Efficient energy consumption, environmental awareness and renewable energy technologies alone cannot succeed in substantially reducing greenhouse emission and energy crisis in Africa. The booming economic growth across the continent continues to tremendously boost the demand for energy- more coal for producing electricity and powering new factories, more oil for fuelling new cars, more natural gas for heating new homes emerging from the increasing population- carbon emission and energy crisis will keep escalating despite the introduction of more energy-efficient vehicles, buildings and appliances and even adoption of new renewable energy sources. To thwart this startling trend of global warming and energy predicament on the continent, new technologies must be developed to store the superfluous nature’s energy in clean, sustainable and cheap techniques.
Renewable Energies technologies were suddenly and briefly fashionable three decades ago in response to the oil embargoes of the 1970’s, but the interest and support were not sustained. In the recent years, there have been dramatic improvements in the performance and affordability of solar cells, wind turbines and biofuels, this paved way for mass commercialization of renewable energy. Apart from being environmental friendly, the high and wildly fluctuating oil prices and natural gas have made renewable alternatives more appealing. However, were a very much aware of the setbacks that come packaged with renewable energy technologies: -expensive and delicate photovoltaic cells make the technology unattainable for many, the fluctuating wind energy makes the endeavour unreliable and the uneven distribution of these natural resources on the continent – these and other setbacks have attributed to the extremely low percent contribution of renewable energy to the continent’s energy grid.
We are living in an era where opportunities for renewable energy are unprecedented, making this the ideal time to advance clean, sustainable and pocket-size power for decades to come. The nature has provided ad lib energy for the living organisms to use, it is our obligation to tap, store and utilize this energy. This endeavour will require a long-time investment of scientific, economic and political resources.
The smiling Sun’s power:
The Sun produces an amazing amount of light and heat through nuclear reactions. The process that produces the sun’s energy is called nuclear fusion where two atoms come together to produce a heavier atom, in result, energy and other tiny elementary are produced. (Randolph, 2009)
In just one second the Sun emits more energy than humans have used in the last 10 000 years. Amazingly, the sun has been shining relatively steadily for the last 4.6 billion years!! (Randolph, 2009)
The amount of sun’s energy that reaches the earth’s surface is mind blowing. Relatively, more energy from the sun hits the planet in one hour than all the energy consumed on earth for a whole year.
In the 20th Century, human beings devised technologies to tap and utilize the sun’s power to produce electricity using solar cells also known as photovoltaic cells. Using semiconductors they are able to convert sunlight into electric current. However, solar power provides just a tiny slice of the World’s electricity: their global generating capacity of 5000 MW is only 0.15 percent of the total generating capacity from all sources. Yet sunlight could potentially supply 5 000 times as much the world currently consumes (Kammen, 2006).
A lot of African Countries have dived into investing in commercial solar energy harnessing to supplement the country’s energy requirement. For Instance Kenya is the global leader in the number of solar power systems installed per capita but not the number of watts added (Kammen, 2006).
Some of the major impediments affecting the solar energy harnessing include but not limited to: the photovoltaic cells used in making the solar panels are relatively expensive to manufacture rendering it impossible for most people on the continent to adopt the technology; the solar panels are also very delicate and fragile.
The above mentioned setbacks have considerably reduced the output of solar energy harnessing to a very low percentage.
Whereas the potential is enormous, if we need to increase the output we get from the sun and because of the intermittent nature of solar radiation as an energy source, excess solar energy produced during sunny periods must be stored. Insulated tanks commonly store this energy in hot water. Batteries often store excess electric energy from voltaic device. However, both methods are bulky and have low efficiency. One possibility is storing the excess solar-generated electric energy in chemical bonds.
Energy is required to break chemical bonds and also the same energy is released when those bonds are made.
