BSE 367 Midterm 2

A four-ton water to air heat pump takes 2700 W to operate according to the manual. This heat pump gets its "4 ton" name from the ton referring to a cooling energy rating (refrigerators used to be cooled by ice, with the ton of ice referring to amount that could melt and keep the temperature). If a ton of cooling is equivalent to equal to 12,000 Btu/hr, what is its cooling COP? (Answer with at least 2 sig figs)

5.2

A small residential wind turbine generates 14 MWh annually and is installed in a location with a 30% Capacity Factor. What is the nameplate capacity of the wind turbine in kW? Use 2 significant figures.

5.3

Assume the irradiance during the winter months to be 350.0 W/m2. Use the efficiency of solar collectors chart in notes. Next, you'd like to estimate what sort of a collector would best serve your needs. Assume the irradiance during the winter months to be 350.0 W/m2. What is the temperature rise per incoming solar irradiance (W/m2) that needs to be attained for this scenario ? Answer in ∘∘C/(W/m2) with 2 significant figures.

0.11

The peak rate for the community is 9 cents per kWh, while off-peak purchase rate is 6 cents per kWh. How much daily profit (in $/day with at least 2 sig figs) is created from using the hydro scenario in the previous problem? Assume the pumping occurs for 12 hours during off-peak and the flow release to produce energy is for 12 hours during on-peak.

0.46

Arrange the following components of generating power from a PV system with battery storage based on the order that you would use this system to toast your bagels for breakfast (i.e., flow of energy from one component to another). 1 is first, and 5 is closest to warm breakfast Array Toaster Inverter Battery Module

1 Module 2 Array 3 Battery 4 Inverter 5 Toaster

Air moving at an average speed of 13.4 m/s enters a wind turbine and exits the turbine at an average speed of 11.3 m/s. The air has a density of 1.0 kg/m3 and 6.0 x 104 m3 of air flow through the turbine in one day. What is the maximum amount of kinetic energy in MJ that the turbine can convert in one day? Use 3 significant figures.

1.56

How much power (in Watts) is in a circuit with a load (resistance) of 3 ohms and a current of 10 amps? Use 3 significant figures.

300

You have a 5 MW rated wind turbine installed in a windy area with a 33% capacity factor based on the wind resources. You can sell wind energy generated to the grid at a rate of $0.08/kWh for 12 hours per day during 'on peak' hours and $0.03/kWh for 12 hours during 'off peak' hours. What is the predicted income from the turbine over a year in $? Answer with at least three significant figures.

794970

Which of the following are environmental risks of hydro power? (select all that apply) a. Erosion of stream bed downstream from the dam b. Displaced people, flora and fauna in areas flooded for reservoirs. c. Heating of water in the reservoir resulting in changing cold-water ecosystems d. Emissions (methane and carbon dioxide) release from biomass decomposition in flooded reservoirs.

All answers

Match the following Symbols and exponents. 6 9 3 -3

M G k m

The primary purpose of thermal mass in a passive solar space heating application is to: a. Reduce heat loss from the building b. Increase the solar energy falling on the collector surface c. Increase the temperature rise in a solar collector d. Reduce daily temperature swings by absorbing solar energy during the day and releasing it at night

d. Reduce daily temperature swings by absorbing solar energy during the day and releasing it at night

Regulated Electrical Energy Utility are regulated in how much they can charge and how much profit they can make. (T/F)

True

Spinning reserve generators operate below full load and increase to meet unexpected electricity demand. (T/F)

True

What is an advantage of concentrating solar energy as compared to other solar technologies? Choose the best answer. a. It can store energy for off-peak use b. It can supply utility-scale water heating c. It can use both beam and diffuse radiation d. It can supply wide-spread energy in high latitudes

a. It can store energy for off-peak use

Which location, on average, has the greatest solar power density (power per surface area)? Choose the best answer. a. Rainforest near the equator b. Central America c. High mountain regions d. Central Australia

d. Central Australia

Assume the irradiance during the winter months to be 350.0 W/m2. Use the efficiency of solar collectors chart in notes. Based on the information calculated in the last 2 questions, what collector type(s) would suit this application? (0.11 C/Wm2) a. Unglazed flat-plate b. Glazed flat-plate c. Evacuated tube type d. Either glazed-plate or evacuated tube

d. Either glazed-plate or evacuated tube

Which of these compounds are considered greenhouse gasses. Oxygen (O2) Ozone (O3) Nitrogen (N2) Nitrous oxide (N20)

(O2) Not a greenhouse gas (O3) Greenhouse gas (N2) Not a greenhouse gas (N20) Greenhouse gas

You work as a solar energy consultant and are explaining the advantages of a photovoltaic solar installation to a client. Your client currently pays on average $125/month in the summer (4 months) and $83/month the rest of the year (8 months) for electricity from the grid. A solar panel would produce all of their energy used in summer. The rest of the year they would pay 14$/month for electricity from the grid. They also qualify for the Investment Tax Credit (ITC) which would reduce their annual tax by $400. What is the year one economic value of this solar installation to your client? Answer to the nearest $.

1452

The wind speed distribution at a certain site is provided below in figure 1. From the lecture in module 6, the distribution is useful in determining what sort of wind speeds a site is going to witness in terms of hours per year. For the sake of simplicity, we will attempt to estimate how much energy can be derived from this wind resource at a speed of 14 m/s annually. Modul Wind Speed - 7 m/s (850 hrs) Avg wind speed - 8.9 m/s (800 hrs) 14 m/s (400 hrs) Power Curve 0-3 m/s = 0 kW 2.4 kW at 13-14 m/s 2 kW from 18-22 m/s 0 kW at 26 m/s What is the cut-out speed of the Skystream 2.4 turbine?

26 m/s

A $8.6 million dollar wind farm with a 20 year lifetime is installed. If the project's levelized cost of electricity is 12 cents/kWh, what is the total lifetime energy production in kW? Use 3 significant figures.

409

You have installed a solar panel at your home that is connected to the electric grid of your local utility.Assume the system produces 8 kW from 9:00 AM to 6:00 PM, and you consume 2 kW during off-peak demand hours (9:00 PM - noon) and 10 kW during peak demand hours (noon - 9:00 PM). See underneath for the energy profile described. peak demand 12-21 produce 8 kW from 9-18 consume 2kW from 0-12, 10 kW from 12-21, 2kW from 21-24 User Purchase price: $0.091/ kWh On-peak sell price: $0.087/ kWh Off-peak sell price: $0.049/ kWh What is the economic value of the solar panel to the homeowner per day ($/day, with two decimal places)?

5.8

The wind velocity distribution in a day is 7 m/s 50% of the time, and 11 m/s the rest of the time. The windmill has a cross-sectional area of 55 square meters. If the density of the air is 1.2 kg per cubic meter, what is the total kinetic energy in this wind stream in kWh in a day. Provide the answer with at least 2 significant figures.

663

A solar panel produces a total of 130 W but has losses of 39 W due to heat. Considering that the heat is the only source of loss in the system, calculate the solar panel efficiency in %.

