An Analysis of the Environmental Impacts of Energy Crops in Nigeria towards Environmental Sustainability J. O. Olaoye Department of Agricultural and Biosystems Engineering, University of Ilorin, Ilorin, Nigeria. Abstract Nigeria as a country today depends solely on fossil fuel bearing in mind that someday this fossil fuel will deplete. Concerns about global climate change and air quality are driving increased interest in biomass and other energy sources that are potentially CO2-neutral and less polluting. Utilization of diverse energy crop in the midst of the abundant renewable resources of the country demands a shift of focus on extensive evaluation of environmental issues associated with the use of biomass (biogas, biofuel and biodiesels). The issues related to the environmental impact assessment of these resources were highlighted and suggestions on effective utilization of the biomass energy towards environmental sustainability were presented. The potentials of various energy crops and animal waste as forms of alternative energy for domestic and automotive applications were evaluated. Keywords: biomass, energy crop, environmental issues, biofuel, renewable energy, environmental sustainability. 1.

Introduction

The term energy crop is used to principally to describe a crop grown primarily to provide a feedstock for biofuels such as ethanol or to be burned for heat or electricity. Examples of energy crops currently in production include corn (Zea mays), sugarcane (Saccharum officinarum), and short-rotation plantations of poplar (Populus spp.), physic nut, a member of the family Euphorbiaceae (Jatropha curcas), sycamore (Platanus occidentalis) and eucalyptus (Eucalyptus spp.). According to Cook and Bevea (1998) large scale biomass energy development could bring significant environmental benefits as well as significant damages depending on the path taken. Sustainable bioenergy development is considered as one that could reduce net greenhouse gas emissions, improve air quality and reduce acid deposition, reduce landfilling, reduce agricultural chemical runoff, and improve habitat for native wildlife. Conversely, inappropriate bioenergy development could do great environmental damage. In particular, the land requirements for biomass production could be immense. The nature and extent of the impacts of these changes in land use will depend on the specifics. Riva (2006) noticed that in Asian countries recent increases in the cost of fossil fuels as a result of the strong energy demand of the fast growing industries growing and the on-going evolution of agriculture in Western countries, are leading to a more specific focus linked to energy issues in the rural areas with a possibly different perspective in respect of the past years. Over-dependence on oil has slowed down the development of alternative fuels. Diversification to achieve a wider energy supply mix will ensure greater energy security for the nation. The domestic demand for petroleum products is growing 204

rapidly. The development of alternative fuels from locally available energy resources should therefore be vigorously pursued. The environmental implication of desirable alternative is highly essential. Energy, and in particular, oil and gas, has continued to contribute over 70% of Nigeria’s Federal revenue. National developmental programmes, and security, depend largely on these revenue earnings. Energy, especially crude oil, has over the past five years contributed an average of about 25% to Nigeria’s Gross Domestic Product (GDP), representing the highest contributor after crop production. The contribution of energy to GDP is expected to be higher when we take into account renewable energy utilization, which constitutes about 90% of the energy used by the rural population (NPC, 1997). According to ECN (1998) over the period 1989-2000, fuelwood and charcoal constituted between 32 and 40% of total primary energy consumption. In year 2000, national demand was estimated to be 39 million tonnes of fuelwood. About 95% of the total fuelwood consumption was used in households for cooking and for cottage industrial activities, such as for processing cassava and oil seeds, which are closely related to household activities. A smaller proportion of the fuelwood and charcoal consumed was used in the services sector. The demand for suitable and affordable energy for domestic and industrial applications is a major concern word wide. Soaring energy consumption coupled with concerns over green house gas emissions is fuelling a growing interest in alternative power sources. In most countries of the south, where wood remains the primary source of energy, there is pressure for the forestry sector to find the means to mobilise “clean” energy, mitigate climate change and support economic development that is environmentally sustainable. Up to 70% of total volume of natural forests may be available for energy generation if the requirements could be met. About 350,000 hectares of forest and natural vegetation are lost annually due to various factors, by the beginning of the last decade, with a much lower afforestation rate of 50,000 hectares/yr. With the depleting natural wood reserves, women and children have to travel as far as six kilometres to collect wood, sometimes fresh trees are cut down and allowed to dry for harvest as fuelwood thus putting further pressure on the vegetation. Recent studies show that national demand for traditional energy (mostly fuelwood and charcoal) is 39 million tonnes per annum (about 37.4% of the total energy demand and the highest single share of all the energy forms). It is projected to increase to 91 million tons by 2030 (ECN, 1998). The deforestation rate is expected to similarly increase if no special programme is put in place to discourage the use of fuelwood, promote the use of its alternatives and replenish through deliberate afforestation and fuelwood lots. This has grave implications on sustainable environment, food security and the health of the low income households who depend on fuelwood. 2. Materials and Methods Six-stage modeling approach for assessing regional or landscape scale environmental impacts were adopted. It includes economic considerations, since economics will determine where energy crops are profitable, what conventional crops they will displace, and what management regimes will be used to produce them. Graham et al. (1998) assessed the environmental impacts of biomass energy from energy crops from 205

