14th North American Waste to Energy Conference

May 1-3,2006, Tampa, Florida USA

NAWTEC14-3196

PYROLYSIS IN WASTE TO ENERGY CONVERSION (WEC)

Alex E. S. Green and Sean M. Bell Clean Combustion Technology laboratory (CCTl),

College of Engineering, University of Florida, Gainesville, Fl

ABSTRACT Solid waste (SW), mostly now wasted biomass, could fuel approximately ten times more of USA's increasing energy needs than it currently does. At the same time it would create good non-exportable jobs, and local industries. Twenty four examples of wasted or under-utilized solids that contain appreciable organic matter are listed. Estimates of their sustainable tonnage lead to a total SW exceeding 2 billion dry tons. Now usually disposal problems, most of these SW's, can be pyrolyzed into substitutes for or supplements to expensive natural gas. The large proportion of biomass (carbon dioxide neutral plant matter) in the list reduces Greenhouse problems. Pyrolysis converts such solid waste into a medium heating value gaseous fuel usually with a small energy expenditure. With advanced gas cleaning technologies the pyrogas can be used in high efficiency gas turbines or fuel cells systems. This approach has important environmental and efficiency advantages with respect to direct combustion in boilers and even air blown or oxygen blown partial combustion gasifiers. Since pyrolysis is still not a predictive science the CCTL has used an analytical semi-empirical model (ASEM) to organize experimental measurements of the yields of various product {CaHbOc} yields vs temperature (T) for r dry ash, nitrogen and sulfur free (DANSF) feedstock having various weight % of oxygen [0] and hydrogen [H]. With this ASEM each product is assigned 5 parameters (W, To, D, p, q) in a robust analytical YeT) expression to represent yields vs. temperature of any specific product from any specified feedstock. Patterns in the dependence of these parameters upon [0], [H], a, b, and c suggest that there is some order in pyrolysis yields that might be useful in optimize the throughput of particular pyrolysis systems used for waste to energy conversion (WEC). An analytical cost estimation (ACE) model is used to calculate the cost of electricity (COE) vs the cost of fuel (COF) for a SW pyrogas fired combined cycle (CC) system for comparison with the COE vs COF for a natural gas fired CC system. It shows that high natural gas prices solid waste can be changed from a disposal cost item to a valuable asset. Comparing COEs when using other SW capable technologies are also facilitated by the ACE method. Implications of this work for programs that combine conservation with waste to energy conversion in efforts to reach Zero Waste are discussed.

1. WASTED SOLIDS AND SOLID WASTE In 1940, when Britain was in deep trouble fighting a

ruthless enemy that then appeared unstoppable, Winston Churchill offered only "Blood, Sweat and Tears" to unite Britain's political factions. At this time in our history we are excessively (60%) reliant on foreign sources for our liquid

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fuels and are increasingly importing our gaseous fuels (now> 15%). Our country is now shedding Blood in its efforts to stabilize regions of the globe that supply these premium fuels. Yet the US is well endowed with solid fuels in the form of wasted solids as well as coal and oil shales. In this paper, in continuation of a long search for altematives to oil [1-10], our focus is on converting our solid waste to energy by advanced thermal technologies (SWEATT). Table 1 is a list of US's abundant supply of wasted solids or solid waste whose organic matter can be made into liquid and gaseous fuels. With recent high natural gas prices and technical reasons that will become obvious this paper will concentrate on advanced thermal technologies (A TT) conversions of solid waste (SW) to gaseous fuels. ATT conversions to liquid fuels involve similar technical considerations but the oil back-out problem has the attention of many government, business and engineering personnel. SWEATT has the attention of only a few.

In the US most of the categories in Table I would now be called "biomass" in part because "solid waste" has a bad public image, bringing to mind old incinerators belching black smoke. However, advances in thermal technologies and gas clean-up systems now being successfully applied in Japan and the European Union (EU) [11] deserve a new image. SWEATT not only addresses US's very urgent need for alternative fuels, but could also mitigate air and water pollution problems. The large carbon dioxide neutral plant matter components in Table I can help in Greenhouse mitigation. The great diversity of physical and chemical characteristics in Table I implies that the world now needs an "omnivorous feedstock converter" (OFC) to change these solid fuels into much more usable liquid or gaseous fuels. Figure 1 is a conceptual illustration of an OFC adapted from a number of prior CCTL papers [8-10].

Figure 2 shows the subdivisions of the US total primary energy supply (TPES) in 2005. The data (in quadrillion British thermal units (Btu) or quads) is taken from the January to October 2005 monthly numbers given in US Energy Information Agency website [12] augmented with estimates of the November and December 2005 consumptions. Since the total consumption is now very close to 100 quads the numbers might also be considered as approximate percentages of US energy consumption. It is seen that over 40% of our energy consumption is in the form of oil that is mainly consumed in our transportation sector. Without doubt the biggest energy problem faced by the US today, as has been recognized for many years, is the need to find alternatives to oil [1-3]. In the 70's and early 80's the CCTL focus was on alternatives to oil in the utility sector. At this time, our focus is on the developing alternatives to natural gas for electricity generation

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via the use of advanced thermal technologies (ATT). It should be noted, however, that A TT can also make major contributions to the solution of our liquid fuel problem in the transportation sector [3].

It is important to differentiate secondary energy supplies (SES) from the primary energy supplies (PES) shown in Figure 2. Secondary energies supplies include steam, syngas, reactive chemicals, hydrogen, charged batteries, fuel-cells and other energy sources that draw their energy from PES's. If a SES is converted to another type of energy, say mechanical energy, via a steam turbine the mechanical energy becomes a tertiary energy supply (TES). This TES can be converted to electrical energy using magnetic generators in which case the electricity is a quaternary (QES) supply. In the case of electricity the many conversions are usually justified since electricity can readily be distributed by wire and has so many uses as a source of energy for highly efficient electric motors, illumination systems, home appliances, computers, etc.

A debate is underway in many communities as to whether its increasing electricity needs should be met with solid fuels, particularly coal, via conventional steam and steam turbine generator systems or via conversion to a gaseous fuel to fuel gas-steam turbine-generator systems. Granting that the steam turbine route has had many advances over the last century our thesis is that converting the solid fuel to gaseous fuel is the advanced thermal technology (ATT) route of the future. The ATT route is not only driven by environmentally acceptable waste disposal needs and increased needs for electricity but also by the need for liquid fuels and gaseous fuels. A number of petroleum resource experts have recently advanced the date that the globe's supply of oil and natural gas will run out. The prices of oil and natural gas that now might be reflecting this drawdown and are already high enough that conversion of organic matter in solid waste to liquid and gaseous fuels makes economic sense. We should recognize, however, that for the most part cartels govern fuel prices not free markets. Thus we should not abandon alternative fuels efforts whenever cartels, for their interests, lower prices.

