The principle of ocean thermal-energy conversion (OTEC) is to use the difference in temperature between warm surface water and cold deep water to power a turbine and thus generate electricity. In tropical seas, surface waters at around 25-30°C overlie cold waters of 4-7°C at depths of 500-1,000m. The warm water can be used to vaporize an intermediate fuel, such as ammonia, which in turn serves to power the turbine. Cold water pumped up from the depths is put to use to condense the ammonia back into liquid form, so that the process can begin again. However, about 80% of the 50-kilowatt output is needed to pump the cold water up from the depths, leaving a net output of only 10–15 kilowatts - obviously a rather low level of efficiency. However, the potential is undoubtedly there.
📝 题目要求
找出文本中的逻辑关系词,并写出对应的逻辑类型
找出文本中的逻辑关系词；并写出所对应的逻辑类型：
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✅ 参考答案与解析
between ...and：并列 thus：因果 such as：举例 so...that：目的 however：转折 between ...and：并列（表明暖水和冷水的温度差异） thus：因果（温度差导致涡扇运动，从而产生电能） such as：举例（举例燃料） so...that：目的（说明最终目的是开始产能过程） however：转折（说明效率较低）