Exploitation of renewable energy resources for environment‐friendly sustainable development in Saudi Arabia

The recent increase in energy costs, driven by a surge in oil prices, has increased world‐wide efforts on the exploitation of renewable/wind energy resources for environment‐friendly sustainable development and to mitigate future energy challenges. Moreover, experience in the wind energy industry has reached high levels in the field of manufacturing and application. This inevitably increases the merits of wind energy exploitation. In order to exploit wind resources, through the establishment of wind power plants, specific attention must be focused on the characteristics of wind and wind machines. The literature indicates that wind‐energy resources are relatively better along coastlines. In the present study, long‐term hourly mean wind speed data for the period 1986–2003, recorded at Dhahran (Eastern Coastal region, Saudi Arabia), has been analysed to examine the wind characteristics including (but not limited to): yearly/monthly/diurnal variations of wind speed, frequency distribution of wind speed, impact of hub‐height/machine‐size on energy production, etc. Data have been checked/validated for completeness. Data analysis indicated that long‐term monthly average wind speeds ranged from 3.8 to 5.8 m/s.

Concurrently, the study determined monthly average daily energy generation from different sizes of commercial wind machines (150, 250, 600 kW, etc.) to assess the impact of wind machine size on energy yield. The study also estimated annual energy production (MWh/year) from wind farms of different capacities (3, 6, 12, 24 MW, etc.) by utilising different commercial wind energy conversion systems (WECS). It was observed that, for a given 6 MW wind farm size, a cluster of 150 kW wind machines (at 50 m hub‐height) yielded about 32% more energy when compared to a cluster of 600 kW wind machines. The study also estimated the cost of wind‐based electricity (COE, US$/kWh) by using different capacities of commercial WECS. It was found that the COE per kWh is 0.045 US$/kWh for 150 kW wind machine (at 50 m hub‐height) whereas COE was 0.039 US$/kWh for 600 kW wind machine (at 50 m hub‐height). The study also dealt with wind turbine characteristics (such as capacity factor and availability factor). These characteristics are important indicators of wind turbine performance evaluation.     

Social acceptance of wind and solar power in the Brazilian electricity system

Renewable energy is often associated with the production of clean electricity and free of significant adverse impacts. However, several studies have been highlighting the importance of the assessment of social impacts of these technologies, including not only the benefits but also the potential negative aspects most frequently affecting local population. The energy matrix in Brazil is already built up on a renewable system largely supported on hydropower but other technologies with special emphasis on wind power start to have a major role, with a strong growth forecasted for this sector in the coming years. This article discusses the integration of solar and wind power in the Brazilian electricity system focusing on the social awareness and acceptance for the population living in high potential regions. For this, a questionnaire was proposed with the aim of evaluating the level of knowledge of wind and solar power, their social acceptance and perceptions towards cost, local development and environmental impacts. The questionnaire was implemented in an academic institution in the State of Rio Grande do Norte (RN) including students and professors as key actors for the present and future energy policy decision making. The implementation process and the obtained results are described allowing to conclude on the high level of acceptance of solar and wind power in the country and the region, with low evidence of not in my backyard syndrome.     

Levellised electricity cost for wind and PV–diesel hybrid system in Oman at selected sites

Solar and wind energy data available for Oman indicate that these two resources are likely to play an important role in the future energy generation in this country. In this paper, a model is designed to assess wind and solar power cost per kWh of energy produced using different sizes of wind machines and photovoltaic (PV) panels at two sites in Oman, which then can be generalised for other locations in Oman. Hourly values of wind speed and solar radiation recorded for several years are used for these locations. The wind profiles from Thumrait and Masirah island are modelled using the Weibull distribution. The cost of wind-based energy is calculated for both locations using different sizes of turbines. Furthermore, this paper presents a study carried out to investigate the economics of using PV only and PV with battery as an energy fuel saver in two villages. The results show that the PV energy utilisation is an attractive option with an energy cost of the selected PV ranges between 0.128 and 0.144 $/kWh at 7.55% discount rate compared to an operating cost of 0.128–0.558 $\kWh for diesel generation, considering the capital cost of diesel units as sunk.     

