Greenhouse Gas Emission And Biomass Cofiring Environmental Sciences Essay

Co-firing biomass with coal reduces GHG emanations ( Battista, et al. , 2000 ) . Biomass co-firing has been viewed as one of the efficient options for cut downing GHG emanations in coal based power coevals. Hughes and Tillman ( 1998 ) confirm that biomass co-firing is adept in decrease of GHG emanations. Largely the decrease is from supplanting of coal by biomass and besides by break uping biomass, forestalling the production of methane ( Hughes and Tillman, 1998 ) . This survey investigated the consequence of co-firing biomass on GHG emanation in Utah.

3.1. Introduction

Climate alteration is one of the serious environmental menaces ; increase in anthropogenetic GHG concentration in the ambiance is the major cause responsible for this alteration ( U.K. DECC, 2010 ) . Over the past two centuries, monolithic deforestation, burning of fossil fuels, and land usage alterations have emitted GHG and caused increase in atmospheric concentrations of GHG. Consequently, the Earth ‘s surface temperature has increased by 0.7i‚°C n the past 100 old ages, which has been unprecedented for at least the past 1,000 old ages ( IPCC, 2007 ) . Average planetary temperatures may lift between 1.1A°C and 6.4A°C above 1990 degrees by the terminal of this century unless any GHG extenuation step is adopted ( U.K. DECC, 2010 ) . Agrarian supports have been affected by clime alteration through alterations in one-year conditions calendar, available dirt wet, alimentary handiness, and alteration in physiological response of harvests ( Rosenzweig and Parry, 1994 ) . Direct effects of clime alteration in agribusiness include addition in ambient CO2 concentration and attendant rise in temperature ensuing in increased drouth and physical harm of harvests and farm animal production by deluging and water-logging. Alternatively, the indirect effects include alterations in harvests, farm animal, plagues, dirts and H2O supplies ( Liverman, 2008 ) .

International attempts to cut down GHG emanations and stabilise concentration can be summarized the series of international dialogues such as the Kyoto Protocol in 1997 and the Copenhagen Accord in 2009. The United Nations Framework Convention on Climate Change is an international environmental pact, which came into consequence in 1994 with the end of accomplishing the stabilisation of GHG concentrations in the ambiance at a degree that would forestall unsafe anthropogenetic intervention with the clime system, and its Kyoto Protocol which was adopted in Kyoto, Japan in 1997 entered into force in 2005 ; sharing the aim of the Convention to stabilise atmospheric concentrations of GHG and enabling such a planetary response to climate alteration. The major characteristic of the Kyoto Protocol is that it sets the binding marks for Annex I states ( industrialised states ) for cut downing GHG emanations. Under the Kyoto Protocol Framework, US are required to cut down its emanation by 7 % from its 1990 degree by the twelvemonth 2012 ( UNFCC, 2008 ) . Similarly harmonizing to Copenhagen Accord, US should cut down 17 % of its GHG emanation by 2020, which can be the serious load of the economic system ( USCAN, 2010 ) . The American Clean Energy and Security Act besides enforced United States to cut down its GHG emanations by 20-30 % below 1990 degrees by 2020 and 80 per centum below 1990 degrees by the twelvemonth 2050 ( U.S.GBC, 2009 ) . The federal Clean Air Act Amendments of 1990 ( CAAA ) attempted to forestall acerb rain by enforcing plant-by works bounds on SO2 emanations from fossil fuel fired power workss. The CAAA besides imposed emanation controls on NOx, which is another acid rain precursor ( USEPA, 2008 ) . Under these demands, “ co-firing biomass at bing coal-burning power workss is viewed as one of many possible conformity options ” ( USDOE/EERE, 2004 ) . Overall, these ordinances have created a demand for environment friendly renewable energies.

Bioenergy has been seen a signii¬?cant potency of extenuating nursery gas ( GHG ) emanation, provided that the resources are developed sustainably and the efficient bioenergy systems are used. Compared to the dodo energy baseline, the current systems and cardinal hereafter options which include perennial cropping systems, usage of biomass residues and wastes and advanced transition systems are able to present 80 to 90 % decreases in GHG emanation. However, land usage alterations and forest direction that lead to a loss of C stocks ( direct ) and in add-on to indirect land usage alteration effects can decrease the net positive GHG extenuation ( IPCC, 2011 ) .

