Numerical modeling of the gasification based biomass co-firing in a 600 MW pulverized coal boiler

Gasification based biomass co-firing was an attractive technology for biomass utilization. Compared to directly co-firing of biomass and coal, it might: (1) avoid feeding biomass into boiler, (2) reduce boiler fouling and corrosion problem, and (3) avoid altering ash characteristics. In this paper, CFD modeling of product gas (from biomass gasification) and coal co-firing in a 600 MW tangential PC boiler was carried out. The results showed that NO_x emission was reduced about 50–70% when the product gas was injected through the lowest layer burner. The fouling problem can be reduced with furnace temperature decreasing for co-firing case. The convection heat transfer area should be increased or the co-firing ratio of product gas should be decreased to keep boiler rated capacity.     

Synergy effects of co-firing wooden biomass with Bosnian coal

The paper presents synergy effects found during the co-firing of wooden biomass with Bosnian coal types in an experimental reactor. The co-firing tests used spruce sawdust in combination with Kakanj brown coal and a lignite blend of Dubrave lignite and Sikulje lignite. Coal/biomass mixtures at 93:7 and 80:20 wt% were fired in a 20 kW pulverized fuel (PF) entrained flow reactor. Over 20 test trials were performed to investigate ash deposition behavior and emissions under different conditions, varying the process temperature, excess air ratio, and air distribution. During the tests, the temperature in the experimental facility varied between 880 and 1550 °C, while the excess air ratio varied between 0.95 and 1.4. There was sufficient combustion efficiency under all co-firing regimes, with burning out at 96.5–99.5% for brown coal–sawdust co-firing. Synergy effects were detected for all co-firing regimes with regard to SO₂ emission, as well for slagging at the process temperature suitable for the slag tap furnace. CO₂ emissions were also calculated for the blends tested and significant reductions of CO₂ found, due to the very low ranking of Bosnian coals.     

How important are current energy mix choices on future sustainability? Case study: Belgium and Spain—projections towards 2020–2030

Despite recent consumption decrease due to recession, European electricity sector is struggling to reach ambitious targets for reductions of greenhouse gas emissions. Our objective is to carry out a macro analysis of the energy mix in two European countries: Belgium and Spain. Life Cycle Assessments are carried for 2005 as well as for seven possible referenced scenarios to reach EU and also national legal objectives at the horizon 2020 and 2030. Ambitious renewable energy sources’ deployment plans can decrease impacts on the environment significantly as those sources replace polluting traditional sources, such as coal/lignite, oil or gas. When concentrating on projections for the future in Spain, results show that a mix with little coal and oil replaced by up to 54% of RES-E energy sources could bring environmental benefits with CO₂ emissions equivalent around 0.2 kg per kWh produced (compared with 0.54 kg in 2005). In Belgium, all future scenarios presented include more coal and gas with a limited share of RES-E; those mixes present more environmental harmful impacts (up to 0.56 kg CO₂ equivalent). This is why RES-E deployment is crucial as long as it is part of an electricity mix with reduced quantities of traditional fossil fuels.     

Cost effects of international trade in meeting EU renewable electricity targets

The European market for renewable electricity received a major stimulus from the adoption of the Directive on the Promotion of Renewable Electricity. The Directive specifies the indicative targets for electricity supply from renewable energy sources (RES-E) to be reached in European Union (EU) Member States in the year 2010. It also requires Member States to certify the origin of their renewable electricity production. This article presents a first EU-wide quantitative evaluation of the effects of meeting the targets, using an EU-wide system for tradable green certificates (TGC). We calculate the equilibrium price of green certificates and identify which countries are likely to export or import certificates. Cost advantages of participating in such an EU-wide trading scheme are determined for each of the Member States. Moreover, we identify which choice of technologies results in meeting targets at least costs. Results are obtained from a model that quantifies the effects of achieving the RES-E targets in the EU with and without trade. The article provides a brief insight in this model as well as the methodology that was used to specify cost potential curves for renewable electricity in each of the 15 EU Member States. Model calculations show that within the EU-wide TGC system, the total production costs of the last option needed to satisfy the overall EU RES-E target equals 9.2 eurocent/kWh. Assuming that the production price of electricity on the European power market would equal 3 eurocent/kWh in the year 2010, the indicative green certificate price equals 6.2 eurocent/kWh. We conclude that implementation of an EU-wide TGC system is a cost-efficient way of stimulating renewable electricity supply.     

Supply amount and marginal price of renewable electricity under the renewables portfolio standard in Japan

The Renewables Portfolio Standard (RPS) in Japan requires that approximately 1.35% of each retail supplier's electricity sales in FY2010 come from renewable energy sources (RES), for example, photovoltaics, wind, biomass, geothermal, and small hydropower. To help retail suppliers and renewable generators develop effective strategies, this study provides a quantitative analysis of the impact of this measure. We assume the supply conditions for electricity generation from renewable energy sources (RES-E) based on regional resource endowments, and we derive the cost-effective compositions of renewable portfolios, RES-E certificate prices, and additional costs to retail suppliers. The future prospects of RES-E are assessed based on technology, region, and year up to FY2010. The analysis reveals that wind power and biomass power generated from municipal waste will provide the majority of the total supply of RES-E under the RPS. It also indicates that the marginal price of RES-E certificates will be approximately 5.8 JPY/kWh (5.2 USc/kWh) in FY2010, in the case wherein the marginal price of electricity is assumed to be 4 JPY/kWh (3.6 USc/kWh). In order to elaborate on this further, sensitivity analyses for some parameters of RES and the price of electricity are provided. The dynamic supply curves of RES-E certificates are also indicated.     

Assessment of the potential biomass supply in Europe using a resource-focused approach

This paper analyses the potential biomass supply in the 15 EU countries (EU15), 8 new member states and 2 candidate countries (ACC10), plus Belarus and the Ukraine. The objective of this study is to make a more detailed assessment of the potential in Europe than previously undertaken. For this purpose five scenarios were designed to describe the short-, medium- and long-term potential of biomass for energy. The scenarios are based on assumptions regarding residue harvests, energy-crop yields and surplus agricultural land. Energy-crop yields are correlated with the national wheat yields, a methodology we have not seen used in biomass assessments before. Our assessments show that under certain restrictions on land availability, the potential supply of biomass energy amounts to up to 11.7 EJy⁻¹ in the EU15 and 5.5 EJy⁻¹ in the ACC10. For comparison, the overall energy supply in the EU15 totalled 62.6 EJy⁻¹ in 2001. Consequently, there are no important resource limitations in meeting the biomass target, 5.6 EJy⁻¹ in the EU15 by 2010, which was set by the European Commission in the 1997 White paper on renewable energy sources (RES). However, given the slow implementation of the RES policy it is very unlikely that the biomass targets will be met.     

State-scale evaluation of renewable electricity policy: The role of renewable electricity credits and carbon taxes

We have developed a state-scale version of the MARKAL energy optimization model, commonly used to model energy policy at the US national scale and internationally. We apply the model to address state-scale impacts of a renewable electricity standard (RES) and a carbon tax in one southeastern state, Georgia. Biomass is the lowest cost option for large-scale renewable generation in Georgia; we find that electricity can be generated from biomass co-firing at existing coal plants for a marginal cost above baseline of 0.2–2.2 cents/kWh and from dedicated biomass facilities for 3.0–5.5 cents/kWh above baseline. We evaluate the cost and amount of renewable electricity that would be produced in-state and the amount of out-of-state renewable electricity credits (RECs) that would be purchased as a function of the REC price. We find that in Georgia, a constant carbon tax to 2030 primarily promotes a shift from coal to natural gas and does not result in substantial renewable electricity generation. We also find that the option to offset a RES with renewable electricity credits would push renewable investment out-of-state. The tradeoff for keeping renewable investment in-state by not offering RECs is an approximately 1% additional increase in the levelized cost of electricity.     

