy to ask such questions, or even useful? It certainly is useful as a thought experiment even if just to overcome the propaganda the rights groups have been feeding us all these years. Beyond that, though copyright is already enshrined in our constitutions, these rights can be pared back just as easily as they were expanded previously.

Please see our manifesto at http://whynotaskme.org/

natural gas from fraking alone satisfies all energy needs for the next 150 years.

I doubt it. The average American consumes about 250 kWh per day. Natural gas accounts for something like 20% of that. Also, energy need is not constant, it will grow over the next 150 years because the population will grow. You can't just take total potential supply and divide it by the existing consumption, when demand is constantly rising.

Where does this 150 year figure come from anyway? The last time someone claimed 100 years, it turned out to be bogus:

By the same logic, you can claim to be a multibillionaire, including all your "probable, possible, and speculative resources."

Assuming that the United States continues to use about 24 tcf per annum, then, only an 11-year supply of natural gas is certain. The other 89 years' worth has not yet been shown to exist or to be recoverable.

Even that comparably modest estimate of 11 years’ supply may be optimistic. Those 273 tcf are located in reserves that are undrilled, but are adjacent to drilled tracts where gas has been produced. Due to large lateral differences in the geology of shale plays, production can vary considerably from adjacent wells.

If and only if we can create an efficient means of power storage

We already have one: Pumped storage. The existing pumped storage systems are 75% efficient, and scientists think they can make future ones that are 90%+ efficient. You don't even need land: "Thinking further outside the box, one could imagine getting away from lakes and reservoirs, putting half of the facility in an underground cham- ber. A pumped-storage chamber one kilometre below London has been mooted."

The amount of vegetable matter that you need to produce the massive amounts of oil that humans use, would take up all the worlds arable land,leaving us nowhere to produce food for the every expanding population.

Indeed. Sustainable energy without the hot air contains the figures. It doesn't look good even for the "promising" plants:

For comparison, world oil consumption is 80 million barrels per day, which, shared between six billion people, is 23 kWh/d/p. So even if all of Africa were covered with jatropha plantations, the power produced would be only one third of world oil consumption.

The only thing that seems potentially viable is algae grown in water enriched with co2 captured from industrial plants. But obviously that requires some advanced carbon capture technology. It would also require land, though not as much as other biofuel ideas.

What about algae?

Algae are just plants, so everything I’ve said so far applies to algae. Slimy underwater plants are no more efficient at photosynthesis than their ter- restrial cousins. But there is one trick that I haven’t discussed, which is standard practice in the algae-to-biodiesel community: they grow their algae in water heavily enriched with carbon dioxide, which might be col- lected from power stations or other industrial facilities. It takes much less effort for plants to photosynthesize if the carbon dioxide has already been concentrated for them.

In a sunny spot in America, in ponds fed with concentrated CO2 (concentrated to 10%), Ron Putt of Auburn University says that algae can grow at 30 g per square metre per day, producing 0.01 litres of biodiesel per square metre per day. This corresponds to a power per unit pond area of 4 W/m2 – similar to the Bavaria photovoltaic farm.

If you wanted to drive a typical car (doing 12 km per litre) a distance of 50 km per day, then you’d need 420 square metres of algae-ponds just to power your car; for comparison, the area of the UK per person is 4000 square metres, of which 69 m2 is water (figure 6.8).

Please don’t forget that it’s essential to feed these ponds with concentrated carbon dioxide. So this technology would be limited both by land area – how much of the UK we could turn into algal ponds – and by the availability of concentrated CO2, the capture of which would have an energy cost (a topic discussed in Chap- ters 23 and 31). Let’s check the limit imposed by the concentrated CO2. To grow 30 g of algae per m2 per day would require at least 60 g of CO2 per m2 per day (because the CO2 molecule has more mass per carbon atom than the molecules in algae).

If all the CO2 from all UK power stations were captured (roughly 212 tons per year per person), it could service 230 square metres per person of the algal ponds described above – roughly 6% of the country. This area would deliver biodiesel with a power of 24 kWh per day per person, assuming that the numbers for sunny America apply here.

A plausible vision? Perhaps on one tenth of that scale? I’ll leave it to you to decide.

So, we have our first solid metric: it's 220 times as hard to make Windows secure as it is for BSD or Linux.

BSD or Linux? Check the paper. It took 100 lines of code with Capsicum, 200 with SELinux, 605 with Linux-with-chroot, 11,301 with Linux-with-seccomp and 22,350 with Windows. So (with your metric) it is somewhere between 2 and 10 times as hard to make Windows as secure as Linux and between 2 and 10 times as hard to make Linux as secure as FreeBSD. And the best score for Linux - the SELinux sandbox - requires enabling SELinux which is a massive blob of code and has introduced several of its own security holes in the last couple of years, while Capsicum is much simple and easier to audit.