Viability of Renewable Energy Inclusive Hybrid Power Systems for Rural Households and Outdoor Telecoms Infrastructures in Nigeria

Viability of Renewable Energy Inclusive Hybrid Power Systems as Distributed Generation for Rural Households and Outdoor Telecoms Infrastructures in Nigeria. By Christian Okwori MNSE,NiMechE Brass LNG LTD, 1680 Sanusi Fafunwa, Victoria Island, Lagos. +2348179033334.owoichoengine@gmail.com. Twitter:@owoichoengine. INTRODUCTION The majority of Nigeria’s 140million population like in most Third World countries, reside in rural and peri-urban areas which are in most cases sparse, scattered, and disperse in manner depending on the respective human settlement culture. See (NPC Report,2006). With the spiraling population and the opening up of more isolated settlements (including farms and outdoor telecoms masts), the challenge of delivering electricity service from the national grid is even more complicated. Developing countries are the losers of an accelerated climate change. These countries largely depend on Agriculture and are severely affected by extreme weather conditions and change in climate condition(Solarserver,2013). With about 70% of Nigerian population being agrarian, the need to seek alternative means is much more dire than ever. Around the world, 1.5billion people must live without electricity (Solarserver,2013). In Nigeria, if generated at all outside the National grid, it is purely by diesel generators. Only 30% of people living in sub Saharan Africa have access to viable electricity(Ouma,2012). However, most of the third world countries and rural communities lack the means(or barely do) to the increasing scarcity and rising prices of fossil fuels, which hampers their development(Solarserver,2013). Considering the fact that only a few rural communities are connected to the National grid, electricity development attention has to shift to decentralized supply and distributed generation(DG). Distributed generation will ensure access to modern electricity and energy services, portable water supply, improved health care and quality of life, economic supply to telecoms facilities (resulting in reduced call tariffs), and development. Distributed generation refers to small on-site, or near-the-load power plants usually less than 1MW operating in stand-alone models interconnected to the grid at distribution or sub-distribution level. See (Dalwadi and Mehta,2012) and (Modipa,2012).The distributed generations are simply small independent non conventional power plants designed to meet the needs of a small group of users. Popular in the options for distribution is a combination of different energy sources, usually involving renewable energies, this is known as Hybrid power. Hybrid Power System is the combination of two or more sources of energy by synergizing their comparative advantages in order to ensure steady and adequate power supply as required at an economic cost. Hybrid power system usually involves at least a renewable energy source. The sources of energies usually combined with each other are: Wind, solar, hydro, fossil fueled generators, biomass/biogas plant, conventional (grid electricity) and possibly; tidal, wave, OTEC, and geothermal energy. The energy source need be optimally exploited and hybrid energy should be investigated with respect to efficiency and distributed generation. Renewable energies in suburban in a suburban set up can be optimally applied if they are interlinked by utilizing the latest technologies (Modipa,2012). The hybrid power system come in varied configuration such as the following: 1. Grid – Wind 2. Grid – Solar 3. Wind – Solar 4. Wind – Diesel Generator 5. Solar – Diesel Generator 6. Solar-wind – Hydro 7. Hydro – Diesel generator 8. Wind-Tidal-Wave 9. Wind-wave 10 Wind – Tidal 11. Wave – Tidal 12. Geothermal – Wind 13. Geothermal – Solar 14. Geothermal – Wind – Solar 15. OTEC – Wind 16. OTEC – Solar 17. Biogas – Solar 18. Biogas – Fuel Cell (Hydrogen cell) 19. Solar- Fuel cell 20. Solar – Biogas – Fuel cell The list of possible combination is endless. Hybrid power in pragmatic definition is solution to getting around problems when one energy source is not enough(Khan and Iqbal, 2010). The main factors determining the application of hybrid power systems are cost. The resources available and also the aim is important. And the availability of one system over the other is usually pegged at the cost of 1KW of electricity (Ouma,2012). In Nigeria, ‘not’ all the sources are (readily) available. Geothermal Energy appears to be available only in the geographical regions of the world falling within the Pacific Rim of Fire and so should not be considered Nigeria based on the present technology level of geothermal energy production. See (Okwori, 2011). However, it is good to point out that the Ikogosi Hot and Cold Water Spring in South-Western Nigerian could be an indication of geothermal energy potential. OTEC (Ocean Thermal Energy