Stand-alone hybrid energy system for sustainable development in rural India

Renewable energy system such as solar, wind, small hydro and biogas generators can be used successfully in rural off-grid locations where grid connection is not possible. The main objectives of this study are to examine which configuration is the most cost-effective for the village. One renewable energy model has been developed for supplying electric power for 124 rural households of an off-grid rural village in eastern India. The load demand of the village was determined by the survey work, and the loads were divided into three sub-heads such as primary load I, primary load II and deferred load. Locally available energy sources such as solar radiation and biogas derived from cow dung and kitchen wastes were used as sensitivity variables. This study is unique as it has not considered any diesel generator for supplying unmet electricity to the households; rather it completely depends on locally available renewable resources. Here in this paper, two different models were taken and their cost and environmental benefit were discussed and compared. The net present cost, levelised cost of energy and operating cost for various configurations of models were determined. The minimum cost of energy of $0.476/kWh with lowest net present cost of $386,971 and lowest operating cost ($21,025/year) was found with stand-alone solar–biogas hybrid system.     

Policy innovation for technology diffusion: a case-study of Japanese renewable energy public support programs

Due to local scarcity of fossil fuel reserves, deployment of renewable energy has been on the Japanese government energy policy agenda for decades. While a significant amount of government budget was being allocated to renewables Research and Development, in contrast very little attention was paid to public support for renewable energy deployment. Against this background, in 2003, the Japanese government enacted legislation based on the renewable portfolio standard (RPS) scheme, which requires electricity retailers to supply a certain amount of electricity from renewable sources to grid consumers. The RPS legislation had been expected to ensure market efficiency, as well as bringing a steady increase in renewable capacity. Later, in 2009, the feed-in tariff (FIT) scheme was introduced to let electricity utilities purchase electricity generated from renewable energy sources with regulated prices. This paper aims to use the choice of renewable policy as a case-study to understand barriers for policy transfer and innovation, mainly through comparative studies between RPS and FIT in Japan. The result of this study shows that, in Japan, most policy-makers face the ‘lock-in’ of existing technology, which frustrates the deployment of renewable energy. For this reason, there is reluctance to allow experimentation that could promote a shift to other energy sources. In order to achieve the rapid change towards green industry, innovation policy needs to be implemented through effective and efficient methods, such as a carbon tax for fossil fuels; enlargement of renewable energy deployment to sources such as wind, geothermal and solar; and conducting further studies toward public preference and willingness to pay for the new clean energy sources.     

中国农村可再生能源的发展现状分析

中国有9亿人民生活在农村地区,农村能源的利用直接影响我国经济社会的全面发展,本文首先介绍了我国的能源资源潜力及农村能源消费结构,指出现阶段正处于从传统能源消费结构向现代能源消费结构变迁的过程中。在分析我国各种可再生能源技术最新发展现状基础上,文中总结了可再生能源CDM碳交易项目的进展,最后分析了我国给与可再生能源发展的鼓励及相关保护政策并提出了了我国农村可再生能源发展的问题及建议。     

Performance evaluation of solar photovoltaic electricity-generating systems: an Indian perspective

The present work seeks to assess the sustainability of different solar photovoltaic (SPV) electricity-generating systems based upon energy, environment and economics. The sustainability indicators evaluated for energy, environment and economics are electrical output, life-cycle greenhouse gas (GHG) emissions and life-cycle cost of electricity generated per kilowatt hour. The selected SPV-based electricity generation technologies for sustainability evaluation are amorphous, monocrystalline and polycrystalline at different locations and tilt angles across India. For SPV systems, most of the emissions are the result of electricity use during manufacturing. In these cases, an average grid mix for the region of manufacture is typically used to calculate energy use and emissions. Based upon these three indicators, a figure of merit (FM) has been proposed. The results proposed that polycrystalline gives the maximum electrical output, minimum GHG emission, minimum cost and maximum FM at a radiation level of 6 kWh/m²/day with latitude and tilt angle of 34° and 35°, respectively. This work will be helpful to users of solar energy, academicians, researchers and other concerned persons, in understanding the importance, severity and benefits obtained by the application and implementation of the SPV electricity-generating systems.     