Analysis of biomass co-firing systems in Taiwan power markets using linear complementarity models

Biomass co-firing systems in power plants generate electric power by the simultaneous combustion of biomass and fossil fuels. The co-firing process reduces investment costs by converting biomass energy into electricity in existing conventional power plants. Biomass co-firing significantly reduces carbon dioxide and sulfur dioxide emissions in power generation. To meet the increase in biomass demand, this paper has considered systematic energy crop production, which is expected to increase in the near future. Our aim is to analyze biomass co-firing systems in the Taiwanese electricity market. In this paper, we study two emerging biomass feedstocks: switchgrass and Miscanthus. We focus on the impact of energy crop co-firing on carbon dioxide and sulfur dioxide emissions for electricity generation. A Nash–Cournot competition model, which simulates potential biomass co-firing scenarios, is formulated for power markets. A case study conducted in the Taiwanese electricity market showed that biomass co-firing lowers total electricity demand and sale. Miscanthus is more economical than switchgrass in terms of the production cost and the land required to generate biopower for the same levels of biomass co-firing.     

Economic modelling of price support mechanisms for renewable energy: Case study on Ireland

The Irish Government is considering its future targets, policy and programmes for renewable energy for the period beyond 2005. This follows a review in 2003 of policy options that identified a number of different measures to stimulate increased deployment of renewable energy generation capacity. This paper expands this review with an economic analysis of renewable energy price support mechanisms in the Irish electricity generation sector. The focus is on three primary price support mechanisms quota obligations, feed in tariffs and competitive tender schemes. The Green-X computer model is utilised to characterise the RES-E potential and costs in Ireland up until, and including, 2020. The results from this dynamic software tool are used to compare the different support mechanisms in terms of total costs to society and the average premium costs relative to the market price for electricity. The results indicate that in achieving a 20% RES-E proportion of gross electricity consumption by 2020, a tender scheme provides the least costs to society over the period 2006–2020 but only in case there is limited or no strategic bidding. Considering, however, strategic bidding, a feed-in tariff can be the more efficient solution. Between the other two support mechanisms, the total costs to society are highest for feed-in-tariffs (FIT) until 2013, at which point the costs for the quota system begin to rise rapidly and overtake FIT in 2014–2020. The paper also provides a sensitivity analysis of the support mechanism calculations by varying default parameters such as the interim (2010) target, the assumed investment risk levels and the amount of biomass co-firing. This analysis shows that a 2010 target of 15% rather than 13.2% generates lower costs for society over the whole period 2006–2020, but higher costs for the RES-E strategy over the period 2006–2010.     

Local-scale analysis of carbon mitigation strategies: Tompkins County,New York,USA

The costs and potential for several carbon mitigation options were analyzed for Tompkins County, NY, within several categories: terrestrial carbon sequestration, local power generation, transportation, and energy end-use efficiency. The total county emissions are about 340 Gg C/year, with current biomass sequestration rates of about 121 Gg C/year. The potential for mitigation with the options examined, assuming full market penetration, amounts to at least 234 Gg C/year (69%), with 100 Gg C/year (29%) at no net cost to the consumer. Effective carbon mitigation strategies for this county based on costs per mg carbon and maximum potential include reforestation of abandoned agricultural lands for terrestrial carbon sequestration, biomass production for residential heating and co-firing in coal power plants, changes in personal behavior related to transportation (e.g., carpooling or using public transportation), installation of numerous residential energy-efficient products and development of local wind power. The principal barriers to the implementation of these approaches are discussed and policies for overcoming these barriers are analyzed.     

A hybrid model for the optimum integration of renewable technologies in power generation systems

The main purpose of this work is to assess the unavoidable increase in the cost of electricity of a generation system by the integration of the necessary renewable energy sources for power generation (RES-E) technologies in order for the European Union Member States to achieve their national RES energy target. The optimization model developed uses a genetic algorithm (GA) technique for the calculation of both the additional cost of electricity due to the penetration of RES-E technologies as well as the required RES-E levy in the electricity bills in order to fund this RES-E penetration. Also, the procedure enables the estimation of the optimum feed-in-tariff to be offered to future RES-E systems. Also, the overall cost increase in the electricity sector for the promotion of RES-E technologies, for the period 2010–2020, is analyzed taking into account factors, such as, the fuel avoidance cost, the carbon dioxide emissions avoidance cost, the conventional power system increased operation cost, etc. The overall results indicate that in the case of RES-E investments with internal rate of return (IRR) of 10% the cost of integration is higher, compared to RES-E investments with no profit, (i.e., IRR at 0%) by 0.3–0.5 €c/kWh (in real prices), depending on the RES-E penetration level.     