Conversion) power system, Wave, and Tidal energy are quite still considered either as technologies in their infancy or not economically prudent or environmentally friendly. Hence most existing plants of these systems in the world are pilot projects for scientific researches. Hence, We are left in this studies with the following options to choose from in our analysis; Wind, hydro, solar, biogas, fossil fuel generator and grid electricity. The idea of grid electricity comes in based on the fact that the grid system itself is not stable. Aside that, some of the excess renewable energy generated can be fed into the greed by means of a Feed-in Tariff set up. The tropical location of Nigeria makes her one of the most suitable countries in the world for solar energy production based on the high solar intensity at the equator year round, especially in the Northern regions of the country bothering the Sahara axis. Wind power is another very viable energy source in Nigeria, especially in the mountainous regions of Benue-Plateau ,Goza, Obudu, Ondo, Abuja, Niger, and Mambilla; Coastal waterfronts of littoral cities, and the vast plains of Sahel and sahara in the far North. Aside the big waterfalls already explored, many potential natural hydro electric power sites such as waterfalls and fast streams still exist in Nigeria, but mainly in remote areas, and mostly in the micro and Pico capacities. One recent innovation in micro-hydro power even makes it possible to generate hydro-electricity from as low a head as 4m or there about(Feedly.com Reports, 2013). There is also the possibility of using artificial hydro electric power like Pump-As-Turbine (PAT) and the storage system for rainfalls. Biomass energy especially biogas is very sustainable in rural areas and livestock farms of rural Northern Nigeria and abattoirs in the south where cattle dung are in plentiful supply. But there is the competition from farmers who use the dung as manure. Telecoms service providers in Nigeria have over the years be blaming the high call tariff they charge their subscribers on inadequate power supply and the outrageous cost of fuelling and maintaining diesel powered generators. Now with hybrid power system the running time and cost of maintaining and fuelling diesel powered generators can be reduced immensely. Hybrid power system in this case are made either as back up to reduce the cost of generating electricity from fossil fuel or to complement renewable energy systems, ensuring continuity of power supply when renewable energy sources fluctuate (Ouma, 2012). Also, in these days of increases sensitization on climate issues, many renewable hybrid power plants are built primarily not for the economic consideration but to signal a duty of care and a sense of moral responsibility in reducing carbon sequestering and emission of green house gases (GHG) which typifies non renewable fossil fuel energy sources. With respect to the fore goings, it is good to understand that majority of the hybrid power systems in practice in most parts of the world are based on the Diesel generator-Solar, Diesiel generator-Wind, Wind – Solar, and Diesel generator – Wind – Solar configuration! This is due to cost, mobility, ease of installation, simplicity of operation, and relative availability among other reasons. Rehman et al(2010) stated that each Mega-Watts-Hour of electricity produced from renewable energy source results in the conservation of about 1.7 barrels of crude oil which means $136 revenue earning at $80 per price of fossil fuel. Wind and Solar energy appear to relief each other in terms of relative optimal availability. For example, in the US Department of Energy metrological data, wind speed is lowest during the summer when the solar intensity is highest and longest. But the wind speed is highest during the winter when there is little or no sunlight. Although with recent innovations, some super performing solar modules have been designed that could capture sunlight to some limited extent even during a snowy day ( Clean Technica Reports, 2012). In the same vein, wind speed is highest at night than in the day. This is based on the fact that wind flow arises due to the differential heating of the earth and the sea, with the hot air being lighter and flowing upwards, and cold air being denser and flowing downwards. The components of a hybrid power system include : the energy sources’ modules (e. g solar panel and wind turbine); electric power control panel; inverters; battery bank (or other forms of energy storage); and charger controllers. The generator used is synchronous. Although the overall system arrangement appears obvious, the system interaction of the source and sink is much complicated (Muljadi and Bialasiecwicz, 2003). With the relentless and steady push by the Federal Government of Nigeria towards the removal of fuel subsidy, which implies increased price of petrol and other petroleum products, it is worth considering