This presentation is an introduction to the sustainable energy challenge. It gives an overview over fossil fuels, the laws of energy, energy efficiency and conservation, and renewable energy sources. The focus is on providing students with the scientific tools for understanding the magnitude of the challenge and analyzing potential solutions.

1. The Sustainable
Energy Challenge

2. Lecture Series in Sustainability
Science
by
Toni Menninger MSc
http://www.slideshare.net/amenning/
toni.menninger@gmail.com
The Sustainable
Energy Challenge

3. The Sustainable Energy Challenge
1. The Age of Fossil Fuels
2. Energy use in global perspective
3. The Sustainable Energy Challenge
4. Review: The Laws of Energy
• The Law of Energy Conservation
• Energy Transformations
• The Second Law
• Heat Engines
• Conversion efficiency
• Energy Return on Investment (EROI)

4. The Sustainable Energy Challenge
5. Energy Efficiency potentials
• Systemic approaches
• Individual approaches
6. Economic Considerations
• External Costs of Energy
• Energy Taxes
• Energy Subsidies
7. Power sources
• External Costs of Energy
• Energy Taxes
• Energy Subsidies
8. Conclusion: Does “Clean Energy” Exist?

5. The Sustainable
Energy Challenge
Oil rig explosion in Gulf of Mexico, April 20, 2010

6. The Sustainable Energy
Challenge
Mountaintop removal coal mining in West Virginia, 2003

7. The Sustainable Energy
Challenge
Fukushima nuclear disaster, March 2011

8. The Sustainable Energy
Challenge

9. The Sustainable Energy
Challenge

10. The Sustainable Energy
Challenge

11. Fossil fuel combustion is the main cause of climate
change and a main cause of air and water pollution and
acid rain
Mining and extraction of fossil fuels is ecologically
and socially destructive: e. g. mountain top coal mining
in the Appalachians, oil spills, coal mine accidents, oil
rig explosions, social unrest (e. g. Nigeria), geopolitical
instability (Iraq, Iran, Central Asia etc.), petro
dictatorships in the Middle East...
Fossil fuels are nonrenewable resources and their
continued use is not sustainable.
The Fossil Fuel Paradox: There is too much and not
enough of it… More than enough to destabilize the
climate system but not enough to preserve our current
oil-dependent lifestyle much longer
The Age of Fossil Fuels

12. Worldwide oil production is expected to peak in the near
future. Although coal is still relatively abundant and
“nonconventional” oil sources may increasingly be
exploited, the era of “cheap oil” is probably over.
Industrial civilization
has been enabled by
a “fossil fuel subsidy”
- sunlight
concentrated and
stored in deposits of
hydrocarbons that
are relatively easily
accessible, easy to
transport, store, and
use.
The Age of Fossil Fuels

13. Oil discovery rate is declining (Hall and Day, American
Scientist 2009)
Peak Oil ?

14. Energy return
on investment
(EROI, EROEI)
is declining
(Hall and Day,
American
Scientist 2009
– required
reading)

15. Petroleum Consumption by the
numbers
• Global supply 2010: 88 million barrels a day ,
or 32 billion barrels a year
• Total US demand : 19 million barrels a day, or
7 billion barrels a year
• The USGS estimates 5 – 16 billion barrels
recoverable in the Arctic National Wildlife
Refuge (ANWR) How long does that last?

16. Source: Tom Murphy
Can we
replace fossil
fuels with
renewables?
The Sustainable Energy Challenge

17. The Sustainable Energy Challenge
Can we meet
the global
energy need at
US consumption
level?
Source: Tom Murphy

18. Energy use in global perspective
http://en.wikipedia.org/wiki/List_of_countries_by_energy_consumption_per_capita
Google public data explorer
Total energy consumption per capita by US state

19. Energy use in global perspective
Google public data explorer

20. Industrial civilization is based
on fossil fuel energy
Primary energy use in more and in less developed countries

23. Tropical deforestation accounted for 10 percent of global
carbon dioxide emissions between 2000-2005 — a
substantially smaller proportion than previously estimated
— argues a new study published in Science.
Read more at http://news.mongabay.com/2012/0621-carbon-emissions-from-
deforestation.html#7lxeme2XSOxrLXg0.99
Gross annual carbon emissions resulting from gross forest cover loss and peat
drainage and burning between 2000 and 2006 in Giga Tons Carbon per year

