Why unit analysis matters
"The two most common things in the universe are hydrogen and stupidity." Every time I start to forget this, something comes along to remind me. Sometimes forcefully.I forget what prompted me to write Unit Analysis. This time, it was a clown who can neither calculate the area of Earth's disc without getting off by a factor of a million (you'd think the ridiculous number would tip him off), nor can he grasp the meaning of "kilowatt-hour". Indeed, he insists that "kilowatts per month" is what people pay for on their electric bill. After receiving a free physics tutorial including definitions of basic units, he topped this off with an insult: "... it would seem you would have problems reading your own electricity meter."
Innumeracy is probably a guarantee of incompetence in basic science, but it takes a special combination of arrogance and ignorance to say "It was written for people to understand how many watts are required in unit time to power things in terms which they understand."
He's too wrapped up in himself to realize that the public doesn't understand these things any better than he does, and one of the biggest reasons they don't is that they don't speak the language. They could learn it by osmosis, except for one thing: all the clowns out there mangling the language of physics, producing such a cacophony that the voices of knowledge cannot be distinguished. In short, Mr. Clown is part of the problem.
Well, why does it matter?
It matters because John Q. Public needs to know that a space heater which consumes 1.2 kilowatts is not going to cost 15 cents a month to run because the electric rate is "12.5 cents per kilowatt". Anyone who does not understand the way time figures into the calculation — and why the electric bill speaks of kilowatt-hours — is almost certain to get it wrong. The buyer who estimates the usage time as 6 hours per day, then multiplies 180 hours per month times 1.2 kW to get 216 kWh and calculates $27, will get it right.
To get it right, all you need is to know that a kilowatt-hour is a kilowatt times an hour. If you keep calling it "kilowatts per hour", you're never going to understand that.
Scientists and engineers use precise language and correct units because that's the only way to get the RIGHT answer. People who use WRONG language or WRONG units can do things like getting an electric bill of fifty dollars when they thought it was going to be fifty cents.
This is not a matter of opinion; there are a few ways of accurately describing how the world works, and innumerable ways of getting it wrong. You can use English or MKS or CGS units, but any correct calculation is going to come up with the same answer after conversions.
This is one place where what you don't know really can hurt you.
Unit analysis matters. Treat it that way.
Labels: innumeracy, unit analysis
¶ 12/19/2006 12:41:00 AM 9 comments
Very important read
I have just finished a very thoughtful article at Energy Pulse, Playing with Fire – The 10 Tcf/year Supply Gap -- Part I. I highly recommend that everyone read this article to see what kind of trouble we're looking at.¶ 12/16/2006 11:17:00 PM 2 comments
Open letter to the USA: Be careful what you ask for
Because even if you get it, you may not like paying the bill.
The US energy situation is suffering — actually suffering — not from too little oil, but arguably too much. The costs of getting what we have are far greater than the pump price, and going upwards.
But that's not the biggest problem. The main problem the USA has isn't an immediate lack of oil or natural gas. It's a lack of imagination.
Imagination? Yes. What other other name is there for a situation where people refuse to reconsider what they desire in light of what it costs, and what they actually need? When people head closer to bankruptcy every time they fill the tank on the 3-ton vehicle they bought, and demand cheaper goods from others instead of changing their own habits?
This is not just a psychological problem. It leads to escalation of failure, which can be disastrous.
All of this could be fixed relatively easily if people would use their imagination to figure out what they really want, and how best to get it. Consider:
- Most people don't really want gasoline. Gasoline is the means. Their goal is to get around in relative comfort. This can be done mostly with electricity or by other means, using far less or even no gasoline.
- Most people don't really want natural gas. What people want is to cook food and supply warm air and hot water. These desires can be met with far less gas, or even none.
- Most people don't want coal. Most people would call the police if you put a ton of coal at their door. They don't even particularly want the electricity made from the coal; what they want is the lights, the TV, and the computer run by the electricity. That's the only use they have for coal: twice removed in causes, and a long way in distance.
So let's exercise that flabby imagination and consider what we'd ask for to get just what we want, without all those pesky consequences.