Economic feasibility of autonomous hybrid wind–diesel power systems for residential loads in hot regions: a step to mitigate the implications of fossil fuel depletion

Today, energy occupies a pivotal position around which all socio-economic activities revolve. No energy means no life, and supply of energy in a cheap, plentiful, long-sustainable and environmentally safe form is a boon for everyone. In the light of rising cost of oil and fears of its exhaustion coupled with increased pollution, the governments worldwide are deliberating and making huge strides to promote renewable energy sources such as wind. Integration of wind machines with the diesel plants is pursued widely to reduce dependence on fossil-fuel-produced energy and to reduce the release of carbon gases that cause global climate change. The literature indicates that commercial/residential buildings in the Kingdom of Saudi Arabia (KSA) consume an estimated 10–40% of the total electric energy generated. The aim of this study is to analyse wind-speed data of Dhahran (East-Coast, KSA) to assess the economic feasibility of utilising autonomous hybrid wind–diesel power systems to meet the electrical load of 100 typical residential buildings (with annual electrical energy demand of 3512 MWh). The monthly average wind speeds range from 3.3 to 5.6 m/s. The hybrid systems simulated consist of different combinations of 600 kW commercial wind machines supplemented with diesel generators. The National Renewable Energy Laboratory's hybrid optimisation model for electric renewables software was employed to perform the techno-economic analysis.

The simulation results indicate that for a hybrid system comprising 600 kW wind capacity together with a 1.0 MW diesel system (two 500 kW units), the wind penetration (at 50 m hub-height, with 0% annual capacity shortage) is 26%. The cost of generating energy (COE, $/kWh) from this hybrid wind–diesel system was found to be 0.070 $/kWh (assuming diesel fuel price of 0.1 $/l). The study exhibits that for a given hybrid configuration, the number of operational hours of diesel generator sets (gensets) decreases with an increase in the wind-farm capacity. Concurrently, emphasis has also been placed on wind penetration, un-met load, effect of hub-height on energy production and COE, excess electricity generation, percentage fuel savings and reduction in carbon emissions (relative to diesel-only situation) of different hybrid systems, cost breakdown of wind–diesel systems, COE of different hybrid systems, etc.     

Viability of solar photovoltaics as an electricity generation source for Jordan

Viability of solar photovoltaics as an electricity generation source for Jordan was assessed utilising a proposed 5 MW grid‐connected solar photovoltaic power plant. Long‐term (1994–2003) monthly average daily global solar radiation and sunshine duration data for 24 locations – distributed all over the country – were studied and analysed to assess the distribution of radiation and sunshine duration over Jordan, and formed an input to the RetScreen Software for evaluation and analysis of the proposed plant's electricity production and economic feasibility. It was found that depending on the geographical location, the global solar radiation on horizontal surface varied between 1.51 and 2.46 MWh/m²/year with an overall mean value of 2.01 MWh/m²/year for Jordan. The sunshine duration was found to vary, according to the location, between 8.47 and 9.68 hours/day, with a mean value of 9.07 hours/day and about 3311 sunshine hours annually for Jordan. The annual electricity production of the proposed plant varied depending on the location between 6.886 and 11.919 GWh/year, with a mean value of 9.46 GWh/year. The specific yield varied between 340.9 and 196.9 kWh/m², while the mean value was 270.59 kWh/m². Analysis of the annual electricity production of the plant, the specific yield, besides the economic indicators, i.e. internal rate of return, simple payback period, years to positive cash flow, net present value, annual life cycle saving, benefit/cost ratio, and cost of energy – for all sites – showed that Tafila and Karak are the most suitable sites for the solar photovoltaic power plant's development and Wadi Yabis is the worst. The results also showed that an average of 7414.9 tons of greenhouse gases can be avoided annually utilising the proposed plant for electricity generation at any part of Jordan.     

Contribution of the sugar cane industry to reduce carbon dioxide emissions in the energy sector: the case of Mauritius

The aim of this paper was to present the contribution of the sugar cane industry to reduce carbon dioxide emissions in the energy sector. Mauritius is taken as a case study. Sugar cane was introduced in Mauritius during the seventeenth century and production of sugar started around 60 years later. Since then, the cane industry has been one of the economic pillars of the country. Bagasse, a by-product of sugar cane, is used as fuel in cogeneration power plants to produce process heat and electricity. This process heat and the generated electricity are used by an annexed sugar mills for the production of sugar, while the remaining electricity is exported to the national grid. In fact, Mauritius is a pioneer in the field of bagasse-based cogeneration power plant; the first bagasse-based cogeneration power plant that was commissioned in the world was in Mauritius in 1957. The contribution of the cane industry in the electricity sector has been vital for the economic development of Mauritius and also in terms of mitigating carbon dioxide emissions by displacing fossil fuels in electricity generation, as bagasse is classified as a renewable source. Data obtained from Statistics Mauritius on electricity production for the past 45 years were analysed, and carbon dioxide emissions were calculated based on international norms. It is estimated that savings on heavy fuel oil importation were by 1.5 million tons of oil—representing a value of 2.9 billion dollars—thus avoiding 4.5 million tons of carbon dioxide emissions. This figure can be further increased if molasses, a by-product of sugar cane juice, is used to produce bio-ethanol to be used as fuel in vehicles.     