70

What do the following units describe? BTU GWh GW Calorie

BTU Energy GWh Energy GW Power Calorie Energy

What information does a lifecycle analysis (LCA) provide? Environmental impacts Social impacts Economic metrics Technical feasibility

Environmental impacts YES Social impacts NO Economic metrics NO Technical feasibility NO

Generated power is easily stored on the grid for later distribution. (T/F)

False

The timing of wind energy generation corresponds with US peak electrical demand. (T/F)

False

Are the following energy technologies dispatchable or non-dispatchable? Wind Solar photovoltaic Natural gas Hydroelectric

Wind Non-dispatchable Solar photovoltaic Non-dispatchable Natural gas Dispatchable Hydroelectric Dispatchable

If solar radiation in a concentrating solar power (CSP) is concentrated from 100 ft2 to 1 ft2, what is this device's concentration ratio (in suns)? a. 100 b. 10 c. 1 d. 1000

a. 100

How many tides (or inflow/outflow cycles) occur per day? a. 2 b. 1 c. 4

a. 2

Tidal barrages are examples of which type of hydropower a. Low head b. High head c. Medium head d. Pulse turbines

a. Low head

What is the wind power efficiency limit in theory? a. Shockley Queisser b. Efficiency Limit c. Betz Limit d. Carnot Efficiency Ideal Rankine Efficiency

c. Betz Limit

Which of the following best describes the flow rate of electrons? a. Conductivity (S/m) b. Resistance (Ohms) c. Current (Amps) d. Voltage (Volts)

c. Current (Amps)

The major components of the US power grid are generation, transmission, and distribution. (T/F)

True

Use the same rock at the top of the same building as in the previous question. This time you tie a parachute to the rock so that some of the potential energy is not converted to kinetic energy due to friction. If the efficiency of conversion from potential to kinetic energy is now 75%, how fast will the 3 kg rock be moving (in m/s) when it hits the ground 10 meters below? a. 12 meters/second b. 11 meters/second c. 14 meters/second d. 10 meters/second

a. 12 meters/second

Assume your answer from the previous question is 1800 kWh, the PV system has a battery and inverter for storage and conversion of the generated energy, respectively. The efficiency of the battery is 80%, whereas the efficiency of the inverter is 96%. What are the respective (approximate) DC and AC forms of the energy generated? a. 1440kWh DC and 1382kWh AC b. 1440kWh DC and 1728kWh AC c. 1728kWh DC and 1440kWh AC

a. 1440kWh DC and 1382kWh AC

Assume the irradiance during the winter months to be 350.0 W/m2. Use the efficiency of solar collectors chart in notes. For the conditions in the previous question (-20C outside raising to 45C) - If a generic evacuated tube type collector was installed at the residence, what sort of efficiency can be expected from this system (based on the chart provided)? (0.19 C/Wm2) a. 20- 30% b. 30- 40% c. 50- 60% d. 0- 10%

a. 20- 30%

What is the Wisconsin requirement on the noise generated by wind turbines? a. 50 db(A) during the day and 45 db(A) during the night at a setback distance of 380 m b. 100 db(A) during the day and 90 db(A) during the night at a setback distance of 380 m c. 380 db(A) at a setback distance of 50 m d. No noise requirements

a. 50 db(A) during the day and 45 db(A) during the night at a setback distance of 380 m

The discount rate is best described as: a. A factor used to normalize money's worth as a function of time using an estimate of the 'opportunity cost' of money b. Reduction in the initial cost of the project from incentives c. A factor used to normalize money's worth as a function of time using the interest rate of a loan d. A factor used to normalize money's worth as a function of time using the interest rate of a loan plus inflation.

a. A factor used to normalize money's worth as a function of time using an estimate of the 'opportunity cost' of money

What basic problem has prevented widespread adoption of solar space heating? a. A problem of supply and demand: Most solar radiation is available during the summer months, whereas the need is during the winter b. Solar energy is not widely available in most area. c. Demand and availability are well-matched, but design costs are prohibitively expensive d. It is a trade-off between heating and lighting applications; you may have one, but not the other

a. A problem of supply and demand: Most solar radiation is available during the summer months, whereas the need is during the winter

Which example best illustrates the first law of thermodynamics? a. A turbine converts kinetic energy to electrical energy b. A glass of water melts an ice cube and becomes colder c. A motor loses energy through heat and friction

a. A turbine converts kinetic energy to electrical energy

What describes a p-type semiconductor a. Absence of an electron from the lattice, giving rise to a hole, implying an overall positive charge b. Absence of a hole from the lattice, giving rise to an additional electron and consequently, an overall negative charge c. They are known to not contain any dopants

a. Absence of an electron from the lattice, giving rise to a hole, implying an overall positive charge

The annual average solar energy (radiation) available to a collector at any point on the earth depends on (select all that apply). a. Angle of incidence (tilt and azimuth angle) of the collector b. Energy Conversion efficiency of the collector c. Latitude (geometric considerations of the relationship between the earth and sun) d. The acceleration due to gravity e. Weather patterns that influence cloud cover

a. Angle of incidence (tilt and azimuth angle) of the collector c. Latitude (geometric considerations of the relationship between the earth and sun) e. Weather patterns that influence cloud cover

Which of the following are potential downsides (perceived, and some that are true) to implementing wind energy, that need to be accounted for when planning and siting wind farms? a. Bat and bird mortality b. Concerns of visual impacts c. Wind has a relatively low energy output-to-input ratio d. Electromagnetic interference e. Shadow flicker due to rotating turbine blades f. Noise considerations

a. Bat and bird mortality b. Concerns of visual impacts d. Electromagnetic interference e. Shadow flicker due to rotating turbine blades f. Noise considerations

Which of the following energy sources is considered dispatchable? Select the best answer. a. Biomass combustion b. Solar c. Wind d. Nuclear

a. Biomass combustion

Ground source heat pumps (GSHP) are not a "source" of renewable energy because they require electric energy to operate, but rather a way to increase energy efficiency for heating and cooling applications. The efficiency rating of a heat pump that indicates how much heat can be "pumped" with a given amount of work from electrical input is... a. COP or Coefficient of performance b. Energy Conversion Ratio c. Heat Pumpability d. Thermal efficiency

a. COP or Coefficient of performance

What is an example of a building passive solar element? Choose the best answer. a. Choosing appropriate insulation for different parts of the house b. Planting shade trees around the entire house c. Installing rooftop solar thermal panels d. Using solar PV for all electricity demands

a. Choosing appropriate insulation for different parts of the house

Which of the following statements are true about global energy use? Select all that are true. a. Conventional energy exceeds renewables b. Energy production is extremely efficient c. Oil and gas are reserves are depleting d. Annual energy consumption is increasing

a. Conventional energy exceeds renewables c. Oil and gas are reserves are depleting d. Annual energy consumption is increasing

Wind velocity near a wind turbine doubles from 5 m/s to 10 m/s. (Assume that the wind turbine is able to operate and has the same conversion efficiency at both velocities.) Are the following statements about the wind energy in this situation true or false? a. Kinetic energy per kg of air increases by a factor of 10 b. Mass flow rate across the wind turbine increases by a factor of 2 c. Electrical power produced increases by a factor of 8

a. False b. True c. True

Mark true/false of the following items - whether or not they can be employed in building as passive solar elements? a. PV modules b. Increase insulation and thermal mass c. Orientation of the building d. Window placement and roof overhang

a. False b. True c. True d. True

You are evaluating several sites to determine the best location for a wind farm. What factors should you consider to find a place with optimal wind speeds? Select the best answer. a. Geography, topography, seasonality b. Topography, humidity, precipitation c. Seasonality, radiation, temperature

a. Geography, topography, seasonality

While larger turbine blades can extract more energy from the wind resource, what is a typical downside to consider (select the best answer)? a. Greater propensity for high-speed wind damage b. Larger blades can cause greater bird mortalities c. Public perception of larger turbine blades is generally negative d. While greater energy may be generated, the overall power is greatly diminished

a. Greater propensity for high-speed wind damage

About what fraction of incoming solar radiation is absorbed at the earth's surface? a. Half b. One-third c. One quarter d. A tenth

a. Half

Which of the following are measures of POWER? (Select all that apply) a. Horsepower b. Joules c. Btu/hr d. kWh (kilowatt-hours) e. Barrels of Oil f. Tonnes of Coal

a. Horsepower c. Btu/hr

Which of these is a common strategy for placement of windows when considering passive solar approaches for building design in the US? a. Large south-facing windows, and small north-facing ones b. Large north-facing windows and small south-facing ones c. Windows on only one side of the building d. Avoiding windows altogether and build more concrete bunkers

a. Large south-facing windows, and small north-facing ones

Why do higher latitudes receive less solar radiation per area than lower latitudes? Select all that are true. a. More atmosphere to travel through b. Less concentrated radiation due to angle of incidence. c. Colder temperatures d. More cloud cover

a. More atmosphere to travel through b. Less concentrated radiation due to angle of incidence.