24. Global Warming: what to do?
● Reduce greenhouse gas emissions (reduce fossil
fuel use, stop deforestation)
● Enhance natural carbon absorption by soil and
vegetation (reforestation, forest management,
conservation tillage, biofuels from algae)
● Technically remove greenhouse gases from the
atmosphere (“carbon sequestration”, “carbon
capture and storage”)
● Try to counteract warming trend with artificial
cooling (“geo-engineering”)
● Do nothing, hope for the best, try to adapt
(“business as usual” (BAU))

25. “Stabilization wedges” proposed by Pacala and
Socolow (Science, 2004)

26. “Stabilization wedges” proposed by
Pacala and Socolow (Science, 2004)
● Wedges 1-4: Energy efficiency and conservation
● Wedge 5: Fuel shift from coal to gas
● Wedges 6-8: Carbon capture and storage (CCS)
● Wedge 9: Nuclear fission
● Wedges 10-13: Renewable energy
● Wedges 14-15: Forests and agricultural soils

27. Key to a sustainable energy
future: large improvements in
energy conservation and the
transition to a “low-carbon”
energy economy.
The Sustainable Energy
Challenge

28. The Sustainable Energy
Challenge
What is “clean”/ ”sustainable”
energy?
How do we define + measure
“energy sustainability”?

29. Sustainable energy considerations
• Energy efficiency
• Availability, intermittency
• Transport, storage
• Environmental impact (pollution, biodiversity)
• CO2 Emissions (based on Life Cycle Analysis)
• Land use intensity
• Material resource requirements
• Energy return on energy investment (EROI)
• Economic cost
• Social acceptance
• … … …

30. Sustainable energy considerations:
Carbon emissions
• Natural gas (methane)
emits less pollution and
less CO2 per unit of
energy compared to coal.
• But it is a potent
greenhouse gas.
Methane leakage
might cause more harm
than is avoided through
fuel shift.

31. Sustainable energy considerations:
Carbon emissions
• Nuclear, wind, solar and hydro power generation
do not emit CO2 during operation but indirect
emissions from the life cycle must be taken into
account. Results are contentious.
World Nuclear Association Oxford Research Group

32. Land use intensity of selected power sources
“Energy Sprawl or Energy Efficiency”, McDonald et al., PLOS One 2009

33. Review: The Laws of Energy
• Energy is a physical entity that can be
measured and quantified.
• Energy (Work) is defined as a force
(measured in N [Newton]) acting through a
distance and measured in J [Joule]:
1J=1Nm
• Power is a measure of
energy flow over time,
measured in W [Watt]:
1 W= 1J/s
Required reading: Energy Literacy

34. Review: The Laws of Energy
• A vehicle must expend mechanical energy
to overcome the forces of friction and air
resistance.
• To climb stairs, you have to expend
energy to overcome the gravitational
force. The amount of gravitational energy
is proportional to the weight of the body
and the vertical height traveled.
• Hydropower generation is proportional to
the height of the dam and the mass of
the water running through turbines.

35. Review: The Laws of Energy
Different kinds of energy have been
measured in different units (Btu, kWh, kcal)
but they can all be converted into each other.
• Mechanical energy (work)
• Heat (Thermal) energy
• Kinetic energy
• Gravitational energy
• Radiation
• Chemical energy
• Electric energy

36. Review: The Laws of Energy
(The Laws of Thermodynamics)
First Law (Law of energy conservation):
Energy can be neither created nor destroyed, only
transformed.
The conversion efficiency
is the percentage of
“useful” energy
efficiency=
𝑜𝑢𝑡𝑝𝑢𝑡 𝑒𝑛𝑒𝑟𝑔𝑦
𝑖𝑛𝑝𝑢𝑡 𝑒𝑛𝑒𝑟𝑔𝑦
x 100

37. Review: Energy transformations

38. Review: The Laws of Energy
Second Law of Thermodynamics (Law of
entropy):
• Heat energy flows spontaneously from higher to
lower temperature but not the other way.
• Heat cannot be completely converted to
mechanical energy. The conversion efficiency of a
heat engine cannot exceed the Carnot efficiency
(1 − 𝑇𝐶/𝑇𝐻), the rest is lost as waste heat.
• The entropy (“disorderliness”) of a closed system
can only increase. High-grade (useful) energy is
dispersed into low-grade (waste) energy.
Decreasing entropy requires importing energy.

