Enhancing biomethane production from flush dairy manure with turkey processing wastewater

The objective of this study was to assess the quantity and quality of biogas produced by co-digesting flushed dairy manure (FDM) and turkey processing wastewater (TPW). An attached growth digester with working volume of 15 L and a 3 L head space was operated at a 5 d hydraulic retention time using five feed mixes containing 100, 67, 50, 33, and 0% FDM by volume. The biogas yield ranged from 0.072 to 0.8 m³ [g VS^?1] and the methane content (quality) of the gas ranging from 56% to 70%. Both the quantity and quality of the biogas increased as the proportion of TPW in the feed increased. An energy balance for the digester based on a dairy farm with 150 animals, showed that augmenting FDM with TPW at 1:1 and 1:2 ratios, feeds C and D, respectively, produced biogas with net positive energy to all year round. The gas produced was enough to run a 50 kW generator to produce electricity for about 5.5 and 9 h for the 1:1 and 1:2 feed mixes. However, the economics were not favorable if the benefits of the digester are based only on the value electricity to be produced. Either, other possible revenues such as carbon credit, renewable energy credits, green tags for electricity, putting a value to the environmental benefits of AD should be considered or subsidies from grants or other incentives programs to make the system economically viable.     

Hydropower in Turkey for a clean and sustainable energy future

Over the last two decades, global electricity production has more than doubled and electricity demand is rising rapidly around the world as economic development spreads to emerging economies. Not only has electricity demand increased significantly, it is the fastest growing end-use of energy. Therefore, technical, economic and environmental benefits of hydroelectric power make it an important contributor to the future world energy mix, particularly in the developing countries. This paper deals with policies to meet increasing energy and electricity demand for sustainable energy development in Turkey. Turkey has a total gross hydropower potential of 433 GWh/year, but only 125 GWh/year of the total hydroelectric potential of Turkey can be economically used. By the commissioning of new hydropower plants, which are under construction, 36% of the economically usable potential of the country would be tapped. Turkey's total economically usable small hydropower potential is 3.75 GWh/year.     

Feed-in tariff design for domestic scale grid-connected PV systems using high resolution household electricity demand data

The advent of large samples of smart metering data allows policymakers to design Feed-in Tariffs which are more targeted and efficient. This paper presents a methodology which uses these data to design FITs for domestic scale grid-connected PV systems in Ireland. A sample of 2551 household electricity demand data collected at 1/2-hourly intervals, electricity output from a 2.82 kW_p PV system over the same time interval as well as PV system costs and electricity tariffs were used to determine the required FIT to make it worthwhile for the households to invest in the PV system. The methodology shows that it is possible to design single, multiple and continuous FITs. Continuous FITs are the most efficient and result in no overcompensation to the housholder while single and multiple FITs are less efficient since they result in different levels of overcompensation. In the PV case study considered, it was shown that the use of three FITs (0.3170, 0.3315 and 0.3475 €/kW h) resulted in a 59.6% reduction in overcompensation compared to a single FIT of 0.3475 €/kW h; assuming immediate and complete uptake of the technology, this would result in NPV savings of over €597 m to the Irish government over a 25 year lifetime.     

Assessment of the renewable energies potential for intensive electricity production in the province of Jaén,southern Spain

The foreseen depletion of the traditional fossil fuels for the forthcoming decades is forcing us to seek for new sustainable and non-pollutant energy sources. Renewable energies rely on a decentralized scheme strongly dependent on the local resources availability. In this work, we tackle the study of the renewable energies potential for an intensive electricity production in the province of Jaén (southern Spain) which has a pronounced unbalance between its inner electricity production and consumption. The potential of biomass from olive pruning residues, solar photovoltaics (PV) and wind power has been analyzed using Geographical Information System tools, and a proposal for a massive implementation of renewable energies has been arisen. In particular, we propose the installation of 5 biomass facilities, totaling 98 MW of power capacity, with an estimated annual production of 763 GWh, 12 PV facilities, totaling 420 MW of power capacity, with an estimated annual production of 656 GWh and 506 MW of wind power capacity in a number of wind farms, with an estimated annual production of 825 GWh. Overall, this production frame would meet roughly a 75% of the electricity demands in the province and thus would mitigate the current unbalance.     

