2. Introduction
Green Fuel: Renewable fuels or alternative fuels, refer to energy sources that are produced
from renewable resources and have a lower environmental impact compared to traditional fossil
fuels like gasoline, diesel, and coal.
These fuels are considered "green" because they contribute less to greenhouse gas emissions
and air pollutants, thus helping to mitigate climate change and reduce air pollution.
Fuel: Any substance that upon burning produces a usable amount
of energy is known as fuel. The burning process is called
combustion.
Examples of Fuel - wood, coal, biogas, LPG, petrol, diesel, etc.
3. ➢ Biofuel: These are fuels derived from organic materials, such as plants and algae. Common types
include ethanol (produced from corn, sugarcane, or other crops) and biodiesel (produced from
vegetable oils or animal fats).
➢ Hydrogen Fuel: Hydrogen can be produced from various renewable sources, such as water
electrolysis using renewable electricity. When used in fuel cells, hydrogen can produce electricity
with only water vapor as a byproduct.
➢ Wind Power: Wind energy can be converted into electricity through wind turbines. While not a fuel
in the traditional sense, wind power is a renewable energy source that can replace fossil fuels in
electricity generation.
➢ Solar Power: Solar energy is harnessed from sunlight using photovoltaic cells or solar thermal
systems. It is also a renewable energy source that can replace fossil fuels in electricity generation.
➢ Geothermal Energy: Geothermal power is derived from the heat stored within the Earth's crust. It
can be used for electricity generation or direct heating applications.
➢ Synthetic Fuel: These fuels are produced from renewable sources using various chemical processes.
For example, synthetic methane can be produced from captured carbon dioxide and renewable
hydrogen.
Examples of Green Fuel
4. Importance of Green Fuel
Environmental Benefits
➢ Mitigating Climate Change
Green fuels produce significantly lower greenhouse gas emissions compared to traditional fossil fuels,
It also reducing the carbon emission (CO2) and other pollutants that trap heat in the atmosphere. Thus
by using green fuels, we can reduce the impact of global warming and climate change.
➢ Reducing Air Pollution
Fossil fuels emit pollutants such as sulfur dioxide, nitrogen oxides, and particulate matter, which can
lead to poor air quality and various health issues. Green fuels produce fewer or no such pollutants,
leading to cleaner air and improved public health.
➢ Resource Conservation
Fossil fuels are finite resources that are being depleted over time. Green fuels, on the other hand, are
derived from renewable sources like sunlight, wind, and biomass. This ensures a more sustainable use
of resources for future generations.
➢ Global Agreements and Commitments: Many countries are signatories to international agreements
such as the Paris Agreement, which aim to limit global temperature rise. Transitioning to green fuels is
essential for meeting these commitments and addressing the global challenge of climate change.
5. Economic Benefits
➢ Job Creation and Economic Growth
The transition to green fuels creates new opportunities for jobs and economic growth in sectors
such as renewable energy production, research, development, and manufacturing. According to a
report by the International Renewable Energy Agency, the renewable energy sector employed 11
million people worldwide in 2018, and this number is expected to continue to grow.
➢ Technological Innovation
Developing and using green fuels requires advancements in technology and innovation, which can
lead to broader benefits beyond the energy sector. These innovations can drive economic
competitiveness and enhance a country's technological capabilities.
➢ Diversification of Energy Portfolio
Relying solely on fossil fuels makes economies vulnerable to supply disruptions, price fluctuations,
and geopolitical tensions. Incorporating green fuels into the energy mix diversifies energy sources and
reduces these risks.
➢ Urban Planning and Sustainable Development
Green fuels enable cleaner transportation options, which are crucial for reducing traffic congestion
and improving air quality in urban areas. They also align with the goals of sustainable
development by reducing the environmental impact of human activities.
6. Different Types of Hydrogen
➢ Generating electricity from hydrogen does not produce pollution because the by-product is only heat
and water. However, the process of producing hydrogen can cause pollution.
➢ Referring to how it is produced i.e., based on the source of production there are different colours of
hydrogen like Grey, Brown, Green, and Blue.
Hydrogen
➢ Hydrogen is the lightest and first element on the periodic table (low density & high
reactivity). Since the weight of hydrogen is less than air, it rises in the atmosphere and is
therefore rarely found in its pure form, H2.
➢ At standard temperature and pressure, hydrogen is a nontoxic, nonmetallic, odorless, tasteless,
colorless, and highly combustible diatomic gas.
➢ Hydrogen fuel is a zero-emission fuel burned with oxygen. It can be used in fuel cells or internal
combustion engines. It is also used as a fuel for spacecraft propulsion.
7. Grey Hydrogen
Hydrogen from hydrocarbons is called grey hydrogen. This is the most common method for hydrogen
production currently. It produced carbon dioxide as a by-product. The carbon dioxide generated during
this process is usually released into the atmosphere, making grey hydrogen a significant contributor to
greenhouse gas emissions.
Black/Brown Hydrogen
Brown hydrogen is produced using coal as its feedstock. But this process causes high pollution, and
carbon dioxide and carbon monoxide are released into the atmosphere, making it an environmentally
unsustainable option.
