Techno-economical study of hybrid power system for a remote village in Algeria

The share of renewable energy sources in Algeria primary energy supply is relatively low compared with European countries, though the trend of development is positive. One of the main strategic priorities of NEAL (New Energy Algeria), which is Algeria's renewable energy agency (government, Sonelgaz and Sonatrach), is striving to achieve a share of 10–12% renewable energy sources in primary energy supply by 2010.This article presents techno-economic assessment for off-grid hybrid generation systems of a site in south western Algeria. The HOMER model is used to evaluate the energy production, life-cycle costs and greenhouse gas emissions reduction for this study. In the present scenario, for wind speed less than 5.0 m/s the existing diesel power plant is the only feasible solution over the range of fuel prices used in the simulation. The wind diesel hybrid system becomes feasible at a wind speed of 5.48 m/s or more and a fuel price of 0.162$/L or more. If the carbon tax is taken into consideration and subsidy is abolished, then it is expected that the hybrid system will become feasible. The maximum annual capacity shortage did not have any effect on the cost of energy, which may be accounted for by larger sizes of wind machines and diesel generators.     

The feasibility of renewable energies at an off-grid community in Canada

Three renewable energy technologies (RETs) were analyzed for their feasibility for a small off-grid research facility dependent on diesel for power and propane for heat. Presently, the electrical load for this facility is 115 kW but a demand side management (DSM) energy audit revealed that 15–20% reduction was possible. Downsizing RETs and diesel engines by 15 kW to 100 kW reduces capital costs by $27 000 for biomass, $49 500 for wind and $136 500 for solar.The RET Screen International 4.0^® model compared the economical and environmental costs of generating 100 kW of electricity for three RETs compared to the current diesel engine (0 cost) and a replacement ($160/kW) diesel equipment. At all costs from $0.80 to $2.00/l, biomass combined heat and power (CHP) was the most competitive. At $0.80 per liter, biomass’ payback period was 4.1 years with a capital cost of $1800/kW compared to wind's 6.1 years due to its higher initial cost of $3300/kW and solar's 13.5 years due to its high initial cost of $9100/kW. A biomass system would reduce annual energy costs by $63 729 per year, and mitigate GHG emissions by over 98% to 10 t CO₂ from 507 t CO₂. Diesel price increases to $1.20 or $2.00/l will decrease the payback period in years dramatically to 1.8 and 0.9 for CHP, 3.6 and 1.8 for wind, and 6.7 and 3.2 years for solar, respectively.     

Economic analysis and optimal design of hydrogen/diesel backup system to improve energy hubs providing the demands of sport complexes

Energy crisis has led the communities around the world to use energy hubs. These energy hubs usually consist of photovoltics, wind turbines and batteries. Diesel generators are usually used in these systems as backup system. In this research, for the first time, an attempt is made to replace the traditional diesel only backup system with hydrogen only system and combined hydrogen and diesel backup system in hybrid photovoltaic and wind turbine energy systems. After introducing the available energy modeling tools and methods, explaining over advantages and disadvantages of each one, HOMER software was selected for this research. The simulations of this research show that using the traditional diesel generator as the backup system of the energy hub, creates a low cost system with the net present cost (NPC) of 2.5 M$ but also produces the highest amount carbon emission which is equal to 686 tons/year. The results of this study also indicate the hybrid renewable energy system which is supported by the hydrogen only backup system has the highest net present cost (NPC) and initial capital cost but reduces the maximum amount of carbon. The calculated NPC and carbon production of the energy hub using hydrogen only backup system are equal to 4.39 M$ and 55,205, respectively. On the other hand, the combined hydrogen/diesel backup system has reduced NPC compared with the hydrogen only backup system. The CO₂ production of this system is also lower than the diesel only backup system. The calculations indicate that the NPC and CO₂ production of the combined backup system are 3.53 M$ and 511,695 kg/yr. By comparing advantages and disadvantages of all 3 scenarios, the micro grid which uses the combined diesel/hydrogen backup system is selected as the most optimal system. The sensitivity analysis of the selected system shows that fluctuations of inflation rate along with the fluctuations of both fuel cells and electrolyzers capital cost do not affect the net present cost (NPC) considerably. On the other hand, fluctuations of capital cost of the main components like wind turbines affect the NPC much more than the others. If the inflation rate drops from 15% to 14% and wind turbine capital cost multiplier reduces from 1 to 0.8, the NPC value will drop by the value of 300,000 $.     