Although coal-burning boilers merely accounted for 45 % of US electricity in 2010, it was besides responsible for 81 % of entire US CO2 emanations in 2010 ( EIP, 2011 ) . In U.S. , the coal-burning power workss emit 2.17 billion dozenss of GHG in 2009 ( Nichols, 2009 ) . In Utah, the coal-burning power workss emit 34.8 metric dozenss of GHG in twelvemonth 2009 ( U.S.EIA, 2009 ) . Scientists, economic experts and policy shapers are seeking for the least cost engineerings to cut down GHG emanations. Battista, et al. , ( 2000 ) demonstrate that biomass co-firing is the lowest cost method for coevals green power and cut downing the dodo based CO2 emanation. McCarl, et al. , ( 2000 ) look into the deduction of GHG emanations of biomass co-fired power workss in Texas. They report that utilizing biomass power for electricity coevals can cut down the GHG emanations. Mann and Spath ( 2001 ) show that the usage biomass for electric power coevals lessens the ( GHG ) emanation by 2 % at 5 % of co-firing and 6 % at 15 % of co-firing, which will be an environmental benefit in the long tally. ( De and Assadi, 2009 ) besides conclude that biomass co-firing with coal in bring forthing electricity is a prospective and an effectual manner for cut downing GHG emanations.

Environmental impacts pose another important concern, particularly GHG emanations which arise largely from the coal burning and the usage of fossil fuels. For illustration, ( Ismayilova, 2007, Mintzer, et al. , 2003 ) estimates that in 2002 entirely, 98.0 per centum of entire U.S. C dioxide ( CO2 ) emanations arose from fossil fuel burning ; one half of which emitted from electricity coevals by coal fired power works and other half from the usage of crude oil merchandises. In contrast, a biomass-fired power works emits CO2 into the ambiance, which is so removed from atmosphere by biomass works growing through photosynthesis ( McCarl, et al. , 2000 ) . Numerous surveies indicate that biomass fuels provide significant benefits to the environment by absorbing C dioxide during growing and breathing it at the clip of burning ( Demirbas, 2003, McCarl, et al. , 2000 ) . This manner biomass fuels non merely take part in the procedure of recycling atmospheric C dioxide but besides do non lend to the pool of nursery gas emanations. Therefore, biomass is considered a zero net C dioxide emanation fuel beginning as it emits the same sum of CO2 which they absorbs during their growing ( Demirbas, 2003 ) . For illustration, the switchgrass C content is 42.04 per centum by weight, or 420.4 g of C per kg of switchgrass. Assuming that all the C in switchgrass is converted from CO2 through the photosynthesis procedure, the CO2 used by switchgrass can be calculated from the C content of switchgrass. This computation is done by ( Qin, et al. , 2006 ) which is equal to 1540.5 g CO2/kg of switchgrass. We farther presume that this C will be released during burning. However, since burning emanations match the photosynthetic consumption, overall there will be net zero emanations from firing biomass as the exclusive feedstock at the power works ( Qin, et al. , 2006 ) . This analysis besides holds for rice straw and logging residue.

Co-firing biomass with coal offers several environmental benefits. Co-firing reduces emanations of C dioxide, a nursery gas, the major contribute to the planetary heating consequence. The biomass co-firing contains significantly less sulfur than coal because of which it besides reduces the emanation of S02 which finally helps in cut downing acerb rain ( NREL, 2000 ) .