Blue Hydrogen
It is the hydrogen produced from hydrocarbons where the emissions generated from the process can be
captured and stored. They are stored underground by industrial carbon capture storage (CSS). This is a
better alternative compared to grey hydrogen. Blue hydrogen is considered a transitional fuel as it
reduces greenhouse gas emissions compared to grey hydrogen, but it still relies on natural gas as its
primary feedstock.
Different Types of Hydrogen
8. Green Hydrogen
➢ Just like the name goes, green hydrogen is generated from renewable sources like wind and solar.
➢ During the process, electricity splits water into hydrogen and water.
➢ Green hydrogen production is a zero carbon emission process, only water or water vapour is the by
product
➢ Green hydrogen is considered to be the most sustainable and environmental friendly type of hydrogen.
➢ Green hydrogen has the potential to revolutionize the energy industry by providing a reliable source of
clean energy.
➢ Green hydrogen is the only variety produced in a climate-neutral manner.
➢ Green hydrogen could play a vital role in global efforts to reach net-zero emissions by 2050.
9. Water Splitting
Water Splitting
➢ Water splitting is a process that enables the production of hydrogen by direct water decomposition in its
elements. The energy required to cleave H-O-H bonds can be supplied by different power sources:
electrical (electrolysis), thermal (thermolysis), or light (photolysis).
➢ Although, the electrolytic water splitting is described as a less environmentally harmful process with a
“zero” CO emission (because O is the only by-product), electrolysers generally powered by the
electricity, which is predominately produced by the combustion of coal or natural gas, resulting in the
release of CO as a byproduct. Therefore, today's research is increasingly oriented on utilizing renewable
harvesting technologies (wind turbines or photovoltaics) to drive the electrochemical/catalytic water-
splitting reaction.
➢ Photochemical/photocatalytic water splitting is a promising option for hydrogen production by renewable
resources such as water and sunlight, which is oriented on the reduction of CO emission.
10. Photocatalytic Water Splitting
It is a artificial photosynthesis process, where water (H2O) splits into hydrogen (H2) and oxygen (O2) in the
presence of a catalyst and natural light.
Photocatalytic water splitting involves three fundamental steps
➢ Photon Absorption: the absorption of photons having energies greater than the photocatalyst
bandgap such that electron–hole pairs are formed in the conduction and valence bands, respectively.
➢ The charge separation and migration of the photogenerated electron – hole pairs from the bulk to
active sites on the surface, where redox reaction should occur.
➢ Surface chemical reactions in which electrons reduce H+ to H2 while holes oxidize H2O to O2.
13. Photoelectrochemical Water Splitting
➢ The photoelectrochemical water splitting concept is based on a
photosynthetic cell. A photoelectrode is used to directly convert
solar energy into chemical energy, which is then used to drive
the water splitting reaction
➢ It involves the use of a semiconductor material (TiO2) to
absorb light and generate electron-hole pairs.
➢ These pairs are then used to drive the water splitting reaction at
the semiconductor/electrolyte interface.
➢ This process requires an external bias voltage to be applied to
the system in order to overcome the energy barrier for water
splitting.
Fujishima - Honda
14. Photoelectrochemical water splitting involves four main steps
➢ Generation of a charge (electron or hole) at semiconductor photoelectrode surface from photo
excitation
➢ Oxidation of water molecule by photogenerated holes at the photoanode surface to generate
molecular oxygen.
➢ Proton transportation from the photoanode to the cathode through electrolyte, where H+ ions at the
cathode surface will be reduced by electrons yielding H2 gas.
➢ Transportation electrons generated at photoanode towards cathode trough external circuit reduce
protons found at the surface of electrode, completing the electrical circuit.
Photoelectrochemical Water Splitting
16. Hydrogen Fuel Cell
Scheme of a Hydrogen Fuel Cell
Hydrogen produced can be
used as the fuel in Hydrogen
Fuel Cell
17. ➢ A fuel, such as hydrogen, is fed to the anode, and air is fed to the cathode.
➢ At the anode, hydrogen molecules are separate into protons and electrons
➢ The protons and electrons produced will take different paths to the cathode.
➢ The electrons go through an external circuit, creating a flow of electricity.
➢ The protons migrate through the electrolyte to the cathode
➢ At cathode, generated hydrogen and electrons will unite with oxygen to produce
water and heat
Mechanistic Steps Hydrogen Fuel Cell
19. Chemistry behind the production of Biodiesel
from Jatropha
Transesterification
➢ Transesterification is a chemical-based production of biodiesel from Jatropha oil.
➢ In this process, a complex fatty acid like triglyceride molecule is taken and it is neutralized. The
glycerin is removed, and an alcohol ester is created.
➢ This process is completed when methanol is mixed with sodium hydroxide, which results in the
production of sodium methoxide, which is then mixed with oil produced from the Jatropha seeds.
➢ When the mixture settles, glycerin is left at the bottom, and the biodiesel (methyl esters) remains on the
top. This methyl ester is washed and then filtered.
➢ In this process, when methanol and potassium hydroxide produces potassium methoxide, which, when
mixed with oil, creates a strong polar bond. This breaks the fatty acids into glycerin and biodiesel
(esters). These esters later become methyl esters. When the KOH is treated with ethanol, it will form
ethyl esters.