for organizations and even urban dwellers in Nigeria to think hybrid energy as an option to fossil fuel. The price of premium motor spirit (PMS or petrol) is much more disturbing because most Nigerians own a fossil fueled power generators than own cars. Some of the numerous possible benefit Nigeria stands to gain from hybrid energy are: reduce noise and air pollution from noxious fumes of exhaust gases, due to lesser generator run time; reduced cost of maintenance; increased redundancy in power supply solutions; ease of rural and remote electrification, and much more. Researchers have proven over time that two or more sources of energy contributing to generated power are more efficient than a single source of equivalent capacity. Statement of the Problem Less than 40million Nigerians have access to electricity and it is not stable(Okon, 2009). Daily, most private organizations get powered by large and medium sized diesel and gas generators, which cost millions to fuel per week. And in most cases, some of these power generated are more than they need. This prompted most experts in the industry to estimate that the number of power generators in Victoria Island, for example, are enough to power the entire Lagos metropolis(Okwori, 2011) Majority of Nigeria’s population are resident in the rural and peri-urban areas. The maximum national electricity generation to the grid ever recorded is a meager 4000MW.This is less than a tenth of what is needed to position the country among the top 20 economies of the world by the year 2020. Aside the inadequate power generation to the grid against a population of 140million people, the grid electricity connections and distributions are often lopsided and illogical. First, some areas which ought to be given greater priority in grid connection are not connected to the grid while some areas that do not need grid connections are connected due mainly to political reasons. It is good to accept that not all villages or settlements need grid electricity connection because a simple hybrid system or renewable energy source can conveniently meet all their power needs. The loss of electric power in transmitting grid electricity to all the wrongly connected villages and satellite towns in Nigeria and the cost of such connection is immense when computed or roughly estimated. Ikeme and Oba (1998), estimated that between 30 to 35% of power generated in Nigerian power stations are lost in the way. Whereas in the US, only less than 1% is lost in the way(Kennedy-Darling et al,2008). Hence the figure of national power generation reported by government officials are significantly more than the actual amount of power available to Nigerian, that is why the figures given by officials rarely reflect facts even though the figures themselves are far from adequate in meeting the populace’s power needs. This further implies we need to optimize electricity transmission and distribution as much as we need to generate it. In all, the chance of meeting up with the country’s electricity need is quite bleak, at least in the short term. Figure 1: variation of wind and solar energy potentials across some selected cities in Nigeria. Hence there is the dire need for Nigerian government, citizens and organizations at all level to look in the direction of renewable energy, especially in hybrid power configuration for a solution in terms of distributed generations either stand-alone or feed-to-greed format as feed-in-tariff. The time has come in which we can neither run away from the problems or pretend they don’t exist! Wind Power System Wind power is the power derived from the energy of moving wind, and is directly proportional to the cube of the prevailing wind speed. According to Betz Law, the maximum power of the wind extractable by a wind turbine is only about 59.3% of the theoretical value. Hence, in modern design of wind turbine, efficiency of design is taken as a percentage of the Betz efficiency. The mechanical power of wind turbine is given by; .....................................................................................................(1) Where, …………………………………………………………………………….(2) P =turbine power, k= constant of proportionality, A =turbine rotor area. ρ=density of air=1.2kg/m3., =coefficient of power. ………………………………………………………………(3) The coefficient of power , the wind speed V, and the Tip-Speed-Ratio ʎ, and turbine torque τ are related by the following expressions; ……………………………………………………………………………………….(4) …………………………………………………………………………………..(5) ……………………………..(6) The corresponding values of , , and ʎ with respect to each other may be obtained from suitable graphs or tables of their standard values, see (Stiebler,2008). And by suitable iterations as given by (Slootweg,2003) thus; ………………………………………………………..(7) …………………………………………………………………………………..(8) Where D=Turbine rotor diameter, R=turbine rotor radius, 𝜃=pitch angle N=number of revolution, i=iteration counter. The wind energy flux density(wind energy per unit area) is given by; ………………………………………………………………………….