Renewables

Assume that the flow from other pools into/out the atmosphere are negligible. What is the percent change in net carbon flux into the atmosphere if we cut emissions from fossil fuels by 10%?

16%

prime mover rotates at 3600 rpm exerting a torque of 30 Nm to provide mechanical power to an electrical generator. The mechanical power available from the prime mover is approximately ______

11 kW

Consider a 3-blade wind turbine with 10 m long blades. At a particular day and time, the wind speed at the height of the rotor is 10 m/s. Assume the air density is 1.225 kg/m³. Approximately, how much wind power is available for the turbine?

192 kW

An electrical load consumes 864 MJ during one day demanding constant power during this day. What is this energy in kWh and what is the power demand of this load during this day?

240 kWh and 10 kW

Consider a photon flux of one mmol/(s m²) at two different wavelengths 460 nm and 390 nm. The power flux at 390 nm is _________ the one at 460 nm.

1.18 times

A mass of 1000 kg molten salt with specific heat capacity 1.54 J/(gK) is used to store heat in a solar thermal facility (one type of renewable power production). How much heat is available to drive an engine for electricity production, if the salt reaches deltaT = 400K  of temperature with respect to ambient temperature?

616MJ

A hydrogen fuel cell consumes 1 g/min of hydrogen. This mass rate is constant for 1 hour. Assume 60% efficiency. Approximately, what was the electrical power produced by this fuel cell during that hour?

1.43 kW

When burning one gram of methane the energy produced is approximately ___________ and the mass of CO₂ produced  is approximately ____________.

-50 kJ and 2.75 g

Why does the Mauna Loa CO2 data show an annual fluctuation?

Growing season of the northern hemisphere

Which option contains all greenhouse gases?

C02, CH4, H2O(g)

Long wave radiation

Outgoing

Short wave radiation

incoming

As a percentage, abundance of CO2 in the atmosphere is _____while nitrogen is ______

low, high

Most of the earth’s carbon is in the _____

sedimentary deposits and rocks

Assume productivity is 0.2kgm^-2/d and biomass at day 30 is 2 kgm^-2. What is the biomass in kgm^-2 at day 31?

2.2

Biomass

kg/m²

primary product

plant

productivity

kg/(m²yr)

nutrients

cycle

secondary producer

herbivore

energy

flow

The term most appropriate for an energy conversion based on a resource that will last a very long time given the expected consumption rate is ____ and for an energy conversion based on a process that includes emission controls to avoid air pollution is ____.

renewable, clean

approximately what are the percentages of Carbon-based and non carbon based electricity production worldwide?

60 and 40

Compare the enthalpy of 2 chemical reactions. Enthalpy of reaction 1 is -200kJ/mol and reaction 2 is +250kJ/mol. We want to use the energy of one of these reactions to drive an engine. Which would yield more energy to drive the engine?

Reaction 1

What is the efficiency of a heat engine extracting 3MJ from the hot reservoir and delivering work of 1MJ?

0.33

Assume a closed thermodynamic system that absorbs 20 kJ of heat from the surroundings to increase its internal energy by 10 kJ. What is the correct staement regarding work?

System performed 10kJ work on surroundings

Inductor at steady state or DC

short circuit

capacitor at steady state or DC

open circuit

supercapacitors ____ than batteries

have lower energy density

At 75% full sun, the power provided to the load when the output voltage is 15V is approximately

30W

Which one is the single most imprtant word to characterise module 2?

carbon

Order these compounds in terms of enhancing the greenhouse effect due to their radioactive properties. Go from high to low

CH4, CO2

methane hydrates are____ there are large deposits _____

clathrate…. the ocean floor

solar fuels are

a term to refer to making the equivalent fossil fuels in a hurry

natural gas

complex hydrocarbons

oil

hydrocarbon terms: large plants

coal

hydrocarbon term: algae and zooplankton

oil and gas

quaternary

holocene

paleozoic

carboniferous

mesozoic

jurassic

earth’s global surface____ data____ shows and increase that can be fit well by ___model.

5-year average of temperature anomaly with respect to 1951-1980…. since 1980…. a doubly exponential.

earth’s global surface temperature shows an increasing trend with respect to the _____ takens as a baseline reached approximately ____ in the early 2000s.