The solid wastes listed in Table I, mostly consisting of what is called biomass in the US, now constitute a minor component (-2.8 %) of the U.S. annual TPES. However, this wasted material could in the near term become a major (> 25%) component comparable to coal and natural gas, both now at about 23%. Since SWEATT is based upon locally available solid waste, it would also create good non-exportable local industries and jobs while mitigating serious U.S. energy import and waste disposal problems. An Oak Ridge National Laboratory study [12] estimates the sustainable supply of the first few biomass categories in Table I at about 1.4 billion dry tons. The remaining categories should readily bring the total sustainable U.S. solid waste available to over 2 billion dry tons. Assuming a conservative higher heating value (HHV) of 7500 Btullb a simple calculation shows that with SWEATT US solid waste contribution to its primary energy supply could reach the 25% level with technologies close to those that are now in place in Japan, EU and a few places in the US [11]. Essentially the U.S. now consumes about 100 quadrillion BTUs (British thermal units), only about 2.8% of which currently come from solid waste. The other renewables, hydroelectric (2.8%), geothermal (0.35%), wind (0.14%) and solar (0.06%), have much further to go than solid waste before becoming a major primary energy source in the US.

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2. ADVANCED THERMAL TECHNOLOGIES The largest solid waste to energy systems in operation

today are direct combustion municipal solid waste (MSW) incinerators [14] with capacities in the range of 1000 to 3000 tons per day. In such mass bum systems the organic constituents of the solid waste are combusted (in a sense converted!) into the gaseous products CO2 and H20. These have no fuel value but can be carriers of the heat of combustion, as in coal and biomass boiler-furnace systems. Along with the flame radiation these gases transfer hest to pressurized water to produced pressurized steam that drives a steam turbine driven electric generator. The steam can also serves as valuable secondary energy supply (SES) to distribute heat for heating buildings, industrial processes etc. The production and use of steam along with the steam engine launched the industrial age and various steam driven systems have reached a very high level of refinement including in waste to energy systems[14].

In SWEATT systems, rather than direct combustion and the use of the heat released to raise steam the solid waste is first converted into a gaseous or liquid fuel. This fuel then serves as a SES that can be combusted in efficient internal combustion engines, combustion turbines or, in the future, in fuel cells none of which can directly use solid fuels. Over the past century automotive and aircraft developments have pushed internal combustion engines (ICE) and gas turbines (GT) to very high levels of efficiency. Furthermore, with the use of modem high temperature GTs Natural gas-fired combined cycle (NGCC) systems the heat of the exhaust gases can be used with a heat recovery steam generator (HRSG) to drive a steam turbine. The HRSG can alternatively provide steam for combined heat and power (CHP) system that can effectively make even greater use of the original solid fuel energy.

If one considers the US's heavy dependence on foreign sources of liquid and gaseous fuels the most challenging technical problem facing us today should be recognized as the development and implementation of efficient ways of converting our abundant domestic solid fuels into more useful liquid and gaseous fuels. In view of the diversity of feedstock represented in municipal or institutional solid waste any successes in Solid Waste to Energy by Advanced Thermal Technology (SWEATT) would obviously advance this more general quest. In effect the US and the world needs an omnivorous feedstock converter such as is illustrated in Figure 1. Here the right block represents a typical gas fired combined cycle system whereas the left block represents a conceptual Omnivorous Conversion System that can convert any organic material into a gaseous fuel.

3. GROSS COMPARISONS OF ATT OUTPUTS We will first consider the gross nature of the output

gas from biomass or cellulosic type material, the major organic components of most solid wastes streams. Apart from minor constituents such as sulfur and nitrogen the cellulosic feed types are complex combinations of carbon, hydrogen and oxygen in combinations such as (C6HIOOS) that might serve as the representative cellulosic monomer.

SWEATT systems might be divided into 1) Air Blown Partial Combustion (ABPC) gasifiers 2) Oxygen blown Partial Combustion (OBPC) gasifiers and 3) Pyrolysis (PYRO) systems. The three approaches for converting waste into a gaseous fuel have many technical forms depending upon

the detailed arrangements for applying heat to the incoming feed and the source of heat used to change the solid into a gas or liquid.

Let use "producer gas" as a generic name for gases developed by partial combustion of the feedstock with air as in many traditional ABPC gasifiers that go back to Clayton's coal gasifier of 1694. We will use "syngas" for gases developed by partial combustion of the feedstock with oxygen as in OBPC gasifiers, which are mainly a development of the 20th century. We will use "pyrogas" for gases developed by an-aerobic heating of the feedstock such as in indirectly heated (PYRO) gasifiers. Our objective is to replace natural gas that has a HHV-lOOO BtU/cft = I MBtu/cft (here M= 1000).

When an ABPC gasifier is used with cellulosic materials (cardboard, paper, wood chips, bagasse, etc), the HHV of biomass producer gas is very low 100-200 BtU/cft for two reasons 1) the main products are CO that has a HHV of 322 Btu/cft and CO2, and H20 that have zero heating values and 2) the air nitrogen air substantially dilutes the output gas.

The "syngas" obtained from biomass with an OBPC gasifiers is better - 320 Btu/cft since it is not diluted by the atmospheric nitrogen. However, it is still somewhat lower than the feedstock molecules because of the partial combustion. The oxygen separator is a major capital cost component of an OBPC gasifier.

With a PYRO system the original cellulosic polymer is first broken to its monomers leading to some CO , CO2, and H20 along with paraffins (CH4, C2H6 and C3HS .. ), olefins (C2H4, C3H6 .. ) and oxygenated hydrocarbons: carbonyls, alcohols, ethers, aldehydes and phenols and other oxygenated gaseous products. Cellulosic pyrogas can have heating values in the 400Btulcft range.

Hydrocarbon plastics such as polyethylene and polyolefins in general are among the most predominant plastics in many solid waste streams. Thus one might use (C2H4) as representative of the monomers in the plastic component of MSW or refuse derived fuels (RDF). Polyethylene pyrolysis products include H2, olefins, paraffins, acetylenes, aromatics (Ar) and polynuclear aromatics (PNA). On a per unit weight basis all but H2 have gross heating values in the range 23-18 MBtuilb (M=lOOO), similar to oil, whereas H2 has a gross heating value of 61MBtu/lb. On a per unit volume basis all polyethylene pyrolysis products have gross heating value ranging from 1-5 MBtu/cft whereas H2 is 0.325 MBtulcft = 325 Btu/cft. Natural gas is typically about IMBtulcft. Thus we would expect the pyrogas from polyethylene to have a gross heating value comparable or greater than that of natural gas and much greater than cellusosic pyrogas.

In summary since cellulosic feedstock is already oxygenated as compared to pure hydrocarbon plastics its pyrogas, syngas and producer gas will all have considerably lower heating values than the corresponding gases from hydrocarbon feedstock. From the viewpoint of maximizing the HHV of SW derived gas PYRO gasification scores better than OBPC gasification that scores better than ABPC gasification.

