Hyperloop heat balance, fixed

Last month I complained that the Hyperloop-alpha proposal has a heat balance problem. Here is the fix for that problem, as promised. I’ve broken up my changes to the design in a series of steps, to make it easier to see that each step is individually beneficial.

Step 1: Hyperloop + 3 MPa steam heat dump

My numbers don’t exactly match Mr. Musk’s.  It seems we have slightly different specific heats for low pressure air, among other things. This diagram should serve as a base case which can be compared directly to the diagram from the Hyperloop-alpha proposal (check the last blog post).

I’ve detailed the steam heat dump system to run up to 3 MPa. Water is sourced from a small tank and steam is dumped into a much larger tank. The tanks are connected, so that as the steam pressure rises so too does the water pressure, which should reduce pumping losses. Eventually even the small tank is completely filled with steam. I've accounted for the two tanks as a single tank here, as the wall-in-the-middle detail should not affect the mass budget at all.

As I predicted in my last post, the heat dump tank is far too big... at least 12 meters long. The tube taking bypass air to the rear nozzle is also far too big, and will interfere with the passenger compartment. Finally, the battery to run the turbines is gigantic.

Step 2: ... + bypass intercooler

By picking off the air output from before rather than after the first intercooler, the heat load is radically reduced to practical dimensions.  The heat going through the first intercooler is not a typo... it's really been reduced to 10% of the prior value. Part of this reduction comes from balancing the pressure ratios across the two compressors.  Unfortunately, the bypass tube is now even larger and less practical.

Step 3: ... + Reduced Tube Pressure

Reducing the pressure in the transport tube to 25 Pascals decreases the compressor power, but oddly increases the amount of cooling required. That's because we're still cooling the same mass flow of air, but compressing that air more.

The cooling tank gets larger, but note that the battery gets cut in half, for significant savings in mass and cost. The bypass tube is smaller but still too large.

Reducing tube pressure should not cause problems with the vacuum pumps. 25 Pa is considered a "rough" vacuum, and corresponds to an altitude of 59 km, where helium balloons operate. The mean free path in this gas is around 0.3 mm, which is small enough relative to vacuum pump turbine blades that the gas still acts like a gas. Ordinary vacuum pumps will work fine.

Turbomolecular pumps, which use different aerodynamics than regular vacuum pumps, generally start operating at 10 Pa or less. I am not suggesting we drop into that range.

Step 4: ... + Cryogenic Heat Dump + Intake Intercooler

The intercoolers above are removing nearly all the energy added by the turbines.  We can avoid adding so much energy in the first place if the turbines operate on cryogenically cold air. This is a big step, but it's necessary because the capsule design in Step 3 is too bulky.

To do it, we swap the water/steam heat dump for a more compact but substantially heavier liquid air heat dump.  Boiling liquid air does not absorb as much heat as boiling water, but it also does not expand as much.  For the same heat absorbed, the tank weighs less but the fluid weighs far more.

The real magic, however, is that the heat is absorbed at a much lower temperature.  The intercooler output will now approach the cold sink temperature of 75 Kelvin.  Once again, the battery loses more weight than we add to the heat dump, for a net savings of cost and mass.

The high speed, low density intake intercooler here is similar to but much less extreme than the one proposed for the Skylon spaceplane.  It is not completely settled technology but much of the R&D has already been done.  In particular, one of the issues would be clogging from frozen water and CO2 ice. In an operating system, the tube air would be dried by prior passages of capsules. So clogging would mainly be an issue when restarting.

The heat dump can also be used as a source of air.  For instance, at low speeds the bow intake compressor may not supply enough air for the air bearings.  Make-up air can be taken from the heat dump.  In an emergency, while waiting for the tube to repressurize, air from the heat dump tank could be used to supply 20 occupants with breathing air for 20 hours.

I think this design largely achieves what Mr. Musk was attempting to accomplish.

Hyperloop heat balance

Key points:

• The Hyperloop proposal implies a steam tank almost as large as the entire vehicle, and at least 3200 kg, which is not accounted for in the Hyperloop mass budget.  This is a design breaker.
• The capsule as configured is using most of it's power to drive a refrigerator which cools the air in the tube.  This refrigerator is not mentioned as such.
• The refrigerator, as configured, will not cool the tube air back to it's ambient temperature.  But refrigeration is unnecessary.

I understand that Elon commutes from Los Angeles to San Francisco every week, and that the high speed rail project will not help him.  I imagine that his frustration with this commute is exactly what has kept bringing his attention back to this Hyperloop thing for so long.  I'm sure the boards at both SpaceX and Tesla have threatened to fire him if he starts another high-risk startup.  The guy has a tough life.  :)

The Hyperloop proposal has one big idea that I like: the air bearings, rather than the usual magnetic levitation.  Air bearings are a well developed technology, and require much less capital in the track.  I had not realized that air bearings were a feasible idea for high speed transport, as this is the first I've read about their air requirements at high speed.  (I called three air bearing companies to verify Elon's numbers, and none of them could offer any guidance on air consumption or even stable operation at near-sonic velocity.)  Elon is implying a 2000:1 lift/drag ratio for the passenger version, and a 2500:1 lift/drag ratio for the vehicle version.  That's incredibly good.  Maglev lift/drag ratios are generally rise to 200:1, which is considered really good.  The Livermore maglev requires substantial forward speed before it gets that efficient.  If Elon's numbers are real then air bearings are awesome... but I'd like to see some evidence.

I don't quite understand Elon's bearing drag power numbers.  Drag power is usually just vehicle speed times the drag force.  He's got an extra factor in there which adds about 10%, and I'm not sure where that comes from.  It's not compressor power, because that is much greater.  If we add the compressor power to the drag power, we get L/D ratios of 426:1 and 634:1 for the two configurations.  Those are still game changing numbers.  These numbers matter because if the air demand of the bearings is higher, the compressor power will increase.  If the compressor power increases too much, the battery will get too big and the Hyperloop idea will not work.

The Hyperloop proposal has another big idea that I don't understand: the Kantrowitz limit.  It's clearly a big problem, because the drag coefficient implied by Elon's numbers here is 3.95.  (That number is suspiciously close to an integer, and suggests that the drag numbers are back-of-envelope and not the result of simulation.)  Compare that to a Tesla S (0.24), or a bullet (0.29).  The only saving grace is that his predicted aerodynamic drag (910 N for the vehicle-carrying capsule) isn't too much more than the bearing drag (187 N), even if you include the prorated compressor power in the latter number (740 N).

At one point, Elon insists that propulsive power should be delivered through the track, rather than from the vehicle.  But his propulsive power (628 kW) is less than the compressor power (868 kW) that the vehicle is already signed up to provide.  It might be simpler to just let the vehicle do the whole job and let the track be passive.  He's already suggested using huge battery packs to deliver the propulsion power, so the only change is to put those packs on the vehicle.  This is a nit, let me get on to my main point.

The proposed bypass refrigerator scheme is fascinating but flawed.  Here's the flow diagram for the vehicle-carrying Hyperloop.  There is a typo: the air coming out of the second compressor should be at 594 K, not 59 K, assuming that second compressor is 72.4% efficient like the first one is.

There are much bigger problems than typos here.

