6 . Called ocean thermal energy conversion (OTEC), the idea is to use surface water warmed by the sun to heat a fluid such as ammonia or water, which then runs a heat engine to produce energy, just like a power plant driven by steam. Cold water from deeper layers of the ocean would then be piped up to cool the fluid and repeat the cycle. Theoretically, oceans could provide vast amounts of electricity like this. Researchers have estimated that there is enough ocean heat to supply 7,000 gigawatt s a year without affecting ocean circulation, enough to supply the world’s electricity demand— if we can access it.
The idea was first put forward in 1881, but went largely unexplored until the 1970s oil. crisis drove a search for new sources of energy. In the years since, demonstration projects have been built, but progress has been “disappointing”, says AI Binger at SIDS DOCK, an organisation that promotes clean energy development in small island countries. In recent years, a fresh urgency to transition away from fossil fuels has brought a suggestion of an OTEC return. “It’s the most promising it’s been in many decades,” says Andrea Copping at the Pacific Northwest National Laboratory in Washington state.
Tropical (热带的) islands are good candidates for OTEC because of their high energy costs— diesel (柴油) generators are common there—and the presence of deep cold water not far from shore, says James Van Zwieten at Florida Atlantic University. Islands also have less space for other types of renewables. A barrier for past projects was the cost of fixing kilometres of large pipes to reach deep water. Global OTEC aims to avoid that by extending a shorter pipe from a platform floating in deep water 10 kilometres offshore, then transmitting electricity back via a cable (电缆), and making use of advances made in offshore wind technology.
“OTEC will be part of providing a reasonable energy transition so these places aren’t depending on diesel imports from the richest petrol states in the world,” says Dan Grech, Global OTEC’s CEO.
1. What can we learn about OTEC technology from paragraph 1?
| A．It mainly uses offshore wind to generate electricity. |
| B．It has been widely applied to the oceans all over the world. |
| C．It can clean the water in the deeper layers of the ocean. |
| D．It depends strongly on the temperature difference in the ocean. |
2. What does paragraph 2 mainly talk about?
| A．The advantages of OTEC. | B．The development of OTEC. |
| C．Successful projects of OTEC. | D．Different opinions on OTEC. |
3. What difficulty did the past projects have with OTEC on islands?
| A．Lacking technology for generating electricity. |
| B．Being far away from the shore. |
| C．Enormous investment in the pipe equipment. |
| D．Great demand for the space. |
4. What is Dan Grech’s attitude towards OTEC?
| A．Opposed. | B．Supportive. | C．Doubtful. | D．Uncaring. |