two different perspectives, the use of biomass for energy was considered in the context of alternative energy options, and the environmental impact of producing biomass from energy crops was also considered in the context of alternative land uses. Using biomass-derived energy can either reduce or increase greenhouse gas emissions; growing biomass energy crops can enhance soil fertility or degrade it. Therefore, one must know the specific circumstances to be able to make a statement about the environmental impacts of biomass energy. It is important to quantify the environmental impacts of major shifts in land use to grow energy crops. Shifting from current agriculture to energy crops could change soil erosion patterns, water quality of regional streams, wildlife populations, and regional air quality. Characterizing these impacts is challenging because they depend on many site- and crop-specific factors. Schafer (2007) quantifies the sustainability of energy crop production by means of the overall efficiency η o that is the energy output divided by the energy input of all processes involved as shown in eqn. 1.  n   n  o    Ai S i i .   [ Ai . ( Si  Pi  K i ) i  1  i  1

 ] .1 

(1)

Where, A denotes the area, S the solar energy, P the energy input of crop cultivation, K the energy input of fuel conversion, ηi the technical efficiency of photosynthesis and i the member of crop rotation. The crop scientist concerns for ηi and to some extent for P while K and P is of engineers and partially animal production scientist’s interest. Please note that the solar-radiation intensity is limited like the cultivating area too. 3. Results and Discussion 3.1 Evaluation of biomass and renewable resources in Nigeria Sambo (2009) and Olaoye (2001) agreed that the availability of biomass resources follows the same pattern as the nation’s vegetation. The rain forest in the south generates the highest quantity of woody biomass while the guinea savannah vegetation of the north central region generates more crop residues than the sudan and sahel savannah zones. The biomass resources and the estimated quantities in Nigeria are presented in Table 1. Three other major renewable energy resources are also identified in conjunction with the prevalence of bomass resources in Nigeria are identified as Solar Energy, wind energy and small hydro power development. In Nigeria, where rivers, waterfalls and streams with high potentials for SHP development is abundant, harnessing of these hydro-resources leads to decentralized use and local implementation and management, thereby making sustainable rural development possible through self-reliance and the use of local natural resources. This can be the most affordable and accessible option to provide off-grid electricity services. Based on Nigeria’s level of hydropower development, small hydropower station is defined as follows: Small = installed capacity of between 2 MW and 10 MW; Mini ≤ 2 MW ; Micro ≤100 kW . In recent studies carried out in twelve states and four (4) river basins, over 278 unexploited SHP sites with total potentials of 734.3 MW were identified. However, SHP potential

