Economic and environmental benefits of landfill gas from municipal solid waste in Malaysia

Discharge of Green House Gases (GHGs) and the management of municipal solid waste (MSW) continue to be a major challenge particularly in growing economies. However, these are resources which can be converted to green energy. Landfill gas which is essentially methane (50–55%) and carbon dioxide (40–45%) (both GHGs) is released from MSW by biodegradation processes. The estimation of this methane and its economic and environmental benefits for environmental sustainability are the objectives of this study. Methane emission from MSW disposed of in landfills was estimated using Intergovernmental Panel on Climate Change (IPCC) methodology. From the study, based on 8,196,000 tonnes MSW generated in Peninsular Malaysia in 2010, anthropogenic methane emission of about 310,220 tonnes per year was estimated. This was estimated to generate 1.9 billion kWh of electricity year^?1 worth over RM 570 million (US$190 million). In addition, this leads to carbon dioxide reduction of 6,514,620 tonnes year^?1 equivalent to carbon credit of over RM 257 million (US$85 million). These results were also projected for 2015 and 2020 and the outcomes are promising. Therefore, the exploration of this resource, besides the economic benefits helps in reducing the dependence on the depleting fossil fuel and hence broadening the fuel base of the country.     

Economic and greenhouse gas emission analysis of bioenergy production using multi-product crops—case studies for the Netherlands and Poland

In the face of climate change that may result from greenhouse gas (GHG) emissions, the scarcity of agricultural land and limited competitiveness of biomass energy on the market, it is desirable to increase the performance of bioenergy systems. Multi-product crops, i.e. using a crop partially for energy and partially for material purposes can possibly create additional incomes as well as additional GHG emission reductions. In this study, the performance of several multi-product crop systems is compared to energy crop systems, focused on the costs of primary biomass fuel costs and GHG emission reductions per hectare of biomass production. The sensitivity of the results is studied by means of a Monte-Carlo analysis. The multi-product crops studied are wheat, hemp and poplar in the Netherlands and Poland. GHG emission reductions of these multi-product crop systems are found to be between 0.2 and 2.4 Mg CO_2eq/(ha yr) in Poland and 0.9 and 7.8 Mg CO_2eq/(ha yr) in the Netherlands, while primary biomass fuel costs range from −4.1 to −1.7 €/GJ in the Netherlands and from 0.1 to 9.8 €/GJ in Poland. Results show that the economic attractiveness of multi-product crops depends strongly on material market prices, crop production costs and crop yields. Net annual GHG emission reductions per hectare are influenced strongly by the specific GHG emission reduction of material use, reference energy systems and GHG emissions of crop production. Multi-product use of crops can significantly decrease primary biomass fuel costs. However, this does not apply in general, but depends on the kind of crops and material uses. For the examples analysed here, net annual GHG emission reductions per hectare are not lowered by multi-product use of crops. Consequently, multi-product crops are not for granted an option to increase the performance of bioenergy systems. Further research on the feasibility of large-scale multi-product crop systems and their impact on land and material markets is desirable.     

Feasibility assessment of poplar bioenergy systems in the Southern Europe

A detailed reliability assessment of bioenergy production systems based on poplar cultivation was made. The aim of this assessment was to demonstrate the Economic feasibility of implementing poplar biomass production for power generation in Spain. The assessment considers the following chain of energy generation: cultivation and harvesting, and transportation and electricity generation in biomass power plants (10, 25 and 50 MW). Twelve scenarios were analysed in accordance with the following: two harvesting methods (high density packed stems and chip production in the field), two crop distributions around the power plant and three power plant sizes. The results show that the cost of biomass delivered at power plant ranges from 18.65 to 23.96 € Mg^?1 dry basis. According to power plant size, net profits range from 3 to 22 million € per yr.Sensibility analyses applied to capital cost at the power plant and to biomass production in the field demonstrate that they do not affect the feasibility of these systems. Reliability is improved if benefits through selling CO₂ emission credits are taken into account.This study clears up the Economic uncertainty of poplar biomass energy systems that already has been accepted as environmentally friendlier and as offering better energetic performance.     