4. ULTIMATE AND PROXIMATE ANALYSIS To optimize the use of the US supply of solid waste

listed in Table 1 it would be helpful to know in greater detail how the main constituents of organic containing feedstock will influence the main products that will evolve from ATT. In most attempts to find the systematic of pyrolysis yields of organic materials such as coal and biomass including the

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initial CCTL studies, it has been customary to characterized the feedstock by its atomic ratios y = H/C and x = OIC [15-20). In its recent studies [21-26]the CCTL has found it more advantageous to work with the weight percentages [C], [H] and [0] of the feedstock after correcting to dry, ash, sulfur and nitrogen free (DASNF) conditions (i.e. pure CHO materials). Figure 3A illustrates [H] vs. [0] coordinates of 185 representative coals and biomass based upon ultimate analyses that have been reported in the literature. Note the simple analytical [H] vs. [0] coalification curve (see figure) and the hovering of the values of the coal and biomass [H] values near 6% after the anthracite region. The larger points on Figure 3A give the [H], [0] positions of lignin (6.1,32.6), cellulose (6.2,49.4) and hemi-cellulose (6.7,53.3), the three main components of all plant matter. Also shown on Figure 3A are the [H] and [0] co-ordinates of several materials that are present in solid waste. These depart substantially above and below the coalification curve. Not shown is polyethylene that would lie at [14.2, 0).

Figure 3B shows the total volatiles (VT) for the CHO materials vs. [0] mostly for materials close to the coalification path. These values are determined by standard proximate analysis procedures that measure the weight loss of a sample after exposure to 950°C for 7 minutes in an anoxic medium. The balance from 100% then represents the weight of the fixed carbon (FC) plus ash. When this residual is burnt the remainder is the ash wt%. An empirical analytical formula is given in the caption to represent general trends of total volatiles along nature's coalification curve. It should be obvious that in the high [0] region pyrolysis is substantially equivalent to gasification. Our subsequent studies point to the fact that the [H] dimension is very important in determining volatile content.

Figure 3C shows the pattern of higher heating values (HHV) vs [0] along the coalification path. The DuLong formula given in the caption is a compromise between those used in the coal and biomass sectors [14, 28). The three diagrams all indicate the importance of the [0] in determining the fuel properties of natural substances. A better expression is needed to represent the total volatile released when [H] lies above the coalification curve.

5. ASEM AND PYROLYSIS Proximate analyses of coal and biomass measured for

over a century provide extensive data on total volatile content. However, the identification of the molecules in these volatiles is still not available for practical engineering applications and remains in the engineering research stage. For the optimum control and application of a pyrolysis system it would be useful to know in detail the expected yields of specific pyrolysis product from various feedstocks.

The Clean Combustion Technology Laboratory (CCTL) of the University Florida has made a number of attempts to find the underlying order of pyrolysis yields of any product CaHbOc vs the [0] and [H] of the DASNF feedstock and the temperature (T) and time (t) of exposure. Since [C] = 100-[0]­[H] it is not an independent variable. Table 2 gives representative slow pyrolysis yields at 1000°C measured at the CCTL during the course of these attempts [17]. In organizing such data as well as data in the literature the CCTL has developed an analytical semi-empirical model (AS EM) that has been useful for a number of applications of pyrolysis [19-27). Attempts have been made to include the time dimension but much more work remains. When the time dimension is

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not a factor the yields of each product for slow pyrolysis (or fast pyolysis at a fixed time) are represented by

YeT) = W[L (T: TO, D)]p[F (T: TO, D)]q (1)

where L (T: TO, D) =1/[1 + exp «TO -T)/D)] (2)

and F(T: TO, D) =I-L(T) = 1/[ l+exp «T - TO)/D)] (3)

Here L(T), is the well known logistic function that is often called the "learning curve". Its complement F(T) = 1-L(T) thus might be called the "forgetting curve". In effect each product is assigned 5 parameters (W, To, Do, p, q) to represent its yield vs. temperature profile. The objective has been to find how these parameters depend upon the [H] and [0] of the feedstock and the a, b, c of the CaHbOc product for the data from various types of pyrolyzers. Studies by Xu and Tomita (XT) [28, 29] that gave data on IS products from 17 coals at 6 temperatures have been particularly helpful in revealing trends of the parameters with [0] and [H]. In applying the ASEM to the CCTL data collection, the XT collection and several other collections a reasonable working formula was found for the yield of any abc product for any [0], [H] feedstock. It was given by

where z = [C]/69, h = [H]/6 and x = [0]/25 and The parameters a, � an9 Y. To, D, p and q were found to have simple relationships to the feedstock and product defining parameters a, b, c [H] and [0]. The final ASEM formulas that fit the data could then be used to extrapolate or interpolate the XT results to any [H], [0] feedstock and temperature. Figure 4 gives an overview of the interpolated and extrapolated outputs Y (T) outputs for a selection of products for four representative feedstock along natures coalification path.

Since hundreds even thousands of organic products of pyrolysis have been identified in the literature to go much further some comprehensive organization of these products is needed. Towards this goal the CCTL has grouped products into the families shown in Table 3 along with the a,b,c rules that connect these groups. This list can be subdivided into pure hydrocarbons i.e. (C.Hb) and the oxygenates (C.HbO, CaHb02, CaHb03 • . . etc). Isomers (groups with identical a, b and c) can differ in detailed pyrolysis properties and hence parameters. We use j = 1, 2, 3 etc ... to denote the first, second, third, etc. members of each group or the carbon number (n). In the CCTL's most recent studies [21-27] of specific feedstock pyrolysis formulas have been proposed and tested for the dependence of the W, To, Do, p, q parameters upon the carbon number of the product within each group. This makes it possible to compact a very large body of data with simple formulas and a table of parameters.

The case of polyethylene is an example of such a study. It is not shown on Figure 3A, as it is far removed from the coalification curve having the position [H] =14.2 on the [0] = o axis. Without oxygen in the feedstock the pyrolysis products are much fewer and the ASEM is much simpler to use than with carbohydrates. Thus only the first 5 rows of Table 3 are needed to cover the main functional groups involved in the organizing the pyrolysis products of polyethylene. Figure 5 gives an ASEM type summary of the product yields vs.

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temperature based upon fits to the experimental data of Mastral et al [32, 33] at five temperatures that were constrained to approximately satisfy mass, carbon and hydrogen balances. Once the parameter systematics is identified the ASEM representation can be used to estimate the pyrolysis product of polyethylene pyrolysis at any intermediate temperature or at reasonable extrapolated temperatures. The experimental data was only available up to 850°C but the extrapolations to 1000°C were constrained in detail to conform to mass, carbon, hydrogen and oxygen balance. Figure 4 also shows extrapolations to 6000 C that might be of interest if one goes to very high temperatures, for example by plasma torch heating. Here we incorporate a conjecture that at the highest temperatures carbon and hydrogen emerge among the products at the expense of the CI-C2, aromatics and PNAs components. While we have already found that an AS EM can begin to bring some order and overview into pyrolysis yields clearly we have a long way to go. When the time dimension is important the overall search is for a reasonable function of seven variables [H], [0], a, b, c, T, and t. Einstein special relativity only dealt with a four variables x,y,z and t.

6. SWCC VS NGCC AND ACE Before World War II also every town had its own gas

works, mainly using coal, as a feedstock. After WW II cheap natural gas became available and became a major PES for home heating and cooking as well as for industrial purposes. In the 1980s factory produced NGCC became available and natural gas became a base load fuel source for many electric utilities hastening the drawdown of US domestic supplies. In the last four years natural gas prices have risen to some 3-7 times greater than they were when these NGCC facilities were built. Thus pursuing SW to energy by advanced thermal technologies (SWEATT) is now a very timely. For most biomass and plastic feedstock pyrolysis is substantially equivalent to gasification.

