I QUANTITATIVE ANALYSIS OF THE STABILITY OF JAPAN'S ENERGY SYSTEM by Tatsuo Oyama MIT-EL-017WP August 1986 Quantitative Analysis of the Stability of Japan's Energy System Tatsuo Oyama Graduate School of Policy Sciences Saitama University, Urawa, Sai tama Japan 338 Tel: 0488-52-2111 ext. 2748 Acknowledgements This research was initiated Researcher at the Economic when the author Institute Research was of Visiting a the Economic Planning Agency in Jap an in 1983, then was finished while he was a the Postdoctoral Fello w at the Laboratory Energy Massachusetts Institute of Technology in in June, from the U.S.A. 1985 to July, 1986. T he author would like to express his sincere thanks to Professors D avid O. Jeremy F. the Shapiro of Massachusetts Institu te Wood of the Energy Laboratory Re search Operations of Technology for Center their very Institute Research of gratefu 1 Tokyo Institute and in to Doctors M. Japan S. Ishikawa for their computational aspects of this research. Mori of of the invaluable suggestions, comments and their sincere co operation. is also at and The the Science Electronics assistance author Device with the ABSTRACT In order to measure Japan's energy system's stability under an uncertain future availability of energy resources, we built mathematical programming / economic equilibrium model based linear programming techniques. Future uncertainty as random variables with a given the economic equilibrium probability point is is upon expressed distribution, obtained by a and iterative convergent computation. Numerical experiments show an optimal energy supply-demand structure with equilibrium prices of primary energy resources the future target year, then instability probabilities of price analysis of an optimal we obtain supply stability our energy system. From solution our energy at and shadow policy is quantitatively evaluated. Key words: Mathematical Programming, Economic Equilibrium Energy System Stability Japan imports Major imported almost 90% energy resources oil, coal, and liquefied her of total are fossil natural gas fuels region countries and politically and Considering the the oil embargo of 1973-'74, it economically unstable which arose during many countries. that we will not always be able to obtain crude energy (LNG). These primary contain which as such resources are mostly imported from Middle Eastern the South Pacific energy. primary difficulties probable is amount an adequate of primary energy resources. The oil embargo by the Arab nations had and a very serious impact on our country's economic system. Therefore, whether or not we can engineering enough obtain primary energy resources to meet future demand concerns us greatly. Once we can meet our demand requirements stable. If we expected we will consider cannot, it is primary and that our unstable. final energy Under energy system is supply given constraints, we can determine whether our energy system is stable or unstable at some future 'target' period. This to measure the stability of our energy system. of Our model analysis expresses the structure our energy [11. Then supply and demand system as a network, as in Hoffman we formulate a linear programming economic in which the supply availabilities of (crude oil and coal) attempts paper are defined iterative convergent procedure is then equilibrium primary as energy random proposed economic equilibrium point. The equilibrium point optimal energy supply and demand structure in the 1 problem, resources variables. to An compute an indicates an future target year. Our mathematical programming / economic equilibrium (MP/EE) model is a mathematical an economic equilibrium programming point optimization as an optimal model that solution finds of the linear programming problem. We define the stability Probability the probability that the given of our energy system as linear programming feasible under the 'randomized' supply availability model is constraints. In addition to these stability probabilities of our energy system at the target year, distributions of prices and demand of two major primary energy resources (crude oil and obtained from the economic equilibrium solutions. quantities coal) are can also We evaluate our energy conservation policy in various demand sectors by combining shadow price analysis with the probabilistic approach. Energy Situation in Japan Japan consumed 440x101 3 kcal (454x106 kl oil equivalent) of primary energy in 1983. Annual growth rates of our total energy supply were above 11% before the 1973, Japan, but since 1973, then they have decreased. coal had the replaced largest share until by oil. The oil share attained shortly first before decreasing since then; the an first oil especially crisis' in Among fuels supplied to 1962, but its highest embargo. rapid after the second 'oil crisis' in 1979. The coal 2 'oil primary was level It decrease share then 78%, in has been occurred has been increasing slightly. Use of natural gas and LNG has increasing since we started importing LNG in 1968, and been presently their share of the market is about 6.5%. Hydro power's share about 21% in the 1950's, but it decreased to around 6% in was 1981. Nuclear power, which appeared commercially in 1960's, now