When I'm at home, I don't give a rat's ass about electricity per se. It's a means to an end. One thing I want is for my house to remain comfortable in the summer. I can do this with an electric air conditioner, or I could pump cold water out of the ground and use it to cool the air in my house. I could use solar heat to dry a dessicant and use that to remove the clammy humidity. My electric needs would decrease to what's needed to run some fans and a water pump. Good architecture (roof overhangs on sun-facing walls, awnings or other exterior shades, windows which can replace hot stagnant air with cool outside air) can make the house far more comfortable without any energy use at all. Demanding lots of electricity would cost me a bundle; a little imagination would make me comfortable for a lot less money.
Same thing about natural gas. If my hot water tank and house stay toasty without burning gas, do I care whether it comes to my house or not? If I don't need any, why would I care what it costs? With good insulation and the right architecture, I could be comfy without natural gas and pay a lot less money. I'm sure spermaceti candles cost a king's ransom these days, but I don't care; I have more and better light without burning a thing in my house. Neither do I need "rock oil" except perhaps to establish a mood.
Gasoline? Technically I don't use it any more, but my diesel car still burns petroleum. I'd have the same utility and a lot less expense and inconvenience if most of my driving was powered by electricity. Plugging in every night or two would be less hassle than going to a filling station once a month to pump smelly liquid into the car's tank, and it would be quite a bit cheaper.
The pursuit of petroleum and natural gas is costing us a huge amount of money, and building up debts which will be with us for generations. A little imagination could give us the same or equivalent goods and cost us a lot less (in several different ways). Isn't it time to get our minds out of their ruts and ask for something a little different?
¶ 12/07/2006 11:58:00 PM 3 comments
More progress I just learned about
It looks like my spec for 50% efficiency in the gas-to-electricity step in Sustainability may have been pessimistic; Fuel Cell Today had an article last year which claimed the possibility of 80% efficiency (see page 4). (I claim overwork as an excuse. Yeah, that's it.)
Further, this is not from a SOFC, it's with a turbine-compounded MCFC. With this sort of efficiency, it would be feasible to dispense with SOFC's entirely. This is the sort of backup technology which practically guarantees that the concept is viable. The one element I cannot pin down is cost.
In other news, LiFePO4 cells are heading toward commodity status.
¶ 12/04/2006 11:16:00 PM 3 comments
Renewable energy and the auto industry
Of all the surprises I've had this year, the biggest was probably these words from the head of GM:
First, electricity offers outstanding benefits... beginning with the opportunity to diversify fuel sources upstream of the vehicle. In other words, the electricity that is used to drive the vehicle can be made from the best local fuel sources—natural gas, coal, nuclear, wind, hydroelectric, and so on. So, before you even start your vehicle, you're working toward energy diversity.
I could have sworn I'd heard similar sentiments before:
if you can make your own "motor fuel" with a solar panel or wind turbine, you will be largely insulated from oil depletion.
Mr. Wagoner continued:
Third, electrically driven vehicles offer great performance...with extraordinary acceleration, instant torque, improved driving dynamics, and so on.
This also sounded familiar:
A car that's quieter, runs its A/C at full speed even when the engine is at idle (or even with the engine off), has superior power steering, can run many kilowatts of electrical loads... is a better car no matter how you cut it.
If the auto isn't going to decline along with the production of oil, it's going to have to shift from petroleum to renewable energy. Maybe the industry (and the nation) won't drop the ball this time.
¶ 12/03/2006 12:27:00 AM 3 comments
It comes almost too fast to keep up
Evidence accumulates that the biofuel recycling step in Sustainability is not only feasible, but here today: Greenfuel just announced production of commercial-quality biofuels from CO2 scavenged from an Arizona powerplant (h/t: Cervus @ GCC).
Further, they mentioned that the CO2 capture efficiency is as high as 80% during daylight hours. This is astounding, and it strongly suggests that a closed-loop system is feasible:
- Burn biomass in fuel cells, gas turbines... doesn't matter.
- Pump combustion exhaust into greenhouses growing algae and replacing CO2 with oxygen.
- Remove algae and process into biofuels.
- Take re-oxygenated atmosphere and feed back to combustion step.
- Add makeup water to replace hydrogen removed with liquid biofuels.
So long as the volume of the greenhouses is large enough to store CO2 and supply oxygen overnight, this requires no exhaust to the atmosphere; it can turn all biomass input into electricity PLUS liquid biofuels. It could even burn its own biofuels to make carbon-free electricity, cycling the carbon in a closed loop. We don't need fuel cells right away; we can start with small gas turbines and work up from there.
What are we waiting for?
¶ 12/01/2006 12:30:00 AM 7 comments