• The air in the tube is not going to be 19 C.  Those Hyperloop capsules dissipate 868 kW of compressor power and 285 kW of propulsive power.  As drawn above, that propulsive power is going to be primarily dissipated into the air in the tube, heating it tremendously.  There is also 59 kW of bearing drag that will be dissipated into the tube wall and somewhat into the air.
• As drawn above, the intercooler is actually acting as a refrigerator.  The air expanded out the back would leave at around 126 Kelvin... 147 degrees C below freezing!  This will suck 209 kW of heat out of the tube air (49 kW for the passenger-only version).
• The intercooler refrigerator does not balance the propulsive drag heating.  Combining the two, I find that the vehicle will still dump 76 kW into the air, heating the air in the tube by 24 C (35 C for the passenger-only version).  By increasing the intermediate pressure and intercooler heat load a bit, this problem can be fixed.
• There is no way the output temp of a lightweight intercooler will be within 7 C of the incoming water temperature.
• The water is absorbing 852 kW, or 2185 J/g.  The water flow rate should be 327 g/sec, not 390 g/sec, to fully boil the water at normal atmospheric pressure.  But that's wrong too...
• To make the steam tank reasonably small, the steam will have to be held at high pressure.  Boiling 20 C input water at 450 psi would absorb 2800 J/g and produce steam at 507 K.  The water rate would then be 304 g/s, the tank would be 638 kg and 42.5 m³.  That's clearly far too large (it's as big as the whole vehicle), but that's the largest pressure my steam table goes to.  Even if the steam is heated to 857 K (supercritical), I don't think the steam tank will be small enough to work.
• The steam tank will be heavy.  Assuming carbon composite overwrap construction and 100 MPa working strain, the steam tank will weigh 3200 kg.  Changing the steam temperature and pressure conditions will vary this a little, but not much.

As a first step, I would take the bypass air directly from the axial compressor, which will remove about 80% of the heat load on the intercooler.  A 5x reduction in the size of the steam tank will get the mass budget back under control, but the steam tank will still be awkwardly large.  As a bonus this should deliver 70% more thrust, but that's still too small to matter much.

It should be possible to dump a fair bit of compressor heat from a radiator on the surface of the capsule.  I think this can reduce the heat load on the intercooler and steam tank by another factor of two, which should bring the steam tank volume into a more reasonable range.  It will still be a major component in the vehicle design.

As a next step, the vehicle can be slowed, perhaps by 10%, which allows some of the air in front of the vehicle to actually accelerate up to the alpha proposal mach .91 number as it goes around.  The compressor inlet and mass flow can then be downsized since it need only handle a portion of the airflow.  I think it should be possible to cut the compressor power numbers in half this way.

In my next post I'll work the numbers on these suggestions.

Mixing Clouds

First, let me recommend a great book: Clouds in a Glass of Beer: Simple Experiments in Atmospheric Physics: Craig F. Bohren: 9780486417387: Amazon.com: Books  It's short and is composed of many short chapters, each with an experiment and an explanation.  Chapter 5, mixing clouds, has always bugged me, and in response to a Quora question I finally did the math on the white stuff coming out of a kettle on the stove.

The clear stuff coming out of your kettle spout is 100% vaporized water.  (I'll sidestep pedantic discussions of the meanings of "steam" and "water vapor".)  It quickly entrains the cooler air around the kettle and mixes with it, forming a mixing cloud, which you can see and most folks refer to as "steam".

The mixing cloud forms because the relationship between the vapor pressure of water and temperature is not linear but rather curved.  It's the red set of dots above.  This is really important, so take a moment with the idea.  As the temperature of the water in the kettle rises from 20 C (room temperature) to 100 C (boiling), the pressure component of the air/vapor mix above it due to the vapor rises from something quite tiny to 1 bar (standard atmospheric pressure).

Now let's dilute that ejected 100% water vapor with some dry air at 20 C.  The mixed result is cooler than 100 C and has a lower vapor pressure than 1 bar (because not all the stuff is water vapor any more).  Once you've accounted for the different heat capacities of water vapor and water, and the thermal expansion or contraction of the constituents, you get the blue curve above.  You read the curve like so: if I mix some amount of 20 C dry air into some 100 C water vapor, so that the result is 60 C, then it's partial pressure of water vapor is 0.29 bar.  At least, that would be the partial pressure if all the water was in vapor form.

The really neat thing here is that the blue curve is ABOVE the red curve all the way down to 26 degrees C, which happens to correspond to 95.8% dry air and 4.2% water vapor.  At any mixing ratio between this and 100% water vapor, there will be more water in the mixing cloud than can be in vapor phase, and some will be in the form of very tiny (micron) water droplets.  However, once the mixing cloud is sufficiently diluted with dry air, there will be less water vapor in it than the maximum that can be in vapor phase, and all those tiny droplets with their huge surface air to volume ratio will immediately evaporate.

What this means is that the mixing cloud grows to 23 times bigger than the pure water vapor expelled from the kettle before it disappears.

More on hot-rock geothermal

When you drill a hole in the ground and flush water or CO2 through it, you cool the rock you've drilled through.  The amount of heat energy that comes up from that hole depends on how much rock you can cool.  And that depends on how conductive and permeable the rock is.

To get a feel for how much energy we're used to getting out of a hole in the ground, let's consider another industry that gets energy out of drilling holes in the ground: oil wells in the United States.  Half of US oil production comes from wells producing over 118 barrels of oil per day (ftp://www.eia.doe.gov/pub/oil_gas/petrosystem/us_table.html).  That's about 6.6 megawatts of chemical energy, which can be converted into about 4 megawatts of electricity.  These wells typically run for 20 years.

Geothermal wells will have to produce similar amounts of energy or the cost of drilling the well will make them uneconomic.

To get 4 MW of electricity from rocks that you cool from, say, 220 C to 170 C, you first need about 16 megawatts of heat, since your heat source is cooler than an oil flame and the heat engine it runs will have a lower Carnot efficiency.  Over 20 years, that flow will cool about 100,000,000 cubic meters of rock 50 degrees C.  If your well is 1 kilometer deep, you need to have cooled a region about 350 meters in diameter around the well.  Geothermal on a scale large enough to make a difference will need thousands of these wells separated by 500 meters or more, but connected by hot steam pipelines to bring otherwise diffuse steam to turbines large enough to be cost effective.

If we are to lose at most 10 degrees C of temperature delta to conduction, the cracks in the rock that carry the flow of fluid cooling it must be separated by less than 25 meters.  If there is significant flow restriction in those cracks, the separation must be closer still.  Rock 1 km down has been under 230 atmospheres of pressure for millions of years, which tends to crush the pores and small cracks the rock would otherwise have.

If the rock is heavily fractured, as it is in the Northern California Geysers field, then water flow through the rock can cool enormous expanses like this.  The Geysers geothermal field has been a great success over many decades, but it has unusual geology.

If the rock is not heavily fractured, then the production of heat from the well will look good at first but then fall off as the rock immediately surrounding the well cools off.  For the investment to pay off, heat production must stay high for two decades or so.

My guess is that using CO2 rather than water as a heat transport fluid might improve the permeability of the rock and make more rock viable for geothermal production.  This might make some areas that would not work with water-based heat extraction economically viable, but I don't think it's going to make hot-rock geothermal work across the country.

