Electricity generation from rice husk in Indian rice mills: Potential and financial viability

Rice husk generated as a by-product of rice processing is an important energy resource. The availability of this resource in India has been assessed and the technologies for exploitation of its energy potential in rice processing industry discussed. Nomographs have been developed for estimation of the husk required to meet the energy demand of parboiling, drying and milling operations. The unit cost of electricity using rice husk gasifier-based power generation systems has been calculated and its financial feasibility assessed in comparison with utility-supplied and diesel-generated electricity. With the cost and efficiency data assumed here, the unit cost of electricity produced by rice husk gasifier-dual fuel engine-generator system varies between Rs 2/kWh and Rs 7/kWh. (Note: 35 Rs approximates to $US 1.)     

Techno-economic assessment on the implementation of biomass gasifier in conventional parboiling rice mills

Enhancement of efficiency in rice processing mills can help rural farmers to reduce the cost of rice production. Parboiling-the hydrothermal treatment of paddy rice, accounts for a significant portion of total rice processing costs and its quality. A rice husk powered gasifier-based parboiling system is an attractive option for rural rice processing mills but has not been widely adopted due to various constraints. Hence, there is a need for technical and economical analysis on gasifier-based rice parboiling system to generate information on efficiency improvement and the cost-effective ways in rice processing industries. This paper presents a techno-economic evaluation of rice husk powered gasifier-based rice processing systems working in either Producer Gas in Hot Gas Mode (PG-HGM) or Producer Gas in Cold Gas Mode (PG-CGM). MATLAB software has been used for mathematical analysis. The research reveals that the biomass gasifier operated rice parboiling system working in both modes can have the overall system efficiency as 49% to 57% with a lowest payback time of 4-2 years. Positive Net Present Cost is observed for the capacities above 1.5 tons/batch in PG-HGM.     

Providing electricity access to remote areas in India: Niche areas for decentralized electricity supply

This paper presents the results of a study undertaken for identifying niche areas in India where renewable energy based decentralized generation options can be financially more attractive as compared to grid extension for providing electricity. The cost of delivering electricity in remote areas considering cost of generation of electricity and also cost of its transmission and distribution in the country have been estimated. Considering electricity generated from coal thermal power plants, the delivered cost of electricity in remote areas, located in the distance range of 5–25 km is found to vary from Rs. 3.18/kWh to Rs. 231.14/kWh depending on peak electrical load up to 100 kW and load factor. The paper concludes that micro-hydro, dual fuel biomass gasifier systems, small wind electric generators and photovoltaic systems could be financially attractive as compared to grid extension for providing access to electricity in small remote villages.     

Net energy analysis of bioethanol production system from high-yield rice plant in Japan

This study analyzes the energy balance of a bioethanol production system from high-yield rice plant in Japan. Two systems are considered in which rice is converted to ethanol: one in which cellulose feedstocks, straw and husk, are used for cogeneration (scenario 1), and the other in which they are converted to ethanol, and byproducts such as lignin and unreacted holocellulose are used for cogeneration (scenario 2). Energy input in the agricultural process including transportation is estimated to be 52.3 GJ/ha from an Input Output Table. The heating values of produced rice and cellulose feedstocks are 120.7 GJ/ha and 162.3 GJ/ha, respectively. The net energy balance (NEB) of scenario 1 is 129.2 GJ/ha, which produces 3.6 kL/ha of ethanol and 9420 kWh/ha of external electricity. On the other hand, NEB of scenario 1 is 11.7 GJ/ha, which produces 7.1 kL/ha of ethanol. Both NEBs are positive, but NEB of scenario 2 is much higher than that of scenario 1. An acid hydrolysis technology of cellulosic biomass applied to scenario 2 needs a large amount of heat energy for sulfuric acid recovery. If an enzyme hydrolysis of cellulosic biomass is developed, there is a possibility of improving NEB of scenario 2.     

Potential for power generation in a large white rice mill

An energy analysis was conducted on the steam power plant of a large white rice mill. The boiler fired by paddy husk raised steam for a steam engine coupled to a generator. Additional electricity was imported to meet the total demand of the mill. Potentials for power generation are assessed on two alternative systems namely the boiler and turbine system and the gasifier and internal combustion engine system. Both cases of husk-match and power-match are considered. For the case of power-match, both alternative power generation systems are economically feasible.     

