Life-cycle assessment of a photovoltaic system in Catalonia (Spain)

The life-cycle analysis (LCA) of photovoltaic (PV) systems is an important tool to quantify the potential environmental advantage of using solar technologies versus more traditional technologies, especially the ones relying on non-renewable fossil fuel sources.This work performs a life-cycle assessment on a 200 kW roof top photovoltaic (PV) system with polycrystalline silicon modules and evaluates the net energy pay-back and greenhouse gas emission rates. The performed life-cycle assessment “upstream” and “downstream” processes are considered, such as raw materials production, fabrication of system components, transportation and installation. The energy pay-back time ratio is determined for the installed technology and two other technologies of PV modules (monocrystalline and thin-film).The analysed PV system, located in Pineda de Mar (Catalonia, Spain), has an energy pay-back time ratio of 4.36 years. Furthermore, a sensibility analysis on solar radiation has been performed.     

Sustainability considerations for electricity generation from biomass

The sustainability of electricity generation from biomass has been assessed in this work according to the key indicators of price, efficiency, greenhouse gas emissions, availability, limitations, land use, water use and social impacts. Biomass produced electricity generally provides favourable price, efficiency, emissions, availability and limitations but often has unfavorably high land and water usage as well as social impacts. The type and growing location of the biomass source are paramount to its sustainability. Hardy crops grown on unused or marginal land and waste products are more sustainable than dedicated energy crops grown on food producing land using high rates of fertilisers.     

A cost-benefit analysis of generating electricity from biomass

A key challenge internationally is the design of future electricity systems which will bring about emissions savings and fuel security at least cost. Peat is used to generate electricity in several EU countries, mainly to take advantage of indigenous resources and increase fuel mix diversity. The Irish government has introduced a target of 30% cofiring of peat and biomass by 2015. This paper assesses the feasibility of achieving this target by calculating the available indigenous biomass resource capable of being cofired; the cost of meeting the target; the benefits in terms of carbon abatement; and finally the present value in economic terms of meeting the target. Results demonstrate that Ireland has only half the necessary resource to meet the 30% target and that the net cost of doing so is greater than the cost of what is currently being paid for peat, in all of the scenarios considered. Thus, it is concluded that while it may be technically possible to meet the target by combining national resources with imported biomass this is never the least cost option, and as a result the targeted focus of Government policy may need to be reconsidered.     

Life-cycle uses of water in U.S. electricity generation

Water use by the electric power industry is attracting renewed interest as periods and zones of arid weather are increasingly encountered, and various regional energy-production scenarios are evaluated. However, there is a scarcity of data on upstream water factors and discrepancies of data from different sources. We reviewed previous studies of water use in electricity generation and used full-life cycle accounting to evaluate water demand factors, both withdrawal and consumption, for conventional- and renewable-electrical power plants. Our investigation showed that moving to technologies like photovoltaics and wind offers the best option for conserving our water supply. We also emphasize the importance of employing a transparent, balanced approach in accounting life-cycle water usages.     

Goal programming model for sustainable electricity production from biomass

In this paper, we present a goal programming model for block level energy planning in order to make a block self‐sufficient in electricity consumption, which includes the commercial energy consumption goal, the goal of generating electricity from biomass and food production goals with linear constraints on the available sources such as human power, animal power, tractor power, land area and on the requirement of the block such as cooking energy, lighting energy and energy for other operations, such as fodder for animal population. We try to achieve these goals through proper allocation of land for different crops. After reformulating the developed goal programming model into a linear programming format, we use the HYPER LINDO software package to solve it in a Pentium‐based IBM‐PC compatible computer system. The developed model is solved for a typical Indian block, namely Nilakkottai Block in Tamil Nadu, India. The model solution shows that the goal of generating electricity from biomass is achieved, the commercial energy consumption goal and pulses requirement goal are under‐achieved and the sugar requirement goal is over‐achieved. Furthermore, the cereal, vegetable and oilseed production goals are achieved. Copyright © 2000 John Wiley & Sons, Ltd.     

Life-cycle assessment of fuel cell stacks

Life-cycle assessment is a useful instrument to evaluate the ecological performance of innovative energy systems. This paper investigates the production process of polymer electrolyte fuel cell (PEFC) stacks, identifies the ecological contributions of various components and materials and compares the results with impacts due to utilization of the stacks in a vehicle (i.e. hydrogen or methanol production and direct emissions). The production of fuel cell stacks leads to environmental impacts which cannot be neglected compared to the utilization of the stacks in a vehicle (the actual driving process). These impacts are mainly caused by the platinum group metals for the catalyst and, to a lesser degree, the materials and energy for the flow field plates. The paper identifies several options how to further enhance the environmental advantages of fuel cells.     