206

sites exist in virtually all parts of Nigeria with an estimated capacity of 3,500 MW. (Sambo, 2009 and Olaoye, 2009). According to ECN (1998) Nigeria lies within a high sunshine belt and thus has enormous solar energy potentials. The mean annual average of total solar radiation varies from about 3.5 kWhm–2day-1 in the coastal latitudes to about 7 kWhm–2day1 along the semi arid areas in the far North. On the average, the country receives solar radiation at the level of about 19.8 MJm –2 day-1. Average sunshine hours are estimated at 6hrs per day. Solar radiation is fairly well distributed. The minimum average is about 3.55 kWhm–2day-1 in Katsina in January and 3.4 kWhm–2day-1 for Calabar in August and the maximum average is 8.0 kWhm–2day-1 for Nguru in May. Given an average solar radiation level of about 5.5 kWhm–2day-1, and the prevailing efficiencies of commercial solar-electric generators, then if solar collectors or modules were used to cover 1% of Nigeria’s land area of 923,773km2, it is possible to generate 1850x103 GWh of solar electricity per year. This is over one hundred times the current grid electricity consumption level in the country. Wind, which is an effect from the uneven heating of the earth’s surface by the sun and its resultant pressure inequalities is available at annual average speeds of about 2.0 m/s at the coastal region and 4.0 m/s at the far northern region of the country. Assuming an air density of 1.1 kg/m3, wind energy intensity, perpendicular to the wind direction, ranges between 4.4 W/ m2 at the coastal areas and 35.2 W/ m2 at the far northern region. (Sambo, 2009). Wind energy conversion systems (wind turbines, wind generators, wind plants, wind machines, and wind dynamos) are devices which convert the kinetic energy of the moving air to rotary motion of a shaft, that is, mechanical energy. The technologies for harnessing this energy have, over the years been tried in the northern parts of the country, mainly for water pumping from open wells in many secondary schools of old Sokoto and Kano States as well as in Katsina, Bauchi and Plateau States. 3.2

Suggested models for assessing regional or landscape scale environmental impacts

Figure 1 shows the six stages of assessing regional or landscape scale environmental impact. These factors can assist to present the desired approach for the evaluation and the results of environmental consequences shall be amplified. According to Graham et al. (1998) the environmental impact can be calculated by linking the environmental impacts per hectare determined in Stage 3 to the land-use changes predicted in Stage 5. Regional wildlife impacts depend not only on how much and what type of land is converted, but also on the location of that land in relation to other land uses. To evaluate these impacts, one must create maps of the changes in regional or landscape pattern created by the projected land use changes. These maps are then used as inputs to spatial models of animal behavior and habitat to examine wildlife impacts. Effects on regional water quality depend on how much and what type of land is converted, where it is in relation to other land, and the topographic position of the land in relation to streams and lakes.

207

3.3

Associated environmental impact of major shift in land use for production of energy crop

Graham et al. (1998) presented four major factors for determination of environmental impacts of energy crop productions. These factors are considered as the associated environmental impact of major shift in land use for production of energy crop. 3.3.1 Crop factors According to Tolbert and Schiller (1996) and Hoffman et al. (1995) in Graham et al. (1998) the issues arising from cultivation of crops may lead to more soil erosion and use more fertilizers than growing short rotation poplar or jathropha. Also, because trees use more water than herbaceous crops, they may reduce stream flow. The type of crop grown is a decisive variable in predicting environmental impacts from energy crop production; crops have different effects on erosion, water availability and quality, wildlife habitat, and air quality. Wildlife will differentiate among crop types; for example, tree crops can provide habitat for forest bird species. Perennial grasses enhance soil carbon more than do annual crops. Tree crops release more hydrocarbons into the air than do herbaceous crops. The management strategies of crop are important factors to consider. These include methods of interplanting to reduce erosion, types and amounts of fertilizer and herbicides to apply and the timing application will affect water quality. Other handling procedure that may induce air quality and loss of nutrient are method of tree harvesting respectively. 3.3.2

Site factors

The difference between the environmental effects of the former land use and of the energy crop determines the environmental value of the energy crop. The physical characteristics of the land will strongly influence the productivity of energy crops and therefore the likelihood that they will be grown. Other related factors are soil type, climate, and topography. While topography is viewed as major factor that will affect erosion and runoff also, the soil type will influence the need for fertilizers and the rate at which pesticides and fertilizers leach to groundwater (Tolbert and Schhilller, (1996), Ranney and Mann (1994)). High organic matter content increases the soil's retention of pesticides and nutrients. In a warmer climate, pesticides break down and volatilize more rapidly. The location of the energy crops in relation to other land uses will strongly influence water quality and wildlife impacts. 3.3.3