39. Review:
Heat engines
The energy conversion process from heat
to mechanical energy taking place in a heat
engine necessarily involves a loss of waste
heat. Carnot's law states that the maximum
conversion efficiency ( )that a heat engine
can achieve depends on the difference
between the absolute temperatures of the
hot (TH) and the cold (TC) reservoir :
Absolute temperature is
measured in Kelvin.
Tabs=Tcelsius+273.15

40. Implication of the Second Law
Heat engines (combustion motor and thermal
power plant) are inherently inefficient! A large
part of the heat energy is lost, unless it can be
made useful for heating (CHP – Combined Heat
and Power)
TH typically 350-550 ºC, about 600-800 K; TC about 25 ºC or
300 K. Optimal efficiency 50-60%, actual efficiency 15-40%.

41. Process Energy efficiency Theoretical limit
Photosynthesis Up to 6%
Muscle 15% - 25%
Internal combustion engine 15% - 20% 55% (Carnot efficiency)
Electric car up to 80%
Thermal power plant 30% - 40%
global average 32%
≈60% (Carnot efficiency,
depends on temp.)
Cogeneration (CHP) Up to 90%
Hydropower plant 80% - 95%
Wind turbine 15% - 35% 59%
Photovoltaic cells 10% - 15% 35% (with caveats)
Solar water heater 50% - 75%
Electric heater 100%
Gas or wood heating (modern) 75% - 95%
Heat Pump COP (Coefficient of Performance) > 1
SEER (Seasonal Energy Efficiency Ratio)
Conversion efficiency

42. Energy return
on investment
(EROI, EROEI)
is declining
(Hall and Day,
American
Scientist 2009
– required
reading)
EROI corn ethanol 1.3:1
http://ngm.nationalgeographic.com/2007/10/biofuels/biofuels-interactive

43. EROI - Energy Return on Investment
• The Energy Return on Investment
(EROI/EROEI) is the energy cost of
acquiring an energy resource. It is not the
same as Energy Efficiency.
• EROI is the ratio of the amount of usable energy
acquired from a particular energy resource to the
amount of energy expended to obtain that energy
resource. Example: EROI = 4 means that each unit of
energy invested yields 4 units of output. Conversely, net
energy output is 75% of gross energy output.
• An “energy resource” with an EROI < 1 is a net sink of
energy.

44. Energy Efficiency potentials: systemic
approaches
● Co-generation (Combined Heat and Power, CHP

45. Energy Efficiency potentials: systemic
approaches
● Co-generation
(Combined Heat and
Power, CHP)
● “Smart Grid”: smooth out
demand curve by giving
incentives to consumers,
efficiently controlling energy
flow during peak demand.
Reducing peak demand will
significantly improve overall
efficiency
http://www.oe.energy.gov/S
martGridIntroduction.htm

46. Energy Efficiency potentials: systemic
approaches
● Co-generation (Combined
Heat and Power, CHP)
● “Smart Grid”
● Transportation efficiency:
Urban design to favor walkable,
bikable neighborhoods, efficient
mass transit, smaller cars, car-
sharing, hybrid technology,
replace short distance air travel
by rail, efficient use of air travel
capacity, move freight transport
from truck to barge and rail
UACDC: Visioning Rail Transit in NWA

47. Energy Efficiency potentials: individual
approaches

48. Energy Efficiency potentials: individual
approaches
● Building efficiency: building size, air-tightness, insulation, low-E
windows, heat-recovery ventilation, passive solar design, reflective
roof, efficient wood heating, geothermal heat pumps, solar water
heating, roof PV cells, zero-energy buildings
● Most contractors oversize air conditioners and undersize air
supply (at least 2 sqft per ton recommended)
● Appliances (inefficient: top-loader washer, oversized French
door refrigerator with in-door ice dispenser)
● Lighting: efficient light bulbs, natural light and movement
sensors in office + retail buildings
● Electronic devices: improved power control for computers,
monitors, printers, TVs, even small devices like cell-phone
chargers etc. can save energy; stand-by mode (“vampire energy
loss”) is a huge energy drain

49. Energy Efficiency: economic
considerations
● Investment in energy efficiency and conservation pays off
● “Conservation is the quickest, cheapest, most practical source
of energy”- Jimmy Carter, 1977
Then why is there so little progress in energy efficiency?
● Up to recently, energy prices have been historically cheap,
especially in North America.
● Economic incentives are effective. Businesses and consumers
respond to increasing energy cost (e. g. increased US demand for
transit, increased interest in home energy improvements)
● Energy policy should be consistent and predictable
● Energy or pollution taxes or similar mechanisms (e. g. cap and
trade) provide consistent economic incentives for conservation.