Life-cycle assessment in the renewable energy sector

The Polish energy industry is facing challenges regarding energetic safety, competitiveness, improvement of domestic companies and environmental protection. Ecological guidelines concern the elimination of detrimental solutions, and effective energy management, which will form the basis for sustainable development. The Polish power industry is required to systematically increase the share of energy taken from renewable sources in the total energy sold to customers. Besides the economic issues, particular importance is assigned to environmental factors associated with the choice of energy source. That is where life-cycle assessment (LCA) is important. The main purpose of LCA is to identify the environmental impacts of goods and services during the whole life cycle of the product or service. Therefore LCA can be applied to assess the impact on the environment of electricity generation and will allow producers to make better decisions pertaining to environmental protection. The renewable energy sources analysed in this paper include the energy from photovoltaics, wind turbines and hydroelectric power. The goal and scope of the analysis comprise the assessment of environmental impacts of production of 1 GJ of energy from the sources mentioned above. The study will cover the construction, operation and waste disposal at each power plant. Analysis will cover the impact categories, where the environmental influence is the most significant, i.e. resource depletion, global warmth potential, acidification and eutrophication. The LCA results will be shown on the basis of European and Australian research. This analysis will be extended with a comparison between environmental impacts of energy from renewable and conventional sources. This report will conclude with an analysis of possibilities of application of the existing research results and LCA rules in the Polish energy industry with a focus on Poland's future accession to the European Union. Definitions of LCA fundamental concepts, its methodology and application are described in the ISO 14040-14049 series of standards. These standards have already been introduced in some countries, but in Poland they are still at the stage of translation into Polish. Nevertheless some companies in Poland try to assess how their products influence the environment and what are the possibilities of technology improvement in the existing production process reduce their environmental impact.     

Cycles in deregulated electricity markets: Empirical evidence from two decades

In this article, we discuss the “cycle hypothesis” in electricity generation, which states that the introduction of deregulation in an electricity system might lead to sustained fluctuations of over- and under-capacity. The occurrence of cycles is one of the major threats for electricity markets as it affects the security of supply, and creates uncertainty in both the profitability of electricity companies and in consumer prices. We discuss the background for these cycles using analogies with other capital-intensive industries, along with evidence from the analysis of behavioral simulation models as well as from experimental electricity markets. Using data from the oldest deregulated markets we find support for the hypothesis in the case of the English and Chilean markets, based on an autocorrelation analysis. Evidence from the Nordpool market is more ambiguous, although we might be observing the first half of a cycle in generation capacity. Comparing a simulation of the English market performed in 1992 with the actual performance we can observe that the qualitative behavior of the model is consistent with the actual evolution. Finally, we discuss possible mechanisms for damping cycles in electricity generation, such as mothballing, capacity payments, and reliability markets.     

Biomass assessment and small scale biomass fired electricity generation in the Green Triangle, Australia

Coal fired electricity is a major factor in Australia’s greenhouse gas emissions (GHG) emissions. The country has adopted a mandatory renewable energy target (MRET) to ensure that 20% of electricity comes from renewable sources by 2020. In order to support the MRET, a market scheme of tradable Renewable Energy Certificates (RECs) has been implemented since 2001. Generators using biomass from eligible sources are able to contribute to GHG emission reduction through the substitution of coal for electricity production and are eligible to create and trade RECs. This paper quantifies the potential biomass resources available for energy generation from forestry and agriculture in the Green Triangle, one of the most promising Australian Regions for biomass production. We analyse the cost of electricity generation using direct firing of biomass, and estimate the required REC prices to make it competitive with coal fired electricity generation. Major findings suggest that more than 2.6 million tonnes of biomass are produced every year within 200 km of the regional hub of Mount Gambier and biomass fired electricity is viable using feedstock with a plant gate cost of 46 Australian Dollars (AUD) per tonne under the current REC price of 34 AUD per MWh. These findings are then discussed in the context of regional energy security and existing targets and incentives for renewable energies.     

Co-firing biomass with coal for electricity generation—An assessment of the potential in EU27

The European Union aims to increase bioenergy use. Co-firing biomass with coal represents an attractive near-term option for electricity generation from renewable energy sources (RES-E). This study assesses the near-term technical potential for biomass co-firing with coal in the existing coal-fired power plant infrastructure in the EU27 Member States. The total technical potential for RES-E from biomass co-firing amounts to approximately 50–90 TWh/yr, which requires a biomass supply of approximately 500–900 PJ/yr. The estimated co-firing potential in EU27 amounts to 20–35% of the estimated gap between current RES-E production and the RES-E target for 2010. However, for some member states the national co-firing potential is large enough to fill the national gap. The national biomass supply potential is considerably larger than the estimated biomass demand for co-firing for all member states. About 45% of the estimated biomass demand for co-firing comes from plants located close to the sea or near main navigable rivers and indicates the possibility for biomass import by sea transport. Thus, biomass co-firing has the potential to contribute substantially to the RES-E development in EU27.     