Geothermal is not renewable

You can group geothermal plants into two types:

• The kind that pump water underground and take steam or hot high pressure water out.
• The kind that drill holes in the ground and use conduction to get heat out.

Admittedly, I don't know a great deal about geothermal systems, but I do understand heat flow reasonably well. And geothermal systems are all about heat flow. Here are the problems that I see:

Conduction is an impractical way to move utility-scale amounts of heat through anything but the thin walls of a heat exchanger. For instance, ground temperatures typically rise about 3 C for every 100 meters you go underground. Ground conductivity is about 1.5 watts/meter/kelvin. Multiply those two and get 45 kW/km^2. Remember that utility-scale power means you need hundreds of megawatts of heat. Bottom line: geothermal isn't renewable. It works by cooling down some chunk of rock in place, rather than by converting heat that rises from the earth's core.

You might think that a big hunk of rock can provide a lot of heat for a very long time. For instance, a cubic kilometer of granite, cooling 30 C, provides 2 gigawatt-years of heat. Figure 20% of that gets converted to electricity. Over 30 years, that cubic kilometer of granite will run a 13 megawatt power plant. We're going to need dozens of cubic kilometers.

You might think that dozens of cubic kilometers would be cheap. Ranch land out in Idaho goes for $360,000/km^2. Assuming you can suck the heat out of a vertical kilometer of rock, the 13 megawatts from that ground are going to bring you a present value of $90 million. Sounds great!

But wait... before you get started, you are going to have to shatter that cubic kilometer of rock so you can pump water through it to pick up the heat. The hydrofracking folks have learned quite a lot about getting fluid out of tight underground formations. I think the useful comparison to make is the value of the fluid extracted. Oil is worth $100/barrel right now, which is $850/m^3. Water from which we will extract 30 C of heat to make electricity at 4 cents a kilowatt-hour at 20% efficiency is worth 28 cents/m^3, ignoring the cost of capital to convert the heat to electricity. There is a factor of 3000 difference in the value of that fluid. Now hydrofracking rocks for heat doesn't have to be as thorough as hydrofracking them for oil, since you can count on ground conduction to do some work for you. But I don't think the difference is going to save a factor of 3000 in the fracking cost.

So, that means geothermal is going to be confined to places where the rock is already porous enough to pump water through. Like the Geysers in Northern California, which is a set of successful gigawatt geothermal plants. I think it's interesting that the output has been declining since 1987.

The problem is thought to be partial depletion of the local aquifer that supplies the steam, because steam temperatures have gone up as steam pressures have dropped. This sounds right to me, but I'll point out that the water in the aquifer is probably sitting in a zone of relatively cool rock which has hotter rock above it. As the aquifer has drained, the steam has to travel through more rock, causing more pressure drop, and thus less steam transport. Where water used to contact rock, steam does now, pulling less heat from the rock, so that the rock face heats up from conduction from hotter impermeable areas.

Wait... how did cool rock end up under hotter rock? The 150 or so gigawatt-years of heat that have been pulled out of the 78 km^2 area over the last 50 years have probably cooled a kilometer stack of rock by about 30 C (or maybe a thinner layer of rock by a larger temperature swing). I'm not at all convinced by the USGS claim that the heat source is the magma chamber 7km down. Assuming the magma surface is at 1250 C (the melting point of granite) and the permeable greywacke is at 230 C, a 78 km^2 area 6 km thick will conduct about 20 megawatts, an insignificant fraction of the energy being taken out.

Refilling the aquifer will help pull heat out of the shallower rock, but that's not going to last decades. To keep going longer they'll need to pull heat from deeper rock, and that's going to require hydrofracking the deeper greywacke.

And that's expensive.

Do powerplants use too much water?

Coal and nuclear powerplants make heat, convert some of that to electriciy, and reject the rest. They use water, and lots of it, to reject the heat.

The USGS says that thermoelectric powerplants (nearly all coal and nuclear) use 49% of the water withdrawn in the US. That sounds like a lot, and it is. It's also misleading.

92% of the water used by powerplants is used for once-through cooling. That means they suck water from the river, use it to cool their condensers, then pump it back the river at somewhat higher temperature. There are legal limits to the temperature they can send back out, and as the intake water temperature rises closer to those limits, they have to pump more water, and eventually shut down the powerplant. This has happened, famously, in France during a heat wave, right when everyone wanted to run their air conditioners.

The other 8% of the water used by powerplants is used in recirculating cooling. In these systems water is used to cool the condensers, but then some of that water is evaporated in those familiar hyperbolic cooling towers, which cools the rest, and the water is cycled around. These systems use a lot less water because they only need to make up the water that evaporates. Of that 8%, about 70% is evaporated and 30% returned to the lake or river it came from.

Since 1990, the US has mostly built gas-turbine powerplants. These reject heat in the form of incredibly hot jet exhaust, and don't need water. But they burn natural gas which has caused us to send our plastics industry to China. I don't think many people appreciate how dumb that was.

New nuclear plants in the US will be either on the coastline or evaporatively cooled, because there is no appetite for increasing the amount of once-through freshwater cooling. And I don't think there will be many evaporatively cooled plants at either greenfield or brownfield sites: Greenfield evaporatively cooled plants require new water rights which are very difficult to secure. Brownfield replacements of older coal fired powerplants will be difficult because nuclear plants are much bigger than older coal plants, reject a lot more heat, and so need a lot more water, getting back to the new water rights problem. That leaves new PWR development for areas with a lot of water (US southeast) and coastlines. [Edit: And any new coastline PWR developments are going to face new hurdles as a result of Fukushima.]

Water rights are one reason why I'm so interested in molten salt reactors. MSR cores and turbines run at higher temperatures than those of pressurized water reactor cores, so they can be air cooled without killing their efficiency (and thus jacking up their costs a lot). Air cooling is a good thing because it removes an entire class of regulatory problems, and thus an entire kind of project risk.

Pumping pool water

I've been looking into the costs of pumping water through the filters and valves and pipe work around the pool, and it's quite interesting. For context, you need to understand that we live in California, in the San Francisco Bay Area (known to our utility PG&E as area X). That means that we're going to be using the pool 9 months a year, and the marginal electricity we'll be using for the pool will cost us $0.424 to $0.497 per kilowatt-hour (Those are the charges for >24.2 kWh/day and >36.3 kWh/day). That sounds like a lot of money, and it's going to sound worse as you read below.

In 1997, marginal electricity with a basic residential rate was $0.122/kWh, so the average cost growth since then is 10.0% per year. That's substantially faster than the discount rate of 6% per year that I usually apply to future money. If the cost growth of energy exceeds the discount rate into the future, it means that the energy I spend to pump pool water 10 years from now will cost more in current dollars than the energy I spend today.

You can't extrapolate a growth curve indefinitely into the future, and the price of electricity in current dollars cannot rise without limit. That said, I'm fairly confident that over the next 40 years the price of electricity will at least keep up with a 6% discount rate. That means that I'm predicting that the electricity the pumps burn 40 years from now costs me just as much, today, as the electricity that the pumps burn today.

