Concept explainers
Energy from the Ocean
Whenever two objects are at different temperatures, thermal energy can be extracted with a
Figure 18-37 Temperature versus depth for ocean waters in the tropics (Problems 93, 94, 95. and 96)
The idea of tapping this potential source of energy has been around for a long time. In 1870, for example, Captain Nemo in Jules Verne’s Twenty Thousand Leagues Under the Sea, said, “I owe all to the ocean; it produces electricity, and electricity gives heat, light, motion, and, in a word, life to the Nautilus.” Just 11 years later, the French physicist Jacques Arsene d’Arsonval proposed a practical system referred to as Ocean Thermal Energy Conversion (OTEC), and in 1930 Georges Claude, one of d’Arsonval’s students, built and operated the first experimental OTEC system off the coast of Cuba.
OTEC systems which are potentially low-cost and carbon neutral, can provide not only electricity, but also desalinated water as part of the process. In fact, an OTEC plant generating 2 MW of electricity is expected to produce over 14,000 cubic feet of desalinated water a day. The governments of Hawaii, Japan, and Australia are actively pursuing plans for OTEC systems.
94. • If we could go deeper for colder water, say to a depth of 4500 m, what is the maximum efficiency that can be achieved?
- A. 6.64%
- B. 7.52%
- C. 14.0%
- D. 25.5%
Want to see the full answer?
Check out a sample textbook solutionChapter 18 Solutions
Physics (5th Edition)
Additional Science Textbook Solutions
Physics: Principles with Applications
University Physics Volume 2
College Physics
University Physics Volume 1
Cosmic Perspective Fundamentals
Physics for Scientists and Engineers: A Strategic Approach, Vol. 1 (Chs 1-21) (4th Edition)
- (a) A shirtless rider under a circus tent feels the heat radiating from the sunlit portion of the tent. Calculate the temperature of the tent canvas based on the following information: The shirtless rider’s skin temperature is 34.0C and has an emissivity of 0.970. The exposed area of skin is 0.400m2. He receives radiation at the rate of 20.0 W—half what you would calculate if the entire region behind him was hot. The rest of the surroundings are at 34.0C. (b) Discuss how this situation would change if the sun lit side of the tent was nearly pure white and if the rider was covered by a white tunic.arrow_forward(a) It is difficult to extinguish a fire on a crude oil tanker, because each liter of crude oil releases 2.80107J of energy when burned. To illustrate this difficulty, calculate the number of liters of water that must be expended to absorb the energy released by burning 1.00 L of crude oil, it the water has its temperature raised from 20.0C to 100C, it boils, and the resulting steam is raised to 300C. (b) Discuss additional complications caused by the fact that crude oil has a smaller density than water.arrow_forward(a) A firewalker runs across a bed of hot coals without sustaining burns. Calculate the heat transferred by conduction into the sole of one foot of a firewalker given that the bottom of the foot is a 3.00-mm-thick callus with a conductivity at the low end of the range for wood and its density is 300kg/m3. The area of contact is 25.0cm2, the temperature of the coals is 700C, and the time in contact is 1.00 s. (b) What temperature increase is produced in the 25.0cm3 of tissue affected? (c) What effect do you think this will have on the tissue, keeping in mind that a callus is made of dead cells?arrow_forward
- Unreasonable Results (a) Calculate the rate of heat transfer by conduction through a window with an area of 1.00 m2 that is 0.750 cm thick, if its inner surface is at 22.00C and its outer surface is at 35.00C (b) What is unreasonable about this result? (c) Which premise or assumption is responsible?arrow_forwardA person inhales and exhales 2.00 L of 37.0C air, evaporating 4.00102g of water from the lungs and breathing passages with each breath. (a) How much heat transfer occurs due to evaporation in each breath? (b) What is the rate of heat transfer in watts if the person is breathing at a moderate rate of 18.0 breaths per minute? (c) If the inhaled air had a temperature of 20.0C, what is the rate of heat transfer for warming the air? (d) Discuss the total rate of heat transfer as it relates to typical metabolic rates. Will this breathing be a major form of heat transfer for this person?arrow_forward(a) How much heat transfer is necessary to raise the temperature of a 0.200kg piece of ice from 20.0C to 130C, including the energy needed for phase changes? (b) How much time is required for each stage, assuming a constant 20.0kJ/s rate of heat transfer? (c) Make a graph of temperature versus time for this process.arrow_forward
- (a) Cherry-red embers in a fireplace are at 850C and have an exposed area of 0.200m2 and an emissivity of 0.980. The surrounding room has a temperature of 18.0C. If 50% of the radiant energy enters the room, what is the net rate of radiant heat transfer in kilowatts? (b) Does your answer support the contention that most of the heat transfer into a room by a fireplace comes from infrared radiation?arrow_forward(a) The number of kilocalories in food is determined by calorimetry techniques in which the food is burned and the amount at heat transfer is measured. How many kilocalories per gram are there in a 5.00g peanut if the energy from burning it is transferred to 0.500 kg of water held in a 0.100kg aluminum cup, causing a 54.9C temperature increase? (b) Compare your answer to labeling information found on a package of peanuts and comment on whether the values are consistent.arrow_forwardIn 1986, a gargantuan iceberg broke away from the Ross Ice Shelf in Antarctica. It was approximately a rectangle 160 km long, 40.0 km wide, and 250 m thick. (a) What is the mass of this iceberg, given that the density of ice is 917kg/m3 ? (b) How much heat transfer (in joules) is needed to melt it? (c) How many years would it take sunlight alone to melt ice this thick, if the ice absorbs an average of 100W/m2, 12.00 h per day?arrow_forward
- (a) A woman climbing the Washington Monument metabolizes 6.00102kJ of food energy. If her efficiency is 18.0%, how much heat transfer occurs to the environment to keep her temperature constant? (b) Discuss the amount of heat transfer found in (a). Is it consistent with the fact that you quickly warm up when exercising?arrow_forwardIn a running event, a sprinter does 4.8 105 J of work and her internal energy decreases by 7.5 105 J. (a) Determine the heat transferred between her body and surroundings during this event. (b) What does the sign of your answer to part (a) indicate?arrow_forwardCompare the SI units of specific heat and latent heat and explain any differences.arrow_forward
- College PhysicsPhysicsISBN:9781938168000Author:Paul Peter Urone, Roger HinrichsPublisher:OpenStax CollegeCollege PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage Learning
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning