Introduction:

One major problem with renewable energy sources is inability to store the
produced energy in a viable manner. This is not a problem with biomass since the
fuels produced from biomass such as ethanol and biodiesel can be stored and used
anytime. However, the electricity produced from solar systems, hydroelectric
dams, geothermal power plants, and wind turbines cannot be stored for later use.
Batteries are not a viable option in today’s technology due to their limited capacity.
One possible solution to this problem is production of hydrogen from renewable
electricity by the electrolysis of water. Once produced, hydrogen can be stored and
used anytime.
Hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable
diatomic gas with the molecular formula H2. It is also the lightest element with a
molecular mass of 2.016 kg/kmol. Hydrogen is a fuel with a higher heating value
of 141,800 kJ/kg and a lower heating value of 120,000 kJ/kg. Note however that
hydrogen is not an energy source like coal, oil, and natural gas since there are no
hydrogen reserves in the earth. Although hydrogen is the most plentiful element in
the universe, making up about three quarters of all matter, free hydrogen is scarce.
Hydrogen must be produced from other fuels such as natural gas or from water
through electrolysis by consuming electricity. Therefore, hydrogen should be
called an energy carrier rather than an energy source.

Literature:
Hydrogen energy production would lead us to a world where our energy demand
can be fulfilled with lower emissions, eliminating or minimizing environmental
damages and where need for inexpensive, proficient, consistent, and clean energy
is encountered. It is conceivable to harvest hydrogen from sustainable and
renewable energy resources. So, hydrogen has the prospective to meet the
increasing worldwide energy demand sustainably. Hydrogen is an energy
transporter; it means that it can be used to store energy if not instantly in use and
this stored energy will be available when the primary energy source is not
accessible or adequate. Hydrogen as energy shipper is claimed to be highly
competent resource for collection, storing and transportation of solar energy.
Furthermore, hydrogen production rate also varies with variations in temperature
and light concentration inputs for the system.
Gheorghe et al. (2017) performed a technical analysis of 100 kg daily capacity
hydrogen generation and storage system as case study. Solar energy is provided for
electrolysis of water, which yield hydrogen energy. In this study, four types of
various H2 generation technical solutions and three types of sub-systems for H2
generation and storage are proposed for efficiency evaluation.
Sakr et al. (2017) performed experimental analysis for production of pure H2 and
O2 on commercial basis through electrolysis of alkaline water powered by solar
energy. Separation between cathode and anode is performed and comparatively
studied using acrylic separator and polymeric membrane method. The other factors
which may also affect electrolysis and H2 production are concentration of
electrolyte, solar irradiation and gap between electrodes. Results depict that higher
efficiency is achieved by using polymeric membrane, with electrode spacing of 5
mm and concentration of electrolyte solution at 10%. To make electrolyzers
economically useful, it is necessary to optimize between performance and
production.
Sharma et al. (2017) reviewed the methods for sustainable solar hydrogen
generation with photon fuel on solar cell. Artificial solar leaf will act as duplication
of natural leaf and strap up full solar spectrum. Design and fabrication parameters
of solar leaf are calculated in this study. Solar fuels can store high solidity of
energy in the form of chemical bonds, also providing mobility facility. This
technique will also help in consecutive control on carbon emission by converting
CO2/CO into useful future fuel. Wide spectrum application of solar irradiation will
convert these harmful gases in to H2 thus presenting environmental benefits. The
focus of study will lead towards economical fabrication of solar leaf and
generation of solar fuels.
Dincer et al. (2017) evaluated innovative methods to produce hydrogen by ranking
method for comparison and evaluation purpose. Results show that renewable
energy resources mainly hydro-electric, geothermal and solar power predict a
unique potential for innovative H2 production systems. Innovative H2 production
technologies eventually attain an utterly sustainable system from various scopes
such as energetic, environmental, economic, social and political dimensions.
Aki along his research group (2018) proposed a hydrogen production system by
the electrolysis (EL-System) by electrical power from PV and the power grid. This
system comprises of Proton Exchange Membrane (PEM) technology to provide
low carbon hydrogen. Three evaluation directories to study system efficiency are
selected as CO2 emissions, capacity exploitation, and operative cost of the whole
system. Results show that hydrogen retail price in the form of investment is
lowered by increased utilization.
Haseli et al. (2018) studied the production of hydrogen energy using three different
hydrogen fuel cells is via permutation of the energy conservation and entropy
balance equations. The results disclose that the maximum productivity of a fuel
cell can surpass that of a Carnot engine working between the same operating
conditions.
Chi et al. (2018) presented various techniques for electrolysis of water for H2
production. Water electrolysis to produce H2 from renewable sources is good
alternating for employment of solar and wind energy resources. Out of other
methods, electrolysis from energy produced by renewable has promising future.
Methodologies discussed in this study for electrolysis are proton exchange,
alkaline water, membrane water, alkaline anion exchange membrane water and
solid oxide water electrolysis techniques.

Our case study:

Consuming 80ml of water in 4 hours yield the amount of hydrogen as,

0.08kg 0.008952kg H2
g
 0.008952kg
H2

Hydrogen Production by Electricity from Solar Energy: