PrepTest 142, Section 2, Question 16
Engineer: Thermophotovoltaic generators are devices that convert heat(40 more words not shown)
Which one of the following(9 more words not shown)
- AThere is no(21 more words not shown)
- BUsing current technology,(33 more words not shown)
- CThe amount steel-manufacturing(26 more words not shown)
- DAt least some(15 more words not shown)
- EThere are at(30 more words not shown)
Reading the argument
How much do the generators cost?
Turning wasted heat into electricity sounds useful. But a smaller electric bill isn't the same as saving money overall. Imagine saving $50 a month after paying a million dollars to buy and install the equipment. The monthly bill has fallen, yet those savings would take an extraordinarily long time to cover the purchase. We can't just ignore the price of getting the savings.
What we’re looking for
The engineer's conclusion is conditional: if plants could feed their waste heat into the generators, they would save money. For the necessary assumption, focus on the cost comparison that even this hypothetical needs. The savings must at least cover the purchasing and installation expense; otherwise, the plan spends more than it saves.
Working the answers
- A
Another method could be even more cost effective while this method still saved money. The engineer argues that the generators would save money, not that they are the best possible use of the waste heat. A comparison with every alternative isn't required.
- B
This concerns whether the plan is possible with current technology. The argument already says what would happen if the plants could use their heat this way. A conditional claim can be assessed without assuming its starting situation is currently achievable. We need an assumption about the claimed savings if that situation occurs.
- CCorrect
If the electric-bill savings couldn't cover the cost of buying and installing the generators, reducing the bills wouldn't establish a net saving. C rules out that basic cost problem.
Covering these costs isn't necessarily enough to prove the whole argument; other expenses might matter too. But it is something the engineer needs. A necessary assumption can remove one obstacle without resolving every possible objection.
- D
Electricity needn't be the plants' primary energy source for lower electric bills to save money. A plant might mostly use gas but still spend enough on electricity for this proposal to matter. The argument needs electricity expenses, not electricity's first-place ranking among all energy sources.
- E
Plants could have other ways to cut their electric bills. Perhaps turning off unused lights or replacing wasteful equipment would also help. Saying heat recovery is a way to reduce bills doesn't require saying that some plants can achieve a large reduction only through energy recovery.
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