The economic feasibility of using a gasifier in front of a gas fired system can be examined with simple arithmetic and algebra using an analytical cost estimation (ACE) method. [6-10]. ACE takes advantage of the almost linear relationship seen in many detailed cost analyses of the cost of electricity (COE= Y) vs. cost of fuel (COF =X) for many technologies, i.e.

Y(X)=K+SX (5).

Here Y is given is in centslkwh and X = is given in $IMMBtu. In Eq. 5 S is the slope of the Y(X) line in cents/kwh/$/MMBtu or 10,000 Btulkwh. S relates to the net plant heat rate (NPHR) via

S = NPHRlIO,OOO (6) or efficiency via S = 34. 12/Eff (7)

[6-10]. For modem coal plants S - 1. The parameter K mainly reflects the capital cost and to a smaller extent the operating costs of a facility as well as interest rates and rate of return to the plant owners. Essentially K = COE if the fuel comes to the utility without cost.

In previous studies [6-10] we found Kng = 2 is a reasonable zero fuel cost parameter for say a 100 MW NGCC system [34, 35]. This low number reflects the low capital costs of the factory produced gas turbines and steam turbines

in NGCC systems. A slope Sng =0.7 is now reasonable reflecting the high efficiency of recent NGCC facilities.

For a gasified solid waste combined cycle (SWCC) system Ksw would generally be higher than Kng because the capital costs and operating cost must include the gasifier and gas clean-up system. The value of Ssw is also higher than Sng because we must first make a secondary energy supply (SES) producer gas, syngas or pyrogas which involves some conversion losses. Ssw = 1 is a reasonable ball park slope for an up to date SWCC system. The Xsw for a SWCC system that would compete with a NGCC system at various Xng must satisfY

By algebra it follow that the solid waste fuel cost Xsw that would enable a SWCC system to deliver electricity at the same cost as a NGCC system paying Xng is given by

Xsw = (Kng-K,w)/Ssw + (SnglSsw)Xng (9).

In what follow all X numbers are in $/MMBtu and all Y and K numbers are in cents/kwh. Let us use Eq. 9 with Kng = 2, Sng =0.7, Ssw = 1 and Ksw = 4 as a reasonable ball park numbers based upon several SWCC analyses [6-10]. Then the first term in Eq. 9 is -2. Now when the Xng= 2 to generate SWCC electricity at the same cost the solid waste provider must deliver the fuel at a negative price i.e. pay the tipping fee -0.7. However, if Xng is at say 6 as it was in 2004 the SWCC utility could pay up to 2.4 for the SW fuel. If the Xng is at 12, the SWCC facility could pay 7.1 to the supplier. This Xsw price is higher than that of coal whose delivered price (Xc) these days usually is in the 2-3 range. This simple cost comparison is illustrated in Figure 6 that shows the opportunities for SWCC systems when natural gas prices are above say $5IMMBtu. The results are slightly less favorable if the Ksw were higher say at K = 5. However, the conclusions that at high natural gas prices SWCC electricity become competitive with NGCC electricity would be similar. It is conceivable that K,w could be held as low as 2ct/kWh by retrofitting a NGCC system stranded by high natural gas prices. In this case the first term in Eq. 9 vanishes and the competitive Xsw = (SngfSsw)Xng. This illustrates the main point that at high natural gas prices with an ATT system SW can be a valuable PES. Indeed, this simple algebraic-arithmetic exercise establishes the feasibility of a New Paradigm in which Solid Waste (mostly biomass but here meaning all solids that are now wasted) become potentially valuable marketable assets.

As described above the values of K and S are the key factors in determining the COFsw to be used in a SWCC would be competitive on a COE basis with the COE using a NGCC system at the available COFng. The ACE method can be extended to the use of SW or biomass with other technologies if we can identify the K and S for each technology. We have previously applied the ACE method to a large body of COE vs COF calculations on biomass use presented in an Antares Group Inc. report (AGIR) [36]. It is reasonable to apply these results to most of the SW listed in Table 1 particularly in small commumhes that have recycling programs involving residential separation of waste that would minimize the cost of making RDF.

The technologies investigated in the AGIR when 100 tons per day forest thinning were available include a Biomass Integrated Gasifier (BIG) CC system BIGCC, a BIG simple

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cycle (BIGSC) system, a BIG internal combustion (BIGIC) system a biomass -gasification-coal cofiring BIGCo system, a direct co-firing of biomass and coal in a coal-steam boiler BCoSt, a direct use of biomass in a feedwater heat recovery arrangement (FWHR), direct use of biomass in a Stoker fire boiler Steam Turbine (SFST) system and direct firing in a combined heat and power plant (CHP) with a steam market at $6/MMBtu. A summary of K's extracted from the AGIR was found in a form

The Ko and KI parameters determined by regression to the data sets in tables in the AGIR leading to very high correlation coefficients are listed in Table 4. Subsequent studies of other technologies and other sources confum such a strong economy of scale for K. Values ofK extrapolated to 25, and 100 MW are also shown. The power level dependence of S has been somewhat more difficult to pin down. We here use the rule

where m was taken as y., in fitting the low power levels "data" in the AGIR. However, other data sets in the literatIue suggest a weaker S(P). Listed in Table 4 are the SI parameters fitting the low P AGIR data and extrapolations of S to 25 and 100 MW based upon the power m = 0.1. Recognizing that low values of K and S lead to low electricity cost, as long as the fuel cost are reasonable, one sees that at 25 MW BCoSt (solid fuel co-firing) and CHP are favorable as concluded in the AGIR report for its lower power levels. However, this ACE analysis suggests that BIGCo (gasification co-firing) and FWHR would also be favorable for biomass at 25 MW. With a caveat about our extrapolations to 100 MW one might conclude that all of the technologies except BIGIC could be competitive by virtue of their low K's. Thus the numbers together with Eq. 5-9 suggest that that at high natural gas prices solid waste, in the broad sense used in this paper, could be moved from disposal costs to marketable assets with several technologies. With some more research on evaluation ofK's and S's for various technologies it should be possible to use ACE as a simple tool for arriving at the best generation candidates for a particular community in the light of the costs of fuels in their locale.

Thus far we have focused on the competition between NG fueled technologies and SW fueled technologies. Competition of SW generated electricity with coal-steam generated electricity appears to be a bigger problem. However, if one includes the more expensive scrubber cost in the K's and externality cost in the coal X's [37] the SWCC route should fare well. Coal burning is now a major issue in many communities yet when one projects technology directions throughout the globe it is clear that the Gasification Age is returning [38].

7. DISCUSSION A) Biochemical Conversion

Renewables to Energy are now gammg strong supporters in the agricultural and environmental communities with most of this support in the US now directed towards bio-

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chemical conversion of biomass rather than thermo-chemical conversion. Fermentation and anaerobic digestion are the two major forms of bio-chemical conversion. Fermentation uses bacteria to break down biodegradable organic material in the absence of oxygen to produce liquid fuels such as ethanol. Anaerobic digestion here refers to similar bacterial processes that are designed to produce gaseous fuel products such as methane.