Intelligent power supply management of an autonomous hybrid energy generator

ABSTRACT

This work deals with the optimization of an hybrid energy system used to supply an isolated site. The proposed system combines a wind turbine, a photovoltaic panel, a diesel generator and a battery bank to electrify atypical home. An energy cost-effectiveness approach is adopted in accordance with meteorological data, time profile of energy consumption, and the cost of different alternative systems. A variety of performances is obtained through simulations within the Homer Pro environment. The selection of an optimal combination is based on the maximum integration of renewable energy in the suggested system with a minimum of gas emission. According to the obtained results, the overall cost of the selected installation is about 72,900 €, with 0.415€ the unit cost of a kWh electric energy provided with a contribution of renewable energy of around 86%. Simulations show a technical and financial benefits of the different configurations obtained to supply the target site. To control the proposed hybrid energy system, a supervision algorithm is developed and implemented on TMS320F28027 DSP platform. The proposed energy system aims to take advantages of renewable energy sources and shift to conventional sources only when necessary in order to ensure source autonomy and service continuity.     

Optimum design and evaluation of hybrid solar/wind/diesel power system for Masirah Island

This paper addresses the requirements of electrical energy for an isolated island of Masirah in Oman. The paper studied the possibility of using sources of renewable energy in combination with current diesel power plant on the island to meet the electrical load demand. There are two renewable energy sources used in this study, solar and wind energy. This study aimed to design and evaluate hybrid solar/wind/diesel/battery system in terms of cost and pollution. By using HOMER software, many simulation analyses have been proposed to find and optimize different technologies that contain wind turbine, solar photovoltaic, and diesel in combination with storage batteries for electrical generation. Four different hybrid power systems were proposed, diesel generators only, wind/diesel/battery, PV/diesel/battery, and PV/wind/diesel/battery. The analysis of the results shows that around 75 % could reduce the cost of energy by using PV/wind/diesel hybrid power system. Also, the greenhouse emission could be reduced by around 25 % compared with these by using diesel generators system that currently utilize in the Masirah Island. The solar/wind/diesel hybrid system is techno-economically viable for Masirah Island.     

电力产业重构中的可再生能源政策——美国的经验

电力工业进行的市场化重构 ,对可再生能源来说 ,可能是一种机会 ,也可能意味着风险。主要的风险就是在不考虑外部性的情况下进行竞争将使可再生能源处于劣势。这种劣势将导致可再生能源发电量比改革前还少 ,同时大气污染更大 ,温室气体排放更多。但是如果采取适当的政策 ,新的市场也可以为可再生能源的发展创造更多的机会。本文在提出这个问题的基础上 ,介绍并分析了美国在进行电力产业重构时 ,为了促进可再生能源的发展所采用的系统效益费、可再生能源份额标准和绿色市场等三种政策方法     

绿证交易、发售电配额制与可再生能源财税减负效应

为促进清洁能源消纳利用和减轻标杆电价政策财税负担,绿色电力证书(绿证)核发和认购制度已在全国试行。为验证两类政策并存下绿证交易的财税减负作用,该文构建绿证定价和财税减负效应模型,分类探讨不同交易机制和配额安排:绿证自由市场、发售电配额强制市场交易如何影响售证方定价策略和配额主体履约抉择,论证绿证市场均衡和政策互动如何影响可再生能源补助支出、电价附加和绿证交易的税负转嫁效应。模型论证与分类市场情景表明:①绿证交易提供了低成本履约的制度安排,有助于财税减负;②电力市场管制和交叉补贴电价政策下,发电商配额导致火电企业最优履约抉择是自建绿电项目而非绿证交易,绿证市场有价无市;③售电配额的市场交易效率更高,但发电商实施领导跟随-产量最优策略将造成电力和绿证价格双攀升,变相增加电价负担;④并网消纳和补贴拖欠削弱绿证价格而降低补贴转嫁,售电配额调整通过跨区绿电需求变化影响税负转嫁。这些结论蕴含的政策意义是:①兼顾绿电支付意愿、成本分担与应用目标,健全绿证认购市场体系;②理顺绿证定价与惩罚机制,确保绿证市场竞争均衡与履约效率;③完善省级配额机制,引导具备成本优势的跨区绿证交易;④协调政策互动效应,增强绿电溢价和绿证减负效应。     