The perspectives of energy production from coal‐fired power plants in an enlarged EU

The aim of this paper is to present the current status of the coal‐fired power sector in an enlarged EU (EU‐15 plus EU member candidate states) in relation with the main topics of the European Strategy for the energy production and supply. It is estimated that 731 thermoelectric units, larger than 100 MW_e, are operating nowadays, and their total installed capacity equals to 200.7 GW_e. Coal contribution to the total electricity generation with reference to other fuel sources, is by far more intensive in the non‐EU part (EU member candidate states), compared to the EU member states. It is expected that even after the enlargement, the European Union will strongly being related to coal. Enlargement will bring additional factors into play in order to meet the requirements of rising consumption, growing demand for conventional fuels and increasing dependence on imports. Besides the technology, boiler size, efficiency, age and environmental performance will determine the necessities of the coal‐fired power sector in each country. Depending on the case, lifetime extension measures in operating coal‐fired power plants or clean coal technologies can play an important role towards the energy sector restructuring. Low efficiency values in the non‐EU coal‐fired units and heavily aged power plants in EU countries will certainly affect decisions in favour of upgrading or reconstruction. The overall increase of efficiency, the reduction of harmful emissions from generating processes and the co‐combustion of coal with biomass and wastes for generating purposes indicate that coal can be cleaner and more efficient. Additionally, plenty of rehabilitation projects based on CCT applications, have already been carried out or are under progress in the EU energy sector. The proclamations of the countries' energy policies in the coming decades, includes integrated renovation concepts of the coal‐fired power sector. Further to the natural gas penetration in the electricity generation and CO₂ sequestration and underground storage, the implementation of CCT projects will strongly contribute to the reduction of CO₂ emissions in the European Union, according to the targets set in the Kyoto protocol. In consequence, clean coal technologies can open up new markets not only in the EU member candidate states, but also in other parts of the world. Copyright © 2004 John Wiley & Sons, Ltd.     

Increasing biomass resource availability through supply chain analysis

Increased inclusion of biomass in energy strategies all over the world means that greater mobilisation of biomass resources will be required to meet demand. Strategies of many EU countries assume the future use of non-EU sourced biomass. An increasing number of studies call for the UK to consider alternative options, principally to better utilise indigenous resources. This research identifies the indigenous biomass resources that demonstrate the greatest promise for the UK bioenergy sector and evaluates the extent that different supply chain drivers influence resource availability.The analysis finds that the UK's resources with greatest primary bioenergy potential are household wastes (>115 TWh by 2050), energy crops (>100 TWh by 2050) and agricultural residues (>80 TWh by 2050). The availability of biomass waste resources was found to demonstrate great promise for the bioenergy sector, although are highly susceptible to influences, most notably by the focus of adopted waste management strategies. Biomass residue resources were found to be the resource category least susceptible to influence, with relatively high near-term availability that is forecast to increase – therefore representing a potentially robust resource for the bioenergy sector. The near-term availability of UK energy crops was found to be much less significant compared to other resource categories. Energy crops represent long-term potential for the bioenergy sector, although achieving higher limits of availability will be dependent on the successful management of key influencing drivers. The research highlights that the availability of indigenous resources is largely influenced by a few key drivers, this contradicting areas of consensus of current UK bioenergy policy.     

