Thursday, August 27, 2009

Coping being cut

Our in-ground pool is actually raised out of the ground slightly (18 inches near the house). This makes the side a nice bench to sit on, keeps cut grass from blowing into the pool, and should interfere with running and jumping into the shallow end at a steep angle.

One consequence, though, is that our coping stones are a nonstandard width. We've decided to have bullnosed coping (so these are bullnosed both sides, also nonstandard), and that requires that the coping overlap the waterline tile by over two inches. This kind of thing adds up:
  • Waterline overhang: 2.5 inches
  • Tile thickness: 0.25 inches
  • Thinset: 0.375 inches (that's a lot, to give the mason plenty of freedom to flatten the wall for the enormous glass tile mosaics that are going in)
  • Bond beam: 12 inches
  • Thinset: 1 inches (the outside of the bond beam is quite uneven)
  • Facing stone: 1.25 inches
  • Exterior overhang: 2.5 inches
All up, we've gone for coping that is 20 inches wide.

We actually had a order placed for some very nice pearl white travertine (from Olympic Stone). When it came time for them to come by and pick up the check... they didn't. We called back and found there was some sort of problem... they didn't actually have the stone. it would be a 3 month delay to get it from Turkey.

Well, that's never a good thing to tell a customer. Martha started looking around, and found another very nice stone, this one a three color granite, from American Soil. This one is more expensive, but it really is pretty, and it's available right now. We ended up buying it. (We may use OSM's pearl travertine for the face of the pool rather than the coping, since they apparently have the 1" stuff available.)

[Update 16-Nov-2009: The pearl against the walnut travertine ended up not looking as good as we'd hoped, so we ended up using the walnut travertine on the sides of the pool. You can see this in the mid-November post.]

By "it", I mean a 12 ton boulder imported from Columbia, California. You can get a sense of scale from the pickup truck at the back right. This rock is a little shorter than I am.

It came from over here:

They're chopping this thing up into 20 inch wide by 36 inch long by 2 inch thick coping stones for us.

This is a cable saw. The cable has some kind of abrasive on it (I've never actually seen the thing stopped, it appears to be running all the time). The huge wheels drive the cable through the stone. Above and below, they're whacking the top off the boulder.

Below, they're cutting the ends off. In this pass, the rock stays put and the machine basically drops through it at a half inch per minute (I'm not really sure, as I never saw the saw make any noticeable progress through the rock).

Here's one of the slabs coming off the cable saw, going into their indoor facility for shaping. You can't really see all the color here, but there is white, black, and some pink to it.

Here's the rock all chopped up:

There's a lot of white in some of these. Hopefully they'll be able to cut around that to some extent.

Not so much in others.

This equipment is usually used to make countertops.

American Soil just got a brand new Italian machine for cutting and bullnosing. This isn't it, since apparently that machine can't cut a straight line just yet.

Each stone should weigh about 140 pounds. I'm sure the mason will be very happy to hear that.

I'm really happy with how this looks. We still have some risk, in that the coping could have huge blobs of white in it, or the grain could get mismatched, but the folks at American Soil seem to be on top of that.

We've also picked up all our glass tile. It gets installed after the coping, but I'll try to post some pictures of the pieces assembled in our garage so you can get a feel for it.

Sunday, August 16, 2009

The Limits to Growth

Folks in an apocalyptic frame of mind will sometimes consider what would happen if everyone in the entire world were to adopt a lifestyle which consumed resources at the rate of those of us in western countries. To keep this blog post short, I'll not address the entire problem, but I would like to point out that carbon emissions need not be a problem.

I'll take as my example the French. French people live a pretty good life on about 6.1 tonnes CO2/person/year, which is the lowest of the countries in the G8. The French low consumption is possible because their electric sector doesn't emit significant CO2 or burn significant fuel and has stable prices (it's 85% nuclear and 10% hydro). So as gasoline prices have gone up (mostly taxes, but large increases in crude costs too), folks have switched to electrified mass transit. Their electric-powered TGV trains carry almost as much traffic as their domestic airlines.

Is French low consumption really a result of nuclear electric production? Yes. Consider Germany at 9.8 tonnes CO2/person/year. That would be 5.9 tonnes CO2/person/year if their electricity sector was nuclear, which is about the same as France.

[Update: for comparison, the United States would be at 11.3 tonnes CO2/person/year if we replaced all our coal and gas fired powerplants with nukes. If we replaced half our air transport with electric trains, it would help a bit more, but I think less than 1 tonne CO2/person/year.]

My point is that the French example can be applied to many countries. Now here's an interesting thought. What if the entire world were to adopt the French lifestyle, including the carbon-free electric system? How catastropic would the emissions be?

The world population is now 6.7 billion, so at 5 tonnes/person/year, that'd be 33.5 billion tonnes/year. Compare that to our current emissions of 28.4 billion tonnes/year. It's larger by 18%. Something to work on, not a catastrophe.

Obviously, it's not quite so easy. Right now, a fair bit of the carbon going into the air comes out of the ground in solid form. If the entire world were to use nuclear electricity, coal production would nearly stop (it's still needed for steelmaking), and all that carbon would be coming from petroleum and natural gas. That would take a fairly drastic increase in production capacity for both, leading to a rapid depletion of existing stocks.

The summary: anti-growth doom and gloom is unnecessary in the electricity sector, so long as folks are willing to follow the French example.

Side note: French reactors are almost all inland and cooled by river water. This is perhaps an example best not followed. The French have laws which prohibit those plants from releasing back into the river water which is too warm. So, during a heat wave two years ago, some power plants reduced generation in order to reduce their output temperature, right as electricity demand was spiking.

Seawater cooling is much more reliable, and doesn't use up fresh water either. Some day, when we have high-temperature molten salt reactors, we will be able to air cool our nuclear plants, and then this will not be an issue. Until then, we should probably build the majority of nuclear power plants near the coast.

Saturday, August 08, 2009

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?"


Seems like a winner to me.