Integrated standalone hybrid solar PV,fuel cell and diesel generator power system for battery or supercapacitor storage systems in Khorfakkan,United Arab Emirates

Renewable energy resources play a very important rule these days to assist the conventional energy systems for doing its function in the UAE due to high greenhouse gas (GHG) emissions and energy demand. In this paper, the analysis and performance of integrated standalone hybrid solar PV, fuel cell and diesel generator power system with battery energy storage system (BESS) or supercapacitor energy storage system (SCESS) in Khorfakkan city, Sharjah were presented. HOMER Pro software was used to model and simulate the hybrid energy system (HES) based on the daily energy consumption for Khorfakkan city. The simulation results show that using SCESS as an energy storage system will help the performance of HES based on the Levelized cost of energy (LCOE) and greenhouse gas (GHG) emissions. The HES with SCESS has renewable fraction (68.1%) and 0.346 $/kWh LCOE. The HES meets the annual AC primary load of the city (13.6 GWh) with negligible electricity excess and with an unmet electrical load of 1.38%. The reduction in GHG emissions for HES with SCESS was 83.2%, equivalent to saving 814,428 gallons of diesel.     

Optimisation of real-time control for hybrid diesel–PV–battery systems

Hybrid diesel–PV–battery systems are one of the most cost effective options for off-grid power generation. A methodology for the optimal operation of such systems for an off-grid application is proposed in this paper. The methodology is based on the minimisation of an energy cost function. Based on this function, an optimal operating point for the diesel generator is identified, taking into account the characteristics of the diesel generator, battery bank and converter as well as the costs of fuel and battery usage. The operation of the diesel generator at this optimum operating point results in an overall energy cost reduction for the hybrid diesel–battery system. Simulation analysis shows that the proposed control strategy can achieve up to 4% reduction in the levelised cost of energy. This is mostly due to the savings made from the efficient usage of diesel generator and battery.     

Cost–benefit analysis of remote hybrid wind–diesel power stations: Case study Aegean Sea islands

More than one third of world population has no direct access to interconnected electrical networks. Hence, the electrification solution usually considered is based on expensive, though often unreliable, stand-alone systems, mainly small diesel-electric generators. Hybrid wind–diesel power systems are among the most interesting and environmental friendly technological alternatives for the electrification of remote consumers, presenting also increased reliability. More precisely, a hybrid wind–diesel installation, based on an appropriate combination of a small diesel-electric generator and a micro-wind converter, offsets the significant capital cost of the wind turbine and the high operational cost of the diesel-electric generator. In this context, the present study concentrates on a detailed energy production cost analysis in order to estimate the optimum configuration of a wind–diesel-battery stand-alone system used to guarantee the energy autonomy of a typical remote consumer. Accordingly, the influence of the governing parameters—such as wind potential, capital cost, oil price, battery price and first installation cost—on the corresponding electricity production cost is investigated using the developed model. Taking into account the results obtained, hybrid wind–diesel systems may be the most cost-effective electrification solution for numerous isolated consumers located in suitable (average wind speed higher than 6.0 m/s) wind potential regions.     

Techno-economic feasibility of photovoltaic,wind, diesel and hybrid electrification systems for off-grid rural electrification in Colombia

Electrification to rural and remote areas with limited or no access to grid connection is one of the most challenging issues in developing countries like Colombia. Due to the recent concerns about the global climatic change and diminishing fuel prices, searching for reliable, environmental friendly and renewable energy sources to satisfy the rising electrical energy demand has become vital. This study aims at analyzing the application of photovoltaic (PV) panels, wind turbines and diesel generators in a stand-alone hybrid power generation system for rural electrification in three off-grid villages in Colombia with different climatic characteristics. The areas have been selected according to the “Colombia’s development plan 2011–2030 for non-conventional sources of energy”. First, different combinations of wind turbine, PV, and diesel generator are modeled and optimized to determine the most energy-efficient and cost-effective configuration for each location. HOMER software has been used to perform a techno-economic feasibility of the proposed hybrid systems, taking into account net present cost, initial capital cost, and cost of energy as economic indicators.     

Baseload wind energy: modeling the competition between gas turbines and compressed air energy storage for supplemental generation

The economic viability of producing baseload wind energy was explored using a cost-optimization model to simulate two competing systems: wind energy supplemented by simple- and combined cycle natural gas turbines (“wind+gas”), and wind energy supplemented by compressed air energy storage (“wind+CAES”). Pure combined cycle natural gas turbines (“gas”) were used as a proxy for conventional baseload generation. Long-distance electric transmission was integral to the analysis. Given the future uncertainty in both natural gas price and greenhouse gas (GHG) emissions price, we introduced an effective fuel price, p_NGeff, being the sum of the real natural gas price and the GHG price. Under the assumption of p_NGeff=$5/GJ (lower heating value), 650 W/m² wind resource, 750 km transmission line, and a fixed 90% capacity factor, wind+CAES was the most expensive system at ¢6.0/kWh, and did not break even with the next most expensive wind+gas system until p_NGeff=$9.0/GJ. However, under real market conditions, the system with the least dispatch cost (short-run marginal cost) is dispatched first, attaining the highest capacity factor and diminishing the capacity factors of competitors, raising their total cost. We estimate that the wind+CAES system, with a greenhouse gas (GHG) emission rate that is one-fourth of that for natural gas combined cycle plants and about one-tenth of that for pulverized coal plants, has the lowest dispatch cost of the alternatives considered (lower even than for coal power plants) above a GHG emissions price of $35/tC_equiv., with good prospects for realizing a higher capacity factor and a lower total cost of energy than all the competing technologies over a wide range of effective fuel costs. This ability to compete in economic dispatch greatly boosts the market penetration potential of wind energy and suggests a substantial growth opportunity for natural gas in providing baseload power via wind+CAES, even at high natural gas prices.     

Torsional torque suppression of generator based on H∞ control theory in isolated power system

Renewable energy power plants, such as wind turbine generator and photovoltaic system, have been introduced in isolated power system recently. The output power fluctuations of wind turbine generator and load deviations result in frequency deviation and terminal voltage fluctuation. Furthermore, these power fluctuations also affect the turbine shafting of diesel generators and gas‐turbine generators, which are the main components of power generation systems in isolated islands. For stable operation of gas‐turbine generator, the torsional torque suppression as well as power system stabilization should be considered. In this paper, the control strategy that achieves torsional torque suppression and power system stabilization is presented based on H_∞ control theory. The effectiveness of the proposed control system is validated by numerical simulation results. Copyright © 2010 John Wiley & Sons, Ltd.     

Small wind power generation using automotive alternator

The objective of this paper is to evaluate the feasibility of using claw pole automotive alternator as a generator for small wind turbine and to compare its energy yield and generated electricity cost with commercially available systems. The comparison is based on the energy yield per swept area and cost per energy produced in a low wind speed climate. Concepts such as the selection of suitable turbine parameters and gear ratio were used to achieve good matching of the turbine characteristics with measured alternator performance in order to improve the energy yield from the alternator in battery charging application. The energy yield from the alternator integrated to a 3.9 m diameter turbine is comparable with many commercially available turbines. The generated electricity cost of a commercially available turbine can be reduced by more than a factor of 2 by replacing its generator with our proposed alternator. The alternator-based turbine system is therefore a low cost solution aimed at making wind energy available to areas where the current cost of wind technology makes it prohibitive.     