1951-1980 average…. 0.5C

Select the best combination to fill the blanks: the carbon in the CO2 emissionof coal-fired power plants can be sequestered before release at the stack by ____ that requires______ because of____.

absorption or adsorption column… regeneration,,,, saturation

ESP

uses electricity to remove fly ash particles by precipitation

SCB

use ammonia to remove NOx from te flue gas

FGD

uses a limestone slurry to remove sulfur before release of the flue gas at the stack

Rank from high to low thees three types of coal fire power plants in terms of efficiency and reduced CO2 emission: subcrit, SC, and USC

USC,SC, subcritical

sub-bituminous

intermediate carbon content and HV

anthracite

highest carbon content and HV

lignite

low carbon content and HV

bituminous

high carbon content and HV

Heat Rate

heat required to produce 1kWh

Heat Value

energy released by burning 1kg of coal

what is the carbon content in percent of coal with formula:

85

Which one is not part of the characteristics to describe a type of coal?

algae content

The path from state 2 to state 3 is approximately ____ with water in the ____phase, whereas the path from 4a to 5 is approximately ___ with water____ phase

isobaric, liquid, isentropic, changing

Peaking Power plant

runs when needed to cover demand

baseload powerplant

runs continuously

which choice best matches power plants that use rankine cycle?

coal-fired. geothermal, nuclear

Energy term: electricity

a fraction of total energy prodcution

Energy term: toe

energy obtained by burning 1 ton of oil

TPES

annual world energy consumption

EJ

convenient unit for energy reserves

The reactants for a hydrogen fuel cell are ____ and the byproducts are____

hydrogen and oxygen…. water and heat

the difference between a battery and a fuel cell is___

that a fuel cell requires constant inflow of reactants whereas the battery does not

A fuel cell converts ____ directly to ____

chemical energy…. electricity

Gibb’s free energy G is _____ minus____

enthalpy….heat

An isobaric reversible process experiments an increase of enthalpy 100kJ. The heat added was

100kJ.

Consider the thermodynamic cycle traced by the solid lines. This is a _____ cycle and the 4-5 path at the right hand side is nearly____

rankine and isentropic.

This is ____ cycle and the path from state 4 to 1 is____

a carnot; a reversible isothermal compression

An isothermal reversible process at 300K experiments an increase of entropy equal to 1kJ/K. What is the heat Q transferred"?

300kJ

The path from 1 to 2 is an ____ and requires____ than the path from 3 to 4 which is an ____.

isothermal expansion; less heat; isothermal expansion

The path from 1 to 2 is an ____ with ____ whereas the path from3 to 4 is an____ with ____. 

Isothermal with increasing entropy; adiabat with constant entropy

For irreversible thermodynamic processes entropy always ____, whereas for reversible processes entropy____.

increase…. remains constant

the PF for an inductor is ___, for a capacitor is____, and for a resistor is _____.

0….0….1

The duty cycle for a ____ DC-DC converter to from 10V to 30V is ____.

boost… 0.666

Consider these graphs what is the correct interpretation?

corresponds to aa 10 mH inductor

Which statement about the voltage is correct?

The current lags the voltage by 20

What is the correct interpretation of the graph?

corresponds to a 1mF capacitor

What does this graph correspond to?

A resistor of 2 ohms

What is the correct phase difference interpretation

V1 lags V2 by 20

A rotor with only one magnet (only one S-N pole pair) must rotate at ___ for voltage to be____.

3600 rpm… 60Hz

in a generator the rotating____ produces a sinusoidal variation of ____ which by Faraday’s law becomes a sinusoidal____.

magnet…. magnetic flux… voltage

steam turbine

one type of prime mover

prime mover

generic term of machine that spins a generator

motor

output torque input electrical power

generator

input torque produces electrical power

An OTEC power plant does not vaporise water to produce steam because 

the warm surface ocean water is not sufficiently hot

the system has heat source at ____ heat sink at ___ and the work is _____

200C, 30C, 33.8kJ/kg

For an ideal Carnot cycle: the isothermal expnasion from volume V2 to volume V3 yields____ the isothermal compression from volume V4 to volume V1

same ratio as

Find the best set of power generation plants that employ a Rankine thermodynamic cycle

coal-fired, geothermal, nuclear

turbine

spins by the steam

boiler

add heat to produce steam

generator

moved by the turbine

steam power plant

rankine cycle

condenser

steam to liquid water

high QL/QH

low efficiency

low QL/QH

high efficiency

geothermal electricity production ____ but is ___ everywhere in the world

can be considered renewable…. not available