Energy storage in remote area power supply (RAPS) systems

Preliminary cost analyses indicate that hybrid RAPS systems are more economically attractive as a means to provide electricity to remote villages than are alternatives such as 24 h diesel generation. A hybrid remote area power supply (RAPS) system is being deployed to provide 24 h electricity to villages in the Amazon region of Peru. The RAPS system consists of modules designed to provide 150 kWh per day of utility grade ac electricity over a 24 h period. Each module contains a diesel generator, battery bank using heavy-duty 2 V VRLA gelled electrolyte batteries, a battery charger, a photovoltaic array and an inverter. Despite early difficulties, the system in the first village has now commenced operation and the promise of RAPS schemes as a means for providing sustainable remote electrification appears to be bright.     

Feasibility of pico-hydro and photovoltaic hybrid power systems for remote villages in Cameroon

Pico-hydro (pH) and photovoltaic (PV) hybrid systems incorporating a biogas generator have been simulated for remote villages in Cameroon using a load of 73 kWh/day and 8.3 kWp. Renewable energy systems were simulated using HOMER, the load profile of a hostel in Cameroon, the solar insolation of Garoua and the flow of river Mungo. For a 40% increase in the cost of imported power system components, the cost of energy was found to be either 0.352 €/kWh for a 5 kW pico-hydro generator with 72 kWh storage or 0.396 €/kWh for a 3 kWp photovoltaic generator with 36 kWh storage. These energy costs were obtained with a biomass resource cost of 25 €/tonne. The pH and PV hybrid systems both required the parallel operation of a 3.3 kW battery inverter with a 10 kW biogas generator. The pH/biogas/battery systems simulated for villages located in the south of Cameroon with a flow rate of at least 92 l/s produced lower energy costs than PV/biogas/battery systems simulated for villages in the north of Cameroon with an insolation level of at least 5.55 kWh/m²/day. For a single-wire grid extension cost of 5000 €/km, operation and maintenance costs of 125 €/yr/km and a grid power price of 0.1 €/kWh, the breakeven grid extension distances were found to be 12.9 km for pH/biogas/battery systems and 15.2 km for PV/biogas/battery systems respectively. Investments in biogas based renewable energy systems could thus be considered in the National Energy Action Plan of Cameroon for the supply of energy to key sectors involved in poverty alleviation.     

Biomass energy utilization in rural areas may contribute to alleviating energy crisis and global warming: A case study in a typical agro-village of Shandong,China

A biomass energy exploration experiment was conducted in Jiangjiazhuang, a typical agro-village in Shandong, China from 2005 to 2009. The route of this study was designed as an agricultural circulation as: crops → crop residues → “Bread” forage → cattle → cattle dung → biogas digester → biogas/digester residues → green fertilizers → crops. About 738.8 tons of crop residues are produced in this village each year. In 2005, only two cattle were fed in this village and 1.1% of the crop residues were used as forage. About 38.5% crop residues were used for livelihood energy, 24.5% were discarded and 29.7% were directly burned in the field. Not more than three biogas digesters were built and merely 2250 m³ biogas was produced a year relative to saving 1.6 tons standard coal and equivalent to reducing 4.3 tons CO₂ emission. A total of US$ 4491 profits were obtained from cattle benefit, reducing fossil energies/chemical fertilizer application and increasing crop yield. After 5 years experiment, cattle capita had raised gradually up to 146 and some 62.3% crop residues were used as forage. The percentages used as livelihood energy, discarded and burned in the field decreased to 16.3%, 9.2% and 9.8%, respectively. Biogas digesters increased to 123 and 92,250 m³ biogas was fermented equal to saving 65.9 tons standard coal and reducing 177.9 tons CO₂ emission. In total US$ 60,710 profits were obtained in 2009. In addition, about 989.9 tons green fertilizers were produced from biogas digesters and applied in croplands. The results suggested that livestock and biogas projects were promising strategies to consume the redundant agricultural residues, offer livelihood energy and increase the villagers’ incomes. Biogas production and utilization could effectively alleviate energy crisis and CO₂ emission, which might be a great contribution to reach the affirmatory carbon emission goal of the Chinese government on Climate Conference in Copenhagen in 2009.     