I want to compare the costs of running the pool with the cost of building it, so I can make decisions about what sort of equipment to install. In the face of electricity that does not discount into the future, I have to put some sort of time limit on how long the pool will be operated. I'm going to pick 40 years. At that point my grandkids are likely to have learned to swim, and there is an about even chance that I'll be dead and won't have to worry about money any more. Over 40 years (9 months a year), each kilowatt-hour burned, per day, costs a total of $4643 in 2010 dollars. The bottom line is that, had I built my new pool in a standard fashion, the electricity to run it would have cost over $150,000 in present value. That's more than the pool! Instead, I've spent a few thousand dollars improving the efficiency of the plumbing so that my projected present value cost is more like $40,000 (which can be improved further).

Those of you with astronomical electricity bills, and pools, may be wondering how did I do that?

Let's get started with a simple result that is relatively new for the residential pool industry: slower is better. If I run a pump at 42 GPM for 16 hours, it'll turn over about 40,000 gallons. If, instead, I run the pump at 84 GPM for 8 hours, it'll move the same number of gallons. However, and this is really important, the pump has to push about twice as hard to move water twice as fast. Power is pressure times flow, so pumping twice as much water up twice the pressure head takes 4 times as much flow power. 4x the power in half the time is 2x the energy, and energy is what you pay for. Bottom line: slow the pump down.

You should also get the most efficient pump possible. If you don't have solar and so don't need variable head, and can mount the pump below the level of the water surface, then get something like a Sequence 5100. Otherwise get an Intelliflow 4x160, which is what I got.

Slower-is-better isn't the complete answer, because of variable pump efficiency and in-line spring-loaded valves. So most pools won't run their pumps 24 hours a day, as I do.

Note that I talked about flow power in the paragraph above. Flow power is pressure (e.g. psi) times gallons per minute. Try it. Most pumps turn electricity into flow power with an efficiency that varies between 15 and 50%. 15% is the efficiency at low speeds (right before the pump stalls and efficiency goes to zero), and 50% is the efficiency at something near top speed. Variable-speed pumps, like the Intelliflow 4x160, usually hit their maximum efficiency at high RPM settings and high flow rates (but I include a counterexample in my spreadsheet link below). As a result, when you run the pump more slowly, less energy is required to move the water, but the pump takes more electricity to produce each joule of flow energy. You can see the pump power and head curves for the 4x160 on page 47 of the user's manual. And I've extracted the numbers off the chart and done efficiency calculations here. Bottom line: best efficiency is at 30 GPM for a normal pool. I'll be forced up to 42 GPM (at a measured 31% efficiency) because the pool is big.

The analysis gets a little complicated because most pools have in-line spring loaded valves, which should be banned. Many solar installations suggest a check valve between the filter and the water line going up to the roof, because the panels drain at the end of the day and you don't want those panels draining backward, through your filter, taking all the scum in there back out through your skimmer. An innocuous little check valve seems like just the ticket. One wrinkle is that the check valve requires something like 1 psi to open, and since the flow is working against that spring, there is a 1 psi drop across the valve at all flow rates. Another wrinkle: yet another spring-loaded valve, in the heater this time, which drops about 5 psi. I'll get to that later.

1 psi doesn't seem like much until you consider that 40,000 gallons pushed through 1 psi at 31% efficiency is 0.935 kilowatt hours. Still not much? The present value is $4343. It's actually a bit worse than that because the constant pressure drop causes the pump to stall at very low speeds, which changes the best operation point to something faster and thus even less efficient.

My last pool (not my design) ran the pump at about 35 psi. As I said, the present value of each psi is $4343, so if this pump had to do the same thing, the present value would be $150,000. That number is so large that you are thinking that it is funny money. It's not. That is this year's electric bill for $3800, and next year's bill for $4000, and the year after's bill for $4200, and so on. It's committed money: if I turn off the pump, the pool turns into a pond and the City folks come by and suggest how to abate mosquitoes. How did I end up with this problem?

Pool equipment is generally designed for low equipment cost, not low energy cost, because the equipment cost is what most homeowners look at. But when we look at cost of energy to drive this equipment, it becomes clear that most pool equipment design is completely insane. The details will come in following blog posts, but in short:

Part	Cost	Pressure drop @ 42 GPM	Power cost	Alternative	Cost	Pressure drop @ 42 GPM	Power cost
Rooftop pressure relief to drain solar panels	$50	8.6 psi for 2-story house	$37,400	Extra 3-port valve and parallel drain to pool	$400	0.1 psi	$430
Gas heater with internal spring-loaded valves (check page 9)	$1800	5 psi	$21,700	Bypass heater with 3" 3-port valve and an actuator	$2050	0.1 psi	$400
DE filter with multiport valve (check page 8)	$700	4 psi	$17,400	DE filter with 2 3-port valves and ozonator	$2100	1 psi	$4,300
100 feet of 2" pipe	$60	1.19 psi	$5,170	100 feet of 3" pipe	$110	0.173 psi	$751
2" check valve	$45	1 psi	$4,300	3" 2-port valve with actuator	$250	0.1 psi	$430
2" 3-port valve	$45	0.5 psi	$2,200	3" 3-port valve	$90	0.1 psi	$430

I've implemented all but one of these on my pool, and it works: I can pump 14 gallons/minute (nearly twice what is required) up through solar panels on my two-story house with 9.5 psi from the pump, and I can pump 40 gallons a minute through the filter at 6 psi. With a fix to bypass the heater (I didn't see that one ahead of time), the pressure drop from circulating water through the solar panels should come down to 5 psi or so.

If you work at Hayward or Pentair and you are wondering how you might fix up your product line to make it more attractive, let me make the following suggestions:

• A $1500 variable-frequency pump with a proper volute, achieving 80% efficiency when operating at 30 gallons/minute and a 5 psi would be a game changer, as it would cut most pool owners' electric bills in half. It would require 3" ports. Please make the main shaft seal ozone compatible.
• Rewrite your manuals to show pool installers how to use 3-port valves to bypass the heater and drain solar panels without spring-loaded pressure relief or check valves. I'll have diagrams for this on my blog shortly.
• A DE filter to go with that snazzy pump, with 3" ports and a valve system with less than 1 psi total drop when clean at 40 gpm. Make the grids ozone-compatible (stainless steel?), and figure out a way to either send the separated air back to the ozone generator or through a catalyst to break down the ozone and nitrogen oxides.
• Introduce or work with Del to produce an ozone generator which has the ozone passively sucked into the intake of the main pump. Alternatively, figure out how to make a low power air pump that forces the ozone into the high pressure water stream after the filter. The current Del air pump is far too power hungry.
• 3" sweep 90 degree and 45 degree elbows, with interiors matched to PVC schedule 40 IDs. There is a trick where you twist the flow as it goes through the corner which might improve losses a bit.
• 3" valves with smooth interior bores. This could be the breakthrough that gets people to take you as seriously as Jandy. The gussets on the valve door interiors now save tens of cents of plastic and cost homeowners hundreds of dollars.
• Since all the big pipework and valves will take up a lot of space, pay careful attention to how all the bits fit together into the space allowed for existing pool equipment pads. Maybe a replacement for the multi-port valve which is made of 3-inch Jandy-type valves would work.
• Fix the pool control systems so that a basic control box:
• can handle 10 valves,
• connects to (and comes with) a flow meter that works down to 10 gpm,
• and has thermistor inputs for solar return as well as intake water, so you can calculate how many BTUs are coming off the roof.