Mind Blowing wind power:
Technological advances are blowing new life into an energy source long tapped by humans: the wind. The first windmills for grinding grain appeared in Persia just over 1 000 years ago. The technology spread through Asia to Europe finding other applications, including pumping water for irrigation and drinking in the America during late 19th Century. However, in 1970s, Danish researchers applied advanced engineering and materials to wind-power generation (Flavin and Dunn, 1998). The technology emerged as potentially serious competitor to fossil fuels. Currently in Northern German, the state of Schleswig-Holstein meets one quarter of its annual electricity demands with more than 2400 wind turbines, and in certain seasons wind power generates more than half the state’s electricity (Kammen, 2006).
Africa has a very high potential for wind power and the technology might be a masterpiece on solving Africa’s energy crisis and global warming. The continent experiences on average, 7.73 ms-1 of wind velocity with regions experiencing outliers of 9.4 ms-1 of wind velocity annually. These are very promising figures and are effectively competing with huge world wind farms in Denmark, Spain, Portugal among others.
From the figure above, most part of the continent have an average wind speed between 5.9 ms-1 and 6.9ms-1 with distinguished regions having extremely high wind speeds of between 8.6ms-1 and even higher than 9.4ms-1 .
Even though we are experiencing such high wind speeds, it still remains as potential as a very tiny percent of the continent’s power grid is contributed by wind power. On a global scale, wind power has a capacity of generating 60 000MW of electric power however 0.5 of the world’s electricity is produced by wind turbines (Kammen, 2006).
The major hindrance of investing in wind power is its reliability. Running a whole national or regional electricity grid on wind power is a gamble since wind constantly changes in speed, direction and even intensity. Not only is unevenly distributed but also easily distracted by landscape and human activities like infrastructure.
But on the other hand, Energy is neither created nor destroyed, but can be changed from one form to the other (Einstein). This means that one of the ways of maximally utilize this enormous wind and solar energy is to convert it into another form of energy which is easily tapped, stored and transported from one region to another. In this way, we are going to revolutionize the whole idea behind renewable energy technologies. By shifting our focus from using the renewable sources to power our factories, homes, cars etc. into tapping the grand energy and storing it for decades to come; we are creating a universe with clean, sustainable and easy energy.
Hydrogen gas as a fuel:
Hydrogen is the first chemical element on the periodic table that exists as a gas at room temperature. Hydrogen gas is odorless, tasteless, colorless, and highly flammable. When hydrogen gas burns in air, it forms water and that is where it got its name which means “water former” (Flavin and Seth, n.d)
As the world succumbs to the threats of fossil fuel exhaustion and extreme environmental hazards resulting from exploitation and use of fossil fuels, attention has been drawn to this gas as a source of energy. Liquid hydrogen was first used to fuel spaceships due to its low density and high energy content.
The major advantage of Hydrogen is that it stores approximately 2.6 times the energy per unit mass as gasoline, and the volume for a given amount of energy. For instance, a 15 gallon automobile gasoline tank contains 90 pounds of gasoline. The corresponding hydrogen tank would be 60 gallons, but the hydrogen would weigh only 34 pounds. (Nelsonville, n.d) As a result, 1 kilogram of Hydrogen gas when burnt produces 118mm Btu* of energy while 1 gallon of gasoline which is equivalent to 3.785 liters produces between 116 and 124mm Btu when burnt in addition to massive CO2, SO2, and PbO among other harmful gases.
Tiny massive energy gas
1000g of Hydrogen gas has the same energy content as 3.785 liters.
2 g of H2 (g) 1 mole of H2 (g)
1000g of H2 (g) 500 mole of H2 (g)
At r.t.p, Hydrogen has a density of 0.07099gcm-3
1 000g of H2 occupy
At this stage are carrying 116mm Btu of power in a tiny 70.99cm-3 of space compared to 3.785 liters of gasoline. Meaning, if we have a five gallon tank gasoline automobile replaced with hydrogen, it will be able to carry:
= 30 925. 60 mm Btu
Compared to maximum 620 mm Btu power produced by a gasoline engine, hydrogen engine will be able to power the automobile over 50 more times!!
As a result of Hydrogen’s low density, high-energy content, environmental friendliness and small size, the demand for Hydrogen has been rising tremendously as the world diverge its attention to this gas as a fuel.