National and regional generation of municipal residue biomass and the future potential for waste-to-energy implementation

Municipal residue biomass (MRB) in the municipal solid waste (MSW) stream is a potential year-round bioenergy feedstock. A method is developed to estimate the amount of residue biomass generated by the end-user at the scale of a country using a throughput approach. Given the trade balance of food and forestry products, the amount of MRB generated is calculated by estimating product lifetimes, discard rates, rates of access to MSW collection services, and biomass recovery rates. A wet tonne of MRB could be converted into about 8 GJ of energy and 640 kg of carbon dioxide (CO₂) emissions, or buried in a landfill where it would decompose into 1800 kg of CO₂ equivalent (in terms of global warming potential) methane (CH₄) and CO₂ emissions. It is estimated that approximately 1.5 Gt y^?1 of MRB are currently collected worldwide. The energy content of this biomass is approximately 12 EJ, but only a fraction is currently utilized. An integrated assessment model is used to project future MRB generation and its utilization for energy, with and without a hypothetical climate policy to stabilize atmospheric CO₂ concentrations. Given an anticipated price for biomass energy (and carbon under a policy scenario), by the end of the century, it is projected that nearly 60% of global MRB would be converted to about 8 EJ y^?1 of energy in a reference scenario, and nearly all of global MRB would be converted into 16 EJ y^?1 of energy by the end of the century under a climate policy scenario.     

Possibilities of application of waste wood biomass as an energy source in Vojvodina

The Autonomous Province of Vojvodina is an autonomous province in Serbia, containing about 27% of its total population according to the 2002 Census. It is located in the northern part of the country, in the Pannonian plain. Fruska Gora is a lonely island mountain in the Pannonian plain. The research presented in this paper highlights the potential of significant contributing to waste wood biomass in the Park “Fruska Gora (Vojvodina, Serbia) and points to the possibility of using biomass for briquettes production—the final product that can be used for energy purposes. The amount of woody biomass per hectare can be calculated if the data about the average number of trees per hectare are known. For the analyzed case, the value found in 1 ha was 383.1 m³/ha or 272 ± 14 tons, and practically measured value was 402 m³/ha, or 289 tons. The relative deviation of calculated and obtained values of Canadian poplar wood biomass per hectare was 5.88%. Quantities of planned wood waste biomass can be used to produce high-quality briquettes for thermal energy generation purposes in the equivalent of 4.8 million kWh. The large energy potentials, in Vojvodina are still substantially unused, and besides of using waste wood from forestry, it is necessary to consider the sustainable use of available waste biomass from the timber industry.     

The use of green waste from tourist attractions for renewable energy production: The potential and policy implications

Quantifying potential renewable energy sources from tourist attractions is a pivotal initial step in developing energy policies and strategies for low-carbon tourist industry development. Although solar energy and wind power have been in use for providing power for tourist attractions, the value of using waste biomass for energy production is still poorly understood. Here we advocate a promising approach that produces energy from green waste created by tourism attractions currently existing in large numbers and is still increasing dramatically. Using the Yangtze River Delta (YRD) of China as an example, we evaluated the potential of utilizing green waste to produce energy from 385 tourist attractions in 16 cities of this region. Our results showed that the total potential energy production using the green waste biomass was estimated at 6740 TJ/yr (1 TJ=10¹² J) with an average of 137 GJ/ha/yr (1 GJ=10⁹ J), accounting for 6% (the average of the Yangtze River Delta, some scenic areas up to 93%) of YRD′s tourism industry′s energy consumption in 2008. The use of green waste for energy production is possible using current technology and could result in a win–win approach by reducing waste and increasing the renewable energy yields.     