Techno-economic analysis of RES & hydrogen technologies integration in remote island power system

The main objective of the present study is the integration of hydrogen technologies as an energy storage medium in a hybrid power system. The existing power system of the island of Milos, which is based on fossil fuel generators and a small wind park, is assessed in the context of this paper. System level simulation results, from both technical and economic point of view, are presented for the currently existing and the proposed island's hybrid power system. The latter integrates a higher number of wind turbines and hydrogen technologies as energy storage medium, and the two system architectures are being compared taking into account not only technical and economic parameters but also Green House – Gas (GHG) emissions, fossil fuels consumption and Renewable Energy Sources (RES) penetration increase. Moreover, a sensitivity analysis has been performed in order to determine the contribution of hydrogen technologies equipment costs; with the cost of energy produced (COE) being the critical parameter. Results show that COE for the proposed power system is higher than the existing one, but on the other hand GHG emissions and fossil fuel consumption are significantly reduced. In addition, RES penetration increases dramatically and the sensitivity analysis indicates that a further reduction in hydrogen technologies equipment and subsidy on wind turbine costs would make RES & Hydrogen-based systems economically competitive to the existing power system of the island.     

GHG emissions and energy performance of offshore wind power

This paper presents specific life cycle GHG emissions from wind power generation from six different 5 MW offshore wind turbine conceptual designs. In addition, the energy performance, expressed by the energy indicators Energy Payback Ratio (EPR) Energy Payback Time (EPT), is calculated for each of the concepts.There are currently few LCA studies in existence which analyse offshore wind turbines with rated power as great as 5 MW. The results, therefore, give valuable additional environmental information concerning large offshore wind power. The resulting GHG emissions vary between 18 and 31.4 g CO₂-equivalents per kWh while the energy performance, assessed as EPR and EPT, varies between 7.5 and 12.9, and 1.6 and 2.7 years, respectively. The relatively large ranges in GHG emissions and energy performance are chiefly the result of the differing steel masses required for the analysed platforms. One major conclusion from this study is that specific platform/foundation steel masses are important for the overall GHG emissions relating to offshore wind power. Other parameters of importance when comparing the environmental performance of offshore wind concepts are the lifetime of the turbines, wind conditions, distance to shore, and installation and decommissioning activities.Even though the GHG emissions from wind power vary to a relatively large degree, wind power can fully compete with other low GHG emission electricity technologies, such as nuclear, photovoltaic and hydro power.     

Study and design of a hybrid wind–diesel-compressed air energy storage system for remote areas

Remote areas around the world predominantly rely on diesel-powered generators for their electricity supply, a relatively expensive and inefficient technology that is responsible for the emission of 1.2 million tons of greenhouse gas (GHG) annually, only in Canada [1]. Wind–diesel hybrid systems (WDS) with various penetration rates have been experimented to reduce diesel consumption of the generators. After having experimented wind–diesel hybrid systems (WDS) that used various penetration rates, we turned our focus to that the re-engineering of existing diesel power plants can be achieved most efficiently, in terms of cost and diesel consumption, through the introduction of high penetration wind systems combined with compressed air energy storage (CAES). This article compares the available technical alternatives to supercharge the diesel that was used in this high penetration wind–diesel system with compressed air storage (WDCAS), in order to identify the one that optimizes its cost and performances. The technical characteristics and performances of the best candidate technology are subsequently assessed at different working regimes in order to evaluate the varying effects on the system. Finally, a specific WDCAS system with diesel engine downsizing is explored. This proposed design, that requires the repowering of existing facilities, leads to heightened diesel power output, increased engine lifetime and efficiency and to the reduction of fuel consumption and GHG emissions, in addition to savings on maintenance and replacement cost.     

