I had the following censored from what appears to be an oil industry astroturf site today:
"It seems to me that we should set a target price of $20/barrel by controlling demand. This is above the cost of production of most oil in the current supply, and there is ample future oil to maintain that price over a decade or so. All we need to do is to direct investments into cheap-to-produce oil exclusively as we cut demand to follow depletion down. This figure that rembrandt posted from the WEO 2008 shows that investments in expensive-to-produce oil is a whole other world.
We can get at least 1 trillion barrels at less than $15/barrel cost of production and that is the amount of oil that got us on to oil so it should be plenty to get us off of oil. Investing in anything more expensive than that looks to be a true waste of money and effort."
What is wrong with the sentiment expressed here? Clearly it is factually accurate. Draw a line across the figure at $15/barrel cost of production and there is plenty of oil below that cost to use to transition off of oil. That can't be the problem. The idea that demand control can control price is historically validated. There was an oil glut from 1884 to 2000 brought about by switching electricity generation off of oil and boosting efficiency in transportation. The price of oil was forced down and then kept low then. That can't be the problem. So, what is the problem?
I think that the problem is that to deal with the finite oil resource in a cost effective way, we need to start shrinking the oil industry now. And, that is not happy news for oil industry advocates. On the Internet, censorship is practiced by corporate sponsored groups or non-democratic governments. Elsewhere the ethos of freedom of expression runs too strongly to tolerate censorship. We must thus take evidence of censorship as evidence of corporate or foreign sponsorship or both. It is not unusual for the oil industry to hide its attempts to influence public opinion with false information. What strength there is in global warming denialist propaganda comes from often hidden oil industry funding. It thus appears that this must be the cause of the censorship I experienced. We are likely seeing an industry scam attempting to manipulate the price of oil.
The present price of oil, $55/barrel, is still way above the cost of production and is thus too high. None of the proposed new investments in oil supply that fall in the expensive range makes any sense compared with real energy sources like wind and solar. So, there is no reason at all not to cut the price of oil in half right now. Oil is still too expensive!
Friday, November 14, 2008
I had the following censored from what appears to be an oil industry astroturf site today:
Posted by Chris Dudley at 10:58 AM
Wednesday, October 15, 2008
Today is Blog Action Day which we've celebrated before. Today I want to say that in Glenville, West Virginia the church needs a coat of paint. That is a sign that people are poor. A lot of US 33 through West Virginia is poor. I have to say that in the midst of that, there are people fighting to keep their mountains whole, to keep the coal in its place in the ground. People with shabby clothes and a mountain song in their hearts. Almost heaven....
West Virginia has produced over 13 billion tons of coal since 1863, about twice the current annual input of carbon into the atmosphere. So, West Virginia is responsible for driving about 1% of world gross domestic product. Yet the poverty rate in West Virginia in the period 2005-2007 (15.2%) was only exceeded by Mississippi (21.1%), Louisiana (17.1%), Texas (16.4%), New Mexico (16.3%) and Kentucky (15.7%), all energy producing states, and DC (19.2%). Why would energy production be associated with poverty? It is pretty simple. We value energy sources that don't take a lot of effort to acquire. So, there is little economic benefit for the region from which energy resources are extracted. This can be changed by charging royalties. Alaska has an 8.1% poverty rate. But in most places the people get raped just as badly as the land.
Fossil energy extraction is a leading cause of poverty around the world even as it seems to boost prosperity elsewhere. Death and human rights abuses also follow in its wake. Closing the book on poverty is going to mean ending our use of fossil fuels.
Posted by Chris Dudley at 9:48 PM
Friday, June 13, 2008
The reason oil is too expensive is that the current price encourages seeking out new oil that is expensive to produce. That is not the same as the reason oil is expensive.
The US Senate defeated a windfall profits tax measure that would have taxed oil companies on the high price of oil. It was defeated on a cloture vote: 51 to 43, a majority supported the closing of debate. It is getting close and one can guess that in November, this will be a deciding factor in some senate races and is already an issue in the presidential race: http://www.iht.com/articles/ap/2008/06/10/america/NA-POL-US-Congress-Oil-Profits.php.
There is not really a good reason not to capture the portion of the profits that are made on domestically produced oil since the only use for them is to reinvest in oil exploration which is becoming fruitless. But, capturing the profits does not do anything about the price of oil except to push it up a little faster since the oil exploration is not yet entirely fruitless. But, oil exploration is pointless now and for this reason it needs to be strongly discouraged. The way to discourage oil exploration is to reduce the price of oil rather than to stomp on a bunch of profit brushfires. While prices are high, some one somewhere will be exploring and finding oil that is expensive to produce even if we (in the US) manage to keep that from happening here through tax policy. Then everyone will be able to buy just as much oil as they can afford and the cancer of expensive oil will metastasize right back here where we might have stamped out incentives to find expensive oil. But, if the price of oil is reduced below the cost of producing expensive oil, then only cheap oil will be pumped from the ground and no one anywhere will bother to explore for expensive oil.