Off-design performance of integrated waste-to-energy,combined cycle plants

This paper focuses on the off-design operation of plants where a waste-to-energy (WTE) system fed with municipal solid waste (MSW) is integrated with a natural gas-fired combined cycle (CC). Integration is accomplished by sharing the steam cycle: saturated steam generated in a MSW grate combustor is exported to the heat recovery steam generator (HRSG) of the combined cycle, where it is superheated and then fed to a steam turbine serving both the CC and the WTE plant.Most likely, the WTE section and the natural gas-fired CC section are subject to different operation and maintenance schedules, so that the integrated plant operates in conditions different from those giving full power output. In this paper we discuss and give performance estimates for the two situations that delimit the range of operating conditions: (a) WTE plant at full power and gas turbine down; (b) WTE plant down and gas turbine at full power. This is done for two integrated plants having the same WTE section, i.e. grate combustors with an overall MSW combustion power of 180 MW_LHV, coupled with Combined Cycles based on two different heavy-duty gas turbines: a medium-size, 70 MW class turbine and a large-size, 250 MW class turbine.For each situation we discuss the control strategy and the actions that can help to achieve safe and reliable off-design operation. Heat and mass balances and performances at off-design conditions are estimated by accounting for the constraints imposed by the available heat transfer areas in boilers, heaters and condenser, as well as the characteristic curve of the steam turbine. When the gas turbine is down the net electric efficiency of the WTE section is very close to the one of the stand-alone WTE plant; instead, when the WTE section is down, the efficiency of the CC is much below the one of a stand alone CC. These performances appear most congenial to what is likely to be the operational strategy of these plants, i.e. paramount priority to waste treatment and CC dispatched according to the requirements of the national grid.     

Potentials of food wastes for power generation and energy conservation in Taiwan

Food waste is approximately 20–30% of the household garbage in Taiwan. There are several ways to use recycled food waste, swine feeding and composting are the two main ways in Taiwan. The objective of this study was to evaluate the potentials of food wastes for power generation and energy conservation in Taiwan. The assessment was conducted by using the related statistics of Taiwan. The results showed that the total amount of food wastes recycled increased from 167,304 to 570,176 Mg y^?1 (+240%) during the period from 2003 to 2006, and increased from 139,614 to 452,550 Mg y^?1 (+224%) and from 22,290 to 112,666 Mg y^?1 (+405%) for swine feeding and composting during the same period, respectively. Potential of food wastes for power generation was 68.0 GWh y^?1, and that excluding swine feeding and composting were 14.0 and 54.5 GWh y^?1 in Taiwan in 2006, respectively. On the other hand, energy conservation potential of food wastes for compost production was 122 MWh y^?1, comparing with energy consumption of chemical fertilizer (ammonium sulfate and calcium superphosphate) production in Taiwan in 2006. The results also suggested that food wastes recycled can not only reduce the amount of the garbage, but also showed the potentials for power generation and energy conservation.     

Kuroshio power plant development plan

As a country lacking energy reserves, Taiwan imports 99.2% of its energy, with only a small portion of indigenous energy, such as hydro, wind, and solar. In 2008, each Taiwanese spent 85,000 NTD dollars (1 USD ～ 32 NTD) to purchase oil, coal, gas, and nuclear fuel from foreign countries, accounting for a total payment of 1.8 trillion NTD, more than the annual budget of the Taiwan government of 1.7 trillion NTD. In the same year, Taiwan emitted about 1% of the world's greenhouse gas (GHG), or 12 tons per person-year, ranking 18th globally. These situations in terms of energy security and carbon emission are very severe.To resolve these severe situations, harnessing the power of the Kuroshio in eastern Taiwan offers a great opportunity. The Kuroshio is a branch of the North Pacific Ocean current. Due to the westward-enhanced effect, this ocean current is strong and stable as it passes through eastern Taiwan. The flow rate is about 30 sverdrup (Sv) or 1000 times that of the Yangtze River, the average speed is 1 m/s, the flow direction is fixed to the north, and the flow path is close to the east coast of Taiwan. By precisely locating high-quality sites and implementing sequential works with careful planning, one can possibly generate exploitable power more than 30 GW. With 30 GW of clean energy, Taiwan could effectively enhance energy security, reduce GHG emission, and lower energy-purchasing cost.This paper proposes a feasibility study to explore the power of the Kuroshio. The content consists of four parts: (1) assessment of Kuroshio power reserves, (2) development of turbine generators, (3) development of turbine-anchor system, and (4) deep-sea marine engineering of turbine clusters. By integrating these technologies above, we propose a project to construct a 30 MW pilot plant. In this project, we also discuss the financial analysis and propose new regulations, environmental impact analysis, risk assessment, and other relevant issues.     