Biomass gasifier projects for decentralized power supply in India: A financial evaluation

Results of a techno-economic evaluation of biomass gasifier based projects for decentralized power supply for remote locations in India are presented. Contributions of different components of diesel engine generator (DG) sets, dual fuel (DF) engine generator sets and 100% producer gas (HPG) engine generator sets to their capital costs as well as to the levelized unit cost of electricity (LUCE) delivered by the same have been analyzed. LUCE delivered to the consumers has been estimated to be varying in the range of Rs. 13.14–24.49/kWh (US$¹ 0.30–0.55/kWh) for DF BGPP. LUCE increases significantly if BGPP is operated at part loads. Presently available 40 kW capacity HPG systems in India are expected to be financially competitive with a DG set of equivalent capacity beyond a break-even diesel price of Rs. 34.70/l. It is expected to be financially more attractive than an equivalent capacity DF BGPP for diesel prices of more than Rs. 44.29/l. In certain specific conditions operating two smaller capacity systems has been found to be attractive as against a single larger capacity system.     

Viability of off-grid electricity supply using rice husk: A case study from South Asia

Rice husk-based electricity generation and supply has been popularized in South Asia by the Husk Power Systems (HPS) and the Decentralised Energy Systems India (DESI), two enterprises that have successfully provided electricity access using this resource. The purpose of this paper is to analyze the conditions under which a small-scale rural power supply business becomes viable and to explore whether larger plants can be used to electrify a cluster of villages. Based on the financial analysis of alternative supply options considering residential and productive demands for electricity under different scenarios, the paper shows that serving low electricity consuming customers alone leads to part capacity utilization of the electricity generation plant and results in a high cost of supply. Higher electricity use improves the financial viability but such consumption behaviour benefits high consuming customers greatly. The integration of rice mill demand, particularly during the off-peak period, with a predominant residential peak demand system improves the viability and brings the levelised cost of supply down. Finally, larger plants bring down the cost significantly to offer a competitive supply. But the higher investment need and the risks related to monopoly supply of husk from the rice mill, organizational challenges of managing a larger distribution area and the risk of plant failure can adversely affect the investor interest. Moreover, the regulatory uncertainties and the potential for grid extension can hinder business activities in this area.     

Economic evaluation of a stand-alone residential photovoltaic power system in Bangladesh

The economics of stand-alone photovoltaic power system is studied to test its feasibility in remote and rural areas of Bangladesh and to compare renewable generators with non-renewable generators. The life cycle cost of these generators are determined using the method of net present value analysis. It is found that the life cycle cost of this experimental PV system is Tk. 43.40/kWh for one family (US $1.00 = Bangladeshi taka Tk.50.00). The life cycle cost for grid electricity is Tk. 20.00/kWh and Tk. 7.75/kWh for generation of fuel costs of Tk. 6.80/kWh and Tk. 0.47/kWh respectively. For a village 1 km away from the distribution line, this cost becomes Tk. 125.00/kWh for a family. For petrol generator life cycle cost is Tk. 50.00/kWh at fuel price of Tk. 22.00 per litre. For diesel generator life cycle cost is found to be Tk. 46.10/kWh at fuel cost of Tk. 15.00 per litre. It is observed that the life cycle cost of one unit of energy from grids that are 1 km away from a village is much higher than the cost of energy from a PV system. Thus, the use of PV system is economically feasible in rural villages and remote areas of Bangladesh, where grid electricity is not available.     

稻壳变工况反应动力学研究

采用热重分析仪研究了稻壳变工况气化特性,考察了气化反应温度、气化介质流量和操作压力对稻壳气化反应特性的影响,利用反应动力学理论对压力影响反应活化能的变化进行了计算。结果表明:稻壳气化反应过程中,碳转化率随温度的升高而增加,气化剂流量在60 ml/min以上时可以消除气化剂向外扩散的影响,随着气化压力的提高,气化反应速率加快,稻壳试样的碳转化率有所增加,在同一反应时刻,该增加关系并不是线性的,当压力较高时,空气与稻壳的还原反应所受影响较弱,稻壳气化反应活化能随压力增加先降低后上升,该现象说明压力过高对气化反应有抑制作用。     

Preliminary feasibility evaluation of solar thermal power generation in India

Results of a preliminary techno-economic appraisal of solar thermal power generation at three locations in India are presented. The study uses System Advisor Model developed by NREL, USA. The results of the study provide useful insight into (a) selecting appropriate reference direct normal irradiance for design of solar thermal power plants, (b) identifying suitable combinations of solar multiple and hours of thermal energy storage and (c) cost reduction potential. The parabolic trough technology is used for exemplifying the procedure for this purpose. The estimated levelised unit cost of electricity is in the range of Rs (US$1=Indian rupees 51.66 on 5 October 2012) 16–21 per kWh for the most likely range of input parameters. The results also indicate possibility of about 30% reduction in unit cost of electricity by year 2021.     

