Renewable sources and technology to harness them are low carbon emissions and serves the need of energy productio

1. CLEANER ENERGIES
ESO405
Saifi Izhar, PhD
Assistant Professor
Environmental Science & Engineering
Indian Institute of Technology (ISM) Dhanbad
Email: saifi@iitism.ac.in

2. Why Do We Need Renewable Energy?
2. Carbon Emissions & Climate Change
• Climate change in the last 150 years as an effect of carbon emissions.
• These changes to the atmosphere are causing the planet to warm
through the greenhouse effect: by releasing huge quantities of
greenhouse gases into the sky – where those gases trap terrestrial
radiation causing heat and the temperature on and around earth’s
surface is increasing.
• No part of the world has been untouched by freak weather conditions
• Most continents have recorded record high temperatures in summer,
record lows in winter and increased frequency of typhoons and
hurricanes, record dry spells, drought and flooding, ice caps melting and
the sea levels are rising which creates food shortages and national
instability
• Renewable sources and technology to harness them are low carbon
emissions and serves the need of energy production

3. CO2 levels in Atmosphere

4. Can we turn the corner on CO2 emissions?
1
st
IPCC
report
Paris
agreement

5. India constitutes 17 per cent of the world’s population but
contribute only five per cent of emissions

6. Major contributor to CO2 emissions

9. IPCC Remarks
The Paris agreement’s goal is to keep the increase of
the global average temperature to well below 2°c
above pre-industrial levels and “to pursue efforts to
limit the temperature increase to 1.5°c”.

10. Atmospheric concentrations of greenhouse gases
Concentration units: parts per million (ppm) and parts per billion (ppb)
CO2 and methane concentrations are reported as mixing ratios
Methane
CO2
Mauna Loa
South Pole

11. Global Warming Potential
GWP100 values are used to combine greenhouse gases into a single metric of emissions
called carbon dioxide equivalents (CO2e). CO2e is derived by multiplying the mass of
emissions of a specific greenhouse gas by its equivalent GWP100 factor. The sum of all
gases in their CO2e form provide a measure of total greenhouse gas emissions.
Two characteristics of atmospheric
gases determine the strength of their
greenhouse effect.
1. ability to absorb energy and
radiate it (their “radiative
efficiency”).
2. atmospheric lifetime, which
measures how long the gas stays
in the atmosphere before natural
processes (e.g., chemical
reactions) remove it.

14. CO2 emissions means Development but is it possible to
develop by cutting CO2 emissions?

15. Is Greenhouse effect is in itself a bad thing for
human existence?

16. Earth energy balance
• The energy balance of the Earth is essentially
zero.
• The Earth radiates the same amount of energy
into space as the amount of EM energy
absorbed from the Sun.
• The amount of EM radiation from the Sun is
primarily in the visible range, and this is
absorbed and then converted primarily to
thermal energy, which has a lower temperature,
around 290 K, that radiates at longer or
infrared wavelengths (peak at 1 * 10−5 m).

17. Laws of Radiation – Energy Spectrum
Sun Earth
W/M2/um
T
x 6
max
10
897
.
2


Short wave Long wave
6000 k 288 K
(m) (K)
• Hotter objects radiate
more total energy per unit
area than do colder
objects. (The Sun, emits
about 160,000 times more
energy per unit area than
does Earth).
• Hotter objects radiate
more energy in the form
of shorter wavelength
radiation than do cooler
objects. (The Sun radiates
its peak energy at 0.5 µm,
which is in the visible range.
While Earth radiates its peak
energy at a wavelength of 10
µm (infrared range)
Wien’s
law

18. Role of Gases in the Atmosphere
 Majority of solar radiation is
emitted in wavelengths
shorter than 2.5 um—
shortwave radiation.
 Oxygen and ozone absorbs
shorter wavelength UV
radiation in the upper layers
of atmosphere.
 The atmosphere is a poor
absorber of visible radiation,
most of this energy is
transmitted to Earth’s
surface.
 None of the gases are
effective absorbers of visible
radiation with wavelengths
between 0.4 and 0.7 um,
which constitutes about 43
percent of the energy
radiated by the Sun.
 Majority of Earth’s surface
radiation is emitted at
wavelengths between 2.5
and 30 um—longwave
radiation.
 Water vapor and carbon
dioxide are the principal
absorbing gases, with water
vapor absorbing about 60
percent of this terrestrial
radiation.
 The atmosphere is
generally a relatively
efficient absorber of
longwave (infrared)
radiation emitted by Earth.
 Atmospheric window is
transparent to the band
of radiation between 8
and 12 um (where
Earth’s radiation is
most intense) which
allows longwave to exit
to space.