obtains almost the same share as hydro power, which both coal and nuclear power consumption is 6%. We expect that will increase in the future, while oil use will decrease. Japanese industrial energy high, between 62% and 69% of industry consuming 70 - demand total has energy historically demand, 80% of the industrial first demand 'oil crisis'. In contrast, has increased steadily with share. energy demand, however, has leveled off at about 60x to 1950's, although we have seen a slight 13% to 15%). In decrease its the share future, of increase industrial total since while in 1981. since recently energy demand, the energy 25% Transportation energy demand has been almost constant heavy Industrial residential-commercial from 17% in 1960 been demand the (from should residential and commercial demand will increase. The domestic constant at around energy 5 0xlO 3 supply in Japan kcal (53x106 kl has oil equivalent) the 1950's, and it has consisted mainly of hydro power and domestic coal. Our domestic energy of the total primary energy supply, a lot countries' for Great domestic ratios, Britain, almost been power, supply less than since nuclear is about other western e.g. 85X for the United States, 49% for West Germany, 3 and 25% for 10% 48% France. Crude oil comprises around 65% consumption, which is totally of our imported total from primary foreign energy countries mostly in the Middle East and the South Pacific. The oil embargo in 1973 induced a large price crude oil from $2.51/bbl for serious effects in 1972 to $10.79/bbl both the world supply-demand system. After this economy first 'oil energy consumption has stopped increasing decreased by 4.4% from 1973 the second Furthermore, 'oil crisis', Crude oil prices $32.97/bbl in 1980. from 1979 decreased to rose Total by 3.4% during Considering events the crude oil supply crisis', a energy our primary large $13.77/bbl the price 1978 to by 10.7% consumption also Through prevailed in decreased energy 1975. from resulted second imports primary in these two 'oil our industrial on crude oil. in the last 10 years or so, we know that to our country can be greatly international political countries. which from has had Our energy system has structurally changed and no longer depends as heavily the our crisis', the same period. crises', energy conservation demand sector. and It of as rapidly. Oil imports caused Our crude oil 1980. 1974. to 1974, and 4.8% from 1974 to Iranian revolution in 1978, also increase. in increase It is probable that we will in induced by a disruption unexpected happening in these of situations oil have yet supplies countries. The influenced oil by exporting another 'oil due some crisis may to effect our energy system both physically and economically. Therefore, it would be very important for us to 4 quantitatively evaluate our energy system's stability under various levels of primary energy supply constraints. The 'stability' of our energy system is fully dependent on the possibility of importing Our energy system can be determined crude to be oil stable corresponding to whether or not we can have a and coal. unstable or sufficient supply of primary energy resources to meet our future energy demand. By defining the supply stability probability of our energy system as the probability that our mathematical has a feasible solution, the programming supply stability energy of model our energy system can be quantitatively investigated. MP/EE Energy Model Energy System and Linear Programming Model Our energy system, which involves energy flow supply regions to final demand sectors, is from illustrated network system in Figure 1. The supply sector consists divisions, including five supply and stockpile-transfer. hydro-nuclear, crude Four oil, regions, kinds coal, and transformed into petroleum products, energy of electricity and consists of four categories: city of various as of a seven domestic production, primary energy LNG-natural gas of are coal products, and secondary gas. The industry, final demand sector residential-commercial, transportation, and stockpile-transfer. A feasible future energy energy demand flow in the network under various 5 has supply to satisfy constraints, the and physical and engineering constraints. The arcs of the network correspond energy flows to unknown variables and network constraints are linear equalities on the of the model, and inequalities using those variables. Thus the problem of finding an equilibrium energy flow can be formulated as a linear programming problem. The goal is to corresponding to obtain an a desirable economic feasible equilibrium energy point flow in our mathematical programming energy model. A desirable energy flow in the network energy system of Figure 1 can be determined as a flow attaining a maximum economic surplus criterion; i.e., minimizing supply cost less demand cost. One can obtain flow by solving linear programming problems an optimal iteratively, energy until satisfying a convergence criterion. Structure of the MP/EE Energy Model In the MP/EE energy variables (xi, yj, correspond the remaining there are five kinds of endogenous wi, dij). Four kinds of them (xi,yj,Zk,WI) Zk, to energy model flows, as in the network of Figure endogenous