From: gary@ke4zv.uucp (Gary Coffman)
Newsgroups: sci.energy
Subject: Re: Energy Conservation
Date: 27 Jul 92 06:22:27 GMT
Reply-To: gary@ke4zv.UUCP (Gary Coffman)
Organization: Gannett Technologies Group

In article <13713@mindlink.bc.ca> Nick_Janow@mindlink.bc.ca (Nick Janow) writes:
>gary@ke4zv.uucp (Gary Coffman) writes:
>
>> Industrial energy demand makes up two thirds of total US energy consumption.
>> Reducing that 75% with homeowner tricks is not likely to be very successful.

Let me take this opportunity to correct an error. US energy 
consumption is spread in near equal thirds between residential/office, 
transport/distribution, and heavy industry. Comes from reading a graph
hurriedly.

>Well, if that is the attitude, of course it won't be successful.  If
>conservation in industry is considered possible and even economic, then it has
>a much better chance of being successful.  Many industries have been saying
>"reducing waste will cost too much money", yet many of those that have reduced
>waste are finding that they have had a positive economic return from doing so.

It depends. Some things that cut energy waste are economic in short order,
other things require very long payback times, and some things simply aren't
economic at all because of requirements to change process technology to one
with lower yield. More below.

>Aluminum requires large amounts of electricity, since the energy is stored in
>the material.  Steel enters a mill cold, is heated for processing, then is
>cooled (quickly or gradually) and leaves the mill cold.  There is potential for
>recovering that heat.  Continuous casting, where the molten iron is not cooled,
>then reheated for forging, is one example of conserving energy through redesign
>of the process.  I'm sure it's not the only possibility.

Aluminum refining *is* very energy intensive, and because of that, the
industry has been very sensitive to energy efficiency. Thus, little savings
is available here. Steel doesn't enter a mill cold, iron *ore* enters the
mill cold. That ore undergoes a chemical reduction reaction with the carbon
in the fuel to make steel. The amount of fuel used in the process directly
determines the grade of steel produced since heat is not the only duty the
fuel serves. The steel produced may be made into ingots to be delivered to
companies that machine products from it, but the vast majority of steel is
shaped into sheet or tube at the mill. It is not cooled and then reheated,
it's *hot rolled* in a continuous process. *Cast* steel is practically
non-existant today. It's mechanical properties are inferior to wrought iron 
and are unsuitable for most machinery applications. 

Aluminum and iron *casting* foundries exist. Some are very large, like
those of the auto engine factories. Many others are quite small job shop
affairs. It would be unmanageably unwieldy to have huge basic refining
plants do short run castings for job shops. The lack of scheduling
flexibility and the long lead time for planning would kill the operation.
Thus raw aluminum ingots, and *iron*, not steel, ingots are produced by
the big basic refiners for resale to the smaller foundries.

Most big steel refineries in the US are old and inefficient, but that 
doesn't mean that they are *energy* inefficient. Most of the problem
is that they are very labor intensive and their design requires batch
processing. That's one reason Japanese steel mills eat our lunch. We
blew up their mills and helped them rebuild after WWII with new technology. 
Many of our mills date to 1900. There is a small US company that is 
competitive with the Japanese. They use electric arc furnaces and non-union 
labor, but they have to operate with steel scrap as their input material
because they don't have a carbon reducing agent as their fuel. That 
restriction has kept them small. They should really be considered a
steel recycling company rather than a steel producing company.

Gary
Xref: sparky sci.energy:3717 sci.environment:10119