Generation of biogas using crude glycerin from biodiesel production as a supplement to cattle slurry

The influence of crude glycerin on biogas production and methane content of the produced biogas was studied, when added to cattle slurry. The experimental design consisted of 5% wt (Gli 5), 10% wt (Gli 10), and 15% wt (Gli 15) of crude glycerin added to cattle slurry, and one control digester without addition of crude glycerin. Anaerobic digestion was carried out in 4 laboratory size CSTR-type biogas digesters with a working volume of 3 L, in semi-continuous regime at mesophilic conditions, over a period of 10 weeks. The highest biogas yields (825.3 mL g^?1 and 825.7 mL g^?1, respectively) relative to mass of volatile compounds added, were produced by the treatments Gli 5 and Gli 10. The control treatment produced 268.6 mL g^?1, whereas the treatment Gli 15 produced 387.9 mL g^?1. This low value was due to the breakdown of the process. Compared to the control, methane contents was increased by 9.5%, 14.3%, and 14.6%, respectively, for the treatments Gli 5, Gli 10, and Gli 15.     

The role of energy storage in accessing remote wind resources in the Midwest

Replacing current generation with wind energy would help reduce the emissions associated with fossil fuel electricity generation. However, integrating wind into the electricity grid is not without cost. Wind power output is highly variable and average capacity factors from wind farms are often much lower than conventional generators. Further, the best wind resources with highest capacity factors are often located far away from load centers and accessing them therefore requires transmission investments. Energy storage capacity could be an alternative to some of the required transmission investment, thereby reducing capital costs for accessing remote wind farms. This work focuses on the trade-offs between energy storage and transmission. In a case study of a 200 MW wind farm in North Dakota to deliver power to Illinois, we estimate the size of transmission and energy storage capacity that yields the lowest average cost of generating and delivering electricity ($/MW h) from this farm. We find that transmission costs must be at least $600/MW-km and energy storage must cost at most $100/kW h in order for this application of energy storage to be economical.     

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.     

A comparative analysis of woody biomass and coal for electricity generation under various CO2 emission reductions and taxes

Mitigating global climate change via CO₂ emission control and taxation is likely to enhance the economic potential of bioenergy production and utilization. This study investigated the cost competitiveness of woody biomass for electricity production in the US under alternative CO₂ emission reductions and taxes. We first simulated changes in the price of coal for electricity production due to CO₂ emission reductions and taxation using a computable general equilibrium model. Then, the costs of electricity generation fueled by energy crops (hybrid poplar), logging residues, and coal were estimated using the capital budgeting method. Our results indicate that logging residues would be competitive with coal if emissions were taxed at about US$25 Mg⁻¹ CO₂, while an emission tax US$100 Mg⁻¹ CO₂ or higher would be needed for hybrid poplar plantations at a yield of 11.21 dry Mg ha⁻¹ yr⁻¹ (5 dry tons ac⁻¹ yr⁻¹) to compete with coal in electricity production. Reaching the CO₂ emission targets committed under the Kyoto Protocol would only slightly increase the price of fossil fuels, generating little impact on the competitiveness of woody biomass. However, the price of coal used for electricity production would significantly increase if global CO₂ emissions were curtailed by 20% or more. Logging residues would become a competitive fuel source for electricity production if current global CO₂ emissions were cut by 20–30%. Hybrid poplar plantations would not be able to compete with coal until emissions were reduced by 40% or more.     

