Exam Questions
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Exam Questions

In the following pages the student questions found at the end of the book are reproduced. This has been done to help lecturers prepare worksheets and exam questions without having to re-type questions out (just cut and paste them). Please acknowledge the source or any questions used.

2. What is Energy

  1. How much mass and energy did the sun need to lose in order to boil an electric kettle back on earth? Estimate the efficiency of this whole chain.

  2. How can the equation E=mc2 be used as a definition of energy? Why is this not as useful a thing to do as it might seem?

  3. What is the difference between energy and power? Give an example of both.

  4. List the seven forms of energy described above and give at least one equation involving each.

  5. What is exergy and why is it important?

  6. A body of mass 100 kg initially rests on a ledge 100 m above the ground.  It then falls freely to the ground under the influence of gravity.  Air friction may be neglected [adapted from SHE97]. 

a)       What are initial and final values of the potential energy?

b)      What are initial and final (i.e. just before impact) values of the kinetic energy?

c)      Calculate the instantaneous velocity at the mid-point of the fall. (Hint: Use energy balance.)

d)      Calculate the values of potential energy and kinetic energy at the mid-height of the fall.

7. A litre of water is uniformly heated so that its temperature increases by 20°C.  What is the rise of its heat energy content? [Adapted from SHE97]. 

 8. A modern electric power station has a full load of 2000 MW.  What are the equivalent values in [from SHE97]:  

a)       Horsepower?

b)      Joules/sec?

c)      kilowatts?

d)      foot-pounds/second?

 9. A large wind turbine at Burger Hill, Orkney , Scotland , is rated at 3 MW.  What is the equivalent rating in horsepower [from SHE97]?

3. The planet’s energy balance  

  1. Produce a table categorizing energy flows on Earth as either solar in origin, or not.
  2. Describe the major structures and processes within the sun.
  3. Describe the key features of the following energy resources: sunlight, rain, wind, the oceans, tides, organic matter and the Earth’s internal energy.
  4. For each of the resources mentioned in Question 3, list any environmental, physical or technological problems that might restrict their use. (This has yet to be covered in the text, so use a mix of imagination and rational thought.)
  5. The daily output of energy from the Sun is 3x1032J.  What fraction of this is intercepted by the Earth [from SHE97]?

4. A History of humankind’s use of energy

  1. In what ways does energy use and innovation drive history?
  2. What are the two central physiological advantages of humans that allow us to run at a variety of speeds?
  3. What changes in technology and practice are required to increase the amount of food raised per human from an early farm?
  4. Ignoring their work capacity, what limits horses from being the perfect agricultural prime mover?
  5. Describe the form, speed, power and manning of classical Greek warships.
  6. Why were the combining of various metals and the invention of the steam engine important to metal production?
  7. Why was coal not initially used in iron production?
  8. What key advantages did steam engines offer over water and wind machines?
  9. How did changes in agricultural practice allow cities to increase in size?
  10. How much primary energy do we use today? How is this use shared amongst fuels and regions? Is the current situation equitable?

 

5. Sustainability,  climate change and the global environment

  1. Define sustainable. What characteristics might a sustainable energy technology have?
  2. (Only for those with suitable computer skills.) Write a simple computer program or spreadsheet that randomly assigns a number of rainy days to each month in the last 300 years and calculates how many years one has to look back to find the same month (January, February, ….) that has as least as many rainy days. Plot the number of years one had to look back against the month in question for the last 100 years.
  3. Describe the natural greenhouse effect.
  4. How do anthropogenic emissions enhance the natural greenhouse effect?
  5. What evidence is there for the natural greenhouse effect?
  6. What evidence is there for the anthropogenic greenhouse effect?
  7. Why might changes in surface albedo change global mean air temperature? Outline which natural surfaces might change in albedo under the influence of climate change and whether they might provide a positive or negative feedback.
  8. Describe the carbon cycle.
  9. In what way does permafrost act as an indicator of climate change and how might it produce a positive feedback?
  10. Outline the most common climate feedback processes detailed in the text.
  11. What are the most important anthropogenic greenhouse gases, what are their global warming potentials and what are their contributions to climate change?
  12. What is meant by radiative forcing?
  13. What is acid rain?
  14. Discuss some of concerns other than climate change that make energy provision typically unsustainable.
  15. Expand the model you built for Problem 5.2 to include the additional radiative forcing from anthropogenic greenhouse gas emissions (see Problem 5.4). This is best done by adding four times the additional forcing to the Solar Constant, S (1370 W/m2), in your atmospheric model. (The factor of 4 is needed because the solar constant is defined in terms of the radiation falling on a disk, not a sphere, at the distance the Earth is from the sun.) Use your new model to examine the likely temperature rise if carbon dioxide concentrations reach 550 ppm.
  16. Use the model you built for Problem 5.2 and Exercise 15 to estimate the change in height of the emission level compared to pre-industrial times. (Hint: calculate the change in emission level that gives the same temperature change as the additional radiative forcing (Exercise 15), and assuming the emission level was previously at 5.5 km. This can be done by estimating the temperature of the emission level from the lapse rate, its height (5.5 km) and the pre-industrial surface temperature, then seeing from what height one needs to descend (at the lapse rate) to give a surface temperature similar to the post-industrial value.)