Implications of technological learning on the prospects for renewable energy technologies in Europe

The objective of this article is to examine the consequences of technological developments on the market diffusion of different renewable electricity technologies in the EU-25 until 2020, using a market simulation model (ADMIRE REBUS). It is assumed that from 2012 a harmonized trading system will be implemented, and a target of 24% renewable electricity (RES-E) in 2020 is set and met. By comparing optimistic and pessimistic endogenous technological learning scenarios, it is found that diffusion of onshore wind energy is relatively robust, regardless of technological development, but diffusion rates of offshore wind energy and biomass gasification greatly depend on their technological development. Competition between these two options and (existing) biomass combustion options largely determines the overall costs of electricity from renewables and the choice of technologies for the individual member countries. In the optimistic scenario, in 2020 the market price for RES-E is 1 €ct/kWh lower than in the pessimistic scenario (about 7 vs. 8 €ct/kWh). As a result, total RES-E production costs are 19% lower, and total governmental expenditures for RES-market stimulation are 30% lower in the optimistic scenario.     

Assessing plantation biomass for co-firing with coal in northern Indiana: A linear programming approach

Tightening environmental regulations and the signing of the Kyoto Protocol have prompted electric utilities to consider co-firing biomass with coal to reduce the levels of CO₂, SO₂, and NO_x in stack emissions. This analysis examines the cost competitiveness of plantation produced woody biomass and waste wood with coal in electricity production. A case study of woody biomass production and co-firing in northern Indiana is presented. A Salix (willow) production budget was created to assess the feasibility of plantation tree production to supply biomass to the utility for fuel blending. Co-firing with waste wood from primary and secondary wood processing activities and local municipalities also is considered. A linear programming model was developed to examine the optimal co-firing blend of coal and biomass while minimizing variable cost, including the cost of ash disposal and material procurement costs. This model was used to examine situations where coal is the primary fuel and waste wood, willow trees, or both are available for fuel blending. The results indicate that co-firing woody biomass is cost-effective for the power plant. Sensitivity analysis explored the effect of waste wood prices on co-firing cost.     

An evaluation of biomass co-firing in Europe

Reduction of the emissions of greenhouses gases, increasing the share of renewable energy sources (RES) in the energy balance, increasing electricity production from renewable energy sources and decreasing energy dependency represent the main goals of all current strategies in Europe. Biomass co-firing in large coal-based thermal power plants provides a considerable opportunity to increase the share of RES in the primary energy balance and the share of electricity from RES in gross electricity consumption in a country. Biomass-coal co-firing means reducing CO₂ and SO₂, emissions and it may also reduce NO_x emissions, and also represents a near-term, low-risk, low-cost and sustainable energy development. Biomass-coal co-firing is the most effective measure to reduce CO₂ emissions, because it substitutes coal, which has the most intensive CO₂ emissions per kWh electricity production, by biomass, with a zero net emission of CO₂. Biomass co-firing experience worldwide are reviewed in this paper. Biomass co-firing has been successfully demonstrated in over 150 installations worldwide for most combinations of fuels and boiler types in the range of 50–700 MWe, although a number of very small plants have also been involved. More than a hundred of these have been in Europe. A key indicator for the assessment of biomass co-firing is intrduced and used to evaluate all available biomass co-firing technologies.     

Biomass co-firing options on the emission reduction and electricity generation costs in coal-fired power plants

Co-firing offers a near-term solution for reducing CO₂ emissions from conventional fossil fuel power plants. Viable alternatives to long-term CO₂ reduction technologies such as CO₂ sequestration, oxy-firing and carbon loop combustion are being discussed, but all of them remain in the early to mid stages of development. Co-firing, on the other hand, is a well-proven technology and is in regular use though does not eliminate CO₂ emissions entirely. An incremental gain in CO₂ reduction can be achieved by immediate implementation of biomass co-firing in nearly all coal-fired power plants with minimum modifications and moderate investment, making co-firing a near-term solution for the greenhouse gas emission problem. If a majority of coal-fired boilers operating around the world adopt co-firing systems, the total reduction in CO₂ emissions would be substantial. It is the most efficient means of power generation from biomass, and it thus offers CO₂ avoidance cost lower than that for CO₂ sequestration from existing power plants. The present analysis examines several co-firing options including a novel option external (indirect) firing using combustion or gasification in an existing coal or oil fired plant. Capital and operating costs of such external units are calculated to determine the return on investment. Two of these indirect co-firing options are analyzed along with the option of direct co-firing of biomass in pulverizing mills to compare their operational merits and cost advantages with the gasification option.     