Globally, about half of the hydrogen produced is used to produce ammonia while the other half is used to convert heavy petroleum sources into lighter fractions suitable for use as fuels. A very little percentage of hydrogen produced is used for commercial fuel use since commercial hydrogen production is a heavy resource investment. (Nelsonville, n.d)
Currently, a large portion of hydrogen gas is produced from fossil fuels as shown in the figure below.
Some of the major commercial methods used include:
1. Steam Methane Reforming
At 700 – 1100° C and in presence of a nickel catalyst, steam reacts with methane to yield carbon monoxide and Hydrogen.
CH4 (g) + H2O (g) CO (g) + 3H2 (g) + Energy
This method produces a carbon monoxide and also the reaction is endothermic and requires a lot of heat to start.
2. Coal Gasification
This is a well-established commercial technology much competitive where oil and natural gas are easily available.
Here coal replaces natural gas and oil as the primary feedstock for hydrogen production. Again this method goes back to the exploitation of fossil fuels.
3. Partial Oxidation Hydrocarbons
This process is used to produce Hydrogen from heavy hydrocarbons such as diesel fuel and residual oil. In this technology, methane and other hydrocarbons in natural are reacted with a limited amount of oxygen (typically, from air) that is not enough to completely oxidize the hydrocarbons to carbon dioxide and water where heat is evolved.
CH4 (g) + O2 (g) CO (g) + 2H2 (g) + heat
4. Thermochemical Production of Hydrogen
When water is heated to above 2500 °C, it separated into oxygen and hydrogen in a process known as thermolysis. However, at such high temperatures, it is difficult to prevent the oxygen and hydrogen from recombining to form water.
5. Sulphur-Iodine Thermochemical Cycle
In this method, sulphur dioxide is fed into the cycle as chemical catalysts in thermolysis.
I2(s) + SO2 (g) + 2H2O (l) 2HI (l) + H2SO4 (aq)
The hydrogen iodide and sulphuric acid are separated usually by distillation
H2SO4. H20 + SO2 + O2
Hydrogen is generated from Iodine.
2HI H2 + I2
6. Biomass Production of Hydrogen
Gasification of biomass could be a way of extracting hydrogen from organic sources. The biomass is converted into a gas through high-temperature gasifying. The hydrogen rich vapour is condensed into pyrolysis oils which can be steam reformed to generate hydrogen. This process has resulted in Hydrogen yields of 12% – 17% hydrogen by weight of dry biomass.
7. Photo biological
This method involves using sunlight, a biological component, catalysts and an engineered system. Specific organisms, algae and bacteria produce hydrogen as a by-product of their metabolic processes. Currently, this technology is still in the research and development stage and the theoretical sunlight conversion efficiencies have been estimated up to 24%.
Electrolysis of Water to Produce Hydrogen
Much of the above outlined technologies in Hydrogen production involve either use extreme complicated technologies or still use fossil fuels to produce hydrogen. However, electrolysis of water presents itself as a clean, simple and environmental friendly technique of hydrogen production.
Electrolysis is the technical name for using electricity to split water into its constituent elements, hydrogen and oxygen (Nelsonville, n.d).
The splitting of water is accomplished by passing a DC current through water. The electricity enters the water at the cathode, a negatively charged terminal, passes through the water and exists via the anode, positively charged terminal. Electrolysis produces very pure oxygen compared to all the other methods and this hydrogen can be used in electronics, pharmaceutical and food industries.
From the effectiveness, simplicity and environmental friendliness accompanied by electrolysis, it may be termed as the best option of hydrogen production of which it is. However, it has one major setback.
As the demand for Hydrogen continues to rise globally, the need for producing clean, adequate and sustainable Hydrogen in a cheap, easy and environmental way emerges.
During electrolysis, 237.13kJ of electrical energy is required to dissociate one mole of water.
H20(l) H2 (g) + O2 (g)
2 grams of water produce 2 grams of Hydrogen.
1g water = 0.0556 moles.
