# Engineer: Thermophotovoltaic generators are devices that convert heat into electricity. The process of manufacturing...

Derek on September 10, 2014

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I am having a hard time with this one, it seems like the correct answer, C, is irrelevant because it does not give information about the future saving resulting from the thermo-thing. If they are absorbing some electricity from their own heat production, and this heat production would absorb and produce some electricity, and having more self-produced electricity would obviously lower the bill then we can assume eventually their bill would decrease, allowing them to pay off the expenses of the installation and begin to save money.

Replies

Melody on September 16, 2014

Here we have a strengthen with necessary premise question. Remember that a premise is necessary for a conclusion if the falsity of the premise guarantees or brings about the falsity of the conclusion. First we check to see if the answer choice strengthens the passage, and then, if it does strengthen, we negate the answer choice to see if its negation makes the argument fall apart. If the answer choice does both those things then it is our correct answer.

Our conclusion is "if steel-manufacturing plants could feed the heat they produce into thermophotovaltaic generators, they would greatly reduce their electric bills, thereby saving money."

Why? Because thermophotovoltaic generators are devices that convert heat into electricity, and the process of manufacturing steel makes a large amount of heat that is currently being wasted.

Answer choice (C) states: "The amount steel-manufacturing plants would save on their electric bills by feeding heat into thermophotovoltaic generators would be sufficient to cover the cost of purchasing and installing those generators."

Does this answer choice strengthen the argument? Yes. If the money that the steel-manufacturing plants are going to save on their electric bills covers the cost of purchasing and installing one of the generators that will be converting the heat to electricity, then the steel-manufacturing plants will, in fact, save money on their electricity bills.

For example, if the cost of the generator and its installation was \$700 and the plant eventually saves \$2000 on their electricity bill, then they have saved \$1300 by investing in the generators.

Does the negation of the answer choice make the argument fall apart? Yes. Negation: The amount steel-manufacturing plants would save on their electric bills by feeding heat into thermophotovoltaic generators would not necessarily be sufficient to cover the cost of purchasing and installing those generators.

If the amount that is going to be saved on the electric bills does not cover the cost of purchasing and installing the generator, then the steel-manufacturing plants would not actually be saving any money, would they? For instance, if in the long run the plants only save \$100 on their electric bills due to the generators, but the cost and installation of the generators reached upwards of \$700, then the plants have lost \$600. Do you see?

So, if we negate this answer choice, the argument falls apart because the plant would no longer necessarily be saving any money.

Hope that helps! Please let us know if you have any other questions.

Kenji on September 5, 2020

would "not necessarily" in this case indicate that it could, but it might not? If so, how does the negation destroy the conclusion? Thanks in advance!

Alex on September 19, 2021

I feel like answer C is out of scope as we don't explicitly know the costs involved.

Alex on September 19, 2021

And we are to assume that saving money on electric bills is equivalent to "saving money overall". Seems like they want us to assume things here that are simply not reasonable to assume.

Alex on September 19, 2021

Answer C does not say anything about the cost of running the generators on a monthly basis. Only the cost of purchasing and installing which are initial costs NOT related to an electric bill?

Ravi on February 5 at 11:30AM

@ScienceMathTutor, it's not out of scope because we need for this endeavor to produce a net gain in savings in electricity. This means that the device has to save enough money to offset any costs involved with the installation and use of the thermophotovoltaic generator. This is why C must be correct if this argument is going to stand any chance of making sense.