Size of land dedicated to energy crops

The size of land earmarked for growing energy crop will produce corresponding impact on the region. The correlation between the impact and the size of land use for energy crop production may not be proportional when considering the wildlife and water quality impacts. Graham and Dowining (1993) showed that the impact of erosion, which can be calculated on a per hectare basis does not depend on land use changes elsewhere and this also will not simply be proportional to the amount of land planted to energy crops in a region. This is because soil type, topography, and former land use all will vary within the region. 3.3.4

Relationships between interactions among factors

The current global climate changes are considered as chains of reaction associated with various intervening factors that cannot be considered in isolation, because they 208

interact strongly in affecting the environment. In considering factors affecting shift in land use conditions, soil, climate, topography, crop type, and crop management all will affect energy crop productivity and therefore the quantity of land needed to produce a specific supply. Also, former land use conditions can influence energy crop productivity. For example, soil compaction as a result of pasture use may reduce expected energy crop yields. These factors should be extended to include the economic forces and policies that will control where energy crops will be grown and what land uses they will displace. According to Graham et al. (1998) assessing the potential environmental impacts of energy crop production requires an integrated approach that considers all these factors. 3.4

Potentials of animal waste/energy Crop and sustainability for energy production

The sustainability of energy crop production must be undertaken to determine establish the stand point of energy crop and food security status of the specific energy crop to be adopted. Olaoye (2009) detailed the conflicting issues on biofuel development and food security challenges. Hence, the process energy efficiency must be evaluated for any specific energy crop of interest by using equation 1. The calculation of the process energy efficiency includes the process energy input and the free energy (exergy) before and after processing. High process energy efficiency of any cultivated crop fosters common acceptance of the crop as energy crop. The evaluation of overall process energy efficiency creates opportunity to infer among other factors the status of the crop as viable crop for anaerobic digestion to produce biogas, conversion of meal feed into manure, and organic farming practices. Crop processing generates usually different products. Some are suitable for energy production others for fibre production, human nutrition or animal feed. 4 Conclusions The prevalence of energy crops in Nigeria was analysed and this was also considered with reference to the other available renewable sources of energy. The effectiveness of using biomass to reduce detrimental environmental impact of other energy sources was reviewed and it was noted that to reduce CO2 emissions from fossil fuels will depend on the net effective greenhouse gas flux for the overall biomass production-use cycle and the relative efficiency of the biomass conversion or end-use process. Therefore, increasing energy efficiency and displacing fossil fuels with renewable energy are two of the leading options for reducing emissions of CO2, the principal greenhouse gas. Suggested models for assessing regional or landscape scale environmental impacts was presented and the associated environmental impact of major shift in land use for production of energy crop were highlighted. The paper has shown that if the sustainability of energy crop production is determined, energy crop production becomes captivating with many win-win situations. Such that environmentally neutral bio-fuels will replace polluting fossil fuels, farmers will get better prices for energy crops, the agrochemical industry will gains from intensification of energy crop production, and turn over of power industry will grow due to increasing energy consumption to produce agrochemicals and to process biomass into fuel. 209

