Deck 20: Hydrogen

Question 1

(a) Given a fuel cell efficiency of 75% and a required energy to the wheels

Answer 1

(a) The input energy for the fuel cell is (0.6 MJ/km)/(0.75) = 0.8 MJ/km. Since

Question 2

Consider the possibility of extracting energy from 1 m3 of water. One
approach would be lift the water to some elevation and then to generate electricity
hydroelectrically (i.e., pumped hydroelectric storage). The second approach would be to
produce hydrogen from the water by electrolysis and then generate electricity from the
hydrogen in a proton exchange membrane fuel cell. Using typical efficiencies as given in
Chapters 18 and 20, how high would the cubic meter of water have to be lifted to provide
the same total electrical energy output as the fuel cell?

Answer 2

The gravitational potential energy is

Question 3

The lightest element that is a solid at room temperature, lithium, absorbs

Answer 3

Question 4

Consider the following three applications of fuel cells for producing

Question 5

Hydrogen gas is burned to provide heat for a typical North American home
(see Chapter 2 for heating requirements). If the hydrogen is stored in a spherical tank at a
pressure of 80 MPa, what would be the diameter of the tank needed to supply the average
monthly heating requirement? Assume a typical furnace efficiency (Chapter 17).

Question 6

A solid oxide fuel cell operates at 55% efficiency using methane as a fuel.

Question 7

One possible use for hydrogen as an energy storage mechanism is for

Question 8

Hydrogen gas is burned according to the reaction

Question 9

Assume that the cost of hydrogen per unit energy is the same as gasoline

Question 10

Consider the situation where all 250,000,000 gasoline-powered vehicles in

Question 11

For stationary applications, mass and volume considerations for a fuel

Question 12

If hydrogen followed an ideal gas law at all pressures, calculate the pressure

Question 13

Calculate the mass and volume of Mg that would be required to store 100 kg of hydrogen.

Question 14

The BMW Hydrogen 7 consumes an average of 13.7 L/100 km of gasoline

Question 15

Question 16

Calculate the percentage of improvement in the energy density of a CHG

Question 17

Calculate the carbon footprint /km) for a fuel cell vehicle

Question 18

The Mazda RX-8 RE hydrogen vehicle has a 110 L CHG tank that stores

Question 19

If the BMW Hydrogen 7 consumes an average of 13.7 L/100 km when

Question 20

Consider a simple model of the burning of butane as the oxidation of the