Energy demand and supply options for primary processing of rice in India

Energy demand for primary processing of rice in India has been assessed and feasibility of two renewable energy supply options evaluated. A model for obtaining least cost energy supply mix for a rice mill has been proposed.     

Assessment of centralized grid connected wind power cost in coastal area of Pakistan

This work presents an assessment of per unit cost of electricity generated from 15 MW wind farm at 40 locations in the coastal areas of Pakistan using the method of net present value analysis. The Nordex N43/600 wind turbine has been selected and used as reference wind turbine. Wind duration curves were developed and utilized to calculate per unit cost of electricity generated from chosen wind turbine. In Sindh province, the minimum cost of electricity generated was found to be 4.2 ¢/kWh at Jamshoro, while the corresponding maximum was 7.4 ¢/kWh at Kadhan site. In Balochistan, the minimum cost of electricity generated was found to be 6.3 ¢/kWh at Aghore, while the corresponding maximum was 21.0 ¢/kWh at Mand site. The study concludes that at most of the locations especially in Sindh province, wind power is competitive to conventional grid connected thermal power even without considering the externalities.     

Market diffusion strategies for the PEM fuel cell-based micro-CHP systems in the residential sector: scenario analysis

At present, one of the most prominent support mechanisms for sustainable energy is implementing Feed-in Tariffs. This study analyzes Feed-in Tariffs for distributed electricity generation in Iran and Feed-in Tariffs for electricity generated by fuel cells in other countries. Based on reviews of the regulations and the support plans for renewable energy development, CHP generators, and fuel cells, four scenarios were designed for pricing the electricity generated from the fuel cells and how to support its market development. Based on these scenarios, the Feed-in Tariffs of electricity from fuel cells or the expected amount of support for each fuel cell unit was calculated. In the case of using a production tax credit (PTC) model, assuming the total export of the generated electricity to the grid, the cost per kilowatt-hour of electricity varied by 9.89–60.78 cent/kWh based on the utilization of different PEM fuel cell products of different companies. Using Iran's small-scale generator support guideline, the electricity generation cost was calculated between 7.032 and 57.921 cents/kWh.     

Techno-economics of small wind electric generator projects for decentralized power supply in India

A techno-economic evaluation of small wind electric generator (SWEG) projects for providing decentralized power supply in remote locations in India is presented. SWEG projects that have either been implemented or are under implementation have been considered. The capital costs of the SWEG projects and sub-systems have been analysed. Levelised unit cost of electricity (LUCE) has been estimated for 19 select places located in different geographical regions of the country. The LUCE is found to vary in the range of Rs. 4.67–83.02/kWh (US$¹ 0.10–1.86/kWh) for wind electric generator projects in the capacity range 3.2–50 kW with annual mean wind speed variation in the range 5–10 m/s. Issues relating to their environmental impact(s), barriers to diffusion and institutional mechanism(s) to implement such projects have also been discussed.     

Assessment of wind energy potential for selected areas in Jordan

This paper presents a technical assessment of wind power potential for seven locations in Jordan using statistical analysis to determine the wind characteristic based on the measured wind data. Rayleigh distribution is used to model the monthly average data and used to estimate the wind power in the selected locations. Energy calculations, capacity factors and cost of wind energy production were determined for the selected locations with wind machines of different sizes ranging between 1.65 MW and 3 MW. The quantitative estimates of the technical and economic potential are presented graphically. Rayleigh parameter is adjusted to the hub height using one seventh power law to estimate the power output of the machine. The energy cost analyses show that all selected sites have high economic potential with unit cost less than $0.04/kWh of electricity. The lowest unit cost per kWh is obtained by using GE 2.5 MW at Tafila site. Finally, the results of this study reveal that Jordan has high potential wind energy and its environmental and energy policy targets can be met by exploitation wind energy.     

Thermoeconomic analysis and artificial neural network based genetic algorithm optimization of geothermal and solar energy assisted hydrogen and power generation

The study aims to optimize the geothermal and solar-assisted sustainable energy and hydrogen production system by considering the genetic algorithm. The study will be useful by integrating hydrogen as an energy storage unit to bring sustainability to smart grid systems. Using the Artificial Neural Network (ANN) based Genetic Algorithm (GA) optimization technique in the study will ensure that the system is constantly studied in the most suitable under different climatic and operating conditions, including unit product cost and the plant's power output. The water temperature of the Afyon Geothermal Power Plant varies between 70 and 130 °C, and its mass flow rate varies between 70 and 150 kg/s. In addition, the solar radiation varies between 300 and 1000 W/m² for different periods. The net power generated from the region's geothermal and solar energy-supported system is calculated as 2900 kW. If all of this produced power is used for hydrogen production in the electrolysis unit, 0.0185 kg/s hydrogen can be produced. The results indicated that the overall energy and exergy efficiencies of the integrated system are 4.97% and 16.0%, respectively. The cost of electricity generated in the combined geothermal and solar power plant is 0.027 $/kWh if the electricity is directly supplied to the grid and used. The optimized cost of hydrogen produced using the electricity produced in geothermal and solar power plants in the electrolysis unit is calculated as 1.576 $/kg H₂. The optimized unit cost of electricity produced due to hydrogen in the fuel cell is calculated as 0.091 $/kWh.     