We can tell that oil is too expensive when people are working to be able to get to work or when people who have retired are choosing between heat and food. The promise of oil has been broken and it is time to give it up as a bad job. So, we need to make sure that people can get to work and keep warm while having something to eat. And, we need a good portion of the remaining cheap oil to get through to a point where these things can be done without using any oil. How do we ensure that we get that cheap oil at a price that reflects what it costs to produce rather than the scarcity of oil compared to how we use it now? We need to be sure that we are not using oil any faster than the remaining cheap oil can be pulled from the ground. If we try to go faster than that, we'll encourage people to look for more expensive oil since oil will seem scarce and thus worthy of investment.
Our policy should be focused on keeping oil inexpensive and to do that we need to aggressively phase out the use of oil. There are some sectors where we can't do this such as aviation, but in most we can move rapidly, and, more importantly, we can move rapidly enough overall. If the US alone, were to cut its per capita consumption to seven gallons a week down from nine, (think carpools and second small cars) we'd cut world consumption by about 6%. Dropping another weekly half gallon a year for fourteen years would cut world consumption by 25%. That is surely enough to keep the world on the cheap oil supplies out to 2025 or so since these supplies will be extended a bit by the reduced demand.
How to implement this policy? We might try simply restricting imports by a quarter or so. This would surely drop the world price of oil below $20/barrel. But, the domestic price of oil would likely be pretty high, $400/barrel or so, and this would encourage all sorts of foolishness in terms of looking for expensive oil domestically. We don't want to encourage that.
We could try imposing a tax, say $380/barrel, and that should solve the problem of encouraging exploration for expensive oil domestically and abroad, but is might be destabilizing for the government since the revenue would cover much more government spending than current taxes and we were warned by the chairman of the Federal Reserve at the beginning of the current administration that paying our national debt would be a bad thing. Also, since domestic oil prices would be even higher than now, we will have failed on the getting to work and keeping warm and eating portion of our problem.
Usually, when we have something serious to undertake, we ration. If we can get gasoline down to about $0.60/gallon by being careful how we use it, then our shared sense of accomplishment should help us do the rest of the transition down to using no gasoline at all. We have an existing rationing plan http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=6307185 and it includes a white market in rations. This means that rations can be sold/traded, placing the cost of (rationing imposed) scarcity on the rations slips rather than the fuel. Getting to work or staying warm end up costing less though you might be making a choice on how to convert either of those two within a few years.
Just now, such an effort is doable, but if we wait for expensive oil to gain a greater share of the world total production, then controlling prices by controlling demand will be more difficult since there will be a floor price for much more of the production. In that situation, we will need to reduce our oil consumption probably just as much, but we won't gain the benefit of getting the cheap oil at a low price.
The core reason oil is too expensive is that the current price encourages exploration for expensive oil. Oil is useful when it is cheap to produce and cheap to buy, but it becomes harmful when it is expensive to buy, and even more harmful when it is expensive to produce since this places a price floor that no amount of consumption control can break. It is crucial not to spend resources on exploring for expensive oil. At present, only the US, as a single market entity, has the power to force only cheap oil to be produced and to end exploration for expensive oil. Others could, in combination, have a similar effect, but may not have the existing coordinated plan in place and thus may not be able to take such action before too much expensive (to produce) oil is on the market. The US should implement rationing as soon as possible to drive down the price of oil below $20/barrel and encourage other countries to also restrain demand. A window of perhaps 20 years of $20/barrel oil might be achieved through managed demand, plenty of time to manage a transition away from oil at low cost.
Posted by Chris Dudley at 9:02 PM
Wednesday, March 19, 2008
There are 284,300 km2 of coral reef in the world. They are basically made of calcium carbonate and if porosity accounts of one third of their volume, their density would be about 1.87 gm/cm3. This then is a carbon density of 0.22 gm/cm3. Coral is very stressed by silt and nitrogen runoff currently and may soon be attacked by ocean acidification, but is one of the ways that atmospheric carbon dioxide is converted into limestone. Coral seeks a certain depth below the surface of the ocean to have the right amount of light for its growth. We may well see 30 cm of sea level rise in the next 50 years since sea level rise appears to be accelerating. How much carbon would be sequestered by coral if we were to ensure that it can grow 30 cm where it is already established?
The total volume would be 8.5x1016 cm3 so the total carbon mass would be 19 Gigatonnes. This covers about 2 years of current carbon emissions or 4 years of carbon that is not already currently being absorbed from the atmosphere. To cover emissions since 1950 when emissions were 5 times lower, we'd need to increase the areas of coral reefs by about a factor of 5. Since corals grow in a range of conditions, establishing reefs in ways that anticipate both water temperature and sea level changes while doing what is needed to control silt and nitrogen runoff can apparently remove the extra carbon dioxide we have introduced into the atmosphere. Growth rates of corals are lower than what is needed (10 gm/m^2/day) by about a factor of three, so increasing the coral surface area by a factor of 15 would make some sense. Once sea level begins to recede, further coral growth would be limited, providing protection against removing too much carbon from the atmosphere.
Doing what needs to be done to protect coral so that it can grow would also likely revive mollusk populations which also sequester carbon as calcium carbonate so that the amount of new reef needed may be less. One way to control nitrogen runoff is to use biochar as a buffer and this also had carbon sequestration potential itself. The changes we need to make to unmake our carbon dioxide waste look as though they also improve our ability to get food through restored land and ocean productivity.
Posted by Chris Dudley at 9:16 AM
Thursday, March 6, 2008
In which, energy can be delivered to homes for less than a penny per kilowatt-hour.