Co-firing of biomass with fossil fuels provides agencies to cut down SO2, and CO2 emanations and it besides may cut down NOx emanations. It is assumed that there is no net emanation of CO2 from biomass burning as workss use the same sum of CO2 during their growing that is released at the clip of burning and because biomass contains less or no S it reduces the SO2 emanation ( Jenkins, et al. , 1998, Pedersen, et al. , 1997, Robinson, et al. , 2003, Wieck-Hansen, et al. , 2000 ) . The bulk of the presentation study modest decrease in NOx ( Aerts and Ragland, 1997, Pedersen, et al. , 1997, Robinson, et al. , 2003, Tillman, 2000 ) but a few study reported that there is no alteration in emanation of NOx ( Boylan, 1996, Robinson, et al. , 2003, Wieck-Hansen, et al. , 2000 ) The effects of co-firing on NOx emanations are much more hard to stipulate than its effects on SO2 or CO2 emanations which is much clearer than the complexness of NOx formation in coal boilers. NOx decrease is due to beef uping of reactions cut downing No in the furnace and/or lower N content in biomass. Every metric ton of biomass co-fired straight reduces dodo CO2 emanations by over a metric ton. If the biomass would otherwise be disposed of in a landfill without methane aggregation and flaring, the dodo CO2 emanation decrease can be the equivalent of about three metric tons of fossil CO2 for every metric ton of biomass burned ( EUBIONET, 2004 ) .

Co-firing offers the low cost engineering of bring forthing electric power with simple alteration in the bing substructure. It besides offer the possibility of cut downing the net CO2 emanations likewise modest decreases in SO2 and NOx emanations, to bring forth green energy on an electrical end product footing, besides supplying employment chances to local industries that generate biomass residue. Therefore, policies that restrain C emanations or promote renewable energy may take to more significant degrees of co-firing ( Demeter, et al. , 1999, Hughes, 2000, Hughes and Tillman, 1998, Robinson, et al. , 2003, Sondreal, et al. , 2001 ) .

Economic benefit of decreases in GHG emanation is non straightforward. However, the economic benefit can be the avoided cost to extenuate the direct decrease of GHG emanations or saved cost to purchase the CO2 emanation licenses from the emanation trading market. Current monetary value of CO2 emanation license is around $ 7/ton of CO2. Based on this we may deduce the economic benefit of the cut downing GHG emanations ( EUBIONET, 2004 ) .

3.2 Methods:

3.2.1 Life Cycle ( LCA ) Appraisal

“ Life rhythm appraisal ( LCA ) is defined as a systematic set of process to measure the environmental facets and possible impacts associated with a merchandise, procedure, or service, by roll uping an stock list of relevant energy and stuff used and wastes release to the environment ” in ISO 14040.2 Draft: Life Cycle Assessment – Principles and Guidelines. Lifecycle Assessment was created as “ a valuable decision-support tool for both policy shapers and industry in measuring the cradle-to-grave impacts of a merchandise or procedure ” ( GDRC, 2004 ) . More specifically, “ the appraisal includes the full life rhythm of the merchandise or service, embracing, pull outing and treating natural stuffs ; fabrication, transit and distribution ; usage, re-use, care ; recycling, and concluding disposal ” ( GDRC, 2004 ) .

Most of the research on bioenergy production processes in the U.S. used life rhythm analysis to quantify the overall environment impacts associated with the merchandise or service. For illustration, Qin, et al. , ( 2006 ) used LCA attack to analyze the fight of switchgrass as a biomass resource for power coevals through developing an apprehension of the economic sciences, technology, energy and environmental facets of biomass as a replacing for coal in power coevals. Mann and Spath ( 2001 ) besides employed the LCA attack to a coal-burning power system that co-fires wood residue capturing all procedures necessary for the operation of the power works, including natural stuff extraction, provender readying, transit, and waste disposal and recycling. Analysts from the U.S. National Bioenergy Center at NREL besides applied the LCA to find the environmental impacts of biomass transition engineerings, utilizing a cradle-to-grave attack that includes biomass feedstock growing, crop, transition, and merchandise usage ( US.DOE/EERE, 2003 ) .

In this survey, we used the findings of the Mann and Spath ( 2001 ) to analyze the economic, environmental and energy deductions of replacing coal with biomass in the electricity generating works and co-firing with coal at 5 % , 10 % , and 15 % ratio. Mann and Spath use a life rhythm appraisal, where all procedures are examined cradle-to grave. They found both life rhythm and works emanations are reduced with co-firing from a closed cringle biomass system ( biomass production dedicated for energy usage ) compared with coal-based electricity coevals. Decreases in emanations include CO2, CO, particulates, SO2, and NOx. Their consequences showed that at rates of 5 % and 15 % by heat input, co-firing reduces nursery gas emanations on a CO2-equivalent footing by 5.4 % and 18.2 % , severally.