Pick the solar PV cell type with the highest conversion efficiency among the following (consider both those commercialized and those being developed) a. Multi-junction b. Monocrystalline Si c. Polycrystalline Si d. Amorphous Si

a. Multi-junction

Match the following geothermal energy sources with their corresponding definitions and applications Hot water reservoirs Geo-pressured reservoirs Natural steam reservoirs a. Deep well releasing high temperature steam at the surface b. Deep ground water at temperatures that suit space heating (generally not suited for electricity production) c. Brine saturated with natural gas under pressure, used for both heat and natural gas

a. Natural steam reservoir b. Hot water reservoir c. Geo-pressurized reservoir

LCA can provide outputs for environmental impacts including: a. Net Energy Return b. Eutrophication Potential c. Greenhouse Gas Emission d. Net Present Value e. Annualized Operational Impact

a. Net Energy Return b. Eutrophication Potential c. Greenhouse Gas Emission

What describes an n-type semiconductor? a. Presence of an extra electron inside the lattice, giving rise to an overall negative charge b. Absence of an electron from the lattice, giving rise to a hole, implying an overall positive charge c. These contain no known dopants

a. Presence of an extra electron inside the lattice, giving rise to an overall negative charge

Which of the following statistics is true about US wind power as compared to other countries? a. Rank #2 in the world in cumulative capacity installed b. Rank #1 in the world in annual capacity of equipment manufactured c. Rank #1 in the world in new capacity built last year d. None of these

a. Rank #2 in the world in cumulative capacity installed

What is true about the silicon used in solar cells? Select all that are true. a. Silica comes from sand and requires toxic chemicals and energy to get into a usable form b. Silicon is widely used in solar cells because it is a superconductor of electricity c. Silicon is a limited supply and high demand for electronics increases its cost d. Polycrystalline silicon has the highest energy conversion efficiency of the widely used silicon forms

a. Silica comes from sand and requires toxic chemicals and energy to get into a usable form c. Silicon is a limited supply and high demand for electronics increases its cost

What is the best description of how the Trombe Wall passive solar concept works? a. Solar radiation during the winter months is captured by the Trombe Wall and stored as thermal mass, and slowly released during the night b. It is a wall; it keeps out solar radiation during the summer months, and keeps the building cool c. Solar radiation during the summer months is captured by the Trombe Wall, and let out at night to provide for heating d. It is effective for keeping Trojan horses at bay

a. Solar radiation during the winter months is captured by the Trombe Wall and stored as thermal mass, and slowly released during the night

Wind energy is ultimately the product of: a. Solar radiation on the earth's surface b. Air heated by geothermal c. Tectonic plate motion d. Wind turbines actually move the air, causing wind

a. Solar radiation on the earth's surface

Wind farms generally have a favorable land-use intensity because (select the best answer): a. The area under the turbines can be used for agriculture/ pasture b. They are installed in forests, thereby preventing soil erosion c. Offshore turbines are placed 'off-shore', so... no land use d. Windmills aid in agriculture by moving water and grinding grain

a. The area under the turbines can be used for agriculture/ pasture

When looking at a wind turbine power curve, what explains the abrupt drop in power to 0 kW at extremely high wind speeds (select the best answer)? a. This happens at the shut-down speed, beyond which it is unsafe to operate the turbine b. This happens at the cut-in speed, when the turbine is not yet turning or generating energy c. The maximum efficiency is reached, which limits how much power can be extracted

a. This happens at the shut-down speed, beyond which it is unsafe to operate the turbine

Match the following wind turbine tower types to their potential applications: Midsize to large wind turbines Small wind turbines Early midsize turbines a. Tilt-down b. Freestanding lattice c. Monotube

a. Tilt-down Small wind turbines b. Freestanding lattice Early midsize turbines c. Monotube Midsize to large wind turbines

Please mark the following statements True or False a. Locations with high solar resource insolation would also have high PV capacity factors. b. As a general rule of thumb, all solar collectors installed on the earth should be pointed to the South. c. The best tilt angle for a solar collector during the winter month in Madison Wisconsin (coordinate: 43 N, 90 W) is somewhere between 45 and near vertical.

a. True b. False c. True

Which of the followings are true about utility-scale concentrating solar therm power. a. Water scarcity is a common challenge for CSP. True b. The power supply is usually far from the demand geographically. True c. It can use both direct and diffuse radiation. False d. The efficiency is generally lower than common PV on the market. False

a. True b. True c. False d. False

What happens to the flow of air after passing through a wind turbine? a. Velocity Drops b. Density Increase c. Cross-sectional area increase d. Pressure Drops

a. Velocity Drops c. Cross-sectional area increase d. Pressure Drops

Which example describes potential energy? Select the best answer. a. Water at the top of a waterfall b. Water spinning a turbine blade c. Water turning into steam d. Water flowing in a river

a. Water at the top of a waterfall

We want the solar collector glazing materials to have a high transmittance for short-wave radiation, and a low transmittance for long-wave radiation, because ______. a. We want to collect the short-wave radiation from the sun, and reflect back the long-wave infrared emitted by the collector. b. We want to collector the long-wave radiation from the sun, and reflect back the short-wave UV emitted by collector. c. The long-wave radiation which is low in energy is not wanted, because it would reduce the average energy intensity of coming light.

a. We want to collect the short-wave radiation from the sun, and reflect back the long-wave infrared emitted by the collector.

Select all of the correct statement(s) regarding windmills and wind turbines a. Windmills are typically drag-based whereas most modern turbines work on the principle of lift b. Drag-type designs are generally more efficient than lift-type c. Drag-type turbine blades are more suited for higher wind speeds than the lift-type d. The Dutch four-arm is an example of a drag-type turbine

a. Windmills are typically drag-based whereas most modern turbines work on the principle of lift d. The Dutch four-arm is an example of a drag-type turbine

Wave energy machine needs three basic things in it's design, a moving part that follows the shape of the wave, a mechanical device/generator to convert the motion to electricity, and a ______? a. fixed frame of reference such as attachment to the ocean floor or a large stabilized body that doesn't move with the waves. b. An automatic device to remove sea life from intake ducts. c. good paint scheme to blend the device into the oceanscape. d. solar device to provide electricity to steer the machine into the waves

a. fixed frame of reference such as attachment to the ocean floor or a large stabilized body that doesn't move with the waves.

Match each type of Hydroelectricity application with the concept that best describes it: Medium head applications High head applications Low head applications a. Use large volumes of water, which usually come from a river. It has the lowest elevation difference among hydro applications. b. Use large water volumes, which usually come from a reservoir (stored water) c. Use small water reservoirs and large elevation differences to impulse a turbine for energy generation.

a. low b. medium c. high

Which of the three main types of wave machines require a two-way Wells Turbine to capture energy from both incoming and outgoing air. a. oscillating water column b. pitching and rolling devices c. Tapered channel devices d. OTEC

a. oscillating water column

One benefit of tidal power is that it a. produces predictable power and energy that can be easier to integrate into the grid. b. Is close to the shore c. has no environmental impact d. Is cheap to build

a. produces predictable power and energy that can be easier to integrate into the grid.

