EG:
My friend MDH4ever, asked me to post this here.
Kb
Reply:
-------------------------------------------------------------------
el_gaviero,
I have noted for quite a while the similarities between the oscillations
in the drilling sectors (and energy in general) and various control
problems which I have encountered in my career as a programmer from 1981-1996.
The oscillations are just like those created
by P.I.D. (Proportional-Integral-Dirative) "loops" which are supposed to
maintain an equilibrium but where 'something' is wrong. That something
can be be poor tuning, such as the gain being too high, or it can be due
to delays between taking an action and seeing a response. This latter is
the type of problem we see in the drilling/price of oil oscillation.
"The cure for low oil prices is low oil prices."
Here is an example: Over across the river from St. Louis there is a
company called Olin that anneals (heat tempers) giant rolls of sheet
brass -- about two tons at a time! Back in 1982 a Modicon 584 controller
(a hot 'ladder logic' machine at the time) was being used to control the
annealing process and the PID loop could not be made to work, so I was
brought in. First time I'd ever seen this kind of problem and kind of
fun. It seemed that no matter what PID tuning parameters were used, the
oven would oscillate out of control, first too hot then too cold, back
and forth, back and forth (sound familiar?). That happened because the
temperature of the two tons of brass was taken at its *center* by a
thermocouple and that temperature controlled a gas valve. When the
system was started the thermocouple would say, "Hey, it's cold in here,
I need some heat," and the gas valve would slowly open to 100% until the
oven was blasting away at 800 degrees. The thermocouple would stay cold
for a looong time, being at the center of two tons of metal! Eventually,
however, the center would start to warm up and the thermocouple would
call for less heat... only it was way too late, the outside of the coil
of metal would have been fried big time (we 'ruined' the same coil of
metal many, many times). The solution to the problem was simple: Don't
do that. Nothing will *ever* make that system work. Ever!
The solution is called cascaded PID, where the central thermocouple PID
loop tells a gas valve PID loop what its *setpoint* should be, and a
second thermocouple monitors the oven's temperature. The interior
thermocouple would tell the oven thermocouple, "500 degrees, please" and
the oven thermocouple would modulate the gas valve to, say, around 60%
open. If the oven warms to 510 degrees the oven thermocouple
*immediately* cuts back the gas valve to, say, 50% (this requires custom
tuning of the gas valve PID loop). As the two tons of metal heat up it
requires less and less heat to maintain the oven at 500 degrees, so the
gas valve is slowly cut back to perhaps 20% near the end of the
annealing process. It's as real as can be and works beautifully once the
time lags involved are understood. (As an aside, many control system
problems are time-lag related.)
The "free market" is like the first case with the time delay. It will
never work. Ever. The only force which can intervene is government, by
mathematically biasing the equation over time, such as by placing (say)
a gradually increasing floor price under the free market, something as
in this limited example:
As a benign King, and worried about the future of energy and future
energy shocks to my country, I decide to impose a variable tax at the
gas pump. Starting today gasoline is not less than $1.50 per gallon (it
might be higher during shortages) and will be increased by one cent per
month forever. In 10 years it will be $2.70. I don't care what crude oil
costs, I just control the minimum gas pump price. As King, I get to
spend the new taxes as I wish (probably on production stabilization tax
breaks, energy conservation and multiple-junction white LED research
issues for more efficient lighting). The gasoline prices begin low
enough that no economic damage is done, but car buyers suddenly take
notice that gasoline will always be more and more expensive and slowly,
in mass, trend gently to buying more efficient cars, as they can see $2
per gallon - absolutely guaranteed - out there just four years away. The
car manufactures slowly notice that they are selling more efficient cars
than before and reallocate their resources accordingly. As people
migrate to more efficient cars they are surprised to discover that they
really aren't spending much more money than they were with their SUVs,
thus the economic impact - being so gradual - is minimal. Even
beneficial - more of a resource reallocation shift.
About 20 years from now the gasoline price is (at minimum) $3.90 per
gallon and most people have chosen to drive cars getting 28+ mpg, just
about the time that crude oil production starts to really drop off.
However, the free market has retuned itself to these new (and ever
increasing) costs and the economic impact is only 1/10th of what it
would otherwise have been -- my kingdom is saved from the terrible fate
of an energy infrastructure collapse.
The example is admittedly limited and simplistic, and there may be a
better point at which to apply a bias to the industry, but this is the
general idea that I'm trying to communicate. The 'free market' can only
'see' out a Very Short Time. Only governments have the power to change
the equation -- if they are clever enough to do so. The alternative will
-- someday, guaranteed -- be chaos. Consider what would happen to our
economy if tomorrow gasoline is just $3 per gallon due to war and it
takes $100 to fill your tank. Think of the increased shipping costs
applied to... everything!
-MDH4ever |