The potential for electricity generation from crop and forestry residues in Spain

We assess the energy contents of agricultural and forestry residues in Spain, and the potential for the generation of electricity from them. The methodology employed is a hierarchical, GIS-based one, and leads through the physical, geographical and technical potential to the economic analysis. The results from the latter are crafted in the form of generation-cost curves, which provide a good indication of how the cost of the energy increases as the generation from these residues does. Geo-referenced data allow for the consideration of the opposing influences on the specific cost of the plant size and the transport costs, which are both incorporated in the model by means of a plant supply area. A representative cost is defined and used to compare costs among biomass sources and combustion technologies. The combined technical potential of agriculture and forestry residues is 118 PJ y^?1 (equivalent to 11.25% of the net electric energy generated in Spain in 2008). The economic potential (defined as the potential with a cost smaller than the representative one) is 46.3 PJ y^?1 (or 4.43% of net electric energy generated in Spain in 2008).     

Solar electricity in a changing environment: The case of Spain

In Spain, solar electricity (photovoltaic and thermoelectric) has reached a stable annual capacity factor above 20% since 2009; while wind achieved 23% since more than 10 years ago. This is the demonstration of an ongoing transition towards a more sustainable energy mix, further corroborated by the reduction of the capacity factor of gas-fired technology, which has seen a decline to values lower than 10% after an initial promising rise; this is a very low value for a fossil-fuel technology. Additionally, hydro installed capacity, which has been stable for the past 20 years, have demonstrated that can be used as a back-up power source in combination with solar and wind electricity, and it is capable of producing energy peaks that may increase from a stable base of 2000 GWh/month up to 6000 GWh/month and therefore meet demand at some particular times when solar and wind are generating less electricity without the need of installing new additional capacity at national level.     

Potential and cost of electricity generation from human and animal waste in Spain

The energy contents of human and animal waste generated in Spain is estimated, as is the electricity that could be potentially generated from such waste. The waste considered is municipal solid waste, sewage sludge and livestock manure; several energy-recovery options are analyzed for the first one, viz the collection of landfill gas, incineration and anaerobic digestion. To estimate the potential, we use geo-referenced statistical human and animal population data disaggregated to the county level. This level of disaggregation allows the implementation of a cost model for the transformation of the waste into electricity, using a variety of technologies. The model considers the cost of transporting the waste to the transformation plant, and takes into account the economies of scale afforded by larger plants for the combined treatment of the waste in the county. The result is a generation-cost curve, which sorts by increasing costs the generation potential in the whole of the territory. The overall limits, in terms of primary energy and without considering alternative uses for the waste are between 725 and 4438 ktoe/y (depending on the energy-recovery method) for municipal solid waste; 142 ktoe/y for sewage sludge; and 1794 ktoe/y for livestock manure. The cost of the electricity generated depends greatly on the type of residue and the technology used for the transformation. Thus, the most economical option is the incineration of municipal solid waste, with an entry cost of around 4 c€/kWh. The generation entry-costs from livestock manure and sewage sludge are on the other hand in excess of 8 c€/kWh.     

Green electricity externalities: Forest biomass in an Atlantic European Region

Renewable energy sources are expected to represent a growing proportion of the primary energy sources for the production of electricity. Environmental and social reasons support this tendency. European and Spanish energy plans assign a role of primary importance to biomass in general and, especially, to forest biomass for the period up to 2010. This paper reviews, organises and quantifies the potentials and values of this renewable resource in the foremost Spanish Region in terms of silviculture. The non-market externalities (environmental, economic and social) are classified, and some of them are quantified to present a synthesis of the benefits of a partial substitution of fossil fuels by forest biomass for electricity generation.     

Decentralized generation of electricity from biomass with proton exchange membrane fuel cell

