CO 2 and Energy. Context: Energy and Climate Change.

CO2 and Energy

Context: Energy and Climate Change

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Context: Energy and Climate Change

Consumption // Population // Energy

CLIMATE CHANGE

ENERGY

POPULATION

CONSUMPTION

SO

CIE

TA

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UC

CE

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NATIONAL SECURITY

PUBLIC HEALTH

AGRICULTURE

Outline Lecture 1

Lecture 1: Current and past energy use– CO2 emissions: where do they come from?

– Current sources of energy

– Emissions from economic sectors

– Energy consumption by end use

– External costs to energy use (besides climate change)

Outline Lecture 2

Lecture 2: Future energy use and climate change mitigation– ‘Business as usual’

– ‘Wedges’ to mitigate climate change

– Energy supply decarbonization ‘tools’

– Specific ‘wedges’ of mitigation

Key references and websites

Energy Information Administration (EIA) http://www.eia.doe.gov/ keeps track of (inter)national energy use and future trends.

The ‘wedge’ paper: “A plan to keep carbon in check” by Socolow and Pacala, Scientific American, 2006.– This is an influential policy-oriented paper on how to

reform energy sector while still achieving economic growth

– Accessible through http://mirlyn.lib.umich.edu

http://www.eia.doe.gov/

http://mirlyn.lib.umich.edu/

Outline Lecture 1 Revisited

Lecture 1: Current and past energy use

–CO2 emissions: where do they come from?

– Current sources of energy– Emissions from economic sectors– Energy consumption by end use– External costs to energy use (besides

climate change)

So CO2 emissions arise from: 1. Cement production (~5 %)2. Deforestation (~20 %)3. Fossil fuel use (~75 %)

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World Carbon Emissions

75%

CO2 source: Cement Production

Cement is produced from limestone, which is mostly calcite (CaCO3).

For production of cement: CaCO3 CaO + CO2

Production of cement emits CO2 for two reasons:

1. CO2 emitted directly2. Production process takes place at

high temperatures only (> 1000 ºC) which requires a lot of energy.

Accounts for ~5 % of CO2 emissions worldwide

CO2 source: Deforestation Massive deforestation occurred

– In developed nations during Industrial Revolution (driven by need for cheap energy)

– In developing (tropical) nations right now, mostly in response to demand for cropland, pastures, and wood.

When forests are cut down, CO2 is released from:– Carbon in trees, plants, etc.

(conversion to wood products preserves only small fraction)

– Carbon in the soil (roots, humus)

Forests absorb “excess” CO2, since elevated CO2 stimulates growth– Removal of forests removes this

natural buffer against climate change

CO2 source: Deforestation

Deforestation is thus an important part of climate change:– It accounts for ~20 % of current CO2 emissions– It accounted for ~35 % of total CO2 emissions since preindustrial

times.

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cement and gas flaringFossil fuels 320

Deforestation 200

Total 520

Compare to 590 GtC in the preindustrial

atmosphere

GtC

CO2 source: Fossil Fuel Use

Sharp increase (16-fold!) in world energy consumption over past century– Why did this occur?

So why has energy consumption increased so much?

GDP/capita is considered the “societal success”

Energy use increases have been driven by growth in population and GDP/capita.

Energy use = (population)*(GDP/Person) *(energy/unit GDP)

Energy and population

Strong population increase since pre-industrial times!


http://www.j-bradford-delong.net/TCEH/1998_Draft/World_GDP/Estimating_World_GDP.html

World GDP/capita

Also strong growth in GDP/capita!


http://www.j-bradford-delong.net/TCEH/1998_Draft/World_GDP/Estimating_World_GDP.html

Energy and GDP

Energy/unit GDP decreases as societies become more developed shift from manufacturing to services (root cause of Michigan’s economic trouble)

But total energy use per capita does not decrease.


EIA Annual Energy Outlook, 2008

Energy use per capita and per dollar GDP in U.S. (index, 1980 = 1)

So why has energy consumption increased so much?

Main drivers of rapid increase in energy consumption have been increases in population and GDP/capita

This is why climate change problem is so difficult: – We can’t affect population (possible, but politically incorrect…)– Reducing GDP to combat climate change is also not feasible

But reduction in energy per unit GDP occurs with shift to knowledge-based economy (developed world now).

Still, reduction in world energy use not realistic!– To reduce CO2 emissions, need to drastically lower CO2 emitted per

unit energy, especially since we want economy to keep growing. – We’ll get to options for reducing CO2/energy in 2nd lecture

Energy use = (population)*(GDP/Person)*(energy/unit GDP)



–Current sources of energy– Emissions from economic sectors



In what forms do we consume energy?