The etymology of the word lukewarm comes from old English meaning tepid rather than from the Evangelist whose name means bringer of light is some traditions. The advantages of using real energy to warm water before it is delivered to a home is the subject of this post so we have a Latin title meant to evoke both light and warmth while perhaps spurring a memory that the Romans would take almost any practical step to get a good bath.
The word plumbing comes from the word lead and, despite its unfortunate origins, this is our main theme. Lead, mercury and other heavy metals cause many of our misfortunes because they cause our minds to no longer function properly. As we end the use of coal as we ended the use of lead in gasoline we may well see further reductions in violent crime. Luke, who traveled with Paul, does not mention what Nero did to Paul. Some argue that this is because he wrote his Gospel and Acts before Paul died but others argue that it is because Luke considered Nero an aberration. The behavior of Nero and the other degenerate Emperors could well be explained by the ubiquitous presence of lead in the Roman environment, only some of which was from the plumbing; they used it to flavor food as well.
In our plumbing, water is delivered to homes at the ambient temperature which is just the average temperature of a region over a year (about 55o F near the Chesapeake Bay). Depending on the depths of the water mains, it may be slightly warmer in the Autumn and cooler in the Spring as the heat from Summer or cooling from Winter reach those depths, but if it is sourced from a well, then these effects are even smaller because the water temperature coming from that low in the earth is constant. The effect of raising the temperature of the delivered water by 20o F on home energy use is important. When the warmer water is heated in a water heater, less energy is required to bring it up to temperature saving about 25% in energy. Further, when the warmer water is mixed with hot water for bathing, less hot water is needed resulting in a 16% savings on hot water use. Together this comes to a 36% savings. In a home where water heating accounts for 20% of energy use, then the overall savings is about 7%. For a well insulated house where water heating accounts for half the energy use, the fractional savings are even larger. And, there is no need to change anything in the home to take advantage of this.
The water pipes we use to deliver water to homes are close to thermal equilibrium with the ground, but if we are to deliver warmed water they will lose heat to the ground. So, we need an estimate of how much heat they would lose. This depends on the thermal conductivity of the soil and the temperature gradient beside the pipe. We can get an upper limit on the steepness of the temperature gradient if we consider a pipe surrounded by a cylinder of insulating earth with a radius that corresponds to the depth at which the pipe is buried. This is rough upper limit. For dry soil such as under a road the distance down to the water table will often be greater than the distance to the surface implying more insulation in that direction. For soil subject to percolation of rain water, heat transfer could be greater downward if the percolation is rapid enough. For a 20 centimeter diameter pipe buried 2 meters below the surface in soil with a thermal conductivity of 1.5 W/m/K and a temperature difference of 10o C we can calculate an energy loss of about 31 Watts for every meter of pipe. For a town of 10,000 homes laid out in a square of 5 by 5 kilometers there needs to be about 250 kilometers of water pipes so the energy lost would be 8 MW. If each home uses 350 gallons of water a day that is about 0.018 litres/second and to raise 18 grams of water per second by 10o C requires 770 watts. So, all 10,000 homes also need 8 MW of power. All told 16 MW of energy input is needed.
For solar energy input we need the collecting area of about 16 house lots. Let's have our town served by four 50 meter high water towers, one at each corner. If we paint the bottom of the tank of each one black, we can arrange mirrors called heliostats around the base of the tower to reflect sunlight on the bottom of the tower. If these are arranged in a circle, then to deliver 2 MW of average power to the bottom of the tower we need to deliver 10 MW at noon so the radius of our circle of mirrors will be about 56 meters. Assuming that the bottom of the tank is 20 meters across, the sunlight will be concentrated in power by a factor of 32. As long as the reflectivity of the bottom of the tank is 10% or less, this poses no danger to vision. The cost of durable (30 year) heliostats is about $126/meter2 so the delivered cost of energy, $4.9 million in heliostats for 2 billion kWh over 30 years is 0.23 cents/kWh. Since this mode of delivery displaces electricity or gas use for water heating this looks like a pretty good deal though not all water use is involved with hot water use. In operation, one of our towers would look something like this spanish power plant, but with a water tower instead of a solar furnace. We don't need hot water, just warm.
But, we can go a bit further. Silicon solar panels are about 20% efficient and currently cost about $5/Watt. They perform within 80% of their initial efficiency for at least 30 years. The main reason they lose their efficiency is owing to cosmic ray induced defects in the crystal lattice which provide places for charge carriers to become trapped. At the bottom of a water tank, they are substantially shielded from cosmic rays and thus should last much longer. Let's assume a lifetime of 60 years. The cosmic rays come mainly from straight up (cos3) and 5 meters of water is about the same as half the atmosphere in terms of mass so that is about 3.8 attenuation lengths for neutrons and panels should last more than 40 times longer mounted under a water tower if they were not also affected by local radioactivity. In practice, we need only be concerned with radioactive contamination of the water in the water tower and the tower itself since the ground is a long way away. Drinking water should not have more than 30 micrograms of uranium per litre according to the EPA so this is a low level of radiation compared to soil. For a steel tower, uranium should have slagged off when the steel was made. So, doubling the life of the panels seems fairly conservative; they might last a couple of centuries or more.