Choose the best definition of solar irradiance. a. solar power per unit area at a given location b. the power output from the sun c. sun's electromagnetic radiation d. the amount of solar power that can be collected by a PV panel

a. solar power per unit area at a given location

A 15 m2 solar array is installed in area that receives an annual average daily solar resource of 4.76 kWh/m2/day. The project is expected to cost a total of $13,400 over the 19 year lifetime of the project. What is the levelized cost of energy (LCOE) for this solar array project? Answer in $/kWh with 3 sig figs.

0.027

Assume the irradiance during the winter months to be 350.0 W/m2. Use the efficiency of solar collectors chart in notes. You want to ensure the availability of hot water even in the dead of winter, and would like to now design the system for the coldest of days, an ambient temperature of -20.0 ∘∘C. Using this new temperature, but the same other conditions, recalculate the temperature rise per incoming solar irradiance that this will necessitate (in ∘∘C/(W/m2)). Correct!

0.19

Which gasses have the highest global warming potential? Rank from highest (1) to lowest (3). Nitrous Oxide Methane Carbon Dioxide

1 NOx 2 CH4 3 CO2

A flashlight moves electricity with a 0.18 A current through a circuit to the light bulb, which has a resistance of 50 ohms. How much power (W) is supplied to the light bulb? Use 2 significant figures.

1.6

Consider the ground temperature to be 5 C and the house temperature to be 30 C. What is the theoretical max COP for a cooling heat pump? (Answer with at least 2 sig figs).

11.1

The solar array is rated to produce 1.00 kW of power. The area where the PV system is installed has a capacity factor of 20.0%. What is the annual energy that this system can be expected to produce (in kWh, DC)? Please answer with at least 3 sig figs

1752

A reservoir of 98 meters releases 802 kg of water over a turbine. Considering that the energy produced is 139 kJ, what is the efficiency of this turbine in %? Assume gravity = 9.81 m/s2 .

18

A wind turbine has a 47 m swept diameter, can obtain 80% of the Betz coefficient for wind throughput, and has a turbine efficiency of 90%. If the wind velocity is 9 m/s and air density is 1.00 kg/m3, what is the maximum power that the turbine can convert from the wind? Answer in kW with 3 significant figures.

269

Consider energy conversion in a parabolic trough concentrating solar power (CSP) system being installed in the Mojave Desert of Nevada, where the average direct normal solar resource is 8.30 (kWh)/(m2 day). This is the sunlight from the daylight hours over a day. The geometry of the parabolic trough creates a solar concentration factor of 90 to 1.0. The receiver tube with the molten salt has 100.0 m2 of surface area that receives the radiation from the parabolic mirrors. How much annual solar energy is collected by the system? Answer in GWh with at least 3 sig figs.

27.3

Consider energy conversion in a parabolic trough concentrating solar power (CSP) system being installed in the Mojave Desert of Nevada, where the average direct normal solar resource is 8.30 (kWh)/(m2 day). This is the sunlight from the daylight hours over a day. The geometry of the parabolic trough creates a solar concentration factor of 90 to 1.0. How much energy-per-area is concentrated from the mirrors on to the molten salt in the receiver tube? Answer in MWh/m2 with at least 3 sig figs.

272

The wind speed distribution at a certain site is provided below in figure 1. From the lecture in module 6, the distribution is useful in determining what sort of wind speeds a site is going to witness in terms of hours per year. For the sake of simplicity, we will attempt to estimate how much energy can be derived from this wind resource at a speed of 14 m/s annually. Modul Wind Speed - 7 m/s (850 hrs) Avg wind speed - 8.9 m/s (800 hrs) 14 m/s (400 hrs) Power Curve 0-3 m/s = 0 kW 2.4 kW at 13-14 m/s 2 kW from 18-22 m/s 0 kW at 26 m/s What is the cut-in speed of the Skystream 2.4 turbine?

3 m/s

Consider energy conversion in a parabolic trough concentrating solar power (CSP) system being installed in the Mojave Desert of Nevada, where the average direct normal solar resource is 8.30 (kWh)/(m2 day). This is the sunlight from the daylight hours over a day. The geometry of the parabolic trough creates a solar concentration factor of 90 to 1.0. How much energy-per-unit area (in MWh/m2) is realized annually at the surface of the mirrors? Answer in in MWh/m2 with at least 3 sig figs.

3.03

1000.0 gpm (gallons-per-minute) of water is released from the reservoir down the hill in order to generate electricity during the day (peak hours) for a 12-hour period each day. The drop of the water is 50.0 m and has negligible friction. Calculate how much energy (in kWh/day) can be generated on a daily basis, if the turbine is 85% efficient. Assume the density of the water is 1000.0 kg/m3. Answer in kWh/day with at least 3 sig figs

316

Assume the irradiance during the winter months to be 350.0 W/m2. Use the efficiency of solar collectors chart in notes. The average ambient temperature during the winter months in Madison, WI is 7.0 ∘∘C. You'd like to have your household provided with hot water at 45.0 ∘∘C. What is the temperature rise that needs to be attained (in ∘∘C)?

38

The wind speed distribution at a certain site is provided below in figure 1. From the lecture in module 6, the distribution is useful in determining what sort of wind speeds a site is going to witness in terms of hours per year. For the sake of simplicity, we will attempt to estimate how much energy can be derived from this wind resource at a speed of 14 m/s annually. Modul Wind Speed - 7 m/s (850 hrs) Avg wind speed - 8.9 m/s (800 hrs) 14 m/s (400 hrs) Power Curve 0-3 m/s = 0 kW 2.4 kW at 13-14 m/s 2 kW from 18-22 m/s 0 kW at 26 m/s At the wind resource depicted by the wind speed distribution chart above, what is the approximate annual frequency (in hr) that the wind can be expected to blow at 14 m/s?

400 hours

How much energy is needed to pump back the water to the top of the reservoir (50 m high) during the night at a flow rate of 1000 gpm (in kWh / day with at least 2 sig figs)? Pumping up the mountain is done for a 12-hr period each night during the off-peak energy demand. The pump has a conversion efficiency of 80% Answer in kWh/day with at least 3 sig figs

464

Approximately how many Quad is 500.0 EJ (exajoules), the world primary energy consumption? (answer with at least 3 sig figs)

472

If the 100-MW natural gas Blout Generating Station in Madison has a capacity factor of 54.12%, how many GWh of energy does the generating station produce in one year? Answer with 3 significant figures.

474

A laptop charger acts like a transformer and reduces voltage from the electrical outlet to a laptop. If electricity enters the charger with 126 V and 1.9 A and leaves the charger to go into a laptop with 20 V and 5.8 A, what percent of the electricity reaches the laptop? Use 2 sig figs.

48

If over a year a refrigerator takes 250 kWh of electricity and can provide 4,500 MJ of cooling per year what is its COP? (Answer with at least 2 sig figs)

5

The wind speed distribution at a certain site is provided below in figure 1. From the lecture in module 6, the distribution is useful in determining what sort of wind speeds a site is going to witness in terms of hours per year. For the sake of simplicity, we will attempt to estimate how much energy can be derived from this wind resource at a speed of 14 m/s annually. Modul Wind Speed - 7 m/s (850 hrs) Avg wind speed - 8.9 m/s (800 hrs) 14 m/s (400 hrs) Power Curve 0-3 m/s = 0 kW 2.4 kW at 13-14 m/s 2 kW from 18-22 m/s 0 kW at 26 m/s At what speed is the wind predicted to be blowing most frequently at the above resource site?

7 m/s

A wind turbine is moved to a region where the wind speed is doubled. By what factor is the turbine's power output increased in the new location (assuming you are in the normal operating range of the turbine)?