Life cycle assessment of power generation alternatives for a stand-alone mobile house

This paper presents comparative life cycle assessment of nine different hybrid power generation solutions that meet the energy demand of a prototypical mobile home. In these nine solutions, photovoltaic panels and a wind turbine are used as the main energy source. Fuel cell and diesel generator are utilized as backup systems. Batteries, compressed H₂, and H₂ in metal hydrides are employed as backup energy storage. The findings of the study shows that renewable energy sources, although they are carbon-free, are not as environmentally friendly as may generally be thought. The comparative findings of this study indicate that a hybrid system with a wind turbine as a main power source and a diesel engine as backup power system is the most environmentally sound solution among the alternatives.     

Energy and greenhouse gas balances of cassava-based ethanol

Biofuel production has been promoted to save fossil fuels and reduce greenhouse gas (GHG) emissions. However, there have been concerns about the potential of biofuel to improve energy efficiency and mitigate climate change. This paper investigates energy efficiency and GHG emission saving of cassava-based ethanol as energy for transportation. Energy and GHG balances are calculated for a functional unit of 1 km of road transportation using life-cycle assessment and considering effects of land use change (LUC). Based on a case study in Vietnam, the results show that the energy input for and GHG emissions from ethanol production are 0.93 MJ and 34.95 g carbon dioxide equivalent per megajoule of ethanol respectively. The use of E5 and E10 as a substitute for gasoline results in energy savings, provided that their fuel consumption in terms of liter per kilometer of transportation is not exceeding the consumption of gasoline per kilometer by more than 2.4% and 4.5% respectively. It will reduce GHG emissions, provided that the fuel consumption of E5 and E10 is not exceeding the consumption of gasoline per kilometer by more than 3.8% and 7.8% respectively. The quantitative effects depend on the efficiency in production and on the fuel efficiency of E5 and E10. The variations in results of energy input and GHG emissions in the ethanol production among studies are due to differences in coverage of effects of LUC, CO₂ photosynthesis of cassava, yields of cassava, energy efficiency in farming, and by-product analyses.     

Energy audit and conservation opportunities for pyroprocessing unit of a typical dry process cement plant

Cement production process has been highly energy and cost intensive. The cement plant requires 8784 h per year of the total operating hours to produce 640,809 tonnes of clinker. To achieve effective and efficient energy management scheme, thermal energy audit analysis was employed on the pyroprocessing unit of the cement plant. Fuel combustion generates the bulk of the thermal energy for the process, amounting to 95.48% (4164.02 kJ/kg_cl) of the total thermal energy input. Thermal efficiency of the unit stands at 41%, below 50–54% achieved in modern plants. The exhaust gases and kiln shell heat energy losses are in significant quantity, amounting to 27.9% and 11.97% of the total heat input respectively. To enhance the energy performance of the unit, heat losses conservation systems are considered. Waste heat recovery steam generator (WHRSG) and Secondary kiln shell were studied. Power and thermal energy savings of 42.88 MWh/year and 5.30 MW can be achieved respectively. Financial benefits for use of the conservation methods are substantial. Environmental benefit of 14.10% reduction in Greenhouse gases (GHG) emissions could be achieved.     

