2. Under the
guidance of
Asst. Prof. Anoop S S
Department of Chemical Engg
AmaJyothi College of Engineering
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3. DEPARTMENT OF CHEMICAL ENGINEERING 3
Introduction
The Energy challenge
Solar power
Photosynthesis
Light and dark reactions
Mimicking the grand design
Scale up
Sustainable future
Reference
Table of Contents
4. A simple thought to begin with…
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8. DEPARTMENT OF CHEMICAL ENGINEERING 8
The Gemasolar plant in Spain. Source: http://www.torresolenergy.com/TORRESOL/gemasolar-plant/en
9. Short comings
at present
Photovoltaic cells remain
expensive
Sunlight is a weather
dependent energy source
Need to design more efficient
storage devices
DEPARTMENT OF CHEMICAL ENGINEERING 9
So we go to an ancient practice called
BIOMIMICRY
13. DEPARTMENT OF CHEMICAL ENGINEERING 13
The light reactions
1. Photophosphorylation
2H2O + NADP+ +3ADP + 3P 2NADPH + H+ + 3ATP + O2
NADP+ : Nicotinamide adenine dinucleotide phosphate
ADP : Adenosine diphosphate
NADPH : stored form of Hydrogen
ATP : AdenosineTriphosphate : C10H16N5O13P3
Takes place in thylakoid membranes in the interior of chloroplasts
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The light reactions
2. Calvin Cycle
RuBP carboxylase enzyme
RuBP : Ribulose biphosphate
G3P : Glyceraldehyde-3-phosphate
▪ Uses reducing power of NADPH
▪ And free energy stored in ATP to assimilate CO2
▪ In form of carbohydrates
CO2 + RuBP 2(3-phosphoglycerate)
3-phosphoglycerate (glucose)
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ΔG=522kJ/mol
Already have technology to capture sunlight
Already have fuel cells to generate electricity
Effective means to break down water using sunlight…?
18. Artificial Photosynthesis - steps
▪ Light harvesting
▪ Charge separation
▪ Water splitting
▪ Fuel production
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Collection of light particles (photons) by antenna molecules and the concentration
of the collected energy in a reaction center.
Collected sunlight is used to separate positive (‘holes’) and negative (electrons)
charges from each other at the reaction center
Positive charges are directly injected into catalytic centers where they are used to
split water into hydrogen ions (protons) and oxygen.
Electrons from step 2 are given more energy from new photons and subsequently
combined with the hydrogen ions and possibly CO2 to produce either hydrogen
or a carbon-based fuel.
Anode(Oxidation):
2H₂O → 4H⁺ + 4e⁻ + O₂
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NiMoZn used to reduce cost
Co-OEC : cobalt-oxygen evolving complex ,
Deposits oxygen at anode side
(on illuminated side of cell)
ITO(Indium tin oxide) layer :
A conducting metal oxide layer to stabilize silicon in water
Si : Act as light harvesting catalyst. Captures solar light.
NiMoZn : Produces H₂ from combining H⁺ & e⁻
Made available from semiconductor at cathode side.
Stainless steel : Used for support . Si is deposited on it.
silicon strip coated with catalysts on each sideTriple junction
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The dream is to make each home its own power station
One can envision sustainocene not long from now
Purchasing an affordable basic power system based on
this gift from nature
A gallon of water and continuous sunlight ;all it needs to power a house for a day
2.5 billion years of evolution
25. References
▪ Thomas Hauch (2011), Artificial Photosynthesis Looking to Nature for Alternative Energy, Dartmouth
UndergraduateJournal of science., pp 14-15
▪ Michael Gràetzal (Aug 1999), The artificial leaf-Bio-mimetic photo catalysis, BaltzerScience Publifhings. Vol
3(1), pp 4-18
▪ Alexandre De Spiegeleer, Bastian Schiffthaler, Hanna Rademaker, andTomas B¨acklund, The artificial leaf.
▪ Robin Purchase, huib de vriend en huub de groot(2015), Artificial photosynthesis, GroeneGrondstoffen
▪ Han Zhou, Xufan Li,Tongxiang Fan, Frank E.Osterloh, Jian Ding, Erwin M.Sabio, Di Zhang and Qixin Guo(2010),
Artificial Inorganic Leafs for efficient photochemical hydrogen production inspired by natural
photosynthesis, Advanced Materials, pp 951-956
▪ Joseph Hupp(2011), Nanostructured Architectures and “Artificial Leaf” Solar Cells, Materials Seminar(Arizona
StateUniv.), GWC 465
▪ Sergey Koroidov (2014), Water splitting in natural and artificial photosynthetic systems, Dept. of Chemistry
Thesis(UmeaUniv.), ISBN: 978-91-7459-800-1
▪ StevenY. Reece, JonathanA. Hamel, Kimberly Sung,Thomas D. Jarvi, Arthur J. Esswein, Joep J. H. Pijpers,
Daniel G. Nocera (Nov 2011), Wireless SolarWater Splitting Using Silicon-Based Semiconductors and Earth-
Abundant Catalysts, SCIENCE, pp 645-647, 789, 925-927,
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28. 500
210
18
200
10
53
0 100 200 300 400 500 600
SILICON
COBALT
STEEL
NICKEL
MOLYBDENUM
ZINC Cost Comparison
In kilograms
DEPARTMENT OF CHEMICAL ENGINEERING 28
Editor's Notes
This statement was made by Willem Alexander King of the Netherlands, at a seminar in Dresden
solar energy •120,000 TW :actual
800 TW Practical
land mass •more sun hits surface in 1 hr, than energy used in one year
Photovoltaic solar panels
Solar collectors on rooftops to heat our water
Concentrated solar power
Cultivate plants and algae, from which food and biofuels are produced
Conventional solar panels take energy directly from the sun and covert it into electricity but only with an efficiency rate of 20 per cent.