 

6. Economics and the environment  

  1. Supply and demand curves have different signs. Why?
  2. Given a country with a GDP of €3 billion and €0.5 billion of money in circulation, what is the velocity of money in the country?
  3. (i) If spending €100 on insulation will save a household €25 per annum on heating bills, calculate the simple pay-back period of the insulation. (ii) If the embodied energy of the insulation (which lasts only a single year) is 1 kWh per cm of depth, and each cm applied will save 2 kWh/d, (where d is the depth in cm), what is the maximum sensible depth of insulation to the nearest cm? There are several answers to this question—discuss their differences.
  4. Explain what is meant by the “tyranny of discounting”.
  5. Given a discount rate of seven percent, what is the greatest sum it is economically worth spending now to stop an environmentally damaging event costing €100,000 from occurring in ten years time?
  6. Describe the relationship between sustainable development and technological change.
  7. Define ISEW. If the ISEW of a country is falling, yet GNP rising, what does this probably imply about the country’s environment?
  8. Why are tradable permits possibly not always a guaranteed way of improving local air quality?

7. Combustion, inescapable inefficiencies and the generation of electricity  

1.       What are the main products of burning fossil fuels?

2.       What is a stoichiometric mixture?

3.       Why is the efficiency of any power station that uses heat to make electricity likely to be very low? What are the likely physical and engineering limits to greatly improving such efficiencies?

4.       How can using electricity derived from fossil fuels to heat a home be more efficient (in terms of mass of carbon dioxide emitted) than using the same fossil fuels directly to heat the home?

5.       Outline with one or more sketches the form of a power station and a national grid. Include relevant temperatures, voltages, etc.

6.       Why do the interconnectors joining countries use d.c rather than a.c?

7.       In the UK the original steam engines designed by Watt and Newcomen used reservoir temperatures of 100°C and 10°C.  What was the maximum theoretical efficiency? [from SHE97]. 

8.       A Carnot Engine has a low temperature sink of 10°C and a maximum theoretical efficiency of 38%.  By how much does the temperature of the high temperature source need to increase in order to raise the efficiency to 50%? [from SHE97]. 

9.       Why do long-distance electrical transmission lines operate at high voltages?

10.   Discuss the main considerations in choosing a suitable location and site for an electrical power generation plant.

8 Coal  

1.       What are the main products of burning fossil fuels?

2.       What is a stoichiometric mixture?

3.       Why is the efficiency of any power station that uses heat to make electricity likely to be very low? What are the likely physical and engineering limits to greatly improving such efficiencies?

4.       How can using electricity derived from fossil fuels to heat a home be more efficient (in terms of mass of carbon dioxide emitted) than using the same fossil fuels directly to heat the home?

5.       Outline with one or more sketches the form of a power station and a national grid. Include relevant temperatures, voltages, etc.

6.       Why do the interconnectors joining countries use d.c rather than a.c?

7.       In the UK the original steam engines designed by Watt and Newcomen used reservoir temperatures of 100°C and 10°C.  What was the maximum theoretical efficiency? [from SHE97]. 