8

The wind speed distribution at a certain site is provided below in figure 1. From the lecture in module 6, the distribution is useful in determining what sort of wind speeds a site is going to witness in terms of hours per year. For the sake of simplicity, we will attempt to estimate how much energy can be derived from this wind resource at a speed of 14 m/s annually. Modul Wind Speed - 7 m/s (850 hrs) Avg wind speed - 8.9 m/s (800 hrs) 14 m/s (400 hrs) Power Curve 0-3 m/s = 0 kW 2.4 kW at 13-14 m/s 2 kW from 18-22 m/s 0 kW at 26 m/s In a year, how much electricity is generated by wind at speed of 14 m/s?

960

You obtain the following solar data from the SAM for the solar radiation falling on a collector surface tilted at different angles for your design location. Based on what you know about the solar radiation what city are we in, which of the following location are you most likely to be at? Hint: think in terms of the Northern hemisphere, Southern hemisphere, or equator. Table is the monthly average of solar radiation in (kWh/m^2/day). Jan0 45 90 5.4 5.5 3.2 Feb0 45 90 5.2 4.7 2.3 Mar0 45 90 5.0 0 3.7 45 1.4 90 Apr0 45 90 5.2 0 3.3 45 1.2 90 May0 45 90 5.4 0 2.7 45 1.0 90 Jun0 45 90 5.4 0 2.4 45 1.0 90 Jul0 45 90 5.9 0 2.7 45 1.0 90 Aug0 45 90 6.2 0 3.4 45 1.0 90 Sep0 45 90 6.0 0 4.2 45 1.2 90 Oct0 45 90 6.0 0 4.7 45 2.0 90 Nov0 45 90 5.4 0 5.2 45 2.9 90 Dec0 45 90 5.3 0 5.4 45 3.3 90 Annual Average0 45 90 5.5 0 4.0 45 1.8 90 a. San Francisco (37.7749° N, 122.4194° W) b. Quito, Ecuador (0.1807° S, 78.4678° W) c. Sao Paulo, Brazil (23.5505° S, 46.6333° W)

b. Quito, Ecuador (0.1807° S, 78.4678° W)

What policy requires electric providers in a given state to provide a fixed percentage of energy from renewable sources? a. Production Tax Credit b. Renewable Portfolio Standard c. Renewable Fuel Standard d. Regulated Utilities

b. Renewable Portfolio Standard

Which two of the following are environmental impacts that should be considered for an energy system project? a. Conversion efficiency b. Resource depletion c. Rate of return d. Air pollution

b. Resource depletion d. Air pollution

What happens once the wind velocity exceeds the rated wind speed for a wind turbine, but is still below the shut-down wind speed? Pick best answer a. The power output decreases b. The conversion efficiency decreases c. The turbine stops d. Nothing happens

b. The conversion efficiency decreases

What is the major cause of "flapping" blades, which lead to fatigue failure? a. Gravity acting on the blades. b. The difference between wind velocities at different height. c. Vibration caused by the generator. d. Hitting on bird/bat.

b. The difference between wind velocities at different height.

Geothermal heat pumps use the following for heating and cooling. Choose the best answer. a. Heat generated deep in the earth from geological activity as an energy source b. Thermal energy difference of the ground versus the air c. Energy stored in the earth d. Steam pockets near the earth's surface

b. Thermal energy difference of the ground versus the air

Why does the power grid use "baseload" power plants? a. They produce the maximum power load continuously b. They are large in scale and low cost c. They respond quickly to changes in demand d. They are easily stopped and started

b. They are large in scale and low cost

The following term describes the closed loop that allows electrons to flow a. turbine b. circuit c. path d. current

b. circuit

What is the unit of energy, joule (J) as expressed in terms of base SI units? a. kg/s b. kg.m2/s2 c. m/s3 d. kg.m/s

b. kg.m2/s2

A geothermal power plant has a rated power capacity of 5 GW and a Capacity Factor of 50%. What is the estimated annual energy output in GWh? a. 5,000 GWh b. 10,950 GWh c. 21,900 GWh d. 43,800 GWh

c. 21,900 GWh

The same 0.5 MW capacity hydro turbine as in the previous question is installed on a river that has a capacity factor of 0.66 how much energy does it produce in one year? a. 333 kW b. 0.5 MW c. 2890 MWhrs d. 8760 MW e. 2890 MW f. 8760 MWHrs

c. 2890 MWhrs

Match the appropriate descriptions of solar thermal types for buildings and space-heating applications a. Solar radiation collection is integrated into the building design to reduce heat loads b. A solar heater uses a anti-freeze fluid to heat up the water. c. Involves a discrete solar collector to gather radiation and requires pump to efficiently move the heat transfer fluid. d. Involves discrete solar collectors with a combination of steam turbines and generators to produce power from higher temperatures achieved Active Passive Closed loop Solar thermal engines

c. Active a. Passive b. Closed loop d. Solar thermal engines

You want to take a hot shower (42°C) with heat provided with domestic solar thermal technology. It is winter in Madison, the ambient temperature is -20°C, and incoming solar radiation is 500 W/m2. Which of the following technologies would be capable of meeting your heating needs? Select all that apply. a. Unglazed flat plate collector b. Glazed flat plate air collector c. Evacuated tube collector d. Glazed flat plate collector

c. Evacuated tube collector d. Glazed flat plate collector

Assume the irradiance during the winter months to be 350.0 W/m2. Use the efficiency of solar collectors chart in notes. Next using this new case where the system is being designed for the coldest winter temperatures (-20 ∘∘C), which of the following collector-types would suit the application (select all that apply)? (0.19 C/Wm2) a. Unglazed flat-plate b. Glazed flat-plate c. Evacuated tube type d. None of these e. Either glazed-plate or evacuated tube

c. Evacuated tube type

Select all the true statements about electricity on the grid a. If electricity produced on the grid is not used it is wasted by going to ground b. Both AC and DC power are transmitted on the grid c. High voltage is transmitted on the grid to minimize losses d. Peaking power plants are used only when there is high electricity demand

c. High voltage is transmitted on the grid to minimize losses d. Peaking power plants are used only when there is high electricity demand

If we look at the energy efficiency instead of the coefficient of performance for a heating system, we would look at how much useful energy you convert to useful energy, compared to how much energy you put into the system. Therefore a 90% efficient furnace provides 90% of the energy you put into it in the form of heat (thermal energy) for your home (what you want) and the other 10% is "lost". But since no energy is destroyed where does that 10% primarily go? a. mechanical energy b. friction in the moving parts c. heat exhausted outside your house d. become light energy

c. heat exhausted outside your house

Match the best application for the following solar collector types a. Domestic water heating b. Water, space and process heating, particularly in colder climes c. Crop drying applications d. Swimming pool heating applications Unglazed flat-plate Glazed flat-plate (air) Glazed flat-plate (water) Evacuated tube

d. Unglazed flat-plate c. Glazed flat-plate (air) a. Glazed flat-plate (water) b. Evacuated tube

Consider a turbine producing electricity that is then used in an electrical motor to spin a wheel. Select the best answer that describes the conversion of energy a. electrical to mechanical b. mechanical to electrical c. thermal to electrical d. mechanical to electrical to mechanical

d. mechanical to electrical to mechanical

The same 1 MW hydro turbine as in the previous question is installed on a river that cannot supply enough water to run it continuously for the entire year. If the turbine is run at full capacity for only 1/3 of the year how much energy will be produced in that year a. 8760 MW b. 333 kW c. 8760 MWHrs d. 1 MW e. 2920 MWhrs f. 2920 MW

e. 2920 MWhrs

You can sell 100 kWh of wind energy for a given day to the grid at $0.06/kWh with half of the time (12 hours) receiving the 'on peak' rate and the other half of the time $0.03/kWh at the 'off peak' rate. What is the approximate value of the energy produced in dollars (assuming steady production for the whole day)? a. about $3 b. more than 6 cents/kWh c. < $4.5 d. about $6 e. about $4.5

e. about $4.5

Which of the following will have an impact on your annual cash flow chart? (Select all that apply) a. ITC incentive b. PTC incentive c. Maintenance Cost d. Discount Rate

a. ITC incentive b. PTC incentive c. Maintenance Cost

Which of the following represent the components of an LCA model? a. Inputs b. Outputs c. Processes d. System boundary e. Environmental impacts

a. Inputs b. Outputs c. Processes d. System boundary

Which of the following is biggest limitation of using the payback period (years to recoup project costs) as a measure of financial success? a. It ignores the size of project's profit potential. b. Does not consider contingency costs. c. Can be misleading if the cash flow is highly variable d. It measures liquidity of your investment

a. It ignores the size of project's profit potential.