Forest owner motivations and attitudes towards supplying biomass for energy in Europe

The European Commission expects the use of biomass for energy in the EU to increase significantly between 2010 and 2020 to meet a legally binding target to cover at least 20% of EU's total energy use from renewable sources in 2020. According to estimates made by the member states of the EU, the direct supply of biomass from forests is expected to increase by 45% on a volume basis between 2006 and 2020 in response to increasing demand (Beurskens LWM, Hekkenberg M, Vethman P. Renewable energy projections as published in the national renewable energy action plans of the European Member states. ECN and EEA; 2011. http://https://www.ecn.nl/docs/library/report/2010/e10069.pdf [accessed 25.04.2014]; Dees M, Yousef A, Ermert J. Analysis of the quantitative tables of the national renewable energy action plans prepared by the 27 European Union Member States in 2010. BEE working paper D7.2. Biomass Energy Europe project. FELIS – Department of Remote Sensing and landscape information Systems, University of Freiburg, Germany; 2011). Our aims were to test the hypotheses that European private forest owners' attitudes towards supplying woody biomass for energy (1) can be explained by their responses to changes in prices and markets and (2) are positive so that the forest biomass share of the EU 2020 renewable energy target can be met. Based on survey data collected in 2010 from 800 private forest owners in Sweden, Germany and Portugal our results show that the respondents' attitudes towards supplying woody biomass for energy cannot be explained as direct responses to changes in prices and markets. Our results, furthermore, imply that European private forest owners cannot be expected to supply the requested amounts of woody biomass for energy to meet the forest biomass share of the EU 2020 renewable energy target, at least if stemwood is to play the important role as studies by Verkerk PJ, Anttila P, Eggers J, Lindner M, Asikainen A. The realisable potential supply of woody biomass from forests in the European Union. For Ecol Manag 2011;261: 2007–2015, UNECE and FAO. The European forest sector outlook study II 2010–2030. United Nations, New York and Geneva; 2011 [abbreviated to EFSOS II] and Elbersen B, Staritsky I, Hengeveld G, Schelhaas MJ, Naeff H, Böttcher H. Atlas of EU biomass potentials; 2012. Available from: http://www.biomassfutures.eu [accessed 14.10.2013] suggest.     

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.     

Global energy security and the implications for the EU

The following article will analyse the global and geopolitical dimensions of the future international energy security and its implications for Europe and the EU-27. In this context, I will discuss to which extent the EU's newly proclaimed “Energy Action Plan” of the EU Spring summit of 2007 and its declared common energy (foreign) policy are a sufficient strategy to cope with the new global and geopolitical challenges. The article concludes the following: (1) The interlinkage between globally designed traditional energy security concepts – that rely just on economic factors and “market-strategies” – and domestic as well as regional political stability demands new thinking with regard to both energy supply security and foreign and security policies. (2) Although after the Russian–Ukrainian gas conflict in January 2006, energy security has forced its way up the European energy and foreign policy agendas, the EU-27 member states have largely failed to forge a coherent European energy security and energy foreign policy strategy after their Spring summit of 2007 because its declared political solidarity has been still lacking. But the 2nd Strategic Energy Review of November 2008 has recommended new initiatives to overcome this lack by promoting concrete infrastructure and other projects for enhancing Europe's supply security and its political solidarity as part of a common energy (foreign) policy. If the EU is able to implement the March 2007 and November 2008 decisions, the EU oil and gas demand will drastically reduce and freeze at current levels. In this case, Putin's energy policies by using Russia's energy resources and pipeline monopolies as a political instrument to enforce its economic and geopolitical interests will be proved as self-defeating in Russia's long-term strategic interests. It will reduce Gazprom's gas exports to a much smaller EU gas market than originally forecasted as the result of a deliberate EU policy of decreasing its overall gas demand and by diversifying its gas imports.