Fermentation to ethanol has the most support at this time since ethanol lends itself to conventional automotive storage although at only 0.6 times the energy density of diesel or gasoline. The ethanol thrust is an extension of the commercial beer, wine and alcohol industries' processing of sugar and starch based feedstock such as com and sugar cane. The use of ethanol as a transportation fuel has considerable political support although some scientists have raised questions as to whether on balance it will help our energy import problem [39]

Anaerobic digestion occurs in compost heaps in which naturally occurring bacteria convert biodegradable waste to methane gas. From the greenhouse standpoint this is a problem since one molecule of methane is some 20 times more damaging as a greenhouse gas than carbon dioxide. To counter this, landfills are outfitted with collection systems and the methane is either flared into CO2 and H20 or, in newer landfills, harnessed as "Green Energy". Some demonstration 'landfills of the future' have added water to the waste as it enters the landfill, to encourage anaerobic digestion of the waste, in effect, creating an in-place bio-reactor landfill.

Unlike thermochemical conversion biochemical conversion is able to process neither the lignin (approximately 25 wt% of plant matter) nor most plastics. Another disadvantage is that the reaction rates of all biochemical conversion processes are vastly slower than thermo-chemical rates. Biochemical processes usually require the 'brew' to ferment for weeks whereas minutes or seconds are sufficient for advanced thermal conversion (ATT). Thus the volume required for bio-chemical processing are correspondingly larger than for A IT processing. Another major disadvantage is the amount of waste material and conversion by-products that are left over once the digestion is complete much of which still has good energy content. However, this residue can be a good feedstock for thermo-chemical processes [II]. We have included SW estimates from alcohol and methane production in Table 1. By utilizing thermo-chemical processes to convert the lignin and plastic content of and bio-chemical process residues we might expect to get much closer to 100% energy recycling of solid waste. SWEATT would also further reduce the final volume of the waste and practically all contaminants will be destroyed by the high temperatures. Co-operation between bio-chemical and thermo-chemical programs thus would clearly be in the national interests.

B) Solid Waste from Bio-Oils The esters of vegetable oils are renewable alternative

fuels that can potentially serve as direct replacements for diesel fuels in compressed ignition engines (CIE). Oils from soybeans, sunflower seeds, safflower, cottonseeds, peanuts, and rapeseeds as well as used oil from restaurants are under considerable investigation as replacements for diesel. Waste from bio-oil programs have been included in Table 1 since only the seeds of the plants are used for bio-oil crops and the rest of the plant becomes solid waste amenable to serve as an input of a SWEATT program.

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C) Recycling and SWEATT While our confrontational society has a tendency to

view waste to energy as a threat to recycling programs the opposite might really be true. Recycling programs in a community can serve to sort the various components or municipal or institutional solid waste into categories that lend themselves to maximize the return on these components. If for example, newspaper or cardboard at a given time has no recycling market but must be disposed of at a cost it should be common sense to make use of the high energy content of this dry feedstock, The same is true for plastic recycling. Thus the market place would be decisive as to whether to recycle via the materials route or the energy route. A recycling community should be able to go the SWCC route with less capital costs than one that does not have waste separation at the source.

D) Solid Waste All iance with Natural Gas (SWANG) The advantages of a biomass alliance with natural gas

(BANG) have been described previously [6-10]. Gasification systems that mainly use cellusosic (biomass) inputs produce a low or medium heating value fuel that will result in derating of a NG designed turbine-generator. By co-utilizing the biomass pyrogas with natural gas one can insure that the input energy requirement matches the output needs at least until the maximum rating of the generator is required. At that point the firing could be entirely on NG. In a solid waste alliance with natural gas (SWANG) an additional option becomes available when the solid waste comes from a recycling community. Then the utility might prepare and store high energy plastics for increased use during times of high electricity demand as a means of following peak loads without calling upon the full use of NG.

E) A TT for Liqu id Fuel Production Pyrolysis/gasification technologies followed by gas

clean-up can greatly reduce emissions of pollutants such as NOx and SOx and toxics such as mercury, arsenic etc. ATTs can treat nearly the entire organic fraction of MSW and can, in general, treat a more heterogeneous feedstock, including high energy content plastics [11]. While this paper is focused on gaseous fuel generation A TIs for liquid fuel production are closely related. Considerable research and development work are now underway on the development of distillation technologies to refme such liquid fuels for transportation applications adding a major driver for the ATT route.

It should be noted that Table 1 does not now list oil shale or tar sands in the US that could substantially increase the available "solid waste" tonnage that could be used to address our need for transportation fuel. A 2005 Rand study [ 40 ] shows that, with in-situ thermal treatment, domestic oil shales could substantially lower our oil import problem. Another route would be to convert our coal to liquid fuels, as South Africa has done for many years. A third route would involve the use of methane hydrates to produce methane for utilization in natural gas fueled vehicles.

F) Sustainability and SWEATT Japan a country with an outstanding Sustainability record

is now the global leader in the conversion of solid waste to energy by advanced thermal technologies (SWEATT). The more than 60 pyrolysis and thermal gasification systems now in operation in Japan have established the technical and environmental feasibility of these systems which should allay

the concerns of environmentalists and risk-averse utility decision makers

8. CONCLUSIONS The main conclusion of this paper is that the US has very

large sustainable supplies of now wasted solids that have an annual energy potential comparable to our current use of coal and also of natural gas. With advanced thermal technologies (A TT) this solid waste could, in the near term, multiply its contribution to our national energy supply by about a factor of 10. Robust technology that can handle municipal solid waste (MSW) or refuse derived fuel (RDF) should also be able to handle agricultural and forestry residues, two of the major SW supply components listed in Table I as well as many of the other materials in the list. Conservation and SWEATT could be the only realistic path to Zero Waste.

Recapitulating the main conclusions of this study are: • The U.S. is excessively reliant on imported oil (60% ) for

its liquid fuels • The US is increasingly reliant on imported natural gas fuel

(now >15%). • The U.S. is well endowed with solid fuels: wasted solids,

coal and oil shale. • The organic matter in SW can be converted into more

useful gaseous or liquid fuels • In most cases A TT provides the fastest and most efficient

conversion method. • SWEATT have lower emissions than combustion waste to

energy systems. • Thermal conversion of solid fuels to gaseous and liquids

fuels has a long history • Utilities are used to high temperatures in the production of

steam. • ATTs (PABC, POBC and PYRO) are extensions of high

temperature steam making. • Conversion to gaseous fuels is essential for SW powering

of fuel cells. • There are many environmental benefits attendant to

SWEATT. • Many areas of engineering research will be needed to

optimize SWEATT. • Co-operation of stakeholders would accelerate the

implementation of ATT. • Conservation and SWEATT together is the fastest realistic

path to Zero Waste.

9. ACKNOWLEDGEMENT This work was supported by Green Liquids and Gas

Technologies Inc.

10. REFERENCES (1] Green, A., ed. (1981), An Alternative to Oil, Burning Coal

with Gas, Univ. Presses of Florida, Gainesville FL. [2] Green, A., et aI., (1986), "Coal-Water-Gas, An All

American Fuel for Oil Boilers," Proc. of the Eleventh Intern. Conf. on Slurry Technology, Hilton Head, Sc.