8.       A Carnot Engine has a low temperature sink of 10°C and a maximum theoretical efficiency of 38%.  By how much does the temperature of the high temperature source need to increase in order to raise the efficiency to 50%? [from SHE97]. 

9.       Why do long-distance electrical transmission lines operate at high voltages?

10.   Discuss the main considerations in choosing a suitable location and site for an electrical power generation plant.

 

9. Oil  

  1. If OECD countries produce only a third less oil than OPEC countries, why does the majority of the power to influence oil prices lie with OPEC?

  2. Describe the geological structures in which oil is found and how it is extracted. (Include a description of primary, secondary and tertiary methods.)

  3. How, and why is crude oil distilled?

  4. Outline the workings of an internal combustion engine. Estimate the Carnot efficiency of such an engine and compare this to typical efficiencies.

  5. If an oil super-tanker can transport 200,000 tonnes of crude oil per journey, how many tanker-journeys would be needed to meet the USA oil import figure for 2004? [Adapted from SHE97]. 

  1. Why does the USA have such a large per capita consumption of oil compared with the rest of the world?

 

10. Gas  

  1. What is natural gas, and how is it formed?
  2. What advantages and disadvantages does natural gas have over oil?
  3. What is the difference between a condensing and a non-condensing boiler?
  4. Use the data in Appendix 1 to list, in order, the world’s ten largest producers and consumers of natural gas.

11. Non-conventional hydrocarbons

  1. Describe the form, location and size of non-conventional carbon resources.
  1. Describe the processing required to access these resources and any advantages or disadvantages the geographic location of these resources might have for world political stability.
  1. Produce a histogram comparing the world’s oil, gas, coal and non-conventional fossil fuel reserves (resources for the non-conventional fuels).

12. Nuclear power  

  1. Describe the form, location and size of non-conventional carbon resources.
  1. Describe the processing required to access these resources and any advantages or disadvantages the geographic location of these resources might have for world political stability.
  1. Produce a histogram comparing the world’s oil, gas, coal and non-conventional fossil fuel reserves (resources for the non-conventional fuels).

13. Hydro-power  

1.              Describe the characteristics of the three common approaches for the converting of potential energy of water into rotational energy.

2.              Which gives the greater increase in power, doubling the flow or doubling the head? (Given the relevant equations.)

3.              Outline the character of the power station with the largest installed capacity in the world.

4.              Discuss the environmental impacts of hydropower.

5. A hydro-electricity supply system has an overall efficiency of 82%.  If the effective head of water is 500 m, calculate the volumetric flow rate needed to generate 300 MW of electrical power. [From SHE97]. 

6. The volumetric flow rate of water in a hydro-electric scheme is 50 m3/s.  The overall efficiency of the turbine, generator and pumped storage motor is 72%.  If the electric power output is to be 150 MW, what head of water is required?  (r = 1000 kg/m3,  g = 9.81 m/s2). [From SHE97].

7. What types of water turbine would be likely to be used in a location where the available head of water is [from SHE97]:

a)              10 m?

b)              100 m?

c)              1000 m?

8. The mean height of the feeder reservoir in the Dinorwig pumped storage hydro-electrical scheme is 568 m.  At rated load the overall efficiency is 86%.  If the plant operates for 5 hours, delivering 1750 MWe, what mass of water has passed through the turbines?  What has been the flow rate? [From SHE97].

9. Estimate the hydro-electric potential of an area or location, chosen from an atlas. Use the following technique, having chosen location X. [From SHE97].

 i)                    What is the lowest altitude of X?

ii)                    What area of X lies more than 300m above the lowest level?

iii)                    What is the annual rainfall on the high parts of X?

iv)                    If all of the rainfall ran to the lowest level, what amount of potential energy per year in MW would be given up by the moving water?

v)                    What factors would prevent all of the rainfall being converted to electricity?

vi)                    Estimate the fraction of the rainfall potential energy that might be convertible to electricity.

vii)                    If your selected location X already contains a hydro-electric power station, compare your estimate of its potential capacity with the station rating. Comment on any large differences.

14. Transport and air quality

  1. How has the need for transport grown in the developed world over the last fifty years? (Use the UK as an example.)
  2. Using the data in Figure 14.4, apportion all travel to the categories business/education or personal.  Which is the greater fraction?
  3. List the major air pollutants from transport systems and describe their health impacts.
  4. Describe (with chemical formulae) how catalytic converters work.