I think that's enough for now. I've been tweaking this post for 10 months, it's time to post!

Bill Gates nails it

http://www.huffingtonpost.com/bill-gates/why-we-need-innovation-no_b_430699.html

His essential argument is:

• We have some agreement on two goals: 30% reduction of CO2 output by 2025, 80% reduction by 2050.
• Some countries will not make much reduction, and some countries, like China and India, will expand their CO2 output quite a bit as their huge populations pass through their own industrial revolution.
• Some portions of our western economies will not reduce their CO2 output easily. (I think this is a minor point.)
• The former goal might be achieved through conservation and improved efficiency.
• The latter goal requires that CO2 output from two sectors, transportation and electricity generation, be reduced to zero. Still more will be required, but this is a baseline.
• Once transport and electricity have been reduced to zero CO2 output, conservation in these areas will not improve our CO2 outputs. This is, for instance, why France doesn't bother subsidizing more efficient electric appliances, as many other countries do -- France's electricity is close to zero CO2, so improved electric efficiency doesn't reduce CO2 emissions.
• Therefore, reworking the economy to reduce transportation and electric consumption does not help towards the 2050 goal. To the extent that it costs money that could otherwise be spent on zero-CO2 electricity and transport, it frustrates progress towards the 2050 goal.

So, what does it take to get to zero CO2 from electricity and transport by 2050? These two subgoals are tied together: transport must be electrified.

Our transport sector currently burns 146 billion gallons of gasoline and diesel every year. In 2050, assuming an increase of 2%/year in transport miles and a fleet efficiency increase from 17 to 23 MPG, it will consume the equivalent of 248 billion gallons of petroleum. If we replace those vehicles with electric vehicles getting 3 km/kWh, those vehicles will consume 3 billion megawatt hours per year. The Nissan Leaf gets 5 km/kWh, so I think an estimate of 3 km/kWh average may be reasonable.

So, the big question raised by Gates' insight is, what can deliver energy like that? To my mind, there are two contenders, wind and nuclear.

The first problem is generation. And the second problem is storage, to cover variations in production as well as consumption.

Here is the generation problem:

The US consumed an average of 470 gigawatts in 2008. The EIA predicts annual increases of 2%/year, so that the average might be 1038 gigawatts in 2050, for the same uses we have today.

The additional 3 billion kWh per year needed to run the electric car fleet, if spread evenly through the year, amounts to 350 GW, which isn't really so bad when thought of in the context of total electric generation. So the grid in 2050 will have to deliver an average of 1400 GW.

1400 average gigawatts could come from 1 million 5 megawatt wind turbines spread over 1.2 million km^2 (at 1.2 watts/m^2). Right now, the US has 1.75 million km^2 of cultivated cropland, so switching US electricity and transport to wind would require a wind farming sector nearly as physically large as our crop farming sector. This is conceivable. After all, 150 years ago most farms had a wind turbine for pumping water. However, 150 years ago that turbine was not the majority of the capital on the farm. These new turbines will cost about $5000/acre, compared with the $2100/acre that farm real estate is currently worth. From an economic standpoint, wind farming would be a much larger activity than crop farming.

The turbines have a 30-year lifespan, so the cost is more than just the initial capital expense. By 2050 all of the turbines installed in the next decade will have worn out, and we'd be into a continuous replacement mode. Cost? $5 trillion in capital outlay for the turbines, another $5 trillion for the infrastructure, and around $160 billion a year (present dollars) for worn turbine replacement.

Here's the storage problem:

The morning commute in any major US city lasts for about 3 hours, with most of the activity in that last hour. The evening commute is longer and more centrally distributed. If we have east-west transmission lines capable of moving most of the commute peak power, we can smooth the U.S. commute peaks into two with four-hour wide centers. Even assuming this transmission capacity, electric consumption during commute hours would be about 500 GW above average.

The current thrust of electric-car research is to improve the batteries so significantly that the cars can be charged overnight and the batteries can provide all necessary power for daytime use. Per vehicle, that's about 18 kilowatt-hours per car, which sounds possible. There is a problem, however: there simply isn't enough material to make these batteries for all our cars.  [Edit: I was wrong, there is.  Lead-acid batteries require 240 kg lead for 18 kWh.  Lithium-ion batteries require 8.5 kg lithium for 18 kWh.]

• Lead-acid batteries would require 60 million metric tons of lead for the 254 million U.S. cars. World production of lead is around 4 million tons/year, and total reserves are around 170 million tons.
• Lithium-ion batteries store 75 watt-hours per pound, and can use about 60% of that (although a five-year life is a goal rather than a deliverable). 18 kWh would require 400 pounds of battery per car, which is physically possible. The U.S. fleet would require 2 million tons of lithium. Total recoverable worldwide lithium is 35 million tons.

The most economical way to store electricity is pumped hydro. Cars could pick up their electricity from metal strips in the freeway. Pumped hydro is at least plausible: the commute surge could be stored by pumping water from Lake Ontario back up to Lake Erie, raising Lake Erie by 60 cm twice a day.

Another way to achieve this goal is with nuclear reactors. Thousands of them. A nuclear electric infrastructure would have five big advantages over a wind infrastructure:

1. It would cost far less to build.
2. It would last 60 years or more.
3. It would not be weather dependent.
4. It would not require secondary storage (still more cost).
5. It would have far less environmental impact (no lakes with tides, no dead birds).

And the biggest advantage of all: it could keep getting bigger.

However, if we are to scale up the existing fleet of 104 reactors by over an order of magnitude, some things are going to have to change.

• Nobody really knows how much it will cost to build the next American reactor. We know that it costs the Koreans and Chinese $1.70/watt, and we know that it used to cost about that much in the U.S. If we build thousands of reactors, the cost will drop back into this range or below.
• Most of the new powerplants will have to be cooled by seawater or air, but not fresh water as is most commonly done today. We do not have enough fresh water to cool thousands of plants. Quite the contrary, by 2050 electric power and waste heat from reactors will be used to desalinate seawater for residential use, as is already the case in Florida and some California municipalities.
• Typical reactor sites will have a dozen or more gigawatt-class reactors, rather than the two or three as is common today. Far from being "extra large", gigawatt reactors are right-sized.
• Either very large new deposits of uranium will be discovered, or most reactors will be breeder reactors.

Bill Gates knows that the nuclear option is going to be the one we eventually choose, and he has a company, TerraPower, developing a new reactor which he hopes will cash in on the $100 billion/year domestic market for nuclear plants. I wish him the best.

Powered Roadways

If it weren't for the battery problem, an electric vehicle could be a fairly reasonable vehicle today: electric motors are powerful, small, and cheap enough, etc. There are two parts to the battery problem, getting enough power and storing enough energy. Both can be solved by delivering power to the EV from the road. This has been considered many times before, and there are electric street cars that do it in Bordeaux.

The usual idea, however, is very expensive because

• most sections of roadway or railway see little traffic and so the benefit of the high-cost infrastructure is spread over few vehicles.
• the third rail power delivery system is made safe by expensive grade separations, fences, or electronic switching
• the vehicles are very specialized and aren't built in large numbers.

So, to the extent that I'm advocating a new idea, it is... electrify urban highways. By which I mean, install a pair of metal strips flush against the paving in one of the lanes, such that ordinary cars aren't affected, but electric cars can lower a suitable pickup onto the strips and receive a few dozen kilowatts. Both the power and the energy storage demands on an electric vehicle's battery are dominated by the demands of highway operation.

Urban freeways are quite unusual as roads go.

• They see quite a lot of traffic: The San Francisco Bay Bridge moves 270,000 vehicles a day across 10 lanes = 1 vehicle every 3.2 seconds over a 24-hour average.
• They see quite a lot of the traffic: 24% of all traffic is on interstate highways, and I'll guess that most of that is on urban interstate highways.
  
• They are short: in the entire US, there are just 15,300 miles of interstate highway in urban areas (same link)
  
• They already have limited access. The safety hazards of a high-voltage electrical system out on the road are relatively minor compared to the existing vehicles using the roadway.
  

I don't have sources to verify the following claim, but I'm fairly sure that in many urban markets, most trips over 10 miles include some freeway. So, if the freeways in your urban area (e.g. Los Angeles or the Bay Area, or both) were electrified, you could make trips anywhere in that area in an electric car with a battery range of just 10 miles.

And, if all we want is 10 miles of range, with no need to deliver dozens of horsepower for minutes on end, existing battery technology is good enough.

The usual counterargument to big infrastructure is that it costs too much. However, electrifying freeways does not because the freeways are just not that big. Consider the Bay Area:

• 300 miles of freeway
• 7 million cars

If, over 10 years, we got to 10% of the cars being EVs with electric pickups, that would be 700,000 EVs, or, one for every 26 inches of freeway. Can 26 inches of roadway be upgraded for less than the cost of equipping an EV with a huge battery? Definitely.

There are many schemes for electrifying roadways, and some are quite complex. Although a simple pair of flush steel rails at 1000V is probably a reasonable implementation, it might be easier to sell to the public if the rails were safe enough to be touched by hand. This too is possible.

Imagine each rail is a hollow box, insulated on three sides, but with a nonmagnetic and top surface. Inside the box is a lightweight, magnetic, conductive cable (probably aluminum and steel), with a small gap between it and the underside of the top surface. The conductive top surface is broken at short regular intervals by an insulator. The bottom of the rail is probably a large conductor for moving electricity thousands of feet.

Without a magnet, the top surface is not electrified, and you can place your hand on it safely. The car's pickup would have a magnet which would ride on the strip, picking up the lightweight inner cable slightly, so that it contacts the top surface and conducts to the car.

Other variations would have a magnetic top surface with a flux gap, such that flux going from one side to the other shorts through the cable and picks it up that way.

System Design for Martha

I need to buy a new computer for Martha.

• Must drive a flat panel display
• Must accept data from a FireWire miniDV camera
• Must have a DVD burner
  
• We have an ancient parallel-port printer.... which would be nice to use.
  

I could buy a Mac Mini. The Mac Mini has the FireWire interface and DVD burner. However, it will never work with that printer (a replacement will cost $150). The graphics would be much better than any mini-ITX integrated graphics I'd get. We'd get the 2.53 GHz, 4 GB memory, 350 GB version, $830. A VMware executive will cost another $70. The whole thing will come in a nice little case and make very little noise, and I will have even less idea how the software works than I do with the PC.

Or, I could build a PC. I'd get a 3.16 GHz Intel E8500, 8GB memory, 500 GB hard drive. I can get a FireWire card and a DVD burner, and a motherboard that sports a parallel port. Martha will be happy that I didn't make her figure out a Mac (more to the point, how to run PC-only software under VMware on the Mac). Vista will almost certainly never work with the printer, and so I'll still have to get a replacement anyway (a wash at $150). Even crammed into a mini-ITX case (with some risk it will not all fit in the case), it'll cost $875. The Mini idles at 14 watts, and any PC I build will idle at 35 watts. The 20 watt difference, over 5 years of 24/7, costs an extra $350.

Update: Since Martha figures she's going to be stuck with the sysadmin, she opted for the PC, to avoid learning about VMware, Boot Camp, or any other virtualization. If we could order the Mac Mini with Windows preinstalled under a supervisor, such that I could have told Martha that she could simply install any Windows programs or drivers, then she probably would have gone for that. Oh well.

Chuck DeVore nails it

Relative Risk: Global Warming and Imported Fossil Fuels vs Nuclear Power

It's from last year, but Representative DeVore perfectly summarizes the environmental aspirations and political logjam in California, and points out that a voter initiative is possibly the only way to cut through the logjam.

Almost time for a new car

Our minivan has hauled our dogs, kids, and gear for almost 9 years, and it's starting to show. In another couple of years, we'll need a new car. So, if you're building cars and wondering what to build next, let me tell you what we want.

The last time I knew I was going to buy a new car, I wrote a letter to Chrysler two years ahead of time. Fat lot of good that did. This time, I'm asking for essentially the same thing. I'll post it on my blog instead.

We want a plug-in hybrid minivan. Plug-in hybrids face a couple of big problems: the batteries are too heavy and the engine runs intermittently, which prevents the catalyst from firing up and leads to nasty emissions. I think both these problems are completely solvable for a practical vehicle that we would buy in a heartbeat.

First, I'll point out that 1100 pounds of lead-acid batteries can store 16 kilowatt-hours, which is the government's definition of an electric vehicle. Those batteries can survive five years of cycles through 30% of their capacity. 4.8 kilowatt-hours is enough to push a minivan 13 miles. That's less than the average daily drive of 33 miles, but for a minivan used for multiple short trips a day, it's easily good enough.

Next, I'll point out that the emissions problems can be solved by delaying the first ignition of the engine. If the minivan can get to 50 MPH on batteries alone, then it can avoid the engine everywhere but on the freeway. For most trips our miniman makes, that means no engine at all for most trips, and that basically eliminates the emissions problem.

Finally, I'll point out that regenerative braking extends the EV range just a bit, and comes with a lot of complexity (control interaction with the friction brakes) and cost (fancy controllers). I'd certainly be willing to live without it if it cost $1000 and only got me an extra mile of range.

Here's what the minivan would look like:

