CO 2 and Energy #2 Jasper Kok Applied Physics Program Climate science & policy enthusiast Lecture for AOSS 480, Ricky Rood.

CO2 and Energy #2

Jasper KokApplied Physics Program

Climate science & policy enthusiastLecture for AOSS 480, Ricky Rood

Outline and review lecture 1

Lecture 1: Current and past energy use– Historic CO2 emissions

and energy use– Current sources of

energy

– Energy use and CO2 emissions of economic sectors

– Energy use and CO2 emissions by end use

0

2

4

6

8

10

1850 1900 1950 2000

Car

bo

n E

mis

sio

ns

(GtC

/yr)

coal

oil

gas

deforestation

cement and gas flaring

World CO2 emissions by fuel and end use

US energy use by sector

Outline Lecture 2

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

Do we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system?

– ‘Wedges’ to mitigate climate change – Energy supply decarbonization ‘tools’

Energy efficiency Renewable energies Carbon capture and sequestration Biofuels

– Specific ‘wedges’ of mitigation– Externality: energy and water

Key reference

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 On local server: Socolow and Pacala

: Keeping Carbon in Check (Scientific American, 2006)

Future energy policy: What are we trying to achieve?

The 1992 UN Framework Convention on Climate Change was signed by most countries. Stated objective:“to achieve stabilization of GHG concentrations in the atmosphere at a low enough level to prevent dangerous anthropogenic interference with the climate system”

This should be done in a time frame sufficient:– to allow ecosystems to adapt naturally to climate change– to ensure that food production is not threatened– to enable economic development to proceed in a sustainable manner

Does ‘business as usual’ allow this? If not, then what energy policies should we introduce (as a world community)?

The green countries have signed UNFCCC!

Outline Lecture 2

Lecture 2: Future energy use and climate change mitigation

– ‘Business as usual’ Do we need to act to prevent ‘dangerous

anthropogenic interference’ in the climate system?

– ‘Wedges’ to mitigate climate change – Energy supply decarbonization ‘tools’

Energy efficiency Renewable energies Carbon sequestration Biofuels

– Specific ‘wedges’ of mitigation– Externality: energy and water

‘Business as usual’ CO2-trajectory path

‘Business as usual’ has CO2 emissions growing at current rate (1.5%/year)– Likely end-of-century warming: ~2.3 – 3.4 ºC

≈ business as usual

‘Business as usual’End-of-century temperature change

“Business as usual” (2090-2099) scenario– Global mean warming 2.8 ºC;– Much of land area warms by ~3.5 ºC– Arctic warms by ~7 ºC

Will ‘business as usual’ lead to ‘dangerous’ climate change?

At > 2ºC– Ecosystems become

threatened– Food supply

jeopardized– Abrupt / irreversible

changes (could lead to large-scale economic damage)

Many scientists think should prevent >2ºC warming EU policy aimed at < 2ºC warming

So what is a ‘safe’ CO2 trajectory and how do we achieve it?

Likely range of ‘business as usual’ by 2100

CO2 stabilization trajectory

Need to stay below ~2 ºC to avoid ‘dangerous’ climate change.

Stabilize at < 550 ppm. Pre-industrial: 275 ppm, current: 385 ppm.

Need 7 ‘wedges’ of prevented CO2 emissions.

Outline Lecture 2

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

Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system

–‘Wedges’ to mitigate climate change – Energy supply decarbonization ‘tools’

Energy efficiency Renewable energies Carbon sequestration Biofuels

– Specific ‘wedges’ of mitigation– Externality: energy and water

What is a ‘wedge’?

A ‘wedge’ is a strategy to reduce carbon emissions that grows from zero to 1 GtC/year in 50 years

The world needs to implement 7 of these wedges to prevent ‘dangerous’ climate change

Examples:– Expand wind energy– Make cars more efficient– Reduce deforestation rates

Developing Vs. developed world

Implementation of wedges would lead to large emission reductions in developed world

Developing world would increase emissions, but less than without carbon constraints

How and where to get the wedges

Need 7 wedges for 2xCO2 stabilization

Where and how is most cost-effective to cut CO2?