50. Case study: “Progress” in automobile
efficiency
“Jevons’ Paradox”
Technological progress
that increases the
efficiency with which a
resource is used tends
to increase (rather than
decrease) the rate of
consumption of that
resource
=> Absent economic
incentives, technology
will not by itself
promote conservation!

51. Economic incentives are effective!
Prices change behavior
Oil
price

52. Economic incentives are effective!
Prices change behavior
High fuel taxes
promote fuel
conservation

53. Energy Efficiency: economic considerations
● Energy taxes are not a “drain” on the economy – they move
resources from less to more energy efficient sectors.
● Revenues from energy taxes flow back into the domestic economy
– money spent importing energy is lost from the domestic economy.
● Revenues from energy taxes can be redistributed to soften the
impact on low-income groups, or used to create jobs, or invested in
energy efficient infrastructure.
● Energy generation and use causes massive negative externalities
(carbon emissions etc.). Taxes designed to compensate for a
negative economic externality are known as Pigouvian taxes.
Standard economic theory predicts that Pigouvian taxes increase
economic efficiency.
● Difficulty: quantifying the externality
● Difficulty: energy intensive industries will go where energy taxes and
regulations are least strict

54. Economic
considerations:
External costs
of Energy
Hidden Costs of Energy: Unpriced Consequences of
Energy Production and Use
A report by the National Research Council’s Committee on Health,
Environmental, and Other External Costs and Benefits of Energy Production
and Consumption
Freely available at http://www.nap.edu/catalog.php?record_id=12794

55. Economic considerations: energy taxes
“Environmental taxes can play a central role in reducing
the fiscal gap in the years to come. These are efficient
taxes because they tax “bads” rather than “goods.”
Environmental taxes have the unique feature of raising
revenues, increasing economic efficiency, and
improving the public health. (…) It is striking how the
political dialogue in the US has ignored a policy that
has so many desirable features. (…) Simply put,
externality taxes are the best fiscal instrument to
employ at this time, in this country, and given the fiscal
constraints faced by the US.”
Economist William D. Nordhaus

56. Energy Subsidies: “Black not Green”
NYT, July 3, 2010: “oil production is among the most heavily subsidized businesses”

57. Power sources – a brief overview
Coal
● Relatively abundant & cheap
● Biggest source of carbon emissions
● Emits many pollutants incl. Mercury, sulfur
● Coal mining often environmentally destructive –
Mountaintop removal in Appalachia
● Carbon Capture and Storage (CCS) technically
feasible method of minimizing carbon emissions
but expensive and energy intensive

58. Power sources – a brief overview
Natural Gas
● Less pollution, 40% less carbon emitted per unit
of energy, potential as transportation fuel
● Problem of Methane leakage
● “Hydrofracking”, a relatively recent drilling
technique, is controversial because of the
use of toxic chemicals, high
freshwater use, potential for
watershed contamination,
disposal of large amounts of
fracking fluid, injection wells
causing small earthquakes …

59. Power sources – a brief overview
Nuclear fission power
● Uranium relatively abundant but not unlimited
● Low GHG emissions during operation, GHG emissions during
construction and mining
● Uranium mining very “dirty”, huge environmental impact
● Socially contentious technology
● Investment cost of building new plants relatively high, protracted
permit and construction process, huge delays and cost overruns
universally observed
● Most existing plants are decades old, amortized and highly
profitable but often fail to comply with modern safety standards.
Operators tend to resist costly upgrades, have big economic
incentives to continue operating unsafe plants. Whose interests
do regulators protect?

60. Power sources – a brief overview
Nuclear fission power
● Safety issues: Fukushima, Chernobyl, Three Mile Island only tip
of the iceberg; there is a long list of incidents involving nuclear
power plants. Incidents often lead to prolonged, expensive
interruption of operation.
● Radioactive Tritium leaked from Yankee power plant in Vermont,
2010 (http://healthvermont.gov/enviro/rad/yankee/tritium.aspx)
● Release of 18,000 liters of solution containing Uranium at
Tricastin, France, in 2008
● Nuclear power plants potential terrorist targets
● Nuclear proliferation concerns
● Waste disposal and decommissioning difficult if not unfeasible,
costs generally not priced into electricity

61. Power sources – a brief overview
Nuclear fission power
Tchernobyl: more than 20 years after
the disaster, the number of fatalities is
still disputed. The lowest estimate – 56
direct deaths and 4000 long term
cancer victims – was published by the
IAEA, an organization constitutionally
charged with promoting nuclear energy.
Anti-nuclear groups estimate 50,000
potential fatal cancer incidents.
Hundreds of thousands of workers
(“liquidators”) came close to the reactor
core during clean-up work.
● Selection of sites to look up on wikipedia: Sellafield, Mülheim-
Kärlich_Nuclear_Power_Plant, Schacht_Asse_II,
Tricastin_Nuclear_Power_Center, Olkiluoto_Nuclear_Power_Plant, Dounreay
http://www.monbiot.com/archives/2006/09/12/a-catalogue-of-idiocy/

62. Power sources – a brief overview

63. Power sources – a brief overview
Wind
● Large wind farms economically competitive
● No fuel required, no GHG emissions during operation
● Low maintenance cost, but large upfront investment
● GHG emissions during construction
● Potential for ecological disruption, impact on birds and
bats uncertain, high land use intensity per Megawatt
(“Energy Sprawl or Energy Efficiency”, PLOS One 2009),
● Power output proportional to square of diameter and third
power of wind velocity, transformation efficiency up to 35%
(small scale turbines less efficient), intermittency and
fluctuation of wind direction and velocity reduces efficiency
further.

64. Power sources – a brief overview
Wind
● Small and intermediate wind
power units valuable for off-the
grid, remote areas, developing
countries but not a significant
contribution to energy needs of
developed countries.

65. Power sources – a brief overview
Hydro power
● Very high conversion efficiency
● No pollution or GHG from operation
● Reservoirs can be used as energy storage
● Potential ecological disruption by large as well as small
dams
● Loss of valuable farmland or wildlife habitat
● Large numbers of people relocated because of large dam
projects
● Power disruption during drought
● Other issues with dams

66. Power sources – a brief overview
Biofuels
● Potentially renewable, low-GHG energy source, potential
alternative transportation fuel
● Many issues:
- Land-use intensity
- Water intensity
- Energy inefficiency: very low EROI in some cases
- Competition with food production
- Deforestation for palm oil plantations in Tropics
● Different kinds of biofuels from different sources (e. g. algae,
cellulosic biomass, recycled vegetable oil, sugar cane, corn):
sustainability assessment different in each case
● Currently no plausible, sustainable large-scale source of
biofuels
Recommended readings: NGM; Thermodynamics of the Corn-Ethanol Biofuel Cycle;
“Hunger Games”; Bioenergy – Chances and Limits

67. Power sources – a brief overview
Solar Power
● Ideal, abundant, pollution free source of power
● Photovoltaics still expensive, manufacturing requires rare
materials
● Maximum production during day time, when demand is highest
● Problems of predictability, reliability, storage
● Land use intensity less than wind but more than coal
● Solar water heating very efficient and cheap, mandatory in
many Mediterranean countries, underused in US (why?)
● Many uses on many scales, including low-tech applications
relevant to developing countries, off the grid use
● Immense potential, few draw-backs

68. Power sources: Solar Power
The land area needed to produce 18 TW of electricity using 8% efficient
photovoltaics, shown as black dots. Source: WikiMedia, Do the Math

69. Germany has promoted
the installation of PV
panels with subsidies.
Good policy?

71. Power sources – a brief overview
Conclusion: does “Clean
Energy” exist?
How would you implement a
national (global?) energy policy
promoting sustainability?

72. This presentation is part of the Lecture Series in Sustainability
Science. © 4/2014 by Toni Menninger MSc. Use of this material for
educational purposes with attribution permitted. Questions or
comments please email toni.menninger@gmail.com.
Related lectures and problem sets available at
http://www.slideshare.net/amenning/presentations/:
• Growth in a Finite World: Sustainability and the Exponential Function
• The Human Population Challenge
• World Hunger and Food Security
• Economics and Ecology
• Exponential Growth, Doubling Time, and the Rule of 70
• Case Studies and Practice Problems for Sustainability Education:
• Agricultural Productivity, Food Security, and Biofuels
• Growth and Sustainability
… and more to come!
The Sustainable
Energy Challenge