[3] Green, A., ed . . , (1991), "Solid Fuel Conversion for the Transportation Sector" FACT-Vol 12 ASME New York NY. Proc. of special session at International Joint Power Generation Conference San Diego

155

[4] Green, A., 2002, "A Green Alliance of Biomass and Coal (GABC)," Appendix F, National Coal Council report May 2002: Proc. 27th Clearwater Conference, March 2003.

[5] Green, A., Hughes, E., (EPRl) and Kandiyoti, R., (Imperial College London) conference organizers, (2004), Proceedings of the First International Conference on Co-utilization of Domestic Fuels, Vol 24, 3, the International Journal of Power and Energy Systems.

[6] Green A.and J Feng , (2003) A Green Alliance of Biomass and Natural Gas for a Utility Services Total Emission Reduction (GANGBUSTER), Final report to School of Natural Resources and the Environment.

[7] A. Green, W. Smith, A Hermansen-Baez, A Hodges, 1. Feng, D. Rockwood, M. Langholtz, F. Najafi and U. Toros, Multidisciplinary Academic Demonstration of a Biomass Alliance with Natural Gas (MADBANG) (2004) Proceedings of the International Conference on Engineering Education, University of Florida, Conference Center, Gainesville, Florida October

[8] Green A., Klausner J, Li Yi A Green Alliance of Natural Gas, Biomass and Utility Desalination Proc 29th Intern. Conf. on Coal Technology, Clearwater Florida, April 2004

[9] Green A., Swansong G. and Najafi F.(2004) Co-utilization of Domestic Fuels Biomass GaslNatural Gas, GT2004-54194, IGTI meeting in Vienna June 14-17.

[10] Green A.and J Feng , (2005) Assessment of Technologies for Biomass Conversion to Electricity at the Wildland Urban Interface Proceedings of ASME Turbo Expo 2005: Reno-Tahoe

[11] California Integrated Waste Management Board, (2005) Conversion Technologies Report to the Legislature, Draft, http://www.ciwmb.ca.gov/Organics/ConversioniEven tsl

[12] Energy Information Administration, (2006) January 2006 Monthly Energy Review , Office of Energy Markets and End Use,U.S. Department of Energy, DOE/EIA-0035(2006/01), Washington D.C., http://www.eia.doe.gov/emeuimer/contents.htrnl

[13] Perlack, R., Stokes, B., Erbach, D., (2005) Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply, Oak Ridge National Laboratory, ORNLlTM-2005166, U.S. Dept. of Energy

[14] Stultz, S., Kitto, 1., ed., (1992), Babcock & Wilcox, Steam 40th Edition, Barberton, OH, Chapter 37 Equipment Specification, Economics and Evaluation.

[15] A. Green, S. Peres, J. Mullin, and H. Xue, Co-gasification of Domestic Fuels, Proc.lJPGc. Minneapolis MN, ASME-NY, NY(1996).

[16] A. Green, M. Zanardi, J. Mullin, Biomass & Bioenergy, 13(1997) 15-24.

[17] A. Green, M. Zanardi, Inti Jour. Quantum Chemistry, 66 (1998) 219-227.

[18] A. Green, J. Mullin, Journal of Engineering for Gas Turbines and Power, 121 (1999) 1-7.

[19] A. Green, J. Mullin, G. Schaefer, N.A, Chancy, W. Zhang, Life support applications of TCM-FC Technology, 31 st ICES Conference, Orlando, FL, July, 2001.

[20] A. Green, P. Venkatachalam, M.S. Sankar, Feedstock Blending of Domestic Fuels in Gasifier/Liquifiers, TURBO EXPO 2001, Amsterdam, GT,- 2001.

Copyright © 2006 by ASME

[21] A. Green, R. Chaube, Pyrolysis Systematics for Co­utilization Applications. TURBO EXPO 2003, June 2003. Atlanta, GA, 2003.

[22] A. Green, R. A Chaube, IntI. Jour. Power and Energy Systems, 24(3) (2004) 215-223.

[23] A. Green, S. M. Sadrameli, "Analytical Represntations of experimental polyethylene Pyrolysis yields", Jour. of Analytical and Applied Pyrolysis, 72 (2004) 329-335.

[24] S. Sadrameli, A. Green, Jour. of Analytical and Applied Pyrolysis, 73,(2005) 305-313.

[25] Green, A., Feng, J., (2006), Systematics of Com Stover Pyrolysis Yields and Comparisons of Analytical and

Kinetic [26] Feng, 1., Green, A., (2006) Peat Pyrolysis and the

Analytical Semi-emperical Model, 1. Energy Sources, (in press), ESO/051103.

[27] Feng, J., YuHong, Q., Green, A., (2006), Analytical Model of Com Cob Pyroprobe-FTIR Data, J. Biomass and Bioenergy, (in press).

[28] Gaur, S., Reed, T., 1998, Thermal Data/or Natural and Synthetic Fuels, Marcel Dekker, New York, NY

[30] Xu, W. C., and Tomita, A., (1987), Effects of temperature on the flash Pyrolysis of various coals, Fuel, Vol. 66. pp. 632-636.

[31] Xu, W. C., and Tomita, A., (1987) Effects of coal type on the flash pyrolysis of various coals, Fuel, Vol. 66, pp. 627-631.

[32] Mastral, F. 1., Esperanza, E., Garcia, P., Juste, M.,(2002) ,J. Anal. Appl. Pyrolysis, Vol. 63, pp. 1-15.

[33] Mastral, F. J., Esperanza, E., Berruco, C., Juste, M., (2003), 1. Analy. Appl. Pyrolysis, Vol. 70, pp. 1-17,

[34] Liscinsky, D., Robson, R., Foyt, A., Sangiovanni, J., Tuthill, R., and Swanson, M., (2003), Advanced Technology Biomass-Fueled Combined Cycle, Proc. ASME Turbo Expo 2003, Power for Land, Sea and Air, Atlanta, GA, USA, GT2003-38295,

[35] Phillips, B., and Hassett, S., (2003), Technical and Economic Evaluation of a 79 MWe (Emery) Biomass IGCC, Gasification Technologies Conf., San Francisco, CA,

[36] Antares Group, Inc., (2003), Assessment of Power Production at Rural Utilities Using Forest Thinnings and Commercially Available Biomass Power Technologies. Landover, MD, Sept.

[37] Ian F. Roth, Lawrence L. Ambs (2004), Incorporation externalities into a full cost approach to electric power generation life-cycle costing, Energy Vol29 12-15 P2125-2144

[38] Rosenberg, W., Walker, M., and Alpern, D, 2005, . "National Gas Strategy", a publication of the

Kennedy School of Government, Harvard University, Cambridge MA.

[39] Pimentel, D., and Patzek, T. W., (2005), J. Natural Resources Research, Vol. 14:1, pp. 65-76.