Tools wedges use:– Improved energy

efficiency– Renewable energies

(wind, solar)– Carbon capture and

sequestration– Biofuels

Outline Lecture 2

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

Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system

– ‘Wedges’ to mitigate climate change

– Energy supply decarbonization tools Energy efficiency Renewable energies Carbon capture and sequestration Biofuels

– Specific ‘wedges’ of mitigation– Externality: energy and water

Efficiency Gains

The low-hanging fruit! Essentially three kinds:

– End-use electricity efficiency (fluorescent bulbs instead of incandescent bulbs)

– Energy generation efficiency (coal plant operating at 60 % efficiency instead of current 40 %)

– Transportation efficiency (60 mpg instead of 30 mpg) Efficiency gains are generally cheap mitigation options But will only get so far before cutting into primary energy

used for economic activity

Kinds of renewable energy

Hydro-power– Already widely

used - not much potential for expansion

Wind– Abundant and

competitive

Solar – Photovoltaic (PV)– Concentrating solar

Renewable energy: Wind

Probably most promising renewable energy source

Supplies ~1 % of world electricity, ~0.3 % in US

Is cost-effective against coal and natural gas

Is undergoing very rapid growth (5-fold increase 2000-2007)

$0.00

$0.10

$0.20

$0.30

$0.40

1980 1984 1988 1991 1995 2000 2005

Wind energy cost in $/kWh

Renewable energy: Wind

Advantages:– Wind energy is relatively

mature technology and is cost effective

– Can be utilized at all scales Large wind farms On small agricultural farms

– Total theoretical potential of wind energy on land/near shore is 5x current energy consumptionLarge potential for expansion

Renewable energy: Wind

Disadvantages:– Horizon pollution and NIMBY

siting problems

– Birds…(though this is often over-stated – about 1-2 birds per turbine per year)

– Wind is intermittent! It can therefore not make up a large fraction of base load (unless effective energy storage)

Renewable energy: Solar Essentially three kinds:

1. Solar heat – Water is heated directly by

sunlight– Used cost-effectively on

small scale in houses

2. Solar photovoltaic (PV)– Uses photo-electric effect

(Einstein!) to produce electricity

– Supplies ~0.04 % of world energy use

3. Solar concentrated– Use large mirrors to focus

sunlight on steam turbine or very efficient PV panels

– More cost-effective than just PV

Renewable energy: Solar Advantages:

– Enormous theoretical potential!– Applicable at various scales

(individual houses to solar plants)– Solar heating can be cost effective– Economy of scale and/or

breakthroughs might reduce costs of PV and solar concentrated

Disadvantages– PV and solar concentrated are

expensive! Currently only cost-effective with government subsidies

– Intermittent – can not make up large portion of base load (except with storage capability)

Outline Lecture 2

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

Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system

– ‘Wedges’ to mitigate climate change – Energy supply decarbonization tools

Energy efficiency Renewable energies

Carbon capture and sequestrationBiofuels

– Specific ‘wedges’ of mitigation– Externality: energy and water

Carbon Capture and Sequestration (CCS)

Main idea:– Burn fossil fuels for

electricity/hydrogen production– Capture CO2

– ‘Sequester’ it in geological formation, oil/gas field, or ocean floor

This principle is immensely important for future CO2 mitigation!– Fossil fuels are abundant and cheap– Renewable energy generally not

mature enough to replace fossil fuels– Coal-fired power plants with CCS

could provide low-carbon energy at competitive costs

Currently successfully employed in ‘pilot’ projects

CCS: Carbon Capture Both conventional and modern types of

coal-fired power plants can be adapted for CCS

Conventional coal-fired power plant:– Burn coal in air (much like the old days)– Exhaust gas is ~15 % CO2 (rest is mostly

nitrogen and water vapor)– Exhaust gas flows over chemicals that

selectively absorb CO2 (‘amines’)– The amines are heated to ~150 ºC to give up

the CO2 and produce a (nearly) pure CO2 gas that can be sequestered.

Modern coal-fired power plant:– Coal is burned with pure oxygen in a

gasification chamber to produce hydrogen and CO2

– The CO2 is filtered out and the hydrogen is burned for electricity

CCS: Sequestration

1. Depleted oil/gas reservoirs (can be even be used to enhance oil/gas recovery – reduces costs)

2. Deep saline (brine) formations – these are porous media in which CO2 can be stored and dissolve in the salty water

3. Use for coal-bed methane recovery (one of those ‘unconventional’ fossil fuels)

4. Ocean floor (very controversial!)

CO2 can be sequestered at ~1 km underground, here pressure is high enough to liquify CO2, which helps prevent it from leaking

Several options for sequestering CO2:

CCS: economics

CCS could become cost-effective with future carbon legislation

Biofuels

Initially hailed as a sustainable substitute for oil

Can help reduce oil imports and improve national security – In US, this is probably main motivation

for recent push (“addicted to oil”, Bush’s 2006 State of the Union)

Two main kinds of biofuels:1. First generation:

Produced by converting sugar in corn, sugar beets, etc., into ethanol (alcohol)

2. Second generation:Produced through “cellulosic conversion” of biomass into sugar, then sugar into ethanol

Climate change impact of different biofuels is very different!