References Cook, J and J. Bevea. 1998. An Analysis of the Environmental Impacts of Energy Crops in the USA: Methodologies, Conclusions and Recommendations. http://www.panix.com/~jimcook/data/ec-workshop.html ECN 2003. Federal Republic of Nigeria, National Energy Policy, The Presidency, Energy Commission of Nigeria. 89 pp ECN 1998. Energy Commission of Nigeria: “World Solar Programme, 1996 – 2005”, Projects of the Government of Nigeria: Project Documents”, ECN Abuja. Graham, R.L., and M. Downing. 1993. Renewable biomass energy: Understanding regional scale environmental impacts. In Proceedings of the First Biomass Conference of the Americas, Burlington, Vermont, August 1993. NREL/CP200-5768. National Renewable Energy Laboratory, Golden, Colorado. pp. 1566-1581. Graham , R. L, W. Liu and B. C. English. 1998. The Environmental Benefits of Cellulosic Energy Crops at a Landscape Scale. Environmental Enhancement Through Agriculture: Proceedings of a Conference, Boston, Massachusetts, November 15-17, 1995, Center for Agriculture, Food and Environment, Tufts University, Medford, MA. http://bioenergy.ornl.gov/papers/misc/cellcrop.html Hoffman, W., J. Beyea, and J.H. Cook. 1995. Ecology of agricultural monocultures: Some consequences for biodiversity in biomass energy farms. In Proceedings of the Second Biomass Conference of the Americas: Energy, Environment, Agriculture, and Industry, Portland, Oregon. NREL/CP-200-8098. National Renewable Energy Laboratory, Golden, Colorado. pp. 1618-1627. NPC (1997). National Planning Commission: “National Rolling Plan (1997 – 1999). Olaoye, J. O. 2009. Biomass as Sustainable Sources of Renewable Energy. In: History and Philosophy of Science: General Studies Approach. Lasisi, R. O. & M. A. Akanji (Eds). Published by General Studies Division, University of Ilorin. ISBN: 978-36284-0-2. Unilorin Press, University of Ilorin, Ilorin, Nigeria. Olaoye, J. O.; 2001, Utilization of Biomass Resources as Renewable Energy in Nigeria. Proceedings of the 2nd International Conference & 23 rd Annual General Meeting of the Nigerian Institution of Agricultural Engineers (A division of NSE); 23: 457 – 462. Published by NIAE Ranney, J.W., and L.K. Mann. 1994. Environmental considerations in energy crop production. Biomass and Bioenergy 6:211-228. Riva, G. 2006. “Utilisation of Biofuels on the Farm”. Agricultural Engineering International: the CIGR Ejournal. Invited Overview No. 15. Vol. VIII. August, 2006. Sambo, A. S. 2009. Strategic Developments In Renewable Energy In Nigeria. International Association for Energy Economics. 3rd Quarters. 2:15 – 19. Schäfer, W. 2008. The role of engineering in organic farming – case energy crops. Beitrag archiviert unter http://orgprints.org/view/projects/wissenschaftstagung-2007.html. Accessed on 26th October, 2010.

210

Tolbert, V.R., and A. Schiller. 1996. Environmental enhancement using short-rotation woody crops and perennial grasses as alternatives to traditional agricultural crops. In W. Lockeretz (ed.), Environmental Enhancement through Agriculture. School of Nutrition Science and Policy, Tufts University, Medford, Massachusetts. pp. 209-216. Wright, L.L., J.H. Cushman, A.R. Ehrenshaft, S.B. McLaughlin, S.A. Martin, W.A. McNabb, J.W. Ranney, G.A. Tuskan, and A.F. Turhollow. 1993. Biofuels Feedstock Development Program Annual Progress Report for 1992. ORNL6781. Oak Ridge National Laboratory, Oak Ridge, Tennessee.

Table 1: Biomass Resources and the Estimated Quantitiesin Nigeria Resources Fuelwood Agro-waste Saw Dust Municipal Solid Waste

Quantity (million tonnes) 39.1 11.244 1.8 4.075

Source: Sambo (2009)

211

Energy (‘000 MJ) 531.0 147.7 31.433 -

Value

(1) Characterization of the Region: Region Climate, Topography, Soil Quality and Types, Location, Management Practices and Profitability of Current Land Uses (6) Evaluation of environmental impacts: Regional Impacts on Soil Fertility, Water Quality, and Air Quality Largely Depend on How Much and What Type of Land is Converted

(2) Development of Energy Crop Management Scenarios and Production Costs: Region Characterization and Appropriate Energy Crop with Soils and Climate Conditions Prediction of Environmental Impacts and Land Use

(5) Determining where land use change will occur: Predict land use changes, Least Expensive biomass for a conversion facility (4) Calculation of probable Farm Gate Biomass Price: Use data from Stage 1 to Calculate Price of Biomass, Use the break-even farmgate price to identify the appropriate energy crop lands

(3) Modeling Crop Yields and on-site Environmental Impacts: Prediction on variations in crop yield associated with soils and climates. Using empirical crop yield information

Fig. 1. Suggested model for assessing regional and landscape scale environmental impact for growing energy crops

212