2kg water = 111.2 moles of water
Electrical energy required to split 2kg of water which will in turn produce 2kg of hydrogen
the speculated global hydrogen demands stands at 400 000 000kg by the year 2020.
For us to produce the 400 000 000kg of Hydrogen in order to serve the demand, we require over 5.9 billion mega joules of electrical energy!!
Africa’s current energy demand
A research done by Centre for Global Development in the year 2012 shows that 600 million people that is 70% of the Africa’s population of sub-Saharan Africa are without electricity. (Moss and Cleave 2013).
The analysis in the graph above shows that we have a very long way to go to cater for our domestic and industrial electricity demands. This means that bringing in another electricity consumer industry which will require 9 of electrical energy from the national grid is unthinkable.
Water, the Golden resource
As much as we are thinking about the electricity to be used in this process, we do not need to forget the fact that water is another parameter that needs to be factored in.
From every kilogram of hydrogen produced, 1000cm3 of water is used
For our ultimate goal of 400 000 000kg of Hydrogen
We are going to consume 400 million litres of water
The question is where are we going to get this water? A research done by United Nations Department of Economic and Social Affairs (UNDESA) in the year 2007 brings to our attention disturbing results on global water scarcity;
- About 700 million people in 43 countries suffer today from water scarcity.
- By 2025, 1.8 billion people will be living in regions with absolute water scarcity, and two thirds of the world’s population could be living under water stressed conditions.
- With the existing climate change scenario, almost half of the world’s population will be living in areas of high water stress by the year 2030, including between 75 million and 250 million people in Africa. In addition, water scarcity in some arid and semi-arid places will displace between 24 million and 700 million people.
- Sub-Saharan Africa has the largest number of water-stressed countries of any region as shown in the map below (Human Development Report 2006).
Source: World Water Development Report 4. World Water Assessment Programme (WWAP), March 2012
However, a clue for this water crisis puzzle lies in this water distribution pie chart on fig 9
98% of the earth’s water source is salt water in the seas and the oceans. This water is untapped since it cannot be used for human consumption and even some industrial use because of its salts content. This is a great source of our 400 million litres of water required.
Pure water is a poor conductor of electricity and therefore a poor electrolyte. In the laboratory experiments, a little acid is normally used to help ionize the water. Sea water already contains dissolved ions which will help ionize the water in readiness for electrolysis.
The use of sea water in this process will not only save our planet’s small amount of fresh water but also help us tap into the huge virgin source of water.
Electrolysis of sea water
When we consider electrolysis of seawater as a raw material for hydrogen production, it would be an obvious advantage to utilize these abundant saline water resources for electrolysis, rather than using fresh water (Abdel et al, 2010)
Some of the common ions present in sea water include:
H+, Ca2+, Mg2+, Na+, Ka+, Fe2+, Al3+ and sometimes Zn2+ and Cu2+ as the Cations and OH– , Cl– , SO42- , NO3–, HCO3– and sometimes F– and NO2– as the ions.
Sea water electrolysis is the technology used in present practice for large-scale electrolytic hydrogen production. To produce hydrogen from seawater as a target product, an electrolysis production procedure can take three main routes:
- Electrolysis to give hydrogen, oxygen and alkalis
- Electrolysis to give hydrogen, oxygen, chlorine and alkalis.
- Electrolysis to give hydrogen and sodium hypochlorite (NaClO).
In the electrolysis of sea water as a source of hydrogen, two options exist for the performance of the electrolysis process. The first option is to subject the water to total desalination to remove all dissolved salts and produce essential distilled water then the distilled water can then be subjected to electrolysis. The disadvantage of this approach are additional capital cost of water treatment and desalination system, and the environment problems arising from the need to dispose the residual salts removed during desalination. The advantages are the ability to develop a technology for direct electrolysis of sea water. (Abdel et al,2010).