Fossil fuels:– Coal– Oil– Natural gas

Other:– Nuclear– Hydro– Renewables

(mostly biomass)

– ‘Hydrogen’Pacala and Socolow, Science, 2004

Current sourcesof energy:

Fossil fuels

Energy sources: Coal Emits most CO2 per unit energy of all

fossil fuels

Accounts for ~29% of world CO2 emissions

Used mostly for electricity and for home heating (especially in developing nations)

Coal burning emits significant amounts of sulfur, nitrogen and particulate matter

Proven reserves are almost endless (~250 years)

Coal is major source of air pollution

Coal emits sulfur and smoke particulates

“Great London smog” of 1952 led to thousands of casualties.– Caused by cold inversion layer

pollutants didn’t disperse + Londoners burned large amounts of coal for heating

Demonstrated impact of pollutants and played role in passage of “Clean Air Acts” in the US and Western Europe

Coal use in the US

After “Great London smog” of 1952, decrease in residential coal use

Use of coal for electricity has been growing consistently because coal is cheap and abundant, and combustion technology is readily available

Coal use by sector in US

EIA Annual Energy Review, 2006

Energy sources: Oil Emits ~75 % of coal CO2 emissions per

unit energy.

Accounts for ~30 % of world CO2 emissions.

Dominates transportation (cars), but also used for home/building heating

Proven reserves are ~40 years of conventional oil. After that, another ~100 years of unconventional oil (tar sands etc.)

U.S. dependency on imported oil is a major national security concern

Energy sources: Natural gas

Least polluting of the fossil fuels: emits ‘only’ ~60 % of coal CO2 per unit energy

Accounted for ~16% of world CO2 emissions

Used for electricity generation and home heating (same as coal)

Proven reserves are another ~65 years

Trend of fossil fuel use

In ‘business-as-usual’ fossil fuels will continue to dominate world energy

China currently adds one coal-fired power plant a week…

International Energy Outlook, EIA, 2007

Reserves of fossil fuels

We won’t be running out of fossil fuels anytime soon! ‘Unconventional’ includes oil sands, oil shale, coalbed

methane, etc..– Unconventional fossil fuels cost more energy/effort to mine

Fuel type: Proven reserves (years)

Unconventional reserves (years)

Oil 41 125

Coal 251 210

Natural Gas 64 360Source: World Energy Assessment, 2004

Current sourcesof energy:

nuclear and renewables

Energy sources: Nuclear

Accounts for ~6 % of world energy consumption and ~ 19 % of US electricity generation

Used only for electricity generation

No CO2 emissions from plant operating, but some from uranium mining (~10 - 20 % of coal emissions per unit energy)

Concerns about nuclear waste storage and nuclear weapons proliferation

Hardly growing in most of developed world.

Nuclear share of electricity generation in U.S.

Nuclear power plant licenses issued in U.S.


Chernobyl

Energy sources: Renewables Mostly from

biomass (wood), hydro power, and biofuels.

Contribution from other renewables (geothermal, solar, wind, tides) are small.

Will discuss all these in more detail in 2nd lecture.

Renewable energy as share of total energy in U.S., 2006


Energy ‘sources’: Hydrogen Hydrogen as a fuel is often misunderstood:

– Hydrogen is NOT a source of energy!– It’s merely an energy carrier, much like electricity

Hydrogen is produced by electrolyzing water:

This requires electricity

Hydrogen burns cleanly

Hydrogen’s significance is that: 1. It can be produced using renewable energy, which

would displace fossil fuel. 2. Emissions are easier to mitigate, because they occur at

a central location rather than individual cars.

In the absence of policies including cost of climate change, hydrogen would be generated using cheap coal-generated electricity


Lecture 1: Current and past energy use– CO2 emissions: where do they come from?– Current sources of energy

–Emissions from economic sectors

– Energy consumption by end use– External costs to energy use (besides

climate change)

Emissions from economic sectors

Industrial: creating products from raw materials (mining, cement, agriculture)

Commercial: stores, municipalities, etc.

Transportation: cars, planes, ships

US energy use by sector


Transportation sector

Sector with fastest growing CO2 emissions in US

Dominated by oil and road transport

Accounts for ~23 % of worldwide and ~32 % of US CO2 emissions


U.S. energy consumption by sector

Buildings sector

Both residential and commercial (stores, municipalities, etc.)

Mostly electricity, except for fuel use for space heating

Accounts for ~39 % of US energy use.



Industrial sector

Includes mining, refining, factories, etc.

The fraction of energy used by this sector generally decreases as countries become more developed.

Also includes agriculture…


U.S. industrial energy consumption by fuel


Agriculture

Use of direct fossil fuel energy relatively low: ~3–4.5 % in industrialized countries.– Half of used energy and direct

CO2 emissions are from fertilizer production (Haber-Bosch process)

BUT… big contributor to deforestation and land use change.

Livestock rearing is most significant contributor

Agriculture: Livestock 2006 report of Food and Agriculture

Organization (FAO) of the UN:– “The livestock sector emerges as one of

the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global.”