15. Figures and philosophy: an analysis of a nation’s energy supply  

  1. Outline how employment in energy industries, energy production and energy consumption has changed in the UK (or your nation) since 1980.
  2. Are there any ethical questions about a country trading in fossil fuels? What are your thoughts about your own use of fossil fuels?
  3. How have UK (or your own nations’) fuel prices changed since 1980?
  4. What is energy intensity and how has it changed in the UK (or your country) since 1980?
  5. Compare the proportions of prime fuels used for electricity generation in the UK between 1980 and 2004.  What are the present trends?

16. Future world energy use and carbon emissions

  1. By drawing distinctions between the developed, transition (Eastern European and former Soviet Union states) and developing world, discuss how the EIA views future levels of car ownership, car use and carbon intensity.
  2. Produce a quantitative and qualitative analysis of the illustrative IPCC scenarios discussed in this chapter.

17. The impact of a warmer world  

  1. Describe the principles and assumptions behind a modern climate model.
  2. Discuss why climate models help to prove the case for anthropogenic climate change.
  3. Detail how temperature, precipitation, crop yield, water resources and sea level are likely to change 2080 and how this will affect humanity. (This could either be in table or essay form).
  4. Describe the predicted size and role of the terrestrial carbon store over the period 2000-2080.
  5. As a fraction of their wealth, who will pay the majority of the costs of climate change—the developed or the developing nations? (Hint: consider the results from IAMs.)

18. Politics in the greenhouse: contracting and converging  

  1. Explain the logic behind the USA not ratifying the Kyoto protocol.
  2. Outline why it is difficult to get agreement amongst nations to reduce emissions.
  3. Outline the process of contraction and convergence.
  4. Why might some consider C+C unfair to many developing nations?

19. Energy efficiency  

1.         Why is it particularly important to ensure that there is no unnecessary energy use in air conditioned buildings?

2.         What are the three forms of heat loss? Give examples of their reduction within buildings.

3.         When is cogeneration likely to be successful?

4.         Discuss the various types of heat exchanger and when they might be used.

5.         Estimate the likely primary energy and carbon dioxide saving in your country if all the tungsten light bulbs found in domestic properties were replaced by compact fluorescents (remember to include the efficiency of electricity generation).

6.         What is embodied energy?

7. A classroom of area 150 m2 is illuminated by 20 standard incandescent lamps rated at 100 W with an illuminance of 1200 lumens and an efficacy of 12 lm/W.  Each lamp costs 50p and is switched on for 8 hours/day, 5 days/week, 40 weeks/year. [adapted from SHE97]. 

 a)         If electricity costs 7 p/kWh calculate the annual running costs.

b)         If the life expectancy of a lamp is 1000 hours and the replacement labour cost is £5 per item calculate the annual replacement cost.

c)         Calculate the total annual electricity costs.

 8. An alternative plan to light the classroom from the previous problem is to use 30 fluorescent tubes, rated at 70 W with an illuminance of 4500 lumens and an efficacy of 64 lm/W.  Each fluorescent tube costs £4 and has a life expectancy of 10,000 hours [adapted from SHE97].

 a)         Calculate the annual running costs if the electricity tariff is 7 p/kWh.

b)         Calculate the annual replacement cost if the replacement labour charge remains at £5 per item.

c)         Calculate the total annual electricity costs.

 9. Compare the performance of the incandescent lamp system with the corresponding fluorescent lamp system. [Adapted from SHE97].  

 a)         What would be the annual cost saving in moving to the fluorescent system?

b)         The cost of the modified installation would be £660.  Neglecting the effects of inflation and depreciation and ignoring any scrap value of the incandescent system, what would be the payback period of the modification?

c)         Compare the illuminance of the classroom using the two systems.

20. Solar  

1.                   Why does good passive solar design require an holistic approach to building design?

 2.                   Why might a South facing window be a provider of energy in winter in Southern France but not in the UK ?

3.                   The land area of Kenya is 570,000 km2. Assuming the country receives solar energy at a rate of at least 250 W/m2, estimate the total solar energy received and compare this value with total Kenyan energy demand (Appendix 1).

