Chapter 20, Problem 93GP

6. Thermal energy storage is a proposed method to store solar energy in between use. This technology works by focusing solar arrays to heat up a molten salt (usually a mix of Na+/K+/Li+/NO, ). Then the energy from the molten salt can be used later to run a steam generator and produce work. a) Suppose 10,000 tons of molten salt have been heated up to 800K (1 ton 907 kg). This molten salt has a heat capacity of 1.5 J/g/K. How much heat is released from the salt when it is cooled to 550 K? b) Now suppose all of this heat is used to heat up water. What volume of water can be heated from room temperature to 100°C using the heat released from the salt? 6:37 1/29/ Home End Insert

The biggest drawback to extensive use of photovoltaic cells is they produce DC electricity. they don’t work well in cold climates. they are expensive to manufacture. they kill bats and birds.     2. Wind turbines are made to be very tall. This is because they are more stable when they are taller. the wind blows faster higher up. they are quieter the higher up they are. they are safer the higher up they are.

The E-I characteristics give information about the ability of PV or solar panel to convert ....................................   a.   Sunlight into heat energy   b.   Wind energy into heat energy   c.   Sunlight into electricity   d.   Wind energy into electricity

5. The University has 1.1 MW of solar panels installed on the upper level of Regents Garage. Over the last year it has generated 1.26 GWh of electricity. According to PEPCO, generating electricity creates 937 lbs of CO2 per kWh of electricity. How many tons of CO₂ emissions were avoided by using the electricity from the solar panels?

How many houses could a single natural gas plant serve? Ignore timing of supply and demand overlap, as well as technical details such as ramping. Assume the average house uses 10,000 kwh per year, and the natural gas plant has a rated capacity of 100 MW, an efficiency of 38%, and a capacity factor of 0.74. a) 25,000 b) 60,000 c) 65,000 d) 30,000 e) 33,000

1. If electricity costs Php 4.50 per kw-hr, how much does it cost to use a 250 watt light bulb for 7 hrs? 2. A typical human consumes 2500 Kcal of energy during a day. Say you decided to run stairs all day. How much energy, in Joules, would you burn in climbing stairs all day?

Plants absorb energy from sunlight. Throngh photosynthesis, they transform the energy to store it. Some of the stored energy is used to maintain life processes, and heat is released as a byproduct. Unused energy remains in chemical form. Sun Heat Sunlight Chemical Energy Plant Which describes the amounts of energy found in the forms of heat and chemical energy in a plant? O A Chemical and heat energy are equal to one another. O B. Their sum s equal to the amount of sunlight energy transfommed. O C. The amount of each is equal to the amount of sunilight energy ransformed. O D. Chemical and heat energy equal half of the amountof sunilight energy absorbed. prt sc delete home 144 144 40 nur & backspace loc 8 R. enter

a) Californian tomatoes (3) Electricity required to heat greenhouse to grow 1 ton of tomatoes = 16,000 kWh Emission factor for electricity generated using natural gas = 0.15 kgCO2eq / kWh Distance from farm to store and back = 20 miles One diesel truck can carry 1 ton of tomatoes Emission factor of diesel truck = 0.08 kg CO2eq per mile   Emissions for 1kg of California tomatoes = __________________________________

The United States has a lot of federally owned land. Unfortunately, uncontrolled natural forest fires destroy large areas in the western US every summer. In 2002, about 1,000,000 acres of standing timber in national forests were consumed. Some consideration is being given to improved management practices that could produce electric power from residual forest thinning. Estimate the lost energy content of burned US forests during 2002. Assuming the US average electricity demand is about 300,000 MWe, how much forested land would be needed to produce all the country's power? Is this a sustainable alternative? How would you manage the forest lands needed? A few facts to consider: • The total forested area on US federal lands in the lower 48 states is about 600 million acres with a standing stock density of about 100 dry metric tonnes of wood per acre, • ● Woody plants and trees capture solar energy via photosynthesis at an average rate of about 0.8 W/m2 which corresponds to producing about…