• Packaging
  • It should have seating for 7: 2+2+3.
  • It should carry many 4' x 8' sheets of plywood in the back.
  • It should have two sliding side doors, etc, just like real minivans.
  • Seats do not have to stow. They can come out like my current minivan's seats do.
  • Including battery pack, it should weigh 5200 pounds. That sounds like a main battle tank, but it's pretty reasonable once you think about the 1100 pound battery pack.
  • Weight distribution should be close to 50:50 front:rear, and the center of mass should be very low, so the thing should handle reasonably well.
  • The thing should be quiet when driving in EV mode.
  • It should plug into a normal 3 prong 120V AC outlet.
• Performance
  • 0 to 60 in 10 seconds. (Requires an average of 115 wheel HP.)
  • 0 to 60 in 20 seconds on batteries. (Requires an average of 57 wheel HP.)
  • 75 MPH up a 6% grade with 1000 pound load. (Requires 77 wheel HP, plus whatever is needed to go in a straight line at 75 MPH. 115 HP ought to do.)
  • Maximum cargo load of 1400 pounds.
  • It should go 13 miles on a 30% cycle of the batteries.
  • It should go 350 miles on a full tank.
  • EV mode should work: the car should be able to cool a hot interior and get to 50 MPH without starting the gasoline motor.
  • 20 MPG from the gas engine alone. That's about 4000 joules/meter of gasoline energy, or 15 cents/mile for gasoline at $3.00/gallon.
  • It should use about 800 joules/meter of battery energy. That's about 4 cents per mile for the electricity, at the average US residential rate (10.5 cents/kWh).
  • The batteries should charge from 70% to 90% in 90 minutes from a standard plug.
  • The batteries should charge through a 30% cycle in 5 hours.
• Drivetrain
  • It should have front-wheel drive from the gas engine.
  • The gas engine should be a 2 liter 4 cylinder engine with around 130 horsepower. That sounds anemic, but add 60 electric horsepower and it's a whomping 180 HP.
  • It should have rear-wheel drive from the electric motors.
  • The motors should deliver 60 horsepower at 30 MPH (torque limited below). This will give excellent performance in deep snow over pavement.
  • The electric motors can have their torque die to nothing at 70 MPH. Any faster and the gas engine is required anyway.
  • It should have about 1100 pounds of lead-acid batteries, which deliver 17.5 megajoules with a 30% cycle. This just hits the 58 megajoule full-cycle battery that the US government is willing to subsidize as an electric vehicle -- $7500!
  • It should have a 330 watt solar panel covering most of the roof. This sounds silly but it's actually a good idea. The panel adds about 4 miles of electric range on an average day in California, at almost the same cost per mile of range as the battery, with very little weight.
• Cost
  • The thing will go 17.5 miles a day in EV mode if charged only at night and parked in the sun, and 27 miles a day if charged at work as well. If used as a daily driver, it'll cover 6,000 to 9,000 miles a year in EV mode.
  • It will save around 5 or 6 cents per mile. Obviously, that's not why people would buy it, but it does make for $300 to $500 saved each year.
  • The roof panel will cost about $1200.
  • Battery swap costs $1800 (half of the new cost). Batteries should last 5 years, or 1800 30% cycles, so that they cost 6 cents/mile. Existing lead-acid batteries already achieve this cost.
  • The added cost will take 10 to 15 years to pay back (if you ignore the subsidy).

I think the drivetrain can be a lot simpler than a Prius drivetrain. In particular:

• The electric motor/generator on the gas engine doesn't need to be big. It needs to be big enough to start the engine quickly (maybe 10 horsepower), and that's about it. I don't want to recharge the batteries from the engine any faster than 10 HP anyway. Gasoline costs 3 times as much as electricity from the plug, so the only reason to charge the batteries with the engine is if I can avoid starting the engine later in the same trip.
• Make sure the heater and air conditioner can run off the batteries. It's important that these be able to run right at the beginning of a trip without having to turn on the gas motor.
• Lead-acid batteries. Forget the fancy batteries. Even lead-acid batteries cost more than the electricity from the plug costs, other batteries are worse. Lead-acid can deliver the necessary range and power without the availability headaches of NiMH or Li-ions.

I think that roof-mounted solar panel deserves some explanation. It has a lot of interesting benefits:

• On a sedan, there wouldn't be enough roof area to make a significant solar panel. A minivan, on the other hand, has a pretty big roof, so the idea works better.
• The car can run its fans continuously when unattended. When you get to your car sitting in the parking lot in Phoenix, it doesn't hurt to sit down or touch the steering wheel. The interior won't disintegrate in the extreme heat either.
• When the ignition is turned off, it should be possible to turn on the A/C and get 70 cfm of air cooled by 40 F. That's enough to turn over the car's air every 2.5 minutes. It won't cool a car that's already gotten to baking temperature in the sun, but it will keep a car cool after you turn it off.
• Batteries don't like to be run down for long periods. With a solar charger, the car will get some juice every day, which can keep the battery topped up if you leave the car unattended for a while. This will improve the battery life, and it's just nice to come back to a car and have it fully juiced.

In our family, Martha would drive this thing, using it primarily to move the kids around. She makes multiple short trips each day, usually not on the freeway, so it would get plugged in regularly and probably only use gas for the trips to my parent's house, which is 55 miles each way. Since we'd get plugged in while at their house, the minivan would end up driving 80 miles on gas, on the freeway, where it gets 26 MPG. If we do twenty trips like that a year, we'd burn just four tanks of gas and our overall gas mileage would be 195 miles per gallon of gasoline.

"When did you last fill up?"

"Spring."

Seems like a winner to me.

World Wildlife Foundation donations suspended

At the July 8-10, 2009 G8 summit in L'Aquila, Italy, Allianz (a global insurance company) partnered with the World Wildlife Foundation to deliver and publicize a report on how the 8 richest countries in the world are doing at reducing their greenhouse gases. Sounds good.

WWF/Allianz "does not consider electricity generated by nuclear power a sustainable option", an opinion shared by many. Their trouble was that any simple ranking of countries will show that nuclear power has made France the world leader in reducing greenhouse gases. Since WWF/Allianz doesn't want to promote nuclear power, they cooked the numbers.

They didn't lie. There have been a number of outraged comments about this report, but these folks did not lie. Their footnotes say specifically that numbers for France were "adjusted as if electricity from nuclear power was generated from natural gas." The report also includes, in footnotes, the numbers correctly calculated.

One of those same footnotes says that "without the adjustment, France would rank first with Germany." Unfortunately, this comment is not supported by either facts, or by the WWF/Allianz numbers. By any numeric measure, France is way ahead of the rest of the industrialized world.

Because I feel that this report is intentionally misleading, my wife and I are suspending our donations to the WWF until they amend their report to rank countries based on facts. We're also going to have a talk with a few friends who also donate to the WWF. We don't do business with Allianz, so there's not much leverage there.

Those of you who don't actually care that much about CO2 emissions or global warming can stop here.

The report ranks the 8 richest countries in terms of their "past, present, and future climate performance". Here I've listed their overall ranking, along with WWF/Allianz' calculation of their emissions per capita and per million dollars of GDP.

1. Germany (12 tons/capita/year, 384 tons/M$ GDP)
2. United Kingdom (11 tons/capita/year, 334 tons/M$ GDP)
3. France (9 tons/capita/year, 276 tons/M$ GDP)
4. Italy (9 tons/capita/year, 328 tons/M$ GDP)
5. Japan (12 tons/capita/year, 367 tons/M$ GDP)
6. Russia (16 tons/capita/year, 1140 tons/M$ GDP)
7. United States (25 tons/capita/year, 567 tons/M$ GDP)
8. Canada (24 tons/capita/year, 668 tons/M$ GDP)

France got dinged because they have not improved emissions much since 1990 (they'd already built most of their nuclear fleet by then). I notice they also got dinged for not having strong mandatory targets imposed on utilities to promote energy efficiency. The report fails to note that in France, saving electricity doesn't significantly reduce CO2 emissions, so there is no need for such mandatory targets.

The report completely failed to note that France is building new nuclear power plants on its borders to export more CO2-free power. Not only is this action going to cause more improvement in Germany's CO2 output than Germany's own utility policies, but it is also going to be profitable, which means that France is going to be able to do it AGAIN in a few years. Germany, on the other hand, is busy bankrupting itself with huge feed-in tariffs, and is already switching from expensive, imported aranthracite coal to cheaper domestic brown coal which emits more CO2 and other pollutants.