Important economic sector:– Employs 1.3 billion people (mostly poor)– Occupies 30 % (!) of Earth’s land

surface through grazing (26 %) and feed production

33 % of arable land for feed production

Agriculture: Livestock Increasing demand for livestock

products (meat, dairy) is one of main drivers of deforestation!– 70 % of deforested land in the

Amazon is occupied by pastures. – Feedcrops cover most of remaining

30 %.– Livestock-induced deforestation

emits ~0.65 GtC per year (compared to ~7 GtC from total fossil fuel use and ~2 GtC total deforestation)

Livestock demand increasing rapidly with increasing world wealth (India, China). Should more than double by 2050.

Agriculture: Livestock Responsible for ~18 % of CO2

equivalent GHG emissions (so including N2O and CH4) Same share as entire US!– 9 % of world CO2 emissions

Fossil fuels burned to produce fertilizer Deforestation and land use changes for

feed production and grazing

– 37 % of world CH4 emissions Fermentation in cattle stomachs (biggest

anthropogenic source) Animal manure

– 65 % of N2O Mostly from animal manure deposited on

soils, with subsequent N2O emission 0

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Lecture 1: Current and past energy use– CO2 emissions: where do they come from?– Current sources of energy– Emissions from economic sectors

–Energy consumption by end use


Energy consumption by end use The three main end

uses of fossil fuel are:

– Electric power plants (~40 % of CO2 emissions)

– Transportation (~23 % of CO2 emissions)

– Direct use of fuel (industrial processes and heating for buildings) (~37 % of CO2 emissions)

So ~40 % CO2 emissions from electricity, 60 % from fuels

Socolow and Pacala , 2006

World CO2 emissions by fuel and end use

Energy consumption by end use:Electricity

Two thirds of world electricity production comes from fossil fuels

One third from hydro and nuclear power

Cost of Electricity

Coal is cheapest and most used source of electricity in US!

Solar Photovoltaic (PV) rather expensive

Electricity generation by source, U.S., 2006

Cost of lectricity in US in 2002

Source: Nathan Lewis, 2009

Reserves of fossil fuels (repeat)

We won’t be running out of fossil fuels anytime soon! ‘Unconventional’ includes oil sands, oil shale, coalbed

methane, etc..– Unconventional fossil fuels cost more energy/effort to mine

Fuel type: Proven reserves (years)

Unconventional reserves (years)

Oil 41 125

Coal 251 210

Natural Gas 64 360Source: World Energy Assessment, 2004

Electricity generation:Switch to renewables in future?

So in ‘business-as-usual’ abundant, cheap, fossil fuel-derived electricity will likely be available until the end of the century.

This cheap electricity can also be used to produce hydrogen fuel, should oil demand exceed supply.

Renewables will thus not play important role until– Externalities are taken into

account (taxes, cap-and-trade)– There are technological

breakthroughs (solar PV, fusion)

Energy consumption by end use:Direct fuel use

‘Direct fuel use’:– Transportation (oil)– Heating in buildings– Industrial processes

Dominated by oil

Currently no real alternatives for transportation fuels– Biofuels do not mitigate

CO2 emission (more in 2nd lecture)

Direct Fuel Use

Pacala and Socolow, 2006



– Current sources of energy

– Emissions from economic sectors


–External costs to energy use (besides climate change)

Externality 1:Energy and National Security

U.S. imports most of its oil– This is a liability, as some of that oil

comes from Middle East (though not as much as one would think!)

– Past (and most of current) U.S. energy policy revolves around energy security – not climate change mitigation

Majority of remaining oil in Middle East

Origin of US oil imports, 2006

US oil trade

Externality 2:Energy and Public Health

The burning of fossil fuels is the dominant source of air pollution, emitting– Carbon monoxide (CO), which is toxic and can cause

headaches and exacerbate heart disease– Nitrogen oxides (NOx), which causes respiratory

problems and leads to smog– Sulfur dioxide (SO2), which produces acid rain and smog– Particulate matter, which causes respiratory problems– Mercury emissions, which are mostly taken in through

fish, where they bioaccumulate.

The overall cost of air pollution on human health is large (~6 % of deaths in EU) but very difficult to quantify

Externality 3:Energy and climate (besides

greenhouse warming) Burning of fossil

fuels is important source of particulate matter (aerosols), which helps cool climate by:– Scattering

radiation– Seeding clouds

Cleaning up ‘dirty coal’ might thus not be good for climate…

To be continued….

So what does our energy future look like?– Can we sustain our economic growth while

avoiding ‘dangerous’ climate change?– What roles can renewable energy, hydrogen,

biofuels, carbon sequestration play in this?

Will discuss in more detail in 2nd lecture on Thursday

CO 2 and Energy. Context: Energy and Climate Change.

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Transcript of CO 2 and Energy. Context: Energy and Climate Change.