(9) The criteria for establishment of wind turbine are as follows in their respective order: Site Selection(and environmental impact analysis); wind measurement; data collection and storage; analysis and modeling; evaluation of results; application of turbine; and investment decision. For further references see (Stiebler,2008; Slootweg, 2003;Okwori, 2012; and Sambo 1998). Wind turbine could be of the vertical axis or the horizontal axis type. But the vertical axis turbine is the most popular and commonly used. The major drawbacks of wind turbines are the noise, oscillating shadows, bed deaths, land vibration, and sight interruption of natural scenery. The cost of wind turbine in Nigeria according to Ngala et al (2007) is between ₦64 to ₦80/KWH for high wind speed location and ₦96 to ₦128/KWH for low wind speed location. The finding also revealed that the cost of wind turbine installation reduces between 9 to 17% any time the installed capacity doubles. Most part of Nigeria are not endowed with high wind speed typical for power generation (Nwosu et al,2012 ;Adaramola and Oyewole, 2011), however, the use of wind turbine in conjunction with solar energy improves the overall energy production. For good estimates, wind speed suitable for power generation should be greater than 4m/s while wind speed less than 4m/s can still be used for non power purpose. The wind energy system is still largely unexplored in Nigeria, though a promising venture it is to emback on. Solar Energy System Solar energy is the energy obtained from sunlight. Although, almost all other sources of energy owe their source to the sun. According to Williams and Calls(1990), the energy radiated by the sun in a year are more than the world has ever made use of since the earth was formed. The mass of the sun is about 330,000 times that of the earth (2.0X1030kg); 75% of which is Hydrogen, 23.32% Helium and the rest are traces of Oxygen, Carbon, Iron, Neon, etc. Its internal temperature is about 5million Celsius and its surface temperature is approximately 5778 Kelvin with a wavelength range between 0.4 and 0.2µm. The sun is in actual fact a mega fusion nuclear reactor under control by Superior Intelligence with about 6.2X1011kg of Hydrogen atom being fused per seconds with an atmospheric pressure 70billion times that of the earth surface. The intensity I of solar radiation (W/m2) on the surface of the earth is given by: …………………………………………………………………………(10) Isc= Solar Constant(W/m2), n= day number in the year. For a flat plate collector, the solar radiation received is given by; ……………………………………………………………………………………………………….(11) Of which the useful power is, …………………………(12) With an overall efficiency over the surface, ………………………………(13) A=area of module surface, F=heat removal factor, t=time, ti=inlet fluid temperature, UL=heat loss coefficient, τ= transmittance,=absorbtance. ta=ambient temperature. The value of solar insolation, irradiation, or intensity is a function of the airmass, declination, hour angle, day number in the year , zenith angle, solar azimuth angle,local solar time, number of peak sun hour, clearness index, variation in day length, emissive power of module surface, maximum hour of optimum sunshine, etc. A comprehensive expose on the subject is outside the scope of this paper. Refer to advanced authorities and related sources. Lagos and the rest of Southern Nigeria have average of 3.5 to 4.0 sun peak hours at minimum, and Northern Nigeria between 5.0 and 5.5 hours. The surface of solar Photovoltaic cell (Solar-PV) is made up of thin cells call wafers. On the surface, there is the negatively charged phosphorous doped silicon n-p-n junction in union the positively charged p-n-p boron doped junction. At the impingement of the n-p-n and p-n-p terminal by sunlight, electric field is immediately set up which transfers voltage. The quality of solar panels vary with reflections in the various matrices of the surface which can be judged by experienced experts as either grade A, grade B, or grade C. Efficiency of solar-PV’s vary with design between 20 to 40% but with daily ground breaking improvement in solar technology, the efficiency is expected to rise in few years time. The cost of solar electricity is expected to even that of fossil fuel at least by 2016, Little(2011). There is currently in the market, nano solar panels which can be spread on uneven surfaces, and beautiful solar tiles which come in different colors of choice for those who are not comfortable with the usual solar-PV’s either for reason of architectural aesthetic beauty or city roof plan compatibility issues; although the solar tiles are more expensive and less efficient than the usual PVs. For inverter capacity and battery bank sizing see further references and advanced literatures on the subject. The investment on solar energy exploration in Nigeria is still in the prestine stage, and virtually