Silicon can be run at much higher light intensity than solar illumination but it loses efficiency when it gets hot. Since we want to heat water in any case, cooling the panels at the bottom of a water tank just requires a bit of plumbing to carry off the 26 kW/m2 of power that is not converted to electricity. This is the reason you can boil water in a paper cup over an open flame. The water keeps the paper cool. Keeping the panels within temperature limits also helps with their durability. What is the cost of electricity if we install silicon solar panels with this plumbing? Lets assume that the plumbing costs as much as the solar panels and we employ a company that charges about the same for labor. Then $15/watt over 60 years at 5 hours per day of illumination comes to about 14 cents per kWh with regular illumination, but 0.43 cents per kWh with the concentration we have arranged in any case using the heliostats. This novel method is about ten times less expensive than using coal and twenty times less expensive than buying electricity. The average 1.6 MW of electricity generated this way could be put to use powering public buildings allowing reduced property taxes.
The idea for delivering warmed water to homes appears to be novel and it actually came to me when a friend asked me to attend a Maryland Public Services Commission hearing about a proposed gas fired power plant which is currently dealing with issues of sources of cooling water with the county government. They are asking for flexibility in their licence application to go with either grey water or dry cooling. My friend was concerned about the potable water they intend to draw because each time the water system in Waldorf expands people where I live have to drill new wells and more springs run dry around the county. The issue with the grey water is that it is 15 miles away from the proposed power plant site while the plant itself is much closer to town. The plant will be throwing off about 400 MW of heat so it seems to me that they could ingratiate themselves with the city of Waldorf by offering to warm the potable water using that heat rather than waiting for the water to be used and sent so much farther away. In the end, this idea may be just fiddling while the ghost energy burns but following Luke in attempting to bring more light than heat I put it forward. There may be a number of applications for this approach of delivering power to homes through tepid water. In cases where artificial reservoirs are used instead of water towers and wells, floating absorbing mats might reduce evaporation and warm the water. I like the water tower arrangement best because it shows how to get the most out of silicon solar panels while they are still bit pricey. It seems to me to be the lowest cost for electricity around. We'll be seeing more of that with solar.
The EPA estimates that 147,000 water systems are ground sourced in the US. If 5% of those have suitable water towers then at 400 kW of electricity generation per tower that is about 3 GW of average generation available at less than a penny per kWh. The required nameplate capacity is about 460 MW or 12% of world production of solar cells in 2007. Since the supply of silicon appears to be adequate, getting a home grown heliostat industry going looks as though it might be a good investment opportunity. Because the water tower bottom environment appears to be a good place to avoid soft errors in electronics as well, companies that need very high reliability in data processing might be interested in sponsoring water tower conversions to provide themselves with an extra-reliable server network in a thermally controlled environment using low cost high circuit density components.
Waste heat may also be available from Fischer-Tropsch or Sabatier process plants that produce hydrocarbon fuels from atmospheric carbon dioxide directly. The relatively steady demand for water compared to seasonal heating suggests than towns that don't have suitable water towers may be able to warm their water supply while producing hydrocarbon fuels for other purposes using low cost wind energy as an energy input. The advantage here is that compared to the home scale plants we considered earlier, the need for heat is constant so that the equipment for producing fuel can be used continuously. Conversion of some existing combined heat and power plants might also take advantage of this if their heat production is also configured to produce cooling so that the heat consumption is fairly steady throughout the year.
Posted by Chris Dudley at 12:33 PM
Thursday, January 10, 2008
Anaximenes thought that the fundamental element was Air. He argued that rarefaction of Air produced Fire and condensation produced Water and eventually Earth. He was a predecessor of Democritus whose atomic theory of matter made possible the insights of Lavoisier and the understanding that the elements were more than four but still finite in the number of kinds.
Democritus is sometimes called the ultimate materialist but a Jungian who examined the structure of myth tagged him for including the spiritual in his theory related to his spherical and slippery soul particles. Almost, these soul atoms seem like the Chi of Lau Tzu or the breath of life of Genesis. Almost, they seem to be what Anaximenes took Air to be.
The direction of density in Anaximenes theory makes sense. Earth will silt out of a pool of Water, Air bubbles in Water and Fire rises in Air. In some ways we see Air becoming Fire as flame fills the Air. Rain also shows Air becoming Water. But what of Air becoming Earth? I'm not sure how he came to this though he is essentially correct about the formation of the Earth from a cloud of gas which at some point was entirely gas though it had already condensed out dust when the solar system formed. And, felt-like dust did play a role. One path he might have taken would be to observe a rotting log becoming soil and further observing that trees, no matter how large they grow, do not leave a depression in the soil around them. Where did the wood come from? Not from Earth. Perhaps from Water which came from Air? As we know now it comes from both water and air, but we need Lavoisier's division of air into its own elements to be clear about how.
Behind all of these ideas is the concept of conservation of matter which Democritus used to arrive at the ideas that there must be irreducible unchanging units, and which Lavoisier began to demonstrate quantitatively. A century after his false conviction and execution in the Terror of the French Revolution, we learned that there is a means of transmutation that ushered in the horrors of the nuclear age. But, even then, the core concept of conservation held but was shifted to baryons rather than elements and we were back to protons, which exist as Air as the basic unit. So, in a large sense, Anaximenes had it right to begin with.