Production possibility frontier analysis of biodiesel from waste cooking oil

This paper presents an assessment of the productive efficiency of an advanced biodiesel plant in Japan using Data Envelopment Analysis (DEA). The empirical analysis uses monthly input data (waste cooking oil, methanol, potassium hydroxide, power consumption, and the truck diesel fuel used for the procurement of waste cooking oil) and output data (biodiesel) of a biodiesel fuel plant for August 2008–July 2010. The results of this study show that the production activity with the lowest cost on the biodiesel production possibility frontier occurred in March 2010 (production activity used 1.41 kL of waste cooking oil, 0.18 kL of MeOH, 16.33 kg of KOH, and 5.45 kW h of power), and the unit production cost in that month was 18,517 yen/kL. Comparing this efficient production cost to the mean unit production cost on the production possibility frontier at 19,712 yen/kL, revealed that the cost of producing 1 kL of biodiesel could be reduced by as much as 1195 yen. We also find that the efficiency improvement will contribute to decreasing the cost ratio (cost per sale) of the biodiesel production by approximately 1% during the study period (24 months) between August 2008 and July 2010.     

Biogas generation potential by anaerobic digestion for sustainable energy development in India

The potential of biogas generation from anaerobic digestion of different waste biomass in India has been studied. Renewable energy from biomass is one of the most efficient and effective options among the various other alternative sources of energy currently available. The anaerobic digestion of biomass requires less capital investment and per unit production cost as compared to other renewable energy sources such as hydro, solar and wind. Further, renewable energy from biomass is available as a domestic resource in the rural areas, which is not subject to world price fluctuations or the supply uncertainties as of imported and conventional fuels. In India, energy demand from various sectors is increased substantially and the energy supply is not in pace with the demand which resulted in a deficit of 11,436 MW which is equivalent to 12.6% of peak demand in 2006. The total installed capacity of bioenergy generation till 2007 from solid biomass and waste to energy is about 1227 MW against a potential of 25,700 MW. The bioenergy potential from municipal solid waste, crop residue and agricultural waste, wastewater sludge, animal manure, industrial waste which includes distilleries, dairy plants, pulp and paper, poultry, slaughter houses, sugar industries is estimated. The total potential of biogas from all the above sources excluding wastewater has been estimated to be 40,734 Mm³/year.     

Net carbon dioxide emissions from alternative firewood-production systems in Australia

The use of firewood for domestic heating has the potential to reduce fossil-fuel use and associated CO₂ emissions. The level of possible reductions depends upon the extent to which firewood off-sets the use of fossil fuels, the efficiency with which wood is burnt, and use of fossil fuels for collection and transport of firewood. Plantations grown for firewood also have a cost of emissions associated with their establishment. Applying the FullCAM model and additional calculations, these factors were examined for various management scenarios under three contrasting firewood production systems (native woodland, sustainably managed native forest, and newly established plantations) in low-medium rainfall (600–800 mm) regions of south-eastern Australia. Estimates of carbon dioxide emissions per unit of heat energy produced for all scenarios were lower than for non-renewable energy sources (which generally emit about 0.3–1.0 kg CO₂ kWh⁻¹). Amongst the scenarios, emissions were greatest when wood was periodically collected from dead wood in woodlands (0.11 kg CO₂ kWh⁻¹), and was much lower when obtained from harvest residues and dead wood in native forests (<0.03 kg CO₂ kWh⁻¹). When wood was obtained from plantations established on previously cleared agricultural land, use of firewood led to carbon sequestration equivalent to −0.06 kg CO₂ kWh⁻¹ for firewood obtained from a coppiced plantation, and −0.17 kg CO₂ kWh⁻¹ for firewood collected from thinnings, slash and other residue in a plantation grown for sawlog production. An uncertainty analysis, where inputs and assumptions were varied in relation to a plausible range of management practices, identified the most important influencing factors and an expected range in predicted net amount of CO₂ emitted per unit of heat energy produced from burning firewood.     