[40] Bartis, 1., LaTourrette, T., et aI., (2005) Oil shale development in the United States: prospects and policy issues, RAND corp. ISE division, National Energy Technology Laboratory, US DoE, Pittsburgh, PA

Copyright © 2006 by ASME 156

NOMENCLATURE

WEC

SW

ASEM

Waste to Energy Conversion

Solid Waste

Analytical Semi-Empirical Model

SWEATT Solid Wast

.e To Energy By Advanced Thermal

Technologies

ATT Advanced Thermal Technologies

DANSF Dry Ash, N itrogen And Sulfur Free

ACE Analytical Cost Estimation EU European Union TPES Total Primary Energy Supply BTU quads OFC CCTL SES PES TES QES MSW ICE GT HRSG NGCC CHP ABPC OBPC PYRO RDF PNA Ar VT FC HHV XT NPHR SWCC AGIR BIG CC IC Co CoSt FWHR

British Thermal Units Quadrillion BTUs Omnivorous Feedstock Converter Clean Combustion Technologies Laboratory Secondary Energy Supplies Primary Energy Supplies Tertiary Energy Supply Quaternary Energy Supply Municipal Solid Waste Internal Combustion Engines Gas Turbines Heat Recovery Steam Generator Natural Gas-Fired Combined Cycle Combined Heat And Power Air Blown Partial Combustion Oxygen Blown Partial Combustion Pyrolysis Systems Refuse Derived Fuels Polynuclear Aromatics Aromatics Volatiles Fixed Carbon Higher Heating Values Xu and Tomita Net Plant Heat Rate Solid Waste Combined Cycle Antares Group Inc. Report Biomass Integrated Gasifier Combined Cycle Internal Combustion Cofiring Coal-Steam Boiler Feedwater Heat Recovery

SFST Stoker Fire Boiler Steam Turbine CIE Compressed Ignition Engines SWANG Solid Waste Alliance with Natural Gas

1 57

Waste Type 1 . Agricultural residues

2. Forest under-story and forestry residues

3 . Hurricane debris

4. Construction and deconstruction debris

5 . Refuse derived fuels

6. Urban yard waste

7. Food serving and food processing waste

8. Used newspaper and paper towels

9. Used tires

1 0. Energy crops on under-utilized lands

1 1 . Ethanol production waste

1 2 . Anaerobic digestion waste

1 3 . Bio-oil production waste

1 4. Waste plastics

1 5 .Infested trees, (beetles, canker, spores)

1 6.Invasive species (cogon-grass, melaluca .. )

1 7. Plastics mined when restoring landfills 1 8 . *Bio-solids (dried pelletized sewage

sludge)

1 9. *Poultry and pig farm waste

20. *Water plant-remediators (algae, hydrilla .. )

Mill ion Dry Tons

-0.98

-0.40

-0.04

-0.02

-0. 1 0

-0.02

-0 .07

-0.02

-0.05

-0.05

-0.02

-0 .Q l

-0.0 1

-0.03

-0.02

-0.02

-0.03

-0.04

-0.02

-0.01

2 1 . *Muck pumped to shore to remediate lakes -0.0 1

22. Manure from cattle feed lots -0.0 1

23. Plants for phyto-remediation of toxic sites -0.01

24. Treated woodp_ast its useful life -0.01 - 2 billion

TOTAL dry tons

TABLE 1 : WASTED SOLI DS THAT COULD BE USED AS A COMPONENT OF U.S.'S PRIMARY ENERGY SUPPLY. ITEMS MARKED WITH · HELP IN WATER REMEDIATION AND THE - DENOTES ESTIMATED VALUES

Copyright © 2006 by ASME

Table 2A: Proximate and U ltimate Analyses

Proximate Analysis U ltimate Analysis

Name %VM %Liq FC Ash C% H % 0 %

Bagasse 59.2 9.8 20 1 1 45.7 1 5.89 40.37 Elephant grass 72 0.35 19 8.65 44.58 5.35 39. 1 8

Pine bark 55 1 0.5 34 0.5 56.3 5.6 37.7 Bond paper 6 1 .93 18.7 8.4 1 1 41.2 5.5 4 1 .9 Newsprint 56.66 25.5 1 5.4 2.4 49. 14 6. 1 43.03

Coal 22.02 1 3.6 57.2 7.2 76.9 5.1 6.9 Wood pellets 61.34 23. 1 15 0.5 47.84 5.8 45.76

Polyolefin 56.58 42.4 1 0 85.7 14.3 0 PETG 5 1 .8 43.7 4.5 0 62.5 4.2 33.3

Tire rubber 2 1 .96 35.6 35.8 6.6 79.1 6.8 5.9

Table 2 B : Mass Percentages at t OOO°C

N ame R2 CO CH4 CO2 C 2 H 2 C2H4 C2H6

Bagasse 1 .26 28.92 5.75 1 8.66 0.32 3.72 0.37 Elephant grass 1 .48 3 1 .84 7.64 24.66 0.38 5. 1 0.65

Pine bark 1 .62 29.58 5.38 1 5.22 0.37 2.56 0. 1 2 Bond paper 1.56 27.4 1 5.59 23.42 0.36 3.34 0.25 Newsprint 1 .3 29.25 5.93 16. 1 9 0.6 3.24 0. 1 5

Coal 1 .26 8.74 6.48 3.48 0. 1 9 1 .63 0.22 Wood pellets 1 .37 33.29 6.52 1 5.96 0.5 1 3.44 0.25

Polyolefin l . l 7 4.72 16.09 6.0 1 0.76 25.39 2.44 PETG 0.64 15.52 4.63 29.06 0.2 1.7 0.06

Tire rubber 1 .32 2.07 1 1 .26 1 .33 0.61 4.97 0.4

TABLE 2: CCTL MEASURED PROXIMATE, ULTIMATE, AND MASS YIELDS OF SOLID WASTE AT 1 000oC, ADAPTED FROM [1 7].

Copyright © 2006 by ASME 1 58

Families a b c

paraffins J 2a+2 0

olefins j+ 1 2a 0 acetylenes j+ 1 2a-2 0 aromatics 5+j 4+2j 0 polynuclear 6+4j 6+2j 0 aldehydes j+ 1 2a 1 carbonyls j 2a I alcohols j 2a+2 1 ethers j+ l 2a+2 1 phenols 5+j 4+2j 1

formic acids j 2a 2

guaiacols 6+i 6+2i 2 syringols 1 7+j 8+2j 3 syringols 2 8+j 1 O+2j 4 sugars 1 4+j 1 0 5 sugars 2 5+j 1 0+2j 5

TABLE 3: ORGANIZATION OF FUNCTIONAL GROUPS BY FAMILY. A, B, AND C ARE THE SUBSCRIPTS IN CAHBOc, WHERE J=1 , 2, 3 . . .