The myth of the formation of Mankind from mud leads to the Ash Wednesday admonition: "Remember that you are dust and to dust you shall return." This is extremely helpful to set a penitent tone, and it is true that we are partly dust. But, by number, if not by mass, we are mostly hydrogen and so to Air we shall return as well whence we came for the most part. It seems fitting then that the conclusion of penitence is resurrection and ascension into Anaximenes' beloved Air.
I had originally thought to title this post Air Mining but decided to give it its present title because I think we'll be fulfilling Anaximenes' quest.
We've become troglodyte during the Stone, Bronze, Iron, Coal and Nuclear Ages, relying more and more on grubbing under the Earth for things that we use. When once the branches of trees and bones of animals were enough, we must have ever harder and hotter substitutes for our tools. But, we have not completely forsaken the air. We still get our water from it, and this, after all is the main constituent of our bodies. We get oxygen from it both to breath and to burn the coal and oil and gas that we drag up from the Earth. This is becoming a problem as last year was the second warmest on record. We get carbon from the air rather than the earth for our food at least, and to do this we also take nitrogen from the air to grow our plants, not being satisfied with the efforts of clover, beans and alder. We fill windows with argon to help with insulation. In bulk, we gather energy from its flow and rely on its mix of transparency and opacity to regulate our global temperature and let in the low entropy power of the Sun. We use its convective properties to carry away heat by constructing ugly cooling towers where even the much higher heat capacity and steady flow of a majestic river are not sufficient to deal with our wasteful methods of producing electricity. We have not forsaken the Air completely, but our deeper and deeper delving in the Earth is abusing it and unbalancing out ecosystem. The brimstone and quicksilver we dig out of the earth with our fuel spreads death through the air across our forests and waterways while the carbon itself accumulates in the atmosphere adding opacity to it, raising temperatures faster than the ecosystem can adapt.
In our discussions of Real Energy we have seen that there is no need to mine the Earth for energy; it is counter productive. And we have seen that if we do need fuel, we can make it directly from the air without burdening the ecosystem. Thus, real energy does away with the Coal and Nuclear ages. But what of the Stone, Bronze and Iron Ages? Can we similarly pull ourselves out of our shadow haunted Cave and return to the open Air? The Coal and Nuclear Ages were about the hubris of out doing the Titan Prometheus but to overcome the Bronze and Iron Ages we must propitiate the Olympian Hephaestus, because while Prometheus' stolen goods are about the means, Hephaestus' art is about the ends, the making of harder substances than wood or bones or stones. And, that is what gave us mines in the first place.
It turns out that an insight of Lavoisier's allows us to break away from Bronze and Iron. He learned that diamond is actually crystallized carbon. Diamond is harder by far than bronze or iron but it is rarely formed in nature, requiring very high temperature and pressure deep in the Earth. Associated with volcanoes, it is perhaps Hephaestus' highest art. But, the feedstock, the concentrated carbon, often ultimately comes from Air unlike copper, tin or iron. Diamond is very permanently sequestered carbon dioxide, though, at a pinch, if we run low on carbon dioxide, it is possible to burn diamond in air. Diamond is also formed industrially using vapor deposition, a direct Anaximenesian approach, but here we will consider an unusual form of diamond, Lonsdaleite, which forms as meteors fall through the atmosphere, because Lavoisier's art seems to provide a simple approach to its production that might allow it to be used in structural applications. There are other forms of carbon that show promise in structural applications including nanotubes and buckyballs, but we want a direct comparison to steel for our demonstration so we'll stick with diamond.
When we looked at mining the air for fuel, we needed to obtain water and carbon dioxide. In this case we will need a supply of carbon dioxide only. The hydrogen and bromine we'll be using will be recycled in the process.
Our project is to construct a transmission line from a wind farm for lower energy cost than using steel by mining the air for our building material. We will build a GW capacity line, similar to current high voltage transmission lines. A difference though is that we will support our conductor using our building material rather than metal cable. This will allow us to change the conductor configuration, use a higher voltage and thus lower line loss.
We'll start with our conductor. High voltage transmission lines are often a composite. A strong cable is used to support the conducting material. This is because the better conductors like aluminum and copper are less strong than steel but the amount of conductor needed is not so great that it would be thick enough to hold up against its own weight and wind forces. You could space pylons more closely, but that would increase the overall use of steel. As we already saw, a conductor 6 cm in diameter (say aluminum) can be used to carry 30 GW of power at three times the voltage currently used High Voltage Direct Current transmission because the larger radius increases the limit set by corona discharge compared to a smaller radius used for the Pacific Intertie which carries 3 GW. We can retain the larger radius by making the conductor hollow. The cross sectional area of the conductor can be reduced by a factor of 30 to meet our 1 GW goal. So, the thickness of our cylindrical conductor will be about 0.5 cm. Diamond has a high tensile strength (about 95 GPa) compared to prestressed steel strands (about 1.6 GPa) so that the cross sectional area we will need will be (proportionally) less than the ratio of the radii of the hollow-to-non-hollow conductor (about a factor of three) times the ratio of steel-to-diamond tensile strengths (about 1/59). So we need about 20 times less cross sectional area compared to steel. By mass, this comes to about a factor of 44 less mass. We'll arrange this in the form of a sheath around the conductor which will need to be in the form of a woven cloth because the coefficient of thermal expansion of metals is a factor of ten or so larger than for diamond. We'll also include a few atmospheres of carbon dioxide within the supportive sheath so that in case it gets heated to 800 C, a breach of the sheath will cause any combustion to be extinguished. We'll also provide for an external conductor to avoid this situation arising from lightning.
