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Difficulty: HardStrengthen

Geothermal power facilities in the Salton Rift circulate hot subterranean brine to drive turbines, after which the cooled fluid is reinjected deep underground. An energy consortium recently proposed extracting dissolved lithium from this brine prior to reinjection. Industry critics contend that commercial extraction will accelerate mineral scaling within reinjection wells, precipitating costly pipe blockages and rendering operations economically unviable. However, plant engineers argue that the extraction process will not increase well-clogging rates, noting that the chemical adsorbent used to capture lithium also extracts dissolved silica precursors from the brine. Which of the following, if true, most strengthens the plant engineers' argument?

  1. A
    Alternative methods of commercial lithium extraction, such as open-pit mining of spodumene ore, require substantially more freshwater than geothermal brine extraction.
  2. B
    The chemical adsorbent used during lithium extraction releases trace organic polymers into the brine that form insoluble precipitates at reinjection temperatures.
  3. Silica precipitation is the predominant cause of mineral scaling and pipe obstruction in geothermal reinjection wells.Answer
  4. D
    The commercial sale of extracted lithium is guaranteed to generate enough profit to offset any conceivable increase in maintenance or drilling expenses.
  5. E
    Geothermal power facilities that utilize flash-steam generation systems achieve significantly higher energy conversion efficiencies than binary-cycle facilities.

Answer

The statement that silica precipitation is the predominant cause of mineral scaling and pipe obstruction in geothermal reinjection wells provides the strongest support.
The engineers argue that lithium extraction will not increase well-clogging rates based on the premise that the extraction medium also removes silica precursors. This argument is vulnerable unless silica precipitation is actually a significant cause of well blockages. By establishing that silica precipitation is the primary agent of mineral scaling, the correct statement demonstrates that removing these precursors eliminates the main source of clogging, thereby strongly reinforcing the engineers' conclusion.

Step-by-Step Solution

1
Isolate the conclusion and supporting premises of the argument.
Conclusion: The lithium extraction process will not increase well-clogging rates. Premise: The adsorbent used to extract lithium also removes dissolved silica precursors.
Strengthen questions require identifying the exact logical gap between the stated evidence and the author's final claim.
2
Identify the underlying unstated assumption linking the premise to the conclusion.
The argument assumes that removing silica precursors has a meaningful mitigating impact on the overall rate of mineral scaling in the reinjection wells.
If silica were irrelevant to well scaling, removing its precursors would not protect against clogging.
3
Evaluate the answer choices to identify the statement that validates this connection.
Confirming that silica precipitation is the primary driver of scaling connects the removal of silica precursors directly to the prevention of well clogging.
Validating that silica is the primary scaling agent provides robust logical support for the engineers' conclusion.

Key Concept

Bridging a causal gap by demonstrating that a removed compound is the primary contributor to the adverse outcome under consideration.
Estimated Time:1m 30s
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