Biomass can be applied as the primary source for the production of hydrogen in the future. The biomass is converted in an atmospheric fluidized bed gasification process using steam as the gasifying agent. The producer gas needs further cleaning and processing before the hydrogen can be converted in a fuel cell; it is assumed that the gas cleaning processes are able to meet the requirements for a PEM-FC. The compressed hydrogen is supplied to a hydrogen grid and can be used in small-scale decentralized CHP units. In this study it is assumed that the CHP units are based on low temperature PEM fuel cells. For the evaluation of alternative technologies the whole chain of centralized hydrogen production from biomass up to and including decentralized electricity production in PEM fuel cells is considered.Two models for the production of hydrogen from biomass and three models for the combined production of electricity and heat with PEM fuel cells are built using the computer program Cycle-Tempo. Two different levels of hydrogen purity are considered in this evaluation: 60% and 99.99% pure hydrogen. The purity of the hydrogen affects both the efficiencies of the hydrogen production as well as the PEM-FC systems. The electrical exergy efficiency of the PEM-FC system without additional heat production is calculated to be 27.66% in the case of 60% hydrogen and 29.06% in the case of 99.99% pure hydrogen. The electrical exergy efficiencies of the whole conversion chain appear to be 21.68% and 18.74%, respectively. The high losses during purification of the hydrogen gas result in a higher efficiency for the case with low purity hydrogen. The removal of the last impurities strongly increases the overall exergy losses of the conversion chain.     

Life cycle energy and environmental benefits of generating electricity from willow biomass

Biomass is a key renewable energy source expected to play an important role in US electricity production under stricter emission regulations and renewable portfolio standards. Willow energy crops are being developed in the northeast US as a fuel source for increasing biomass energy and bioproduct demands. A life cycle inventory is presented that characterizes the full cradle-to-grave energy and environmental performance of willow biomass-to-electricity. A willow biomass production model is developed using demonstration-scale field experience from New York. Scenarios are presented that mimic anticipated cofiring operations, including supplemental use of wood residues, at an existing coal-fired generating facility. At a cofiring rate of 10% biomass, the system net energy ratio (electricity delivered divided by total fossil fuel consumed) increases by 8.9% and net global warming potential decreases by 7–10%. Net SO₂ emissions are reduced by 9.5% and a significant reduction in NO_x emissions is expected. In addition, we estimate system performance of using willow biomass in dedicated biomass gasification and direct-fired generating facilities and demonstrate that the pollution avoided (relative to the current electricity grid) is comparable to other renewables such as PV and wind.     

Assessment of the possibilities of electricity and heat co-generation from biomass in Romania's case

The assessment of different systems for electricity production from biomass in Romanian specific conditions shown the most suitable system for electricity (and heat) (co) generation from biomass is the system based on boiler and steam turbine of 2 MW running on wood-wastes (bark). A pulp and paper mill - S.C. “LETEA” S.A Bacau - which needed electricity and heat, and, in the same time, had large amount of bark from technological process, was found as the most suitable location for a demonstrative project.     

Economic impact of solar thermal electricity deployment in Spain

The objective of the work is to estimate the socio-economic impacts of increasing the installed solar thermal energy power capacity in Spain. Using an input–output (I–O) analysis, this paper estimates the increase in the demand for goods and services as well as in employment derived from solar thermal plants in Spain under two different scenarios: (a) based on two solar thermal power plants currently in operation (with 50 and 17 MW of installed capacity); (b) the compliance to the Spanish Renewable Energy Plan (PER) 2005–2010 reaching 500 MW by 2010.     

The feasibility of co-firing biomass for electricity in Missouri

Bioenergy is one of the most significant energy resources with potential to serve as a partial replacement for fossil. As an agricultural state, Missouri has great potential to use biomass for energy production. In 2008, Missouri adopted a renewable portfolio standard (RPS) yet about 80% of its power supply still comes from coal. This paper describes a feasibility study of co-firing biomass in existing coal-powered plants in Missouri. Specifically, this study developed a linear programming model and simulated six scenarios to assess the economic feasibility and greenhouse gas impacts of co-firing biomass in existing qualified coal power plants in Missouri.The results of this study indicate that although co-firing can reduce the emissions of GHG and environmental pollutants, it is still not an economically feasible option for power generation without additional economic or policy incentives or regulations which could take environmental costs into account. Based on these results, strategies and policies to promote the utilization of biomass and to increase its competitiveness with fossil fuels are identified and discussed.     

Economic buy-back rates for electricity from cogeneration: Case of sugar industry in Vietnam

Cogeneration of heat and power could be an attractive option for meeting electricity demand in Vietnam, which is facing acute shortage in generation capacity due to high demand growth spurred by rapid economic growth of the country. The sugar industry has significant potential for cogeneration. This paper focuses on the cogeneration potential of the sugar industry and estimates, based on avoided cost, the economic rate at which excess power could be sold to the utility. We found that cogeneration would be a financially viable option for medium and large size sugar plants. Time-of-day rates would be the most suitable form of buy-back rate and the IRR ranges between 12% and 15% in this case. The sensitivity analysis indicates that cogeneration plants would be vulnerable to changes in buy-back rates and investment costs. The internal rate of return is more sensitive to changes in buy-back rates than those in investment costs. Medium and large sized plants would be in a better position to withstand such changes in the business environment.