Mark all the true statement about levelized cost of electricity (LCOE): a. LCOE is used to compare costs among different energy sources without taking into account purchased power price b. LCOE provides a way to compare the relative cost of energy produced by different energy-generating sources regardless of project scale or operating time frame c. LCOE has units of money (dollars) per project lifetime. d. LCOE is affected by programs that increase the price of renewable electricity.

a. LCOE is used to compare costs among different energy sources without taking into account purchased power price b. LCOE provides a way to compare the relative cost of energy produced by different energy-generating sources regardless of project scale or operating time frame

Select all the TRUE statements about LCA a. Life cycle assessment is the investigation and valuation of the environmental impacts of a product or service b. LCAs are governed by ISO standards c. There is only one correct way to perform an LCA d. The output of an LCA will tell you definitively if a process is sustainable e. LCAs can only determine environmental impacts for energy systems

a. Life cycle assessment is the investigation and valuation of the environmental impacts of a product or service b. LCAs are governed by ISO standards

Which following relationships are true for electrical resistance according to Ohm's Law? Select all the correct answers a. P=R x I2 b. P=V2 / R c. R=P / V2 d. P=V2 / I

a. P=R x I2 b. P=V2 / R

Are the following examples of power or energy? a. A light-emitting diode (LED) consuming 20 mA at 2.4 Volts b. A 530 calories peanut butter and jelly sandwich c. A weight lifted 0.5 meters with 100 N d. A solar panel generating 250 Watts

a. Power b. Energy c. Energy d. Power

Mark all the true statement about real discount rates a. Real discount rate takes into account both risk and inflation b. A real discount rate refers to the discount rate before taking inflation into account c. The real discount rate avoids purchasing power erosion through inflation, investors consider the real interest rate, rather than the nominal rate d. SAM modeling uses the real discount rate for some of its calculations. e. The real discount rate will be higher than nominal discount rate.

a. Real discount rate takes into account both risk and inflation c. The real discount rate avoids purchasing power erosion through inflation, investors consider the real interest rate, rather than the nominal rate d. SAM modeling uses the real discount rate for some of its calculations.

Select the following true statements about what an energy model can provide: a. Simplify calculations and quantify energy and economic inputs and outputs b. Run simulations of alternative technologies or systems c. Generate figures and tables to help communicate findings d. Avoids costs of having to build a prototype of the system

a. Simplify calculations and quantify energy and economic inputs and outputs b. Run simulations of alternative technologies or systems c. Generate figures and tables to help communicate findings d. Avoids costs of having to build a prototype of the system

The Net Present Value is best described as: a. The sum of all of the initial and ongoing cash flows (costs and income) adjusted to 'todays' value. b. An estimate of the 'opportunity cost' of money over time. c. The sum of the annual cash flows for the project adjusted to their future value at the end of the project.

a. The sum of all of the initial and ongoing cash flows (costs and income) adjusted to 'todays' value.

Which of these renewable energy sources is the most "dispatchable" (i.e. most likely to be available when we need it)? a. Solar b. Hydro c. Wind

b. Hydro

Which of the following units does NOT represent units of energy (or work)? N = Newtons, m=meters, s=seconds, J=joules (Select all that apply) a. N * m b. J / s c. (Kg m2 ) / s2 d. kJ

b. J / s

The discount rates for Gary and Sandy are 5% and 3% respectively. If they both receive a similar payment in 10 years from now, from an investment made today, whose investment has higher present value? a. Gary b. Sandy c. the same d. can not tell

b. Sandy

The availability of which of these renewable energy sources is more coincident with electrical demand? a. Wind b. Solar c. Tidal

b. Solar

Combusting fuels like gasoline and ethanol (made from biomass) releases carbon dioxide. What is true about the carbon dioxide that the fuels release? Select all that are true. a. The CO2 has a different physical form b. The CO2 from the ethanol is recycled in a short cycle c. The CO2 from the gasoline is recycled in a long cycle d. The CO2 has the same physical form

b. The CO2 from the ethanol is recycled in a short cycle c. The CO2 from the gasoline is recycled in a long cycle d. The CO2 has the same physical form

POWER is best described as... a. The amount of energy used multiplied by the time over which is it used. (Energy x time) b. The rate of energy production or use c. The total amount of energy that has been used to perform a task.

b. The rate of energy production or use

If you are given a unit of POWER (such as a kW) what information do you need to calculate ENERGY production or use? a. The cost of Power. b. The time period (duration) of power production or use. c. The cost of energy. d. The peak power use.

b. The time period (duration) of power production or use.

During which of the following times would electric energy have the highest economic value in the US market? Choose the best answer. a. 1 - 3 pm in January b. 5 - 7 pm in April c. 3 - 5 pm in July d. 7 - 9 pm in October

c. 3 - 5 pm in July

A hydro turbine has a maximum power output of 1 MegaWatt. If it ran at full capacity for one year how much energy would it produce in that year? a. 2890 MegaWatts b. 1 MegaWatt c. 8760 MegaWatt Hours d. 2890 MegaWattHours e. 8760 MegaWatts

c. 8760 MegaWatt Hours

Which of following devices is essential to connect PV panels to the grid? a. AC-DC rectifier b. AC-AC converter c. DC-AC Inverter d. DC-DC converter

c. DC-AC Inverter

What is true about techno-economic analysis? Select all that are true. a. Reduces environmental impacts of a project b. Applies to only new technologies c. Evaluates physical and economic properties of a technology to determine feasibility d. Utilizes software like NREL's SAM software

c. Evaluates physical and economic properties of a technology to determine feasibility d. Utilizes software like NREL's SAM software

When does electric energy have the highest economic value in the US market? a. Night-time hours in summer months b. Night-time hours in winter months c. Mid-afternoon in summer months d. Mid-afternoon in winter months

c. Mid-afternoon in summer months

Which of the following best illustrates a quantity of power? a. Candy bar with 600 calories b. 10 W light bulb on for 1 hour c. Solar panel producing 300 J./s d. Bike moved 10m with a 5 N force

c. Solar panel producing 300 J./s

The rated capacity of a power production facility is.. a. the annual average power production b. The minimum power output of the facility before it needs to be shut down c. the maximum power that the facility is able to produce under optimal conditions d. the total annual energy production of the facility

c. the maximum power that the facility is able to produce under optimal conditions

Total primary energy consumption in China is 142 EJ, which is equivalent to 3.94 x 107 _____. What unit makes this statement true? a. MW b. GW c. MWh d. GWh

d. GWh

Please mark all of the following that do NOT obtain the originating energy from solar radiation? a. Hydropower b. Solar Thermal c. Wind Energy d. Geothermal energy e. Biofuels

d. Geothermal energy

What is true about an offshore wind turbine with a nameplate capacity of 3 MW? Choose the best answer. a. It produces on average 3 MW of power anually b. It produces on average 3 MW of power each day c. It produces a minimum of 3 MW of power in poor conditions d. It produces a maximum of 3 MW of power in ideal conditions

d. It produces a maximum of 3 MW of power in ideal conditions

Which of these describe "base-load" electrical generation facilities? a. Electric energy sold because of favorable market conditions b. Electric energy purchased to meet demand c. High cost of production and respond quickly to changes in demand d. Low cost or production and respond slowly to changes in demand

d. Low cost or production and respond slowly to changes in demand

The water is maintained in the dam at a height 100.0 m by a river which annually puts 300,000 cubic meters of water through a turbine at the bottom of the dam (Volumetric flow in and out the turbine are equal (V1=V2V1=V2) at 300,000 m3/yr. Assume the density of water is 1,000 kg/m3 and g=9.81 m / s2. As a reminder: PE = mass x gravity x height and mass = density x volume Calculate the annual potential energy contained in the water that is held back by the dam. Assume an average height of the water, h of 100.0 m. Express the answer in GJ (at least three significant figures).