Table Air Emission

15 % co-firing

5 % co-firing

No co-firing

Emissions

% alteration from

Emissions

% alteration from

Emissions

( g/MWh )

no co-firing

( g/MWh )

no co-firing

( kg/MWh )

Particulates affair

8.1

-12

8.9

-3

9.2

Carbon dioxide

954

-6

1003

-2

1018

Carbon monoxide

0.2

-5

0.3

-1

0.3

Sulfur dioxide

5.9

-12

6.5

-3

6.7

Nitrogen oxides

3.1

-8

3.3

-2

3.3

Beginning: A lifecycle appraisal of biomass co-firing in a coal-burning power works ( Mann and Spath, 2001 )

3.3 Consequences and Discussion

Mann and Spath ( 2001 ) findings mentioned on table 14 is used to calculate the tabular array 15 and table 16.

Table Air Emission

5 % co-firing

No co-firing

Emissions

% alteration from

Entire PM and

Emissions

( kg/MWh )

no co-firing

GHG reduced ( kg/MWh )

( kg/MWh )

Particulates affair

1519600173

3.3

51222478

1570822651

Carbon dioxide

17125381726

1.5

256112388

17381494114

Sulfur dioxide

110982035.1

3

3414831.9

114396867

Nitrogen oxides

54967804.08

2.4

1376921.44

56344725.52

Table. Air Emission

15 % co-firing

No co-firing

Emissions

% alteration from

Entire PM and

Emissions

( kg/MWh )

no co-firing

GHG reduced ( kg/MWh )

( kg/MWh )

Particulates affair

86141845.85

12

11700192.48

97842038.33

Carbon dioxide

10145595178

6.3

680839063

10826434241

Sulfurdioxide

62745295.13

11.9

8509232.78

71254527.91

Nitrogen oxides

32967866.93

6.1

2127646.82

35095513.75

Table 15 summarizes the emanation of air pollutants from the power workss emitted with biomass and without biomass co-firing at 5 % co-firing rate. The consequences show that the pattern of co-firing reduced the huge bulk of pollutants emitted from the power workss. The consequences show that the emanations which have serious impacts on human wellness and the environment are well reduced due to co-firing. Particulate affair and SO2 is reduced by about 3 % with 5 % of biomass co-firing than the coal fired entirely. It besides reduces the CO2 emanation ; the major green house gas by 3 % with 5 % biomass coal co-firing. Other major pollutants NOx has been reduced by about 3 % at 5 % co-firing rate.

Similarly, table 16 summarizes the emanation of air pollutants from the power workss emitted with biomass co-firing at 15 % co-firing rate and without biomass co-firing ( coal fired entirely ) . The consequences show that the pattern of co-firing aids to cut down the huge bulk of pollutants emitted by the power workss. The emanations which have serious impacts on human wellness and the environment are well reduced because of biomass coal co-firing. The tabular array depicts that particulate affair ; a major air pollutant which had inauspicious consequence on human wellness every bit good as SO2 ; a major GHG gas were reduced by about 12 % with 15 % of biomass coal co-firing than the coal fired entirely. Same manner it besides reduces the CO2 emanation ; a major GHG by 6 % at 15 % co-firing rates. Mean while it reduces another major air pollutant NOx by 6 % with 15 % of biomass coal co-firing than the coal fired entirely.

The similar findings has been found by Mann and Spath ( 2001 ) and Tillman ( 2000 ) They explained that sum of SO2 produced is reduced due to the low S content of the biomass provender compared with the coal. The smaller measures of S non merely reduced the SO2 production but besides reduced the sum of calcium hydroxide and limestone required for the fluke gas killing. Because bulk of the system particulate emanation are due to the production of these absorbents, overall system particulate are reduced because of co-firing Mann and Spath ( 2001 ) . The decreases of NOx in the analysis were assumed due to the lower sum of fuel edge N in the biomass. Tillman ( 2000 ) estimates that power works NOx may be reduced by 9.8 % and 26.4 % for 5 % and 15 % co-firing rates severally.