Electricty generation from woody biomass fuels compared with other renewable energy options

The future New Zealand biomass resource from exotic plantation forest arisings could supply 970 GWh/year by the year 2002. Associated wood processing residues could supply 280 GWh/year. Purpose grown fuelwood plantations could supply 2060 GWh/year with potential to rise to 10,000 GWh/year by 2012.Currently the annual electricity demand is around 30,000 GWh 70% of which is generated by hydro power. Natural gas, a resource with estimated reserves of only approximately 14 years currently supplies 25% of generating capacity. This paper describes how part replacement of gas by biomass could be a feasible proposition for the future.Life cycle cost analyses showed electricity could be generated from arisings for (US)4.8–6 c/kWh; from residues for (US)2.4–4.8 c/kWh; and from plantations for (US)4.8–7.2 c/kWh. For comparison the current retail electricity price is around (US)4–5.5 c/kWh and estimates for wind power generation range from (US)5–10 c/kWh. Future hydropower schemes will generate power between (US)4–9 c/kWh depending on site suitability.     

Kinetics of rice husk char gasification in an H2O or a CO2 atmosphere

Rice husk gasification has been attracting increasing attention in rice-producing countries, but the technology has not yet achieved optimal efficiency. Only a few studies have reported on the gasification kinetics of rice husk char, and the influence of some important parameters has not yet been investigated. This paper provides an experimental database and kinetic models of gasification of a rice husk char particle in an H₂O or a CO₂ atmosphere. A complete parametric study of rice husk char gasification was performed in a wide range of operating conditions, relevant to those that exist in industrial gasifiers. Two kinetic models were developed to predict the conversion of a particle, taking into account changes in the reactive surface. Results of this study could help researchers and engineers in the design, modeling or optimization of a new efficient rice husk gasifier.     

Economic feasibility of electricity production from energy plantations present on community-managed forestlands in Madhya Pradesh,India

This paper assesses economic feasibility of utilizing community-managed degraded forest areas for raising energy crops and using the produced biomass for electricity production in the state of Madhya Pradesh, India through gasification technology. Three fast-growing species, three gasifiers of different capacities, three capital costs, and two scenarios of carbon payments were considered for analysis. Sensitivity and risk analyses were undertaken for determining the effects of variations in inputs on selected outputs. Results suggest that 5 million megawatt hour electricity can be generated annually which will prevent 4 million tons of carbon dioxide emissions per year. The production cost of a unit of electricity was found inversely related to the scale of production. The average cost of electricity at the consumer level produced using 100 kW gasifier was $0.15/kWh, which was greater than the price of electricity supplied from grid i.e. $0.08/kWh. The unit cost of producing electricity using Acacia nilotica was lowest among all the selected species. Technological advancements suitable government incentives are needed to promote electricity generation from forest biomass through gasification technology. This will help in spurring economic development and reducing overall ecological footprint of the state.     

稻壳灰高值利用制备ZSM-5分子筛

以稻壳灰制备的硅溶胶为硅源，采用水热合成法制备ZSM-5分子筛。通过XRD、SEM、ICP及XRF等测试手段，系统考察反应时间、模板剂（TPABr）用量及未加铝源对ZSM-5分子筛形貌、结晶度及合成残液组成的影响。结果表明：当反应时间达到10 ~ 12 h，反应物料基本完全进入分子筛中，继续延长反应时间，虽能进一步促进物料反应和提高产品结晶度，但同样会造成分子筛颗粒增大和单位能耗增加；随模板剂用量的减少（SiO₂/TPABr = 0.05、0.04和0.01），分子筛结晶度逐渐降低（89.41%、81.97%和69.77%），但分子筛的形貌、颗粒大小及产率并没有明显变化；由于稻壳灰本身特性，制备的硅溶胶含有一定量的铝（0.0143%），在未外加铝源的情况下可成功制备出ZSM-5分子筛，且分子筛的形貌、结晶度及产率均未受到明显影响。