 4.                   How could the performance of a solar water heater be improved? Does it always make sense to reduce the collector temperature to improve the efficiency?

5.                   Assuming an efficiency of forty percent, what area of collector might be needed to heat 200 litres of water in southern Australia by 30°C in two hours?

 6.                   Ignoring any inefficiencies or losses, how long would it take in theory for the Odeillo solar furnace to boil one kilogram of water originally at 20°C?

 7.                   Estimate the solar energy provided by all the world’s windows. Don’t forget to include heat losses from these windows. Compare your answer to world primary energy demand.

8. A solar collector is mounted at an inclination of 45° to the horizontal.  If the sun rises to an inclination of 54° above the horizon what proportion of the radiation is then falling normally onto the collector? [From SHE97].

 9. A solar collector in Northern England is mounted with its axis inclined at 54° to the horizontal.  If the total annual radiation energy on a horizontal surface is 1000 kWh/m2, divided equally between direct and diffuse components, what is the radiation received by the collector? [From SHE97].

 10. A flat-plate solar collector, mounted at the latitude angle and south facing, has an effective area of 2 m2.  Water is pumped in through this collector at the rate of 20x10-6 m3/s and the mean temperature difference between the inflow and outflow is 18.4°C.  The collector is used to heat indirectly the water in a storage tank of capacity 50 gallons (227 litres) for 5 hours continuously.  If the system operates at a typical efficiency, calculate the temperature rise in the storage tank.  What is the power rating of the flat-plate collector in W/m2? [From SHE97].

 11. A solar collector is to be mounted on the south-facing roof of a dwelling, feeding a storage tank with a capacity of 30 gallons (136 litres).  The circulating pump is to operate at the rate of 20x10-6 m3/s.  On a warm, sunny day the difference of water temperature between the inflow and outflow at the collector is typically 15.5°C and this difference exists for 6 hours.  What is the operating efficiency of the system if the temperature of the water in the storage tank is increased by 20°C? [From SHE97].

 12. It is proposed to use a roof-mounted solar water-heating system to supplement the energy input into certain industrial process. The south-facing solar collector is to be used to heat indirectly the water in a storage tank of capacity 5000 gallons (22,700 litres).  Water can be pumped through the collector by a range of available water pumps.  On a typical summer day, there are 5.6 hours of sunshine which causes an average temperature difference of 16.5°C between inflow and outflow of the collector. [From SHE97].

 a)                   If the anticipated efficiency of the system is 42.6%, what rate of water pump flow in m3/s is needed to cause a temperature rise of 12°C in the storage tank?

b)                  If this pump is used and the temperature of the storage tank becomes 14.5°C, what is the efficiency of the collector system?

 13. Give a broad specification for a solar water heating installation for a typical UK domestic dwelling (i.e. three-bedroom, semi-detached house) occupied by four persons.  In particular, specify the necessary area of collector and the capacity of the supplementary water tank.  The installed commercial cost is quoted at £3200.  Estimate the pay-back period if the household is (i) a heavy user of hot water, (ii) a light user of hot water. [From SHE97].

 14. A flat-plate collector of area 2 m2 has a water inflow temperature of 15°C and an outflow of 49°C while the incident radiation is constant at 725W/m2.  Calculate the approximate thermal efficiency. [From SHE97].

 15. The absorber of a solar concentrator system operates at 550°C.  The collector receives 200 W/m2.  If the concentrator ratio is 50 and the absorber emissivity is 0.05, what proportion of the input power is re-radiated?  [From SHE97].

 16. A solar power tower plant receives an effective average radiation of 1000 W/m2 from its concentrator collectors.  The conversion efficiency of the collector heliostats into thermal energy is 53%.  If the plant fluid operates at 600°C and the sink temperature is 100°C, calculate the area of heliostats and the land area required to generate 100 MW of thermal power.

21. Photovoltaics  

  1. Compare the efficiencies of a polycrystalline silicon photovoltaic cell at 20°C (where its efficiency is ten percent) with that at 35°C and 50°C. Estimate the maximum energy that could be used by a cooling system in these two cases that would still be energetically worthwhile.
  2. Describe how a photovoltaic cell works.
  3. Describe and contrast crystalline, polycrystalline and amorphous silicon photovoltaic cells.