Biofuels – First Generation In US, mainly corn-based ethanol

– Heavily subsidized by federal government to reduce oil dependence (~$1.90/gallon)

Effect on climate change is negative:– Energy used in production is comparable to energy content– Significant amounts of N2O (a potent GHG) can be produced through fertilizer

use– More carbon would be sequestered by letting crop land lie fallow– Raises food prices Tropical deforestation, which releases more carbon

than saved from fuel production over > 30-year period

Source: Fargione et al., Science, 2008

Biofuels – Second Generation Produced from plants containing cellulose

– Cellulosic conversion to sugar is very difficult and expensive! (cows have 4 stomach compartments for a reason…)

Second generation biofuels are better for climate change:– Similar amount of carbon sequestered as fallow cropland– But, competition with food still leads to tropical deforestation and net

release of carbon!

US 1st generation

biofuel

US 2nd generation

biofuel

Biofuels – do they help or hurt? In general, biofuels that compete with food will not contribute to

mitigating climate change– Direct link between food demand/prices and tropical deforestation

Production of first generation biofuels (directly from food such as corn) is not a solution to climate change and should be avoided!

Production of second generation biofuels (from biomass) is only helpful if it doesn’t compete with food production (so not grown on cropland)– Second generation biofuels from agricultural waste could play important

role, but is currently not cost-effective

In light of these recent results (2007/2008), EU is reconsidering past biofuel mandates and subsidies

Outline Lecture 2

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

Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system

– ‘Wedges’ to mitigate climate change – Energy supply decarbonization ‘tools’

Energy efficiency Renewable energies Carbon sequestration Biofuels

–Specific ‘wedges’ of mitigation– Externality: energy and water

Where can we create ‘wedges’ in the energy system?

Power generation (40 %)– This is the ‘easy’ target because

of availability of cost effective low-carbon options (wind, CCS)

Direct fuel use (36 %) – This can be ‘switched’ to low-

carbon electricity

Transportation (24 %)– This is the tough nut to crack!– Currently no real feasible low

carbon alternatives Lot of infrastructure in place for

fossil fuel-based transportation!

??? ???

How to create ‘wedges’: Power Generation

Several options, each one wedge:– Increase efficiency of coal-fired

power plants from 40 to 60 % ($)– Replace coal-fired to natural gas-

fired power plants ($)– Double nuclear electricity to replace

coal-fired power plants ($$)– Use CCS for low-carbon coal-fired

power plants ($$)– Expand wind energy 30x to replace

coal-fired power plants ($$)– Expand solar energy 700x to

replace coal-fired power plants ($$$)

How to create ‘wedges’: Direct Fuel Use

Several options, each one wedge:– Improve building

insulation ($)– Replace natural gas

heat with low-carbon hydrogen from wind/coal with CCS ($$$)

– (and general switch to electricity heat instead of fuel heat)

How to create ‘wedges’: Transportation

Several options, each one wedge:– Increase car efficiency from 30

to 60 mpg ($)– More compact world with less

travel 5,000 instead of 10,000 miles/vehicle ($)

– Switch to low-carbon hydrogen ($$$)

– Switch to sustainable biofuels unlike corn ethanol, these must not compete with food production! ($$$)

Outline Lecture 2 Lecture 2: Future energy use and climate change

mitigation– ‘Business as usual’

Why we need to act to prevent ‘dangerous anthropogenic interference’ in the climate system

– ‘Wedges’ to mitigate climate change – Energy supply decarbonization ‘tools’

Energy efficiency Renewable energies Carbon sequestration Biofuels

– Specific ‘wedges’ of mitigation

–Externality: energy and water

Must address climate change without exacerbating freshwater shortage

Both energy and water are critical resources

Many areas already suffer water stress – note Africa, India, China, where

greatest population growth is projected to occur

Projected to become worse with increasing population, pollution, and climate change– Dry areas are generally projected

to become drier. Must address energy challenge

without exacerbating water scarcity

So where is our fresh water used?

You can take many, many, very long showers for a pound of steak…

Greatly expanding biofuels from ethanol to substitute oil would probably be bad idea…

Class on Thursday

Ben Santer will be lecturing on Thursday– He’s a well-known climate scientist!– Few contemporary scientists get their own

Wikipedia page…(http://en.wikipedia.org/wiki/Benjamin_D._Santer)