Life Cycle Analysis of wind–fuel cell integrated system

After ratification of the Kyoto Protocol, Canada’s Kyoto greenhouse gas (GHG) emission target is 571 Mt of CO₂ equivalent emitted per year by 2010; however, if current emission trends continue, a figure of 809 Mt is projected by 2010 (Cote C. Basic of clean development mechanism—joint implementation and overview of CDM project cycle, 2003 regional workshop on CDM-JI, February 2003, Halifax). This underscores the need for additional reduction of 240 Mt. The Federal Government Action Plan 2000 aims to reduce this gap from 240 to 65 Mt (Cote C. Basic of clean development mechanism—joint implementation and overview of CDM project cycle, 2003 regional workshop on CDM-JI, February 2003, Halifax). In order to accomplish this goal, renewable energy use in all sectors will be required, and this type of energy is particularly applicable in power generation. Traditional power generation is a major source of greenhouse gas (GHG) emissions after industrial and transportation sectors (Environment Canada. Canada’s Greenhouse Gas Inventory 1990–1998. Final submission to the UNFCCC Secretariat, 2002 [Available from: http://www.ec.gc.ca/climate/resources_reportes-e.html]. Although wind energy, solar power and other forms of renewable energy are non-GHG emitting in their operation, there are GHG emissions in their different stages of life cycle (i.e. material extraction, manufacturing, construction and transportation, etc.). These emissions must be accounted for in order to assess accurately their capacity to reduce GHG emission and meet Kyoto targets. The current trend in electricity generation is towards integrated energy systems. One such proposed system is the wind–fuel cell integrated system for remote communities. This paper presents a detailed Life Cycle Analysis of the wind–fuel cell integrated system for application in Newfoundland and Labrador.The study confirms that wind–fuel integrated system is a zero emission system while in operation. There are significant emissions of GHGs during the production of the various components (wind turbine, fuel cell and electrolyzer). However, the global warming potential (GWP) of wind-integrated system is far lower (at least by two orders of magnitude) than the conventional diesel system, presently used in remote communities.     

The utility of energy storage to improve the economics of wind–diesel power plants in Canada

Wind energy systems have been considered for Canada's remote communities in order to reduce their costs and dependence on diesel fuel to generate electricity. Given the high capital costs, low-penetration wind–diesel systems have been typically found not to be economic. High-penetration wind–diesel systems have the benefit of increased economies of scale, and displacing significant amounts of diesel fuel, but have the disadvantage of not being able to capture all of the electricity that is generated when the wind turbines operate at rated capacity.Two representative models of typical remote Canadian communities were created using HOMER, an NREL micro-power simulator to model how a generic energy storage system could help improve the economics of a high-penetration wind–diesel system. Key variables that affect the optimum system are average annual wind speed, cost of diesel fuel, installed cost of storage and a storage systems overall efficiency. At an avoided cost of diesel fuel of 0.30 $Cdn/kWh and current installed costs, wind generators are suitable in remote Canadian communities only when an average annual wind speed of at least 6.0 m/s is present. Wind energy storage systems become viable to consider when average annual wind speeds approach 7.0 m/s, if the installed cost of the storage system is less than 1000 $Cdn/kW and it is capable of achieving at least a 75% overall energy conversion efficiency. In such cases, energy storage system can enable an additional 50% of electricity from wind turbines to be delivered.     

Five-year technology selection optimization to achieve specific CO2 emission reduction targets

Long-term planning for replacement of fossil fuel energy technologies with renewables is of great importance for achieving GHG emission reduction targets. The current study is focused on developing a five-year mathematical model for finding the optimal sizing of renewable energy technologies for achieving certain CO₂ emission reduction targets. A manufacturing industrial facility which uses CHP for electricity generation and natural gas for heating is considered as the base case in this work. Different renewable energy technologies are developed each year to achieve a 4.53% annual CO₂ emission reduction target. The results of this study show that wind power is the most cost-effective technology for reducing emissions in the first and second year with a cost of 44 and 69 CAD per tonne of CO₂, respectively. Hydrogen, on the other hand, is more cost-effective than wind power in reducing CO₂ emissions from the third year on. The cost of CO₂ emission reduction with hydrogen doesn't change drastically from the first year to the fifth year (107 and 130 CAD per tonne of CO₂). Solar power is a more expensive technology than wind power for reducing CO₂ emissions in all years due to lower capacity factor (in Ontario), more intermittency (requiring mores storage capacity), and higher investment cost. A hybrid wind/battery/hydrogen energy system has the lowest emission reduction cost over five years. The emission reduction cost of such hybrid system increases from 44 CAD per tonne of CO₂ in the first year to 156 CAD per tonne of CO₂ in the fifth year. The developed model can be used for long-term planning of energy systems for achieving GHG emission targets in a regions/country which has fossil fuel-based electricity and heat generation infrastructure.