22. Wind  

1.                   Summarise the effect of various parameters on the cost of a modern wind turbine.

2.                   Explain quantitatively why a wind turbine can never have an efficiency of greater than fifty percent?

3.                   At what rate does aerodynamic noise from a wind turbine increase with tip speed? What limit does this place on tip speeds and under what wind conditions is this most important? How does this limit reduce the possibility that such a machine can trigger an epileptic event?

4.                   Outline the major concerns over wind power (one paragraph on each).

5.                   Outline your personal feeling about wind power and its impact on the countryside.

6.                   What is meant by the re-democratisation of the energy supply?

7.                   How many birds might be killed in your country per annum if 10% of electricity were produced from wind power? (Hint: find your nation’s electricity demand by searching the web.)

8.                   (i) Given an average wind speed of 10 m/s and a wind turbine with a swept diameter of 20 m, and assuming an efficiency of extracting energy from the wind of forty percent, how much power might such a turbine produce? (ii) If the wind speed were to increase to 15 m/s, how much might now be produced? (iii) Assuming the turbine were to operate seventy percent of the time and the electricity produced be sold at £0.05 per kWh, how much extra money per annum might be generated by this relatively modest increase in wind speed?

9.                   Estimate the sound pressure level at a house 400 m from the edge of a 49 turbine wind farm laid out on a square grid. Assume the machines have a swept radius of 40 m and produce a sound power level of 100 dB(A). Might this level be likely to cause complaint?

 10. Estimate the diameter of a wind turbine that would generate 10 MW of electrical power in a 15m/s wind. [Adapted from SHE97].

 11. A large propeller-type wind turbine has a diameter of 70 m. If the speed of rotation at full-load is regulated to 32 rpm when the speed is 48 km/h, what then is the value of the tip-speed ratio? [Adapted from SHE97].

 12. A two-blade propeller is used as a wind turbine directly on the shaft of a small electric generator.  Assign typical efficiencies to the wind turbine and the generator and calculate the blade diameter required to generate 500 We in a wind of average speed 25 km/h. [Adapted from SHE97].

23. Wave  

  1. Estimate the minimum length of wave power device capable of replacing all of Norway ’s electricity generation (107 TWh).

  2. Describe the major wave power technologies.

  3. Compare (using Equation 23.4) the power extractable from the following typical Atlantic wave conditions (period, s ;height, m): storm (14, 28), average (9, 7), calm (5.5, 1). What does this say about the robustness of any design.

4. What is the power extractable from a deep-sea wave system of wavelength 140 m and height 3 m? [From SHE97].

 5. The western coast of Scotland is struck by Atlantic waves of theoretical maximum power 70 kW per metre of wave width.  If a typical wave height is 2 m what are the corresponding frequency and periodic time?  Estimate the realistic power available on-shore. [From SHE97].

 6. Estimate the necessary length of a proposed wave-power receiver station to collect 10 MW of usable power if the maximum theoretical power is 70 kW/m. [From SHE97].

24. Tidal and small scale hydro  

  1. Why are the tides dominated by the moon rather than the sun?
  2. Why is the tidal range greater in the Atlantic than the Pacific?
  3. What advantages and disadvantages does tidal power have over wind power? (Don’t forget to consider the densities of the media.). Explain the natural symbiosis that could exist between the two.

  4. Why do tidal dams require a greater number of turbines than traditional hydro-power stations?

5. In a pumped storage scheme combined with a tidal power project water is pumped from the high tide level to an additional height of 1 m.  The tidal range is 6 m.  Calculate the proportion of extra energy gained [From SHE97]:

 a)       Neglecting losses

b)      If the pump motor is 80% efficient

 6. The mean tidal range of the Rance scheme is 8.45 m and its basin area is 22 km2 If the mean output is 75 MW, what proportion of the theoretical power capacity does this represent? [From SHE97].

 7. Calculate the electrical power output from the proposed Severn estuary tidal power scheme in Britain if the mean tidal range is 8.8 m and the basin area is 50 km2. [From SHE97].

