#16 - Engineer: Thermophotovoltaic generators are devices

[Administrator]

Complete Question Explanation

Assumption. The correct answer choice is (C)

Assumption arguments require us to understand what an author must be thinking in order to make
a certain claim. In this case, the author claims that steel-manufacturing plants could save money by
using thermophotovoltaic (literally, “heat-light-electricity”) generators to convert wasted heat into
electricity. To save money, this new process must cost less money overall than the current process
does. In other words, purchasing, installing, and maintaining the generators must cost less than the
anticipated savings created by generating electricity rather than purchasing it. This is one of the
author’s assumptions.

Answer choice (A): Pay careful attention to the wording of the conclusion in any assumption
question. Here, the author uses conditional language (“if steel-manufacturing plants could…they
would greatly reduce”). Since the suggested money-saving process is offered as the sufficient
condition, the author does not have to believe that installing thermophotovoltaic generators is at
least as cost effective as other methods. In fact, the author could maintain his argument even if these
generators were very ineffective compared to other methods as long as they were still more costeffective
than the current method.

Answer choice (B): Again, the language of the conclusion is critical in eliminating this incorrect
answer choice. The author does not argue that steel-manufacturing plants can or should or must
install these generators; only that it would work save money if they could. By using the word
“could”, the author leaves open the possibility that such an approach is not currently possible and
is not committed to the belief in answer (B). Also note that the testmakers mention “convert at least
some of that heat into electricity” as a way to distract test-takers who have noticed similar wording
in correct Assumption answers.

Answer choice (C): This is the correct answer choice. In fact, the author must believe more than
this, since merely covering the cost of purchasing and installing would not result in savings, but the
author must at least believe this statement. To test your answer, negate this statement and ask what
would happen if the author believed that the savings on electric bills would not be sufficient to cover
the cost of purchasing and installing the generators. If this were true, the author would not be able to
argue that using the generators would save money.

Answer choice (D): The word “primary” is the key issue here. Regardless of whether electricity or
coal or nuclear power is the primary source of energy for any plant, the argument is still feasible as
long as at least some plants have electricity of any kind. Negating this answer does not invalidate the
author’s belief in his claim.

Answer choice (E): Answer choice (E) suffers from the same flaw that answer choice (A) does. It
does not matter if converting heat to electricity is the only way to reduce electricity. There could be a
dozen other ways to do so without impairing our author’s belief in his claim, so long as this method
actually would reduce the company’s overall costs.

[beniakc]

I attempted to use the assumption negation tech on this one. I had it down to B and D (wrong either way). In looking back at my notes, I see that the word "some" is a caution word on these questions, but I cant remember why, could you please explain.
After reading the question 7 or 8 times, I see now why B was wrong if negated. I missed a word by reading fast.

[Steve Stein]

In that one, the engineer points out that Thermophotovoltaic generators turn heat into electricity, and steel production makes a lot of unused heat. The engineer concludes that if steel producers could feed heat into Thermo-generators, they could reduce their energy bills and thus save money.

Keeping in mind that those generators aren't free, of course, there is some question as to whether the result would be a net savings for the steel makers. Correct answer choice C provides the assumption required: If the savings on electricity weren't enough to cover the cost associated with the addition of generators, the engineer's conclusion would fail.

The problem with answer choice B is that the author's specific conclusion is that if steel plants could feed their heat into Thermogenerators, they could save money. The problem with D is that even if we negate, or take away, this assumption, the negated version ("some" when negated becomes "none")does not weaken the author's conclusion: it doesn't matter if electricity is not the primary source of energy for any steel mills, because the conclusion is merely that some electricity cost savings would result.

[Nina]

Although I know C is correct, but I don't quite understand why A is incorrect. I think answer A eliminates other alternative ways of using the heat produced by the steel-manufacturing process to save money. Why is C comparatively more correct?

Thanks a lot!

[Nicholas Bruno]

Hi Nina!

On Question 16, the conclusion is that the generators would greatly reduce a steel manufacturer's electric bill (and thus save it money). A says that there is "no other way that is more cost effective". Notice the difference between A and the conclusion of the stimulus: the conclusion does not say that there are or are not more cost effective means of saving electricity. Thus A is not relevant to the conclusion.

In other words, the conclusion is not comparing generators to anything else. It is possible for there to be another process by which the steel manufacturer saves FAR more money - but that would not disprove the fact that the generator would also save money.

On the other hand, C directly relates to the conclusion (of saving money) by eliminating the possible argument that the generators cost more to install than any amount of savings.

[Nina]

Thanks Nicholas! It's clear now

[moshei24]

I see why the answer is (C). The issue I have with this question is with the stimulus compared to (B). The stimulus says they could feed the heat they produce in to thermophotovoltaic generators. (B) seems to qualify that and say, yes, but in order for that to ever work, you need the assumption that feeding the generators will result in at least some of the heat being converted to electricity. If you negate that, you get that even if they could feed it to the generators, it still won't be able to to be converted to electricity, which ruins the stimulus. Is it that the it's presumed that if it could feed the generator, it will be converted to electricity?

Also, you could argue that (C) isn't the best answer, because the stimulus didn't qualify what you're saving money on. Can't it mean that you're saving money on your electricity bill, and not be referring to your overall monetary output?

Can you please explain these two issues to me?

Thanks!

[Jason Crandall]

First of all, thanks for phrasing your question so clearly. It's much easier to address a specific misunderstanding when you do a good job of describing your thought process.

The major issue with (B) is the phrase, "using current technology." The author's phrasing in the final premise is, "So if steel manufacturing plants could feed the heat they produce....". This wording leaves open the possibility that not only are steel manufacturing plants not using thermophotovoltaic generators in this manner currently, it may not even be possible for them to do so at all (for reasons that are not stated explicitly).

Think of it this way: if you negate (B) and tell the author that converting heat in steel manufacturing plants to electricity through thermophotovoltaic generators is currently impossible, the author would just say, "Yeah, but IF you could, it would be great, wouldn't it?"

Further, with (C), it's exactly because the author doesn't qualify what the plant would save money on that the answer is correct. Itemizing costs would involve inappropriate assumptions that are superfluous to the stimulus. The testmakers are savvy enough that if they had intended "thereby saving money" to be read as you suggested, the wording would have been either "thereby saving money on electricity" or something akin to, "thereby reducing utility costs".

Please let me know if that helps. Thanks!

[moshei24]

Thank you.

I think I'm just making it more difficult for myself. I do see why (C) works, and with (B), I was just trying to force it to work, too. But my main question is this: when it says in the stimulus that if it could feed heat into the generators, it's presumed that that heat could also be converted to electricity? Like, it wouldn't require an extra assumption to say that once the heat is fed to the generators, they could convert it to electricity? That is already presumed?

[Jason Crandall]

Read the first sentence very carefully. It says that TPV generators are devices that convert heat to energy. It does not say that wasted heat from steel manufacturing processes could be used this way.

The author acknowledges (or at least, allows) that there may, in fact, be some issue preventing steel manufacturers from harnessing their energy in this way. The author only addresses what WOULD happen IF steel manufacturing plants COULD feed the heat they produce into TPV generators.

Answer choice (B) is simply about the belief that this process is currently possible for steel-manufacturing plants, which is not a claim the author has to believe in order to believe the given conclusion.

Does that help? If not, I'm happy to address it again.