The potential for hydrogen-enriched biogas production from crops: Scenarios in the UK

There is increasing international interest in developing low carbon technologies to provide hydrogen renewably. Hydrogen can be produced through dark anaerobic fermentation using carbohydrate-rich substrates, and methane can be produced in a methanogenic second stage. The suitability of a range of crops for hydrogen and methane production in the UK is examined, using selection criteria including yield, harvest window and composition of the crops. The annual potential for hydrogen and methane production is calculated using the selected crops, taking into account the energy required to grow and harvest the biomass and run the process. The fermentable energy crops fodder beet, forage maize, sugar beet and rye grass were identified as the most suitable substrates for this farm-scale process. A conservative estimate of the amount of agricultural land in the UK excluding permanent grassland not already used for food production or energy crops (currently unused “set-aside” land) has been made (294,960 ha). If this was used to grow a rotation of the selected crops, 9.6 TW h net energy could be produced per year. This equates to electrical power for 2.2 million homes in the UK annually and a reduction of CO₂ emissions by over 2.3 million tones per annum in the UK.     

Modeling climate change mitigation from alternative methods of charcoal production in Kenya

Current carbon accounting methodologies do not accommodate activities that involve emissions reductions from both land-use change and energy production. This paper analyzes the climate change mitigation potential of charcoal production in East Africa by examining the impact of changing both land management and technology. Current production in a major charcoal producing region of Kenya where charcoal is made as a by-product of land clearance for commercial grain production is modeled as the “business-as-usual” scenario. Alternative production systems are proposed based on coppice management of native or exotic trees. Improved kilns are also considered. Changes in aboveground, belowground, and soil carbon are modeled and two distinct baseline assessments are analyzed: one is based on a fixed area of land and one is based on the quantity of non-renewable fuel that is displaced by project activities. The magnitude of carbon emissions reductions varies depending on land management as well as the choice of carbonization technology. However, these variations are smaller than the variations arising from the choice of baseline methodology. The fixed-land baseline yields annualized carbon emission reductions equivalent to 0.5–2.8 tons per year (t y^?1) with no change in production technology and 0.7–3.5 t y^?1 with improved kilns. In contrast, the baseline defined by the quantity of displaced non-renewable fuel is 2–6 times larger, yielding carbon emissions reductions of 1.4–12.9 t y^?1 with no change in production technology and 3.2–20.4 t y^?1 with improved kilns. The results demonstrate the choice of baseline, often a political rather than scientific decision, is critical in assessing carbon emissions reductions.     

Assessment of renewable energy resources potential for electricity generation in Bangladesh

Renewable energy encompasses a broad range of energy resources. Bangladesh is known to have a good potential for renewable energy, but so far no systematic study has been done to quantify this potential for power generation. This paper estimates the potential of renewable energy resources for power generation in Bangladesh from the viewpoint of different promising available technologies. Estimation of the potential of solar energy in Bangladesh is done using a GIS-based GeoSpatial Toolkit (GsT), Hybrid System Optimization Model for Electric Renewables (HOMER) model and NASA Surface Meteorology and Solar Energy (SSE) solar radiation data. The potential of wind energy is estimated by developing a Bangladesh wind map using NASA SSE wind data and HOMER model. A review of country's biomass and hydro potential for electricity generation is presented. The technical potential of gird-connected solar PV is estimated at 50,174 MW. Assuming that 1000 h per year of full power is the feasible threshold for the exploitation of wind energy, the areas that satisfy this condition in the country would be sufficient for the installation of 4614 MW of wind power. The potential of biomass-based and small hydro power plants is estimated at 566 and 125 MW, respectively. The renewable energy resources cannot serve as alternative to conventional energy resources, yet they may serve to supplement the long-term energy needs of Bangladesh to a significant level.     

Waste-to-energy possibilities for industrial olive and grape by-products in Extremadura

The olive and grape agro-industrial sectors have a major economic importance in Extremadura. Annual production of olive oil is more than 50×10³ t, and of wine is more than 3×10⁶ hectolitres. The large amounts of by-products are in most cases under-used, although they could be converted into a zero cost of the waste at the point of origin. In this context, the present work describes an estimate of plant size, and an economic analysis of grate firing+steam turbine (GF/ST) and fluidized bed combustion+steam turbine (FBC/ST) waste-to-energy solutions using industrial olive and grape by-products in Extremadura. The fuel is dry olive husk waste (OH), olive mill wastewater (OMW), OH+OMW sludge, and grape waste from wineries, with total calculated specific costs of 3.28, 8.09, 2.67, and 2.05 € GJ⁻¹ with respect to the lower heating value (LHV), respectively. The logistics component corresponding to trucking the biomass to the power production plant is that of greatest economic importance, even when the logistics strategy includes de-centralized drying plants.For real onsite availabilities of OH 21.084×10³ t, OMW 37.483×10³ t, olive sludge 87.462×10³ t, and grape waste 89.486×10³ t, the gross power is 19.13 MW for a GF/ST plant and 20.46 MW for an FBC/ST plant. The results are compared using standard economic indices—net present value (NPV), profitability index (PI), internal rate of return (IRR), and payback time (PBT). A sensitivity and risk analysis of the proposals showed the GF/ST option to be the better suited to the studied scenario, with better values for all the indicators.     

GIS assessment of large CSP plant in Duqum,Oman

This paper discusses solar power prospects in Wilayat Duqum in Oman. First, the geographic and topographic information about the selected region is presented. The methodology of producing solar radiation map for Duqum using GIS tools is then presented. The results obtained show very high potential of solar radiation over Wilayat Duqum during the whole year. A slope analysis has allowed calculating the yearly electricity generation potential for different concentrated solar power (CSP) technologies such as the parabolic trough, parabolic dish, tower, and concentrated PV. Based on the development plan of the Duqum region, and the topologies of the land areas in the region, it is suggested that, for the CSP technologies requiring large amount of water for washing the mirrors, the selected area is a flat land (slope < 1%) located proximity to the sea (～2 km) inside a total industrial area of around 50 km², hence, allowing easy future expansion of the plant. It was proposed to start with a 100 MW power plant which is expected to consume about 2.4 km² of flat land for the parabolic trough CSP technology. The total calculated potential of yearly electricity generation would be about 2.3 TWh. If half of the selected land (0.5 × 50 km²) is reserved for future expansion of the plant, the total future capacity can attain 1 GW of electric power. The selected area can also accommodate in the future different types of CSP technologies as they mature with time.     

A novel polygeneration system integrating the acetylene production process and fuel cell

This paper presents a novel polygeneration system that integrates the acetylene process and the use of fuel cells. The system produces acetylene and power by a process of the partial oxidation/combustion (POC) of natural gas process, a water–gas shift reactor, a fuel cell and a waste heat boiler auxiliary system to recover the exhaust heat and gas from the fuel cell. Based on 584.3 kg/h of natural gas feedstock, a POC reactor temperature of 1773 K, an absorber pressure of 1.013 MPa and a degasser pressure of 0.103 MPa, the simulation results show that the new system achieved acetylene production of 1.9 MW, net electricity production of 1.7 MW, power generation efficiency of 26.8% and exergy efficiency of 43.4%, which was 20.2% higher than the traditional acetylene production process. The new system's exergy analysis and the flow rate of the products were investigated, and the results revealed that the energy conversion and systematic integration mechanism demonstrated the improvement of natural gas energy conversion efficiency.     

High-frequency irradiance fluctuations and geographic smoothing

Using six San Diego solar resource stations, clear-sky indices at 1-s resolution were computed for one site and for the average of six sites separated by less than 3 km to estimate the smoothing of aggregated power output due to geographic dispersion in a distribution feeder. Ramp rate (RR) analysis was conducted on the 1-s timeseries, including moving averages to simulate a large PV plant with energy storage. Annual maximum RRs of up to 60% per second were observed, and the largest 1-s ramp rates were enhanced over 40% by cloud reflection. However, 5% per second ramps never occurred for a simulated 10 MW power plant. Applying a wavelet transform to both the clear-sky index at one site and the average of six sites showed a strong reduction in variability at timescales shorter than 5-min, with a lesser decrease at longer timescales. Comparing these variability reductions to the Hoff and Perez (2010) model, good agreement was observed at high dispersion factors (short timescales), but our analysis shows larger reductions in variability than the model at smaller dispersion factors (long timescales).