Solar photovoltaic investments and economic growth in EU: Are we able to evaluate the nexus?

A core question in energy economics may be stated as follows: Is the cost–benefit analysis being correctly applied when we encourage investments in renewables, as an alternative to the traditional energy sources? The relationship between energy consumption and economic growth has been extensively treated within economics literature. Yet, literature on the nexus between specific energy sources and GDP is almost inexistent. In this article, we intend to explore the relationship between a certain type of renewable generation technology (solar PV) and GDP. The present and above all the planned energy mix might differ widely from one country to another. Thus, the analysis by source of energy generation becomes a helpful instrument for policy-making. Using a fixed effects panel data methodology and a sample of eighteen EU countries, we find that a 1 % increase in solar PV installed capacity and in electricity production from renewable sources has a positive impact on GDP of 0.0248 and 0.0061 %, respectively. We also conclude that a 1 % growth on greenhouse gas emissions positively affects GDP by 0.3106 %. Further evidence reveals that, in terms of country-specific analysis, Germany, France, Italy and the UK have the most significant estimations for fixed effects. In fact, Germany is a solar PV technology producer, France has a very active nuclear sector, with little pressure for both renewables development and CO₂ reductions, Italy had in this period a strong governmental support to this sector, and the UK has a strong connection between the solar PV and the industry sectors.     

Renewable energy potential in India and future agenda of research

ABSTRACT

Demand of electrical energy is exponentially increasing causing environmental problems due to extensive use of fossil fuels. Hence, research has been promoted in renewable energy technologies to mitigate environmental pollution. Indian subcontinent is rich in renewable energy sources (RES). This paper describes potential of RES and region-wise installed capacity in India. Estimated potential of RES is 57 GW which is targeted to be 175 GW by 2022. A logical framework for our future research work has been presented. This includes performance optimisation of solar pumping system and reliability assessments of the designed system using reliability indices.

Abbreviation: RES: Renewable energy resources; SHP: small hydro plants; GOI: Government of India; MNRE: Ministry of New and Renewable Energy; LHP: large hydropower; BCM: billion cubic metres; PEC: per-capita energy consumption; JNNSM: Jawaharlal Nehru National Solar Mission; DNI: direct normal irradiance; SPV: solar photovoltaic; UMPP: ultra mega green solar power project; GIS: geographic information systems; WMS: wind monitoring stations; MPWL: Madhya Pradesh windfarms Ltd.; MIB: mat river basin; SWAT: Soil and Water Assessment Tool; ROR: run of river; SMS: short message service; CDM: clean development mechanism; NIOT: national institute of ocean technology; LOLP: loss of load probability; CSO: Central Statistics Office; CEA: Central Electricity Authority; TERI: The Energy and Resources Institute; WPI: Wind Power India; IEA: International Energy Agency; EAI: Energy Alternatives India; BKP: Biomass Knowledge Portal; IRENA: International Renewable Energy Agency; GAIN: Global Agricultural Information Network; NITI: National Institution for Transforming India; NIWE: National Institute of Wind Energy; UP: Uttar Pradesh; J&K: Jammu and Kashmir; HP: Himachal Pradesh; NR: northern region; MP: Madhya Pradesh; WR: western region; TN: Tamil Nadu; AP: Andhra Pradesh; SR: southern region; ER: eastern region; NER: north eastern region; A&N: Andaman & Nicobar     