unexploited to any significant extent despite the promise and abundance of supply. The European Union in a project being spearheaded by Siemens Engineering is working on obtaining about 15% of its energy from (Nigeria’s) neighboring Sahara desert. The main challenge of solar energy in Nigeria remains the cost of solar module. For an average family in Nigeria living in 3 bedroom apartment, the cost of solar installation is about ₦1.4million. The battery bank redundancy is a matter of choice, space, and affordability. The panel cells are to be replaced every 5years with service life up to 25years. Cleaning depends on season, weather, and dustiness of the local environment. The projected cost of solar energy per kilowatt-hour in Nigeria is put at about ₦15/KWH which is now less than that of the grid(PHCN) at ₦23/KWH for households. The cost of electricity by diesel generator and petrol(gasoline) generators are almost the same,₦70/KWH. Although that of diesel is like any other source is much cheaper with larger capacities, unlike petrol generators that are not designed for large capacities due to drop in their thermal efficiencies and consequent excessive fuel consumption. Hydro Power, Biomass, and Jatropha Oil Hydro power is the power derived from the kinetic and potential energy of falling and flowing waters respectively. Much of the potential large sized hydro power sites in Nigeria are fairly exploited with construction plans underway for most of the unexploited sites. But most of the micro and Pico Hydro sites are still ignored. Such sites are better exploited by individuals and communities. Biomass energy is advisable in Nigeria at the moment in terms of sewage system exploration, municipal solid waste (MSW) and biogas digesters (plants). It is strongly advised in this publication that the cultivation of vegetable oil plants, in arable lands, fuel oils (such as ethanol) processing for biofuels are not suitable in our environment(Nigeria) at least at the present technology and the time being. For they are likely to spell grave consequencies in food production, peace, and socio-economic well-being, though acceptable for pilot projects and research purposes, And the government should forthright stop selling land to foreign countries and companies who are already in land grabbing fray in Nigeria for this or sinister purposes. Jatropha oil is a non edible vegetable oil which can be used to run generators and whose remains can be burned as biomass. The optimum exploration of this promising plant in Nigerian peculiarity should be cultivated only in the non arable arid lands especially of the North for the reasons being that the jatropha plant also grows in dry, arid, or barren lands. Also, the massive cultivation of cash crops with higher financial value than food crops could result in problems of food shortage as has been bitterly experienced in some climes of the Third world. Figure 2: altitude, wind, speed, and average temperature of some major cities across Nigeria. CONCLUSION The application of renewable energy inclusive hybrid system as stand-alone or connect-to-grid, and for private or distributed generation is both physically and economically viable especially with respect to wind and solar energy, and also jatropha oil generators, and biomass for the big cities. Hydro energy potential in pico and micro scales are also plentiful and unexploited. There has to be some form of private sector and community driven revolution to that effect. Figure 3: a jatropha generator, wind, and solar hybrid power arrangement. Areas with less than 4m/s wind speed are still suitable for wind energy for non power purpose such as; agriculture, milling, water pumping, etc. Or the use of vertical axis turbine could be resulted to, though less efficient. There has to be public exposure and enlightment as well as education on the technology. Figure 4: a solar-PV and jatropher powered generator scheme Figure 4: Nigeria wind speed map courtesy: Fadare, 2010. City Avg. Temp.(0C) Winspeed(m/s) Altitude(m) Cordinate Lagos 27 3.5 39.3 6035N3020E Ilorin 26 3.5 307.4 8029N4035E Minna 27 5.0 256.4 9037N6032E Makurdi 28 4.5 112.9 7044N8032E Jos 22 9.5 1290 9052N8054E Enugu 27 4.5 141.8 6028N7033E Porthercourt 27 3.0 19.5 4051N701E Maiduguri 27 8.0 353.8 11051N1305E Yola 28 6.0 186.1 9014N12028E kano 26 13.5 472.5 1203N8032E Table: average values of wind speed, temperature, and height of some major cities in Nigeria. Recommendation Whole or partial replacement of fuel subsidy with renewable energy subsidy due to the high cost of renewable energy modules and storage system. Stoppage of grid connections to rural areas and isolated amenities with the replacement of such with renewable energy systems or a hybrid system involving renewable energy. Setting a target of 50% renewable power source for telecoms BTS or 70% use of renewable energy inclusive energy systems. 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