19. Energy Balance model

20. Case a: Earth is pure Blackbody

21. The energy balance of the Earth is
essentially zero

23. Greenhouse Effect
 Water vapor and carbon dioxide
are the principal absorbing gases,
with water vapor absorbing about
60 percent of this terrestrial
radiation.
 The atmosphere is generally a
relatively efficient absorber of
longwave (infrared) radiation
emitted by Earth.
 In effect, the atmosphere acts as
an infrared ‘blanket’. This
increase in surface temperature
(relative to what it would be
without the atmosphere) is called
the greenhouse effect.
 This greenhouse effect is due to
background concentration of
gases (Natural)

24. Case b: When Earth is not blackbody
Emissivity is defined as
the ratio of the energy
radiated from a material's
surface to that radiated
from a perfect emitter,
known as a blackbody, at
the same temperature and
wavelength and under the
same viewing conditions.
It is a dimensionless
number between 0 (for a
perfect reflector) and 1
(for a perfect emitter).

26. Solar
Terrestrial
visible infrared
Fin Fout
increase greenhouse gas by ΔG
Fin Fout
Climate equilibrium: Fin = Fout
ΔG
Radiative forcing: ΔF = Fin – Fout > 0
Climate change arises from disruption of radiative equilibrium
increase albedo by ΔA
Fin Fout
ΔA
Radiative forcing: ΔF = Fin – Fout < 0
visible infrared
visible infrared
positive radiative forcing
warming
negative radiative forcing
cooling
[
[
radiative fluxes

27. Importance of avoiding climate tipping points
Armstrong McKay et al.,
These become increasingly likely as warming exceeds 1.5oC above
preindustrial

28. IPCC [2022]
• Temperature response to ΔF is similar for all radiative forcing agents
• Aerosols offset 30% of greenhouse warming, drive uncertainty in radiative
forcing
Contributions to radiative forcing since pre-industrial
times and temperature response

29. Increasing attention to methane in climate policy
Biden at COP26 announcing Global Methane Pledge, now signed by 150 countries

30. Why this attention on methane?
1. Methane has a short atmospheric lifetime
emission
Methane
(CH4) CO2, H2O
atmospheric oxidation (9 years)
ozone pollution
Reducing methane emissions now would have a fast impact on climate
It could save us from the ‘2 degrees of danger’ (maybe even 1.5)
Molecule for molecule, methane is 25x more potent than CO2 on 20-yr horizon
Reducing methane would also improve air quality by decreasing ozone pollution

31. 2. Simple measures could go a long way to decrease methane emissions
Fix leaks detected by
satellite or aircraft
Flare excess gas
…or use it
recover gas from landfills
Recover/digest gas from animal feeding operations,
manure ponds, wastewater plants
Upland rice agriculture
There may be economic benefit to decreasing methane emissions
and there is no stockage problem, unlike for CO2
Why this attention on methane?

32. Over 100 million
observations per year
Balasus et al., 2023
TROPOMI satellite observations of atmospheric methane, 2021
coal
livestock
landfills
livestock
landfills
rice
oil/gas
rice
oil/gas
livestock

33. Methane is still a powerful lever for near-term climate action
…while we decrease CO2 emissions and develop carbon capture technologies
CO2 emission decrease to near zero
Time
Climate
risks
CO2 emission decrease
+ carbon capture
Business as usual
CO2 emission decrease
+ carbon capture
+ methane emission decrease
Start of climate
action

34. Why Do We Need Renewable Energy?
3. Energy Security
• Energy security is a relative newcomer to public perception when we
consider the greater need for renewable energy.
• The IEA defines energy security as the uninterrupted availability of
energy sources at an affordable price.
• Being dependent on other countries for our energy supply is problematic
in itself, because
• when international relations between supplier and receiver sour,
increased wholesale prices threatening to destabilize the economy is
the least that could happen.
• If a supply is cut off, then disaster could strike. For this reason alone,
we need spare capacity and multiple avenues of energy acquisition
• For example natural gas supply in Europe is largely by Russia and Ukraine
conflict has caused shut off supply to Europe
• When renewable sources are developed in-country, there could be less
reliance on outside entities and unstable regions of the world.

35. Oil, coal and gas prices spiked in the immediate aftermath of Russia’s
invasion of Ukraine and have been volatile ever since. Energy
commodity price volatility began mounting in December 2021 when
reports of a potential Russian invasion of Ukraine increased. In the first
two weeks after the invasion, the prices of oil, coal and gas went up by
around 40%, 130% and 180% respectively

36. Why Do We Need Renewable Energy?
4. Economic Stability
• Renewable energy offers a
constant and sustained supply
(such as hydroelectric, wave
power, solar and biofuels)
• Energy prices are likely to
remain stable and in turn, keep
the economy stable
• In many cases, energy produced
from renewable sources is
already cheaper than that
produced by non-renewable
means

37. Why Do We Need Renewable Energy?
5. Environmental Damage
• Search for new pockets of oil and have to drill longer and deeper to
acquire it.
• When local wildlife and environmentally sensitive areas are threatened.
• Example: Protests against fracking and new drilling in Europe and North
America
6. Public Health
• Oil, gas and coal drilling and mining have high levels of air pollution
that are pumped into local environments and the wider atmosphere
• The best part about renewable energy sources like solar, wind, and
hydroelectric power is that once they are installed they essentially
produce no emissions of carbon dioxide or other greenhouse gasses!