The challenge now is to design an electrolyze system capable of utilizing sea water for direct electrolysis. It is probable that these systems could operate at low power density. The challenge is enormous, new technology must be developed to solve the probable corrosion and contamination problems and the evolution of undesirable electrochemical products such as chlorine. The advantages are possible lower capital cost and natural elimination of the waste brine which is only enriched with salts. It may be possible to recover economically significant quantities of the metals present in sea water, in particular magnesium in a form of magnesium hydroxide. (Abdel et al, 2010).
The sea water electrolyzes efficiently produce hypochlorite solution from chlorine generated chlorine which confirms the predominance of the production of chlorine at the anode over oxygen (Ravichandran et al, 2011). The two main factors contributing to the evolution of chlorine gas as the main anodic product rather than oxygen are reported to be as follows:
- First in un-buffered solution in solutions such as sea water, both oxygen and chlorine evolution which H+ as follows:
2H2O (g) O2 (g) + 4H+ (aq) + 4e
The chlorine generated at the anode undergoes immediate hydrolysis which also generates H+ as follows.
Cl2 + H2O HClO + Cl – + H+
HClO ClO– + H+
2Cl– Cl2 + 2e
(Abdel et al, 2010).
The pH at the anode surface becomes acidic during electrolysis, which favours chlorine evolution as it is independent of pH (Ravichandran et al, 2011).
- Although oxygen evolution should be the preferred evolution according to the thermodynamic potentials, this is only valid at zero current.
2Cl– Cl2 + 2e E = 1.36V
2H2O 4H+ + O2 (g) + 4e– E = 1.23V
Nevertheless, oxygen evolution dominates under certain conditions which may be summarized as follows.
- Sea water electrolysis at very low current density (<mA/cm2).
- Operating the cell at far in excess of the limiting current for chlorine evolution.
On the other hand, the above two circumstances are impractical because sea water oxidation at low current density would require a very large electrode area, and electrolysis at above the limiting current would lead to IR heating and high power consumption, which would be uneconomical. (Ravichandran et al, 2011).
In that regard, if we have to use sea water oxidation as one of the ways of producing hydrogen since it is available in plentiful supply on the earth, we need to develop electrolyze systems that will be both economic and environmental friendly.
Wind, Solar and Sea Water equation to Hydrogen
Having explored the wind energy, solar energy and the sea water potential in our disposal it is our obligation to design technologies that would utilize these resources into creating a super clean energy source. Having explored the wind energy, solar energy and the sea water potential in our disposal,it is our obligation to design technologies that would utilize these resources into creating a super clean energy source on the African continent.
- Kammen, M. Daniel. “The Rise of Renewable Energy”, Scientific American, 2006. Print. June 2014. Pg. 85-93.
- Lavine H Randolph. “Sun.” Microsoft Student 2009. DVD, WA: Microsoft Corporation, 2009.
- Holladay April. “Solar Energy.” Microsoft Student 2009. DVD, WA: Microsoft Corporation, 2009.
- Flavin Christopher and Dunn Seth. “Will Renewable Energy Come of Age in the 21st Century?” n.d DVD August 2014.
- Human Development Report 2006. UNDP, 2006 coping with water scarcity. Challenge of the twenty-first century. UN-Water, FAO, 2007.
- H.K. Abdel-Aal, K.M. Zohdy and M. Abdel Kareem. “Hydrogen Production Using Sea Water Electrolysis” Higher Technological Institute, Tenth of Ramadan City, Egypt. March 2010 Web. November 2014.
- Subbiah Ravichandran, Rengarajan Balaji, Balasingam Suresh Kannan, Swaminathan, Elamathi, Dharmalingam Sangeetha, Jothinathan Lakshmi, Subramanian Vasudevan and Ganapathy Sozhan. “Sulfonated Polystyrene-Block-(Ethylene-Ran-Butylene)-Block-Polystyrene (SPSEBS) Membrane for Sea Water Electrolysis to Generate Hydrogen”. The Society of solid-state and electrochemical Science and technology. 2011, Volume 33, Issue 27, Pages 157-166. Web. October 2014.
- Nelsonville. “Hydrogen production” Ohio College. n.d May 2014.