The United States clearly needs to clean up its act. Which country should we model our environmental policies after?

Germany: 51% of German electricity comes from coal-fired powerplants. They are building or planning another 26. These will add 23 gigawatts of production. Germany will be forced close its coal mines in 34 years when it runs out of coal, at which point their coal imports will peak until they will switch to imported Russian methane. Germany also produces 4.4 gigawatts from wind turbines. There is a lot of talk about wind turbines but the power comes and will come from coal.

France: France closed its last coal mine in 2004. 4% of its electricity comes from coal. 78% of France's electricity comes from nuclear, and produces no CO2. Most of the rest (11%) comes from hydro, and produces no CO2. France exports 18% of it's electric production, and most of that (5.9 gigawatts, more than $2 billion a year) is sold to Italy, which is one reason why Italy's CO2 outputs are low.

Bottom line: WWF/Allianz fudged the numbers to support a policy goal. That's wrong, and we're stopping our contributions until they fix it.

It's a shame, by the way. I liked some of the other stuff they were doing.

Why New Nuclear

Senator Alexander Lamar has a white paper which well summarizes how I feel about our desperate energy situation, and lays out a plan for how to fix it:

Blueprint for 100 New Nuclear Reactors in 20 Years

It does have a thought which was new to me, however: Russia, China and India, as well as a host of other countries, have already built out a fair bit of coal, and are beginning a large build of nuclear. If their nuclear build fails, they will fall back on coal, and nothing the US does will change the course of global warming. If their nuclear build succeeds and surpasses us, they will cement their existing lead in the next major source of energy, and they will end up owning the base of our entire economy.

And this base is enormous. The US GDP was almost $14 trillion in 2007. Generation of electricity, at about $40/MWh, was $170 billion that year. But that electricity sold for $90/MWh, for a total of $373 billion. Electricity sales are 2.7% of our entire economy.

And consider industries that are part of that industrial base. In 2007, the United States used 4.1% of our electricity (170 million of the 4156 million MWh) to smelt 23 billion pounds of aluminum. That aluminum sold for $26 billion. The aluminum smelters probably spent around $40/MWh for that electricity, so the juice was 26% of their cost of goods sold. Since aluminum is an easily transported global commodity, their profit margins are thin and small changes in their costs can lead to large changes in who makes the aluminum.

We need to own our energy supplies. We need our own large forge to build the reactor pressure vessels (right now we depend on Japan). We need American companies to build, own, and operate these reactors. And we need it now.

What we really need is to stop the Waxman-Markey cap&trade bill, and adopt Alexander Lamar's plan instead. Write your congressman.

My Response to the New York Times

Here's a link to the New York Times article "Combative Start to Senate Climate Hearings".

And, here's my response:

I’m a Californian, I vote, and I want more nukes in my state. I’m fed up with the high cost of electricity. I’m pissed off that we switched from making plastics with our natural gas to making electricity — and shipped our plastics industry to China. That’s not environmentalism, it’s offshoring, as a direct result of public policy that my representatives voted in.

My power company is not incented to make good decisions about the power mix: when natural gas prices rise, they pass along the cost. When they look at natural gas they see a lower capital cost, and so they get the same return on less capital. Fine for them, but we get stuck with power prices that whipsaw our producers out of business. Ever noticed how inflation is quoted without the volatile food and energy component? We chose to make our energy prices volatile!

What we need right now are projects like the Hoover and Grand Coulee Dams: big, expensive government-funded projects that get lots of people working in well-paying jobs and deliver locked-in low priced power for a century or more. Nuclear plants are way better than hydro plants since they don’t kill fish (or anything else, for that matter).

I want to vote for a future in which energy prices are not volatile, and where the aluminum smelters and plastic plants come back to where we can regulate them and work in them. But I seem to be stuck between a choice between Green folks, who want to build temporary windmills which will kill our economy, and Conservatives who want to stick with imported fuels, which will kill our economy. Give me a third choice!

Another insulated pool

Back when I posted about the insulated in-ground pool that I'm building, I asked if anyone else is building such a pool. I've received a few answers:

• One reader in Melbourne is building such a pool.
• Several have been built in the United States, but only one of the ones I've heard of is residential. The rest are all commercial facilities.
• Insulated pools are standard when the pool sits on top of a parking structure. Apparently installations like these are simply impossible to heat if the pool is not insulated, and there are structural isolation benefits as well.

Up until now, though, no pictures! Thankfully, the reader from Melbourne has recently written in to share a few pictures of his insulated pool. Here's the standard picture of the dig:

The pool is 46 feet long, which is exactly the same length as mine. His is skinnier (10 feet wide) and more shallow (max 6 feet), which is appropriate for a lap pool. Below, it looks like they are installing an in-floor cleaning system. Very nice.

Below is a pic of the insulation going in. He is using Dow Highload 100, sold there as Dow HD300, in the same thickness that I used (2 inch). He says:

The insulation I'm using is Dow HD300 in 50mm boards. This product is made for insulating under coolroom floors with trucks driving on top, and is overkill given its compressive strength specs of 2% compression (1mm) after 20 years of 250 kPa or around 25 tons per sq meter. However, the pool contractor and engineers had never seen pool insulation done before and through an abundance of caution over-specified for the highest compressive strength product they could find to be sure it wasn't going to settle. With the loads from this pool of only around 2 tons per square meter, we have more than an order of magnitude margin of safety. In the end, the cost differential between this and lesser rated products was so small that in the interests of getting the pool contractor comfortable with signing off we went with the HD300.

The contractors didn't glue the boards to the soil with foam, instead they used the rather unsubtle method of nailing it through with steel rod. I had two concerns about this:

• This will mean there's some heat conduction losses through the steel rod from the soil to the concrete, though the total surface area of steel in contract with the cement shell would still be minimal so this probably isn't a big deal.
• A risk of the rod eventually rusting and applying pressure to the concrete shell, but the foam will (I hope) compress enough to accommodate any rust expansion and prevent concrete spalling off the shell were this ever an issue.

The upside is at least I don't have to worry about the compression issues for the expanded foam glue you'd used and hence avoids the risk you mention in your blog that this may place extra strain on the shell as it settled, and from the photos it seems the contractors have got a good solid base without the rocking problems you'd mentioned.

The steel rod seems like a good idea. I tried to find an equivalent product here and failed, which is why I ended up with the polyurethane foam. One other contractor I've talked with in the U.S. also used foam, but I neglected to ask him if he chose not to use steel nails for some reason.

Here in California we use Dobies to seperate the rebar from the ground/insulation. Dobies are simple 3" x 3" x 3" concrete cubes with a wire in them. Check out the much snazzier looking rebar spacers they use in Australia. The wall does not appear to have a bond beam at the top, but instead is pretty thick the whole way up.

Insulating the piping has been a major effort on my project. It's not clear in these pictures if this pool's piping is insulated.

Gunite going in:

His pool is in basically the same condition as mine right now. Note the clever combination of bench seat and stairs at the right hand side of the pool. Very nice. The pool looks deeper than it is because the lot slopes up to the left, and the left hand side of the pool is a retaining wall (raised bond beam).

It's a nice looking project, and I'm very curious to see how it turns out. Thanks a lot, Melbourne!