We can largely ignore the improvements in weight that diamond conveys in the construction of our conductor because most of the weight is in the conductor itself. Also, we needn't really have gone to the trouble to improve our conductor since our wind farm may only need to build out a transmission line that is 100 miles or so long and conventional conductors using high voltage alternating current would do the job. So, this portion is mostly for fun. Much more of the embodied energy in out transmission line is in the pylons and we turn to this now.
Steel used in construction has a lower tensile strength than prestressed strands by a factor of 2 so that we can reduce the cross section of our structural members by a factor of 124 using diamond as opposed to steel and ignoring the reduced mass of the pylon itself. The amount of mass is thus a factor of 276 less. The embodied energy of steel is 32 MJ/kg so all we need to do is figure out how much energy we need to make 3.6 gm of diamond and we will be able estimate our energy savings.
We already calculated that to condense carbon dioxide from the air we need 0.77 MJ/kg so things are looking pretty good. We'll take a supply of hydrogen and form methane using the exothermic Sabatier reaction which means that we will need to recycle the water produced at this point. The energy input is about 14 MJ/kg. After these energy inputs we are basically doing room temperature chemistry (Lavoisier's specialty) producing bromoform from methane and then producing poly(hydridocarbyne) from the bromoform. We'll input about 2 MJ/kg of carbon using free radical halogenation to make the bromoform. The polymer is then painted in solution on our growing structural element and warmed using argon gas. The waste heat from the methane formation can be used for this step. To be safe, lets add another 14 MJ/kg to be sure the bromine, argon solvent and remaining hydrogen all get properly recycled. This assumes we use oxidation of hydrogen to separate our reactants but the hydrogen bromine can probably be handled with less energy input. So, in all we need about 31 MJ/kg to produce our structural element, similar to the value for steel. But, to replace the steel we need much less so we need a factor of 280 less energy to build a pylon.
Take a deep refreshing breath. Anaximenes would say "I told you so."
Now, world steel production is only 1.3 billion metric tons per year and to replace that we would need only 4.7 million metric tons of diamond compared to about 3 billion metric tons of carbon in our fossil fuel pollution. But, there are probably other materials that could be replaced as well. Concrete production comes to around 12 billion metric tons and wood is harvested at 3 billion metric tons per year. So, we might begin to sequester a few percent of our carbon emissions by mining the air for carbon. Leaving the trees alone might have the largest effect, since this would both take up carbon in forests and help to bring our estuaries back into balance.
We've been looking at Energy Returned on Energy Invested (EROEI) recently. How would replacing the steel in a wind turbine with diamond affect this value? The amount of steel used in 3 MW wind turbine is described in this life cycle analysis which estimates the EROEI to be 20. Assuming 10% steel by mass for the reinforced concrete foundation, the structure contains about 460 metric tons of steel/iron. Using our conversion factor of 32 MJ/kg, this is about 14 million MJ of embodied energy and about 55% of the 7405 MWh of energy used in construction of the turbine. So, replacing steel with diamond would give 3333 MWh instead. Thus the EROEI would be boosted by a factor of 2.2 to 44.
Back in our pylon, we would want to use the same method for protecting against combustion that we used in our conductor, namely, filling hollow structural elements with several atmospheres of carbon dioxide so that a combustion rupture would be self-extinguishing. This probably has fabrication advantages as well. The thermal conductivity of diamond is quite high and we need to build our tubes by painting layers which are warmed using argon gas to remove the hydrogen in the poly(hydridocarbyne) and the solvent. Thus, having heat flow down the tube once this is done will allow us to rapidly paint on the next layer. Arranging our painting and warming heads periodically around the growing mouth of the tube would essentially have us spinning the tube into existence. At a rate of tens of microns per second growth, we can grow a meter long tube in about a day. Our manufacturing facility would bear an uncanny resemblance to a uranium centrifuge enrichment facility with all that spinning going on, but would not be prone to seismic risk since the rotational frequencies would be much lower, in the neighborhood of tens of Hertz.
Lonsdaleite, our chosen form of diamond, has still not been characterized fully experimentally and the samples studied so far show a hardness somewhat lower than common diamond. Thus, we might have to use more than we have anticipated. Theoretical study suggests that the Lonsdaleite structure may be slightly stronger than regular diamond and that present samples are affected by defects and impurities. In any case, other carbon structures are even stronger. Fullerite may be twice as strong as regular diamond. The choice of what to mine the air for will likely come down to ease of fabrication and required energy. But, our passage through our troglodyte phase and our flirtation with Hephaestus would seem to be ending and drawing to a close the Ages with which we understand history. For our new Age, the name Carboniferous has already been taken and Anthropocene seems too ominous. Let's just call it the restoration of the Holocene instead.
Posted by Chris Dudley at 11:00 PM
Wednesday, January 9, 2008
Energy returned on energy invested (EROEI) is a measure of the feasibility of an energy source and so it should be useful for comparing different energy sources to try to pick which one to use. Here we are mainly concerned with real energy, but from time to time I get into discussions with people who feel that nuclear power is a good thing because it is suppose to have a high EROEI. They are deceiving themselves but they are being encouraged by the nuclear industry in this self-deception so lets look at the numbers. We won't do a full life cycle analysis, just find a few of the problems.
EROEI can be calculated as (net energy out)/(energy expended)+1. We can see that EROEI=1 is the break even point because if you are not getting any net energy out then you have zero in the numerator of the fraction and you are left with 1 in the sum. This is the situation where it takes just as much energy to get energy as you actually get. The classic example would be when an oil well needs a barrel of oil to extract a barrel of oil. Oil wells shut down before this happens. If an oil well gets two barrels of oil gross for every one used to run it then the EROEI(thermal) for the well is 2. We have pumped two barrels total to get one barrel net: 1/1+1. We are tagging the EROEI as thermal because that will be important later. Now let's consider an oil field where the output of half the wells are used to run the whole field. We'll consider this from the perspective of the oil input. The oil input produces itself in half the wells leaving an equal amount to take away (net). So, EROEI(thermal)=1/1+1, the same result as you might guess. For a similar system using nuclear power with half the reactors enriching uranium to power all the reactors we have net thermal energy from half the reactors (Eu/2) and energy input from half the reactors (Eu/2) so again we get EROEI(thermal)=(Eu/2)/(Eu/2)+1=2.
Now, we've introduced the tag thermal. This is important. The net energy is not really net until we figure out how its is used. For the example of nuclear power just now, we know that the power plants that are not used for enrichment will be producing electricity with a fairly low thermal to electric conversion factor near 30%. So, we should account for this by applying this to the net energy. We get EROEI(actual)=(Eu/2*0.3)/(Eu/2)+1=1.3. For the oil, it may be used in a furnace in which case EROEI(thermal) is just fine, or it may be used in an engine in which case we would have a similar conversion factor: EROEI(actual)=(1*0.3)/1+1=1.3. Or, it might be stored until fuel cells are available to use it in which case EROEI(actual)=1.7 might be about right. Because of this ambiguity, we want to know the scope of our calculation. Are we ending at the well head, at the furnace or at the wheels? In the case of electricity, we always end at the toaster so when comparing sources, this is where we want to set our scope.
Let's look at the EROEI of the French nuclear program. The French have 58 reactors of which three are devoted to uranium enrichment so we can estimate the EROEI(thermal)=55/3+1=19.3 and the EROEI(actual)=(55*0.3)/3+1=6.5. Because we are only looking at the energy input for uranium enrichment and ignoring the energy inputs for mining, ore processing, plant construction and decommissioning, and unmaking of the nuclear waste this is really an upper limit on the EROEI(actual) of the French nuclear program even if our method of estimating is a little imprecise.
We can use our estimate of the EROEI of the French nuclear program to make another estimate. Suppose that instead of enriching uranium from 0.7% U235 to 3% U235 for fuel, it is enriched to 25% U235 and then diluted this back down to 3% as the US is now doing. Since the US is using cold war enriched uranium, the process used in France, gaseous diffusion, is an appropriate model. Assuming that the depleted uranium that is a product of the enrichment process has a U235 content of 0.3%, Then one unit of natural uranium becomes about 0.14 units of 3% enriched uranium or 0.016 units of 25% enriched uranium with the remainder being depleted uranium. It takes about 1.55 times more energy to get to the higher level of enrichment. So, if France were following the US example, we'd have five of 58 reactors carrying out enrichment rather than three; EROEI(thermal) would be 53/5+1=11.6 and EROEI(actual) would be 4.2. Again, these are upper limits owing to neglect of other energy inputs.
The problem that we run into with the nuclear industry is that they will sometimes admit that the EROEI values they calculate are thermal values, but then they will compare these with actual values from real energy sources which power the toaster without conversion. So, if they calculate an EROEI(thermal) of 20 for nuclear power they'll compare this with an EROEI(actual) of 12.5 for silicon solar panels and say "Hey, nuclear is better!" But, as we have seen, the EROEI(actual) for nuclear power is less than 7 and thus lower than for the solar panels. We've noted before that extending the use of silicon to 100 years gives an EROEI(actual)=33 and recycling makes it approach 99 eventually. The reported values for the EROEI of wind power are also actual and they come in near 20 or above, again better than nuclear power.
The World Nuclear Association has put together a table (2) of estimates of EROEI from a number of sources but they are comparing thermal figures with non-thermal figures in many cases. Let's summarize their table here making the following corrections: for nuclear power we'll use a conversion of 30%, for coal, 40% and for gas 60% assuming a combined cycle:
|Hydro||50, 43 and 205|
|Nuclear (centrifuge)||18.1, 18.4, 14.5, 13.6 and 14.8|
|Nuclear (diffusion)||6.0, 6.7, 5.8, 7.9, 5.3, 5.6 and 3.9|
|Coal||12.2, 7.4, 7.32, 3.4 and 14.2|
|Gas (piped a lot or liquefied)||3.4, 3.76 and 4|
|Solar PV||12-10, 7.5 and 3.7|
|Wind||12, 6, 34, 80 and 50|
Here we also have corrections to their table 2 to be consistent with their table 1 for their own calculations. Their calculations are the first listed in each nucelar row and the rest are taken in the order they give them as well. I have not checked that they copied correctly from the references they cite (they left the referernces out) but the solar PV values look familiar and are somewhat out-of-date now. In all, nuclear power does not look as good as wind, even with centrifuge enrichment and with current solar EROEI for thin film PV around 30 in 2009, it does not look good in comparison there either. If the row marked just solar is concentrated solar thermal power, then a commenter below has kindly provided a reference which did not fear to look at conversion to electricty, finding an EROEI of 27 with thermal storage and 34 without (this last is a correction spotted by Brad F at TOD). And, it should be remembered that silicon can get to 30 if you are willing to wait just a little longer than the warrantee duration. It is notable also that present day coal does better than present day (diffusion sourced) nuclear power in most estimates. In all, the renewable sources of electricity, hydro, wind and solar do better than the non-renewable sources, which is pretty much what you would expect since they don't need fuel.