Productive use of bioenergy for rural household in ecological fragile area,Panam County,Tibet in China: The case of the residential biogas model

Bioenergy is the major domestic energy for rural households in developing countries due to its cheap or easy-getting characteristics. Productive use of bioenergy is an important strategy for rural households to improve not only their income, but also their health, living environment and so on. In Tibet of China, which is rich in cattle dung and firewood as the major energy sources for rural households, the efficiency of energy utilization is just about 10%. In order to improve energy utilization efficiency and the living conditions for rural residents, the Tibet Autonomous Region government introduced residential biogas model (RBM) to local households, which was a comprehensive utilization system of energy integrated with residential biogas digester, vegetable greenhouse and livestock shed. This paper aims to show the productive use of the bioenergy by the RBM, which could be depicted as the feasibility and the benefits on economic, eco-environmental and social aspects of biogas utilization, based on household questionnaires in Panam County. In RBM, biogas digester works as the biomass material supplement loop to transform originally biomass flow from single-direction to recycling-direction. The results indicate that the output of unit biogas digester could replace 1.44 t of firewood, 1.65 t of agricultural residues and 1.75 t of cattle dung, respectively. The net incremental benefit of RBM could reach 5550.72 Yuan in 15 years. The reduced amount of CO₂ emission when substituted by biogas in other agricultural areas and the areas of semi-agricultural and semi-husbandry in Tibet could be (76.66–79.89) × 10⁴ t/year and the capability for nitrogen storage could achieve (0.39–0.99) × 10⁴ t/year. The amount of cattle dung replaced by biogas could reach 78.29 × 10⁴ t/year; this means that the saved cattle dung, 3.51 t/hm², could be reallocated back to cultivated land to improve the soil fertility and to keep the balance of nutrient elements in cultivated land. Biogas utilization reduces the labor opportunity costs of women compared to use of traditional bioenergy sources. It could be concluded that the productive use of bioenergy through RBM in this area has its capability to release the current pressures on biomass sources by adjusting patterns of rural energy consumption, and to improve the conditions of health, environment, economy and energy conservation.     

Agricultural biogas plants in Poland: Investment process,economical and environmental aspects,biogas potential

The formal and legal requirements as well as the support system for building agricultural biogas plants in Poland have been presented. There are currently 24 agricultural biogas plants operating in Poland. The fermentation substrates are slurry, food waste and maize silage. It is most often mesophilic fermentation. Produced biogas is combusted in cogeneration and thus obtained electrical and thermal energy is used for the biogas plant's own needs and sold. The support system for biogas plants' operation in Poland is based on a system of certificates. In this system it is cost-effective to use waste for fermentation whilst it is not cost-effective for a biogas plant to run on maize silage. It has been calculated that in Poland the theoretical annual biogas potential for cattle slurry is 3646 million m³, for pig slurry it is 2581 million m³, for poultry manure it is 717 million m³, from maize after seed harvest it is 1044 million m³, from municipal waste biofraction it is 100 million m³ of biogas.     

Estimate of the electric energy generating potential for different sources of biogas in Brazil

The increasing interest in the recuperation of the biogas coming from organic residues, associated with its energetic use is a subject that has been widely discussed. Biogas was merely seen as a sub-product obtained from anaerobic decomposition (without oxygen) of organic residue. In the paper is carried out an evaluation of the quantities of organic residues coming out from the sugar and alcohol industry (vinasse), urban solid and liquid wastes (garbage and sewage) and livestock residues (bovine and swine manure) in Brazil. Finally the electricity generation potential of biogas out of the evaluated sources of organic residues in Brazil is estimated. The results of this study indicate that the potential regarding the production of biogas out of the aforementioned organic residues of electricity production using could meet an energy demand of about 1.05 to 1.13 %. Constraints for biogas energy utilization are identified and discussed.     