294

A hydro turbine has a maximum power output of 0.5 MW. If it ran at full capacity for one year how much energy would it produce in that year? a. 4380 MegaWatt Hours b. 0.5 MegaWatt c. 2890 MegaWatts d. 4380 MegaWatts e. 2890 MegaWattHours

a. 4380 MegaWatt Hours

Which voltage will have the lowest loss of energy during transmission (per distance transmitted)? a. 500 kV b. 312 kV c. 15 kV d. All will be the same

a. 500 kV

If you are given the rated capacity (a power unit like kW) and the capacity factor (e.g. 50% or 0.5) of an energy production facility, how do you calculate the total annual energy production? a. multiply the rated capacity the capacity factor and then by the total time ( e.g. hrs) in a year. b. Multiply the rated capacity by the hours per year and divide by capacity factor. c. Divide the rated capacity by the capacity factor. d. Call Homer Simpson, who works at a nuclear power plant.

a. multiply the rated capacity the capacity factor and then by the total time ( e.g. hrs) in a year.

How much energy have you applied to 3 kilogram rock when lifting it 10 meters from the ground to the top of a building? (to the nearest 2 significant figures, assume 100% efficiency and acceleration of gravity = 9.8 m/s2). a. 29 kW b. 30 Watts c. 29 kJ d. 290 Joules e. 290 Watts f. 30 Joules

d. 290 Joules

A Watt-hour is equal to which of the following SI fundamental units? Select the best answer. a. 3600 J s b. 3600 N/s c. 3600 (kg m2)/s3 d. 3600 (kg m2)/s2

d. 3600 (kg m2)/s2

Inverters are used to change high voltage electricity to low voltage electricity. (T/F)

False

Rank the following SI prefixes from smallest (1) to largest (4). Nano (n) Milli (m) Centi (c) Deci (d)

Nano (n) 1 Milli (m) 2 Centi (c) 3 Deci (d) 4

Match the device to the power type produced or used (AC or DC) Solar panel Battery Wind turbine Typical US home

Solar panel DC Battery DC Wind turbine AC Typical US home AC

A battery provides power to the motor in an electric car. The motor "pushes" the car with 108 kN of force and moves the car 23 meters every 6 seconds. How much power, in kW, is the battery providing to the motor? Assume 100% energy conversion. Power = ____kW (Use 3 significant figures)

414

Match each term to its description: a. One thousand watts operating for an hour b. Any material that will not allow electric current to pass through it c. The property of a substance to oppose the flow of electricity d. The nation-wide linked system that moves electricity from one place to another e. A name given to the use of computer intelligence applied to the transmission and distribution of electricity insulator power grid kWh smart grid resistance

kWh a. One thousand watts operating for an hour insulator b. Any material that will not allow electric current to pass through it resistance c. The property of a substance to oppose the flow of electricity power grid d. The nation-wide linked system that moves electricity from one place to another smart grid e. A name given to the use of computer intelligence applied to the transmission and distribution of electricity

Let us consider that a family's annual electricity consumption is 11,000 kW-h. Assuming the energy expenditures of the family totaled $ 1,500 per year, calculate the unit price of energy (in $/kWh, with at least 4 significant figures) charged by the utility company.

0.1364

Let us consider that a family's annual electricity consumption is 11,000 kW-h. What is their average power consumption (in kW, with at least three significant figures)?

1.26

A hydroelectric dam has 646 kg of water go through its turbine per day. All of the water goes through the intake and enters the turbine at a velocity of 8 m/s and leaves the turbine at 5 m/s. The water spins the turbine and the generator produces electricity by converting the change in kinetic energy (KE in - KE out) into electrical energy. If the turbine has an efficiency of 100%, how much electricity in kJ does the hydroelectric dam produce daily? Use 2 significant figures. Daily electricity = _____ kJ (2 sig figs)

13

If you drop the 3 kg rock you lifted to the top of the building, how fast will it be moving (in m/s) when it hits the ground 10 meters below. Assume that the conversion from Potential to Kinetic Energy is 100% efficient? (answer with at least 2 significant figures)

14

A solar panel array project, rated at a nameplate capacity of 10 kW installed in an area with a capacity factor of 25%, is expected to cost $61,800.00 over its lifetime of 18 years. What is the levelized cost of energy (LCOE) of this project (in cents per kWh)? 3 sig figs.

15.7

A Madison-area water tower holds 3800 cubic meters of water at an average height of 48 meters. (Assume the water has a density of 1000 kg/m3). How much potential energy in MJ is stored in the water? Use 4 significant figures.

1789

A school has a photovoltaic solar panel array that captures 221 kWh of energy each day. The school uses 80% of the energy from the array and sells the remaining 20% to an electric utility. Purchasing electricity from the electric utility costs the school 10 cents/kWh. Selling energy back to the utility earns the school 8 cents/kWh. What is the total daily earnings plus savings of the school from generating 221 kWh of energy? Answer in $/day with 3 significant figures. There are 100 cents per US dollar.

21.2

A small company is considering installing solar panels to bring their electricity costs. The system consists of solar panels, an inverter, and a battery. The company electricity usage is 15000 kWh/year. The panels are rated at 1.0 kW per module and the area they live in has a capacity factor of 0.30. The system does lose some energy after the modules (from storage at night in batteries, converting from DC to AC, and transformation to the correct voltage). Combined, these are accounted for as energy conversion efficiency of 80.0%. If the company installed 20 modules how much surplus of electricity would they be able to sell to the grid (in kW-h per year, at least 3 significant figures)?

27048

The water is maintained in the dam at a height 100.0 m by a river which annually puts 300,000 cubic meters of water through a turbine at the bottom of the dam (Volumetric flow in and out the turbine are equal (V1=V2V1=V2) at 300,000 m3/yr. Assume the density of water is 1,000 kg/m3 and g=9.81 m / s2. As a reminder: PE = mass x gravity x height and mass = density x volume How much kinetic energy (KE) is realized if all the water in the previous problem is released through an opening at the bottom of the dam. You can assume 100% conversion. Express the answer in GJ (at least three significant figures)

294

A small company is considering installing solar panels to bring their electricity costs. The system consists of solar panels, an inverter, and a battery. The company electricity usage is 15000 kWh/year. The panels are rated at 1.0 kW per module and the area they live in has a capacity factor of 0.30. The system does lose some energy after the modules (from storage at night in batteries, converting from DC to AC, and transformation to the correct voltage). Combined, these are accounted for as energy conversion efficiency of 80.0%. What would be the maximum income the company be able to obtain selling the excess to the grid (in $ every year, at least 5 significant figures), if they install 20 modules? Assume they get $0.12/kWh during the peak hours $0.05/kWh during the non-peak hours. Hint: you may assume the solar panel generate power during peak rate hours - which generally coincide.

3246

The water is maintained in the dam at a height 100.0 m by a river which annually puts 300,000 cubic meters of water through a turbine at the bottom of the dam (Volumetric flow in and out the turbine are equal (V1=V2V1=V2) at 300,000 m3/yr. Assume the density of water is 1,000 kg/m3 and g=9.81 m / s2. As a reminder: PE = mass x gravity x height and mass = density x volume If the kinetic energy from the years worth of flowing water is transformed into electrical energy using a turbine how much power can be created (in kilowatts, kW). Assume 100% efficient and continuous operation. Please report the answer with at least three significant figures.