AGIR COE = Ko +K/p I/2 + S] COF /p1i4

Centslkwh Cents/kwh BTUlkwh MW Technology Ko K] S I P (MW)

BIG CCsyn -2.82 45.2 3.5 1 1 0, 15, 25

BIG SCSyn 0.33 34. 1 2.06 2, 1 0, 15

BIG ICsyn 3 .74 1 6.4 2 .06 2, 1 0, 15

Solid Fuel Co firing 1 .27 1 .9 2 . 1 7 2 , 10, 1 5 Gasification Co firing 2.02 7. 1 2.34 2, 10, 15 FWHR 0.29 1 0.7 2 .38 3 . 1 3 .20 SBST -4.44 39. 1 4.5 0.7, 1 0, 15 CHP -26.6 48 7 .41 0.5, 4, 6

25 MW 1 00 MW

Cents/kwh BTU/kwh Cents/kwh BTU/kwh K S K S

6.22 1 . 66 1 .70 1 .44 7 . 1 5 1 . 08 3 .74 0.94 7.02 1 .08 5 .38 0.94

1 .65 1 . 1 4 1 .46 0 .99

3.44 1 .23 2 .73 1 .07 2 .43 1 .20 1 .36 1 .04 3 .38 2 .39 -0.53 2.08

- 1 7.00 4.50 -2 1 .80 3 .92

TABLE 4: ACE PARAMETERS FOR VARIOUS TECHNOLOGIES, WHERE COST OF ENERGY (COE) IS MEASURED IN CENTS/KWH AND THE COST OF FUEL (COF) IS MEASURED IN $/MMBTU. THE K AND S PARAMETERS EXTRAPOLATED TO THE 25 AND 1 00 MW POWER LEVELS (P) ARE SHOWN. ADAPTED FROM [ ] .

159 Copyright © 2006 by ASME

SdidWcae (9IV) Rfu!e [shed FUel (REf)

9ares:s NatLIa GaS Ebsdids O:xal

(see T;tie 1)

�� - J Ncturai Gas

• Conti ned

�v----Processor

I GaSficaticn Agerts I Cycle CatGtysts

Absatert- Reactcrrts Ar, 9:elrn, 0" mi, Nnll3 Gas

.. I Gererator r--� � Gas nltine

Gasifierr.-�oIyzer Gas ... -OearrUp

-V J Generator r--Heat RocCJllay

Uqlifier Steam Gene-aar

o-ROO) I

3ecmTLItine f-rl Fi tte--Dsti lIer I ., Products

�ociaty UqJid Activated Corboll I 8ectricity I Crenicas Fuas Coke, Astl

FIGURE 1 : DIAGRAM OF THE OMNIVOROUS FEEDSTOCK CONVERTER (OFC) ILLUSTRATING THE ADDITION OF A SOLID WASTE SYSTEM TO AN EXISTING NGCC PLANT TO CREATE AN EFFECTIVE SWCC SYSTEM.

Copyright © 2006 by ASME 1 60

U SA Energy Consumption Renewables

3

n �

2.5 Biomass -

Solid Waste 2 2.8

1 .5 -� Hydroelectric I

2.8 lGeothermal1 0.35 r- -

IWind Energyl 0 14

r- -

Isolar Energy

n r""l 0.06 0.5

o 2005

FIGURE 2: (LEFT) TOTAL 2005 ANNUAL USA ENERGY CONSUMPTION OF PRIMARY ENERGY SOURCES IN QUADS (RIGHT) RENEWABLES. NOTE: DATA FROM NOVEMBER AND DECEMBER 2005 WAS ESTIMATED FROM 2004 DATA.

1 6 1 Copyright © 2006 by ASME

o 1 0 2 0 3 0 4 0 5 0 6 0 1 0 T-------------T-�----------;_----------------------------------------�--------��

P U P S C = 1 0 0 - H - O F o o d W a s t e

8 +-------------+-------------1----------------------GP------------------------------� • •

•

•• # ..

. . .. .. , H = 6 ( 1 -e x p ( -0 12 )

•

• •• • ••

. :. .. •

h v b itb s u b it b

.. I • � ••• •

'#.�.t •

• P E T G

lig n ite b le o n a r d

•

.. # •

p e a tb b a r k

H e C e •

I

:qr.rI". c a r b o a n th Iv b it b it b h v b ita s u b ita lig n it e a b r o w n p e a ta p e a tc s h e lls a Q r ic Ec ro p

C O A L S O L D M A TU R E A D U L T Y O U N G D E V E L O PING IN F A N T C O A L S

F IGURE 3A: WEIGHT PERCENTAGES OF HYDROGEN [H] VS [0] FOR 1 85 DANSF CARBONACEOUS MATERIALS (BLACK D IAMONDS) VS OXYGEN WT%. CLASSIFICATION LABELS ARE GIVEN AT THE BOTTOM SCALE AND [0] VALUES ON TOP SCALE. ADAPTED FROM [4].

40 �-- __ ·-,-------,------.-------�----�

35 +-.����-----r------�----��----�

30 +--- . . ��--���----1_------�----�

> �5 +-----_+--_.._+-�--�._----�----� ::I:

20 +-----�------�------+_�--��

n �----_+------� ��-- �L---�------� o 20 30 40

FIGURE 38: HIGHER HEATING VALUES (HHV) OF 1 85 CARBONACEOUS MATERIALS (CORRECTED TO DANSF) VS. [0]. THE SMOOTH CURVE REPRESENTS HHV= A([C]/3+[H]-[O]/8)

Copyright © 2006 by ASME

50 )

1 62

F IGURE 3C: TOTAL VOLATILE WEIGHT PERCENTAGES VS [0] FOR 1 85 DASNF CARBONACEOUS MATERIALS (SQUARES) FROM PROXIMATE ANALYSIS. THE CURVE THROUGH THE DATA POINTS SATISFIES VT =62([H]/6)([O]/25) 1/2. THE ANALYTIC F IXED CARBON (FC) IS SHOWN.

A n t h r a e ita ( 9 4 . 3 , 3 )

,J...._--1 C .. .

H 2 H 2 0 H C

C 0 2

B it u m i n o u s

!l:OO liOO

C O

H e _...j..---"'t C H "

C 0 2 H 2

l ODI) 1 200

2 S +---____ +-______ +-______ +-______ +-___

C O

T . r · U +-____ +-+-______ +-___ �+_------+_---

ok---+--_.J C 0 2 10 +-��--+---����----+-------4_��

=:.::...L-----t-----tji i·O �oo fOO 1 000 12:00

FIGURE 4: WT. % YIELDS VS. TEMPERATURE ( IN 0c) FROM PYROLYSIS OF ANTHRACITE, BITUMINOUS, L IGNITE, AND WOOD WITH ([C], [H], [OJ) AS SHOWN. HC REPRESENTS C2 AND C3 GASSES, BTX, PHENOL AND CRESOL. ADAPTED FROM [ ] .

1 63 Copyright © 2006 by ASME

1 00�------------------��----------------------------------------�

75

50

25

o 400 600 800 1 000 6000 I

FIGURE 5: YIELDS VS. TEMPERATURE FOR POLYETHYLENE IN VARIOUS HYDROCARBON GROUPS. ADAPTED FROM [ ] .

COE vs COF

.:::

� r---- --�����-+-------jf------j .5 w �-r--J����----------r-� o o r-�������---'---1--�--�

-4 -2 o 2 4 6

COF in $IMMBtu 8 1 0 1 2

FIGURE 6 : COE VS. COF FOR SWCC AND NGCC AT XNG= 2, 6, 1 2 . ADAPTED FROM [ ).

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