There are some, particularly nuclear power proponents, who might object to my procedure here saying that EROEI should only be applied to the energy source itself and not compared with other sources in this manner. We can easily overcome these objections by subtracting one from each of the numbers in the table. This gives us a new measure which we can call Energy Delivered on Energy Expended (EDOEE). For this measure, break even occurs at the value zero (it was at the value 1 previously). This allows us to look at another set of issues. Two sources in the table require primarily electrical energy be expended to make them work. For nuclear power, enrichment is done using electricity and for solar power refining silicon is also done in this manner. This means that the mix of generating sources is essentially the same for both. Nuclear proponents will often try to hide this by saying that enrichment of uranium is done using nuclear power, but electricity is fungible so this is quite dishonest. But, since both produce electricity, they have the potential to change the mixture of generating sources. Which can do this producing the least amount of emissions? Here we are talking about future growth so we should use the high numbers for nuclear power (around 14) since enrichment capacity is currently inadequate to supply even the current set of nuclear reactors to the end of their design lifetimes so new enrichment facilities would need to be built. Enrichment causes deaths owing to criticality accidents. And, we should take at least the EDOEE for thin film solar (29) (which also uses electricity) since competition will drive out the low EDOEE producers. By taking the ratio, we see that solar power can make electricity generation free of carbon dioxide emissions with half the associated emissions to get the job done. For a utility scale solar installation at an average US location, the two are about equal.
The emissions associated with either are not that large though, and so the largest gain comes in doing the job quickly so that fossil fuel use for general consumption is eliminated. Here, wind has an advantage. 20 GW were installed in 2007. For nuclear power, it is not clear that new construction can keep up with the retirement of existing reactors. With 30 reactors under construction and a ten year construction timescale, that comes to about 3 GW/year of new nuclear power without accounting for retirement of old reactors. So, the pace of nuclear energy is slow. In fact, it is even slow compared to solar which produced 3.8 GW of new capacity in 2007. With growth rates for wind at 30% and solar at 50% annually, both are faster off the block than the essentially replacement level activity in nuclear power. Now, these are all nameplate capacities and we do need to look at the capacity factors which are 82% for nuclear power worldwide, about 35% for wind and about 20% for solar, so wind is ahead of solar by a factor of nine. New nuclear power, not adjusted for retirements, is ahead of solar by a factor of three or less and wind is ahead of nuclear by a factor of three or more. At the present rates of growth, solar will match wind in adding capacity factor adjusted new capacity in 15 years at which point is would be adding 1920 GW of namplate and 384 GW of adjusted capacity. It seems unlikely that that nuclear power will be adding that much capacity in fifteen years while the growth of solar power seems sustainable over the next decade or so owing to the rapidly falling cost of production.
Comparing EROEI(actual) or EDOEE shows us that less effort is needed to eliminate fossil fuel use in electricity generation using wind and solar power compared to nuclear power. This probably partly explains why both wind and solar are doing so much better than nuclear power in getting the job done. It also tells us how much of our time we'll be spending on paying our energy bill rather than say educating our children or improving our health. Those sources which require more effort will be more expensive and a greater drain on our resources. Since nuclear power appears to have little to contribute to accomplishing what we need to do to reduce fossil fuel emissions, it can be viewed as a wasted effort which hinders that accomplishment. Such wasted efforts generally lead to financial losses so it would seem prudent to avoid placing public money at risk in such ventures.
On critic of this entry (mcrab) has proposed a Virtual EROEI (VEROEI) which, instead of adjusting the output of thermal sources of electricity by their conversion efficiency to electricity, one would multiply the outputs of the electricity only sources, hydro, wind and PV solar by factor of three to make a comparison. This is an interesting suggestion and it would provide a fair comparison of relative EROEI between the thermal and more direct sources, giving simliar results to what we have just done using EDOEE. In a way this is a fair thing to do since, if we are to electrify transportation, a wind mill only needs to put in a third as much energy as a gas pump. So, the virtual thermal energy returned is quite a bit more. And, it is true that one can get 4 times as much low grade heat with electricity as with, say, heating oil using a heat pump. But, we can only get a one-to-one conversion when we make fuel using electricity and then only if we have a use for the process heat. Further, to intercompare thermal sources, VEROEI is not all that useful since gas produces twice as much electricity as nuclear power for the same thermal input (one does not want the nuclear fuel to melt). VEROEI may be useful for comparing oranges to oranges, but for apples-to-apples, the method adopted here seems clearer and more physical.
Posted by Chris Dudley at 11:03 AM