9.32

If electricity going into a transformer is at 513 V and 142 A and exits the transformer at 101 V and 432 A, what is the efficiency of the transformer? Answer in % with at least 3 sig figs.

59.9

A commercial administrative building generates wind energy on its property and uses it to supplement its energy demand, and sell the rest to the grid, making use of generous sell-back rates. The rate structure is provided below, and the energy profile is shown in the figure. Purchase price: $0.08/ kWh On-peak sell price: $0.05/ kWh Off-peak sell price: $0.03/ kWh What is the economic value of the wind farm installation to the company per day ($/day)? off peak from 0-12 on peak from 12-24 generation is consistent at 40 kW consumption is 20 kW from 0-8, 100 kW from 8-16, 20 kW from 16-24

64

How much power is in a circuit (in W) for a circuit that has 9.0 amps of current and 8.0 ohms of resistance? Please provide the answer in W with at least 2 sig figs.

648

A small company is considering installing solar panels to bring their electricity costs. The system consists of solar panels, an inverter, and a battery. The company electricity usage is 15000 kWh/year. The panels are rated at 1.0 kW per module and the area they live in has a capacity factor of 0.30. The system does lose some energy after the modules (from storage at night in batteries, converting from DC to AC, and transformation to the correct voltage). Combined, these are accounted for as energy conversion efficiency of 80.0%. If the goal is to offset current energy consumption using solar PV, how many modules would need to be installed? (give answer as whole modules, can't buy a half module) Correct!

8

You have installed a wind turbine at your rural home. The turbine generates 715 kWh of energy in one year. Your household uses 441 kWh of the energy generated by the wind turbine and sells the rest to the electric utility. You can purchase electricity from the utility at a price of 10.8 cents/kWh and you are paid 6.7 cents/kWh for the energy you sell back to the grid. How many cents/kWh should you value the energy generated by the wind turbine? Answer with 3 significant figures.

9.23

You have a 0.5 MW rated wind turbine that is installed in a location that has a capacity factor of 0.28 based on the wind resources. Assume you can sell wind energy to the grid with the following rates: 10 cents/kWh for 12 hours per day - peak rate6 cents/kWh for 12 hours per day - off-peak rate What is the predicted income from the turbine over a year (in $)? There are 100 cents per US dollar. Answer with at least 3 sig figs.

98112

Which type of organization is likely to accept the lowest discount rate on a renewable energy project? a. Home owners in a residential energy project b. Investors in a utility scale energy project c. Venture capitalists in renewable energy project d. Publicly traded company investing in a energy project

a. Home owners in a residential energy project

When does electrical energy have its highest economic value in the US energy market? Select the best answer. a. Hot afternoons b. Cold nights c. Morning rush hour d. It's about the same all the time

a. Hot afternoons

Which technologies have greenhouse gas emissions during energy production? (All have some GHGs emissions during equipment manufacturing). Wind power Nuclear power Natural gas combustion Coal combustion

Wind power Zero GHGs Nuclear power Zero GHGs Natural gas combustion Significant GHGs Coal combustion Significant GHGs

An oven uses 1.2 kWh of electricity. What is this equivalent to? a. 4320 kJ b. 1200 W c. 4320 Wh d. 1200 J

a. 4320 kJ

What is an example of kinetic energy? Pick the best answer a. A hydropower turbine rotating b. A charged solar battery c. A pile of wood burning d. A river above a waterfall

a. A hydropower turbine rotating

Potential energy is the energy associated with Please mark all that apply a. A mass lifted a specified height above a reference point (in a gravity field) b. A temperature difference c. A compressed spring d. A mass in motion

a. A mass lifted a specified height above a reference point (in a gravity field) c. A compressed spring

How does the average per capita power consumption in North America compare to the world average? Note: the per capita energy consumption would be in units like kW/person (Select the best answer) a. About 4 times higher b. About 2 times higher c. About 2 times lower d. About the same

a. About 4 times higher

Which of the following energy technologies depends on energy from the sun? a. Biofuel b. Tidal c. Geothermal d. Nuclear

a. Biofuel

In the following scenarios, what is the most appropriate metric? a. You need to calculate how much annual energy will be produced for 60 MW hydroelectric station b. You are selecting the best river for a hydroelectric station c. You are comparing two Internal Combustion Engine d. You are calculating the useful energy output given the total energy input

a. Capacity Factor b. Capacity Factor c. Conversion efficiency d. Conversion efficiency

What aspects of sustainability does the triple bottom line consider? Select the best answer. a. Environmental, Social, Economic b. Air quality, Water quality, and Fossil fuel use c. Pollution, Global Warming, and Resource Utilization d. Environmental, Economic, and Technical

a. Environmental, Social, Economic

Select the following true statements about techno-economic analysis: a. Evaluates physical and economic properties of a technology (e.g. renewable energy) to determine its feasibility b. Investigates cash-flows over the lifetime of a project c. Reduces environmental Impacts of a project d. Defines return on investment (ROI) of a project e. Applies to only new technologies

a. Evaluates physical and economic properties of a technology (e.g. renewable energy) to determine its feasibility b. Investigates cash-flows over the lifetime of a project d. Defines return on investment (ROI) of a project

What are the distinctive characteristics of wind turbines and windmills? a. Blades cannot spin faster than the wind Windmill b. Blades can spin faster than the wind c. Blades are lift devices like airplane wings d. Blades are drag devices like sailboat sails

a. Windmill b. Wind turbine c. Wind turbine d. Windmill

If calculated cash flow is negative in a particular year it means that... a. Your Cash outflows (investment, operating costs. loan payments, etc) exceeded you Cash Inflows (energy sales income,savings in avoided energy) in that year b. Your project will not be profitable in the long term c. Your discount factor is too high, making the time value for that year non-profitable d. Your capital cost exceeds your project income

a. Your Cash outflows (investment, operating costs. loan payments, etc) exceeded you Cash Inflows (energy sales income,savings in avoided energy) in that year

How much power is in an electrical circuit that is 120V and 15 amps? a. 8 W b. 1.8 kW c. 1.8 kJ d. 8 J

b. 1.8 kW

What is equivalent to 1 kW (kilowatt)? a. 3.6 J b. 3600 kJ/h c. 3600 J/h d. 3.6 kJ

b. 3600 kJ/h

You have installed a wind turbine at your rural home. About 1/2 of the energy generated by the wind turbine is used directly by your household and 1/2 is sold to your electric utility. Your normal purchase cost of electricity is 10 cents/kWh. You get paid 6 cents/kWh for the energy you sell back to the grid. What is the value (to you) of the energy generated by your wind turbine? a. About 6 cents/kWh b. About 8 cents per kWh c. About 10 cents/kWh d. less than 6 cents/kWh e. more than 10 cents/kWh

b. About 8 cents per kWh

Which of the following are measures of ENERGY? (Select all that apply) a. KiloWatt b. BTU (British Termal Unit) c. HorsePower d. Tonnes of Coal e. Barrels of Oil f. Watt

b. BTU (British Termal Unit) d. Tonnes of Coal e. Barrels of Oil

What is the physical quality that measures the rate of electrical energy transfer in a circuit? a. Voltage b. Current c. Resistance d. Power

d. Power

The rated capacity of an renewable energy system (wind turbine, solar panel, etc) is a. the amount of electricity a generator produces over a specific period of time b. the average power generated, divided by the rated peak power c. the exact amount of electricity the generator provides to the grid as long as it operates d. the amount of energy that an energy installation will provide under ideal conditions of operation

d. the amount of energy that an energy installation will provide under ideal conditions of operation