emulate the systems already exist in nature
Evolution of photosynthesis formed an O2 cloud around us possible
We owe our very existence to a few cellular level reactions
energy from the light is converted into chemical energy in the forms of ATP and NADPH
These two molecules allow the CO2 and H2O to be converted into glucose
Photosynthesis requires both a source of energy and electrons that are needed to convert CO2 to a carbohydrate
When light energy is absorbed by a chlorophyll molecule its electrons gain energy and move to higher energy levels in the molecule (photoexcitation)
PS-I : P680 loses electrons and gets oxidized
PS-II :
Photoactivation of chlorophyll a results in the splitting of water molecules and the transfer of energy to ATP and reduced nicotinamide adenine dinucleotide phosphate (NADP).
light energy is trapped by chlorophyll to make ATP (photophosphorylation)
at the same time water is split into oxygen, hydrogen ions and free electrons
the electrons then react with a carrier molecule nicotinamide adenine dinucleotide phosphate (NADP), changing it from its oxidised state (NADP+) to its reduced state (NADPH):
NADPH is important for photosynthesis because it allows CO2 and H2O to combine to make glucose NADPH NADPH stands for Nicotinamide adenine dinucleotide phosphate
carbon dioxide from the atmosphere is captured and modified by the addition of hydrogen to form carbohydrates
carbon fixation
The new system consists of three main components: two electrodes—one photoanode and one photocathode—and a membrane. The photoanode uses sunlight to oxidize water molecules, generating protons and electrons as well as oxygen gas. The photocathode recombines the protons and electrons to form hydrogen gas. A key part of the JCAP design is the plastic membrane, which keeps the oxygen and hydrogen gases separate. If the two gases are allowed to mix and are accidentally ignited
Semiconductors such as silicon or gallium arsenide absorb light efficiently and are therefore used in solar panels. However, these materials also oxidize (or rust) on the surface when exposed to water, so cannot be used to directly generate fuel. adding a nanometers-thick layer of titanium dioxide (TiO2) onto the electrodes could prevent them from corroding while still allowing light and electrons to pass through.
The photoanode requires a catalyst to drive the essential water-splitting reaction. Rare and expensive metals such as platinum can serve as effective catalysts, but in its work the team discovered that it could create a much cheaper, active catalyst by adding a 2-nanometer-thick layer of nickel to the surface of the TiO2. This catalyst is among the most active known catalysts for splitting water molecules into oxygen, protons, and electrons and is a key to the high efficiency displayed by the device.
The photoanode was grown onto a photocathode, which also contains a highly active, inexpensive, nickel-molybdenum catalyst, to create a fully integrated single material that serves as a complete solar-driven water-splitting system.
A critical component that contributes to the efficiency and safety of the new system is the special plastic membrane that separates the gases and prevents the possibility of an explosion, while still allowing the ions to flow seamlessly to complete the electrical circuit in the cell. All of the components are stable under the same conditions and work together to produce a high-performance, fully integrated system. The demonstration system is approximately one square centimeter in area, converts 10 percent of the energy in sunlight into stored energy in the chemical fuel, and can operate for more than 40 hours continuously.
If the two gases are allowed to mix and are accidentally ignited, an explosion can occur; the membrane lets the hydrogen fuel be separately collected under pressure and safely pushed into a pipeline.
feeds this hydrogen to bacteria that is then engineered to make isopropanol.
Isopropanol is an alcohol molecule that can be used as fuel, similar to ethanol or gasoline, and can be separated from water using salt
Ralstonia eutropha.
An enzyme in this bacteria takes the hydrogen back to protons and electrons, and these are combined with carbon dioxide within the same chamber.
The researchers then extract this bacteria, with the protons, electrons and carbon dioxide and metabolically engineers it to make isopropanol.
Anthony Sinskey, professor of microbiology and of health sciences and technology at MIT
Amin Salehi, from the University of Illinois, found a different approach to the research.
Using sunlight to split water into hydrogen and oxygen, his team has developed a catalyst called 'nanoflake tungsten diselenide' that simultaneously converts carbon monoxide in the leaf - at greatly improved efficiency compared with conventional metal catalysts.
When combined with the hydrogen the carbon monoxide produces a fuel called syngas that can then be used as the basis of hydrocarbons
Artificial leaf can make oxygen in space with water and light
Hydrogen from a solar panel and electrolysis unit can currently be made for about US$7 per kilogram, the firm estimates; the artificial leaf would come in at $6.50. (It costs just $1–2 to make a kilogram of hydrogen from fossil fuels).
cutting down the expense of the light-harvesting part of the system
resculpt the silicon into flexible micrometre long wires
avoid silicon altogether, in favour of solar cells made from other kinds of semiconductors, or perhaps organic materials
dye-impregnated plastic could be used to absorb the light, then pass the photons on to the silicon to generate the current for photo-catalysts
Tata’s dream come true:
Tata’s dream come true Ratan Tata has earlier expressed his desire to build a car that runs on water. He has already invested $15 million for supporting research in the field. The product is slated to hit the market after 18 months
1 litre 13000 watts