Large scale hydrogen production from wind energy in the Magallanes area for consumption in the central zone of Chile

The energy proposal of this research suggests the use of places with abundant wind resources for the production of H₂ on a large scale to be transported and used in the central zone of Chile with the purpose of diversifying the country's energy matrix in order to decrease its dependence on fossil fuels, increase its autonomy, and cover the future increases in energy demand. This research showed that the load factor of the proposed wind park reaches a value of 54.5%, putting in evidence the excellent wind conditions of the zone. This implies that the cost of the electricity produced by the wind park located in the Chilean Patagonia would have a cost of 0.0213 US$ kWh^?1 in the year 2030. The low prices of the electricity obtained from the park, thanks to the economy of scale and the huge wind potential, represent a very attractive scenario for the production of H₂ in the future. The study concludes that by the year 2030 the cost of the H₂ generated in Magallanes and transported to the port of Quinteros would be 18.36 US$ MBTU^?1, while by that time the cost of oil would be about 17.241 US$ MBTU^?1, a situation that places H₂ in a very competitive position as a fuel.     

Geothermal energy potential for power generation in Turkey: A case study in Simav,Kutahya

Geothermal energy and the other renewable energy sources are becoming attractive solutions for clean and sustainable energy needs of Turkey. Geothermal energy is being used for electricity production and it has direct usage in Turkey, which is among the first five countries in the world for the geothermal direct usage applications. Although, Turkey is the second country to have the highest geothermal energy potential in Europe, the electricity production from geothermal energy is quite low. The main purpose of this study is to investigate the status of the geothermal energy for the electricity generation in Turkey. Currently, there is one geothermal power plant with an installed capacity of 20.4 MWe already operating in the Denizli–Kizildere geothermal field and another is under the construction in the Aydin–Germencik field.This study examines the potential and utilization of the existing geothermal energy resources in Kutahya–Simav region. The temperature of the geothermal fluid in the Simav–Eynal field is too high for the district heating system. Therefore, the possibility of electrical energy generation by a binary-cycle has been researched and the preliminary feasibility studies have been conducted in the field. For the environmental reasons, the working fluid used in this binary power plant has been chosen as HCFC-124. It has been concluded that the Kutahya–Simav geothermal power plant has the potential to produce an installed capacity of 2.9 MWe energy, and a minimum of 17,020 MWh/year electrical energy can be produced from this plant. As a conclusion, the pre-feasibility study indicates that the project is economically feasible and applicable.     

Life cycle assessment of energy generation from biogas—Attributional vs. consequential approach

Many studies that apply life cycle assessment methodology avoid a strict differentiation between attributional (aLCA) and consequential (cLCA) life cycle assessment. The main distinction that can be made is that an aLCA approach describes a state of average production systems of an economic system while in contrast the consequential approach describes changes (induced by political decisions) in production systems within the economic system. The task of this study was to analyze a biogas system from an environmental point of view and thereby to work out the methodological differences of aLCA and cLCA approaches. The Life cycle inventory quantity primary energy demand (PED) as well as the impact categories global warming potential (GWP), eutrophication (EP), acidification (AP) and photochemical ozone creation potential (POCP) were analyzed. The aLCA approach was split into three scenarios, a physical, an economic and a core product focused one (with focus on the main product) to show the impact of by-product handling. The cLCA approach was split into a local scenario using on-site data and a general scenario using higher aggregated data to show the effects of substitution caused by the introduction of a new technology. The results of the two approaches were compared with the environmental impact of the current average and marginal German electricity mix. Global warming potential per functional unit varied between 3.8 g and 12.5 g of CO2 equivalent in the biogas scenarios. Compared to the average and marginal German electricity mix savings in PED, GWP and partly in AP and POCP can be achieved. However, high variations in the proportion to the reference electricity system, the total quantity results as well as the contribution of single processes to the total result were found. This makes it indispensable to distinguish accurately between the aLCA and the cLCA approach.     