 8. In North America the Bay of Fundy-Passamaquoddy area near the border of New Brunswick and Nova Scotia in Canada , and Maine in the USA , is considered to be a prime tidal power site.  It has a basin area of 700 km2 with an average tidal range of 10.8 m.  Calculate the theoretical maximum power capability and the estimated realistic power available. [From SHE97].

25. Biomass  

1.                   Outline how photosynthesis works.

2.                   Show how the basic efficiency of photosynthesis can be estimated for first principles, then continue the estimation to include other less fundamental factors.

3.                   From a biomass perspective, describe combustion, pyrolysis, gasification, fermentation and digestion.

4.                   Compare biomass use within the industrialised nations on a per capita basis and a percentage of national energy use basis.

5.                   How much of your country’s land area would be required to replace fossil fuel use by biomass?

6. In a country where there is about 28 million tonnes of domestic waste each year and the energy efficiency of collection is 50% how much energy in kWh is potentially available? [adapted from SHE97].

 

26. Geothermal  

1.                   Describe the current structure of the planet.

2.                   What are the two sources of energy that are accessed by geothermal power? Estimate the size of each.

3.                   Outline the geology and technology required by both a hot and a dry-rocks approach to geothermal power.

4.                   Summarise the design of the Hacchobaru geothermal power station and the uses for which water in the temperature range provided by wet-rock technologies could be used (not just what it is used for in Kokonoe-Machi).

5. Why does water in the geothermal aquifers remain in the liquid state even though its temperature may be much higher than 100°C? [From SHE97]. 

6. A geothermal district heating scheme issues a flow rate of 22.5 litres/sec with a well-head temperature of 70°C.  It rejects water at 40°C and runs for a period of 162 days/year.  If the overall combustion efficiency of an oil burner is 73%, how much oil is saved per year?

27. Fast breeders and fusion  

  1. Why are fast breeder reactors so called?
  2. What advantages do fast breeder reactors have over thermal fission reactors?
  3. Outline the reactions behind fusion in the Sun and on Earth.
  4. Discuss how heat might be extracted from a fusion reactor and the scale of the world resource.
  5. Why is fusion unlikely to be a “solution” to climate change?
  6. What are the two main roles lithium plays within a fusion reactor?

28. Alternative transport futures and the hydrogen economy  

  1. Estimate the charging time required to give an electric car a range of 300 km, if charged through a domestic 13 amp socket.
  2. Why does a switch to fossil-fuel derived methanol as a road transportation fuel make environmental sense and pave the way to a sustainable alternative?
  3. Detail the four main types of losses from a hydrogen-oxygen fuel cell.
  4. Produce a table that contrasts the reactions, tolerance to impurities, temperatures, electrolytes, catalysts and other pertinent data for the various fuel cells discussed in the chapter.
  5. Explain what is meant by “the greening of natural gas”. What is its main attraction as a way of reducing carbon emissions compared with other sustainable technologies?

29. Carbon sequestration and climate engineering  

  1. Compare and contrast the various sequestration options available.
  2. Is it possible to solve carbon dioxide related climate change by sequestration? (Hint: compare anthropogenic emissions of carbon dioxide with the world’s sequestration potential for each storage approach.)
  3. If sequestration were fully implemented, would the world still have a potential climate problem from the emission of other greenhouse gases?
  4. Why would the reflection of sunlight before it reaches the Earth not truly solve climate change?

30. A sustainable, low carbon future?  

  1. Why does the above analysis assume that energy use in industrialised countries such as the UK will not increase greatly in future years? Present percentage change figures for GDP, energy supply and energy use to support your case.
  2. Produce a table that compares the UK fuel mix in 2000 with that expected in 2050 under the low-carbon scenario.
  3. Why is the cost of nuclear power critical to a discussion of the future energy mix? Present, qualitatively, possible future fuel mixes given nuclear power costs of €0.035 and €0.049/kWh.
  4. Why is it important for us to make reductions early? Quantitatively, what is the economic benefit to the UK of doing so?
  5. Why might supply-side efficiency decline under a low-carbon scenario?
  6. For each of Pacala’s and Socolow’s Options, list any issues or problems that you see.

 

Appendix 1: Country Specific Energy Data

Appendix 2: Answers to In-Text Problems

Appendix 3: Bibliography and Additional Reading