中国农村清洁能源发展分析及建议

本文从我国农村地区发展清洁能源对于保护环境和促进农村社会经济可持续发展的现实意义入手,首先描述了当前阶段我国农村地区的能源消费结构和生产方式,分析了清洁能源在我国城市和农村地区发展不平衡的问题,进一步阐述了农村地区发展清洁能源在改变能源消费结构,合理利用能源,促进节能减排,改善农村生产生活条件,促进社会和谐发展等方面的重要性.随后介绍了现阶段我国农村清洁能源发展的基础设施和政策法规环境以及适合不同地区的清洁能源技术和发展情况.本文认为农村清洁能源可以分为三种主要发展模式,即自给自足的分散模式、可规模化生产的集中模式和与生态经济结合的循环模式,并从不同模式的表现形式、技术特点、地域特征、用能环境、基础设施、能源性质、发展阶段、投资规模、服务要求、创新侧重点等方面进行了比较分析.文章最后就当前农村地区清洁能源发展所面临的问题提出了有针对性的政策建议,并指出农村要基于当地当前生产生活条件,因地制宜地选取适合的清洁能源发展模式.     

可再生能源发展情景设计及评价研究

通过对当前主要的情景设计及评价方法的研究,认为目前我国可再生能源发展迅速,但初期的部分基本工作尚未完成.尤其是可再生能源的供给潜力及其经济可开发性评价.基于此,提出一种基于动态成本曲线的可再生能源发展战略情景仿真模型.动态成本曲线生成的基本原理是在静态成本曲线基础上,考虑技术进步、可再生能源外部价值对静态成本曲线的影响,从而生成不同时期的可再生能源成本曲线,进而构成可再生能源动态成本曲线.考虑不同种类可再生能源技术进步水平、外部环境价值的变化,设计不同的可再生能源发展情景.基于可再生能源动态成本曲线,并对不同的可再生能源发展情景下的投资成本、能源效益、经济效益和社会效益进行了综合评价.最后通过一个案例,分四种情景,即不考虑技术进步,低环境方案情景;不考虑技术进步,高环境方案情景;考虑技术进步,低环境方案情景;考虑技术进步,高环境方案情景;分别给出了四种情景下的装机总量、投资总额、创造就业、污染物和温室气体减排量.     

Threshold effects of renewable energy consumption on economic growth under energy transformation

China proposed that non-fossil energy consumption account for 20% in total energy consumption. EU increased the target of renewable energy consumption share from 27% to 35% in 2030.Energy transformation and increasing renewable energy consumption are important energy strategies for all countries at present. Then, is the impact of renewable energy consumption on economic growth positive or negative? Are there any differences in the direction or magnitude of the impact among countries or regions, and what are the determinants behind them? We apply panel threshold effect model to test threshold effects of renewable energy consumption on economic growth of EU. Empirical result shows: first, the impact of renewable energy consumption on economic growth is negative. Second, renewable energy consumption has significant threshold effects on economic growth. Third, now, energy consumption intensity and GDP per capita of most EU members are in the appropriate threshold regimes. In contrast, more and more EU members are in the high-subsidy group. Fourth, the average annual growth rates of renewable energy consumption showed no significant difference between high-subsidy and lowsubsidy countries from 1990 to 2014. Therefore, subsidy with high economic cost is not the onlyeffective means to increase renewable energy consumption.     

Economic analysis of biogas and compost projects in a palm oil mill with clean development mechanism in Malaysia

This article is a case study to compare the economic viabilities of biogas generation and compost projects in a palm oil mill in Malaysia with and without clean development mechanism (CDM). Biogas is captured from anaerobic ponds or digester tanks treating palm oil mill effluent (POME) and converted to green renewable electricity for grid connection, while compost is produced from the shredded empty fruit bunch and raw untreated POME. The both technologies were compared by considering the changes of the materials flow and energy balances. A palm oil mill with a capacity of 54?t fresh fruit bunch per hour has the potential to produce either 6.9?GWh of electricity from biogas or fertilizer equivalent to 488?t of nitrogen, 76?t of phosphorus and 1,065?t of potassium per year. The economic analysis for 10?years project term analysis indicated that CDM gave a significant impact and ensured economic viability for both projects with 25?% of internal rate of return (IRR), RM 12.39 million of net present value (NPV) and 3.5?years of payback period (PBP) for biogas project, whereas 31?% of IRR, RM 10.87 million of NPV and 2.9?years of PBP for compost project, respectively. In addition, sensitivity analysis indicated that the profitability of both projects will vary depending on the economic situation, such as electricity price which is based on the government policy, whereas compost price that depend on fertilizer market price with 43?% NPV change in 20?% range of fertilizer value.