Laboratory investigations on continuous bio-methanization of energy crops as mono-substrate without supplementation

Continuous bio-methanization of an energy crop, namely the beet silage, was investigated in this laboratory-scale work as mono-substrate, using a mesophilic biogas digester controlled by a fuzzy logic control (FLC) technique and without using any supplementing or buffering agent, despite the low pH of the substrate around 3.80. The temperature, pH, redox potential (ORP), daily biogas production and composition of digester biogas were continuously measured online. During the operation, the hydraulic retention time (HRT) varied between 24.8 and 9 days, as the organic loading rate (OLR) ranged from 2.6 to 4.7 g L^?1 d^?1. The average pH, specific gas production rate (spec. GPR) and volumetric gas production rate (vol. GPR) were determined to be 7.12, 0.31 L g VS^?1 d^?1 and 1.084 L L^?1 d^?1, respectively. The average methane (CH₄) content of digester biogas was about 56%. The FLC technique, which was developed at HAW Hamburg for anaerobic conversion of acidic energy crops to methane, determined the daily feeding volume (～ OLR/HRT) for the biogas digester, depending on the feedback from online pH and methane measurements, and on the calculation of the spec. GPR. The spec. GPR was calculated by the corrected daily biogas production. Through online monitoring of pH, biogas production rate and composition, and by use of the FLC technique, the acidic beet silage could continuously be converted to biogas, without using manure or any other kind of buffering or supplementing agent(s). The lab-scale anaerobic biogas digester performed stable and safe, without encountering any problems of instability, as indicated by an adequate amount of buffering capacity, a VFA content below 0.5 g L^?1 and a neutral pH range throughout the study.     

Biowaste energy potential in Kenya

Energy affects all aspects of national development. Hence the current global energy crisis demands greater attention to new initiatives on alternative energy sources that are renewable, economically feasible and sustainable. The agriculture-dependent developing countries in Africa can mitigate the energy crisis through innovative use of the available but underutilised biowaste such as organic residues from maize, barley, cotton, tea and sugarcane. Biogas technology is assumed to have the capacity to economically and sustainably convert these vast amounts of biowaste into renewable energy, thereby replacing the unsustainable fossil energy sources, and reducing dependency on fossil fuels. However, the total energy potential of biogas production from crop residues available in Kenya has never been evaluated and quantified. To this end, we selected five different types of residues (maize, barley, cotton, tea and sugarcane) from Kenya and evaluated their energy potential through biomethane potential analysis at 30 °C and a test time of 30 days.The specific methane yields for maize, barley, cotton, tea and sugarcane residues obtained under batch conditions were respectively 363, 271, 365, 67 and 177 m³ per tonne volatile solids. In terms of energy potential, maize, cotton and barley residues were found to be better substrates for methane production than tea and sugarcane residues and could be considered as potential substrates or supplements for methane production without compromising food security in the country. The evaluated residues have a combined national annual maximum potential of about 1313 million cubic meters of methane which represent about 3916 Gigawatt hour (GWh) of electricity and 5887 GWh of thermal energy. The combined electrical potential is equivalent to 73% of the country’s annual power production of 5307 GWh. Utilization of the residues that are readily available on a ‘free on site’ basis for energy production could substitute the fossil fuels that account for a third of the country’s total electricity generation. Besides, exploitation of the potential presented by the biowaste residues can spur an energy revolution in the country resulting in a major economic impact in the region.     

The cost of integration of parabolic trough CSP plants in isolated Mediterranean power systems

In this work, a technical and economic analysis concerning the integration of parabolic trough concentrated solar power (CSP) technologies, with or without thermal storage capability, in an existing typical small isolated Mediterranean power generation system, in the absence of a feed-in tariff scheme, is carried out. In addition to the business as usual (BAU) scenario, five more scenarios are examined in the analysis in order to assess the electricity unit cost with the penetration of parabolic trough CSP plants of 50 MWe or 100 MWe, with or without thermal storage capability. Based on the input data and assumptions made, the simulations indicated that the scenario with the utilization of a single parabolic trough CSP plant (either 50 MWe or 100 MWe and with or without thermal storage capability) in combination with BAU will effect an insignificant change in the electricity unit cost of the generation system compared to the BAU scenario. In addition, a sensitivity analysis on natural gas price, showed that increasing fuel prices and the existence of thermal storage capability in the CSP plant make this scenario marginally more economically attractive compared to the BAU scenario.