Final answer:
The primary difficulty of using desalination plants for fresh water production is the high cost of energy required for the process, particularly for methods like reverse osmosis.
Step-by-step explanation:
The primary difficulty that must be overcome in the use of desalination plants to provide fresh water is the high cost of energy involved in the process. Desalination is a technique that removes salt and other minerals from seawater to produce fresh water suited for human consumption and irrigation. However, due to energy-intensive methods such as reverse osmosis and distillation, desalination can be prohibitively expensive. Furthermore, running these plants requires significant energy input, usually from fossil fuels, leading to high operational costs and also contributing to environmental concerns.
While desalination plants are crucial in arid regions and heavily populated areas with scarce freshwater resources, the financial and environmental costs raise challenges. The process of reverse osmosis, for example, involves forcing water through a semipermeable membrane using high pressure to separate pure water from dissolved salts. Although effective, the energy required for such high pressure is considerable. Strategies to optimize the energy consumption and integrate renewable energy sources are critical to make desalination a more sustainable and economically viable option for water supply.