variables (dij) indicate 1, while "flexible" demands for imported primary energies of crude oil and coal. xi, iM = (1,...,17) : primary energy transported from the supply regions and the stockpile-transfer node yj, jeN = {1,...,14) : primary energy transformed into petroleum products, coal products, or secondary 6 energy; primary energy directly consumed in demand sector kK Zk, = {1,...,28) : petroleum and coal products transformed into secondary energy or consumed in demand sector : wi, laL = {1,...,5} energy consumed secondary in final demand sector dj, = {R,L}, jJ iI = { ±1, ±2,..., ±6) variables indicating the perturbation of primary energy resources' (R:crude oil L:coal) demand from their standard demands Using the programming above variables, model are expressed constraints in the linear as follows: (1) Availability Constraints of Primary Energy Resources In the energy network of Figure 1, primary energy enter the system through supply nodes. amount The resources of primary energy at each supply node has an upper bound determined by the physical, economical or, sometimes, in the political situations supply regions. The physical availability of each primary energy resource from each supply region is given as follows: xi (1) isM. b, (2) Flow Conservation Constraints The set of nodes in the network is divided into three groups supply nodes corresponding to supply regions, demand nodes indicating demand sectors intermediate nodes. At from each p=13 to p=16, intermediate 7 node and remaining pe{1,...,12}, in-flow has to be equal Z x Z yj = z yj + iEMp jENp jENp = jENp kaKp kEKp to out-flow. Therefore, yj p=1,2,3 (2) Zk p=4,...,10 (3) p=11,12 (4) Zk = Z leLp WI (3) Upper and Lower Bounding Capacity Constraints Upper and lower bounds are given for the variables indicating production of petroleum and coal products {Zk, and consumption laL). constraints of electricity are written and city gas These as follows: LBZk Zk UBZk, kKI'CK (5) LBWIl Wi UBW1, 1EL (6) where LBZk, UBZk, LBWi and UBWi are lower {Zk) ({w, kK'CK}, and upper and ({w), respectively. K' is a proper subset constraints (5) are given for some variables of of bounds of K, hence {Zk). (4) Yield Constraints of Petroleum Products Refinery systems have their own restrictions regarding the yields of physical petroleum and engineering products. Each petroleum product has both lower and upper production bounds. yLjC yj YUjC 3s;jS6 C = xI + X2 + X4 + X7 + X + X12 + X 5 - Y2 where yLj and yuj are the lower and upper petroleum product indicated (7) bounds of the yield by yj, and C is the total entering the refineries. 8 crude of oil (5) Demand Requirement Constraints for Imported Primary Energy Resources Imports of primary energy resources are restricted by the following constraint: Z xi Dk i6Mk where J and J- + Z jaJs dkj - Z jaJ- dkj ke(R,L) (8) indicate sets of positive and negative indices of J=(±l, ±2,..., ±6), respectively. The inequality expresses the flow of left each side primary of the energy above resource from each supply region to Japan, while the right side expresses the perturbed demand of each primary from standard demand. The variable energy (dkj), with resource the the superscript k deleted, is illustrated in Figure 2, where the demand quantity De corresponds to the standard Each variable interval dkj has an demand upper Dke in bound the constraint corresponding (8). to the in Figure 2. 0 dk j k6(R,L),jJ. k jA, (9) (6) Final Energy Demand Requirement Constraints In the four demand residential-commercial, nodes corresponding transportation and to industry, stockpile-transfer, the following final energy demand requirement constraints have to be satisfied: Z jeNp yj + C keKp Zk + C leLp wi 9 Dp p=13,...,16 (10) (7) Objective Function The total supply defined cost of the energy system as the sum of fuel costs region and transporting in each supply the CIF cost. The transformation i.e., Figure transformation the fuel cost to be the cost this model, we define the resource and in 1 is costs. In of obtaining it to cost is defined Japan, the to be cost for transforming primary energy resources into petroleum and of coal products, electricity, and city gas, and consists mainly the capital fuel cost necessary for energy transformation. cost per thermal unit (1010 kcal) be ci, iM, transformation be dj, jN. The transformation is given by e, written cost per unit kcal of petroleum the let the and and coal products cost per kcal of secondary IeL. Then the total energy supply cost energy can be as follows: Z cixi + Z djyj isM jeN However, the demand total cost for meeting + cost of the energy system, energy demand, a forecast a step function g(q)dq = jEJQ (11) Z elw. lsL approximation to the area under the nonincreasing By using Let in Figure defined is given demand as as + jeJQ an curve. 2, the cost is .Pjdj (12) dj, (13) where Q = Q a 10 and J is a set contained of indices to the demand from (12) the constant of corresponding from 0 to Q, in the range corresponding {j} in demand and Pj is a the j-th in the Figure intervals commodity interval. cost corresponding the demand curve from 0 to Q following to Subtracting to the 2, price integral obtain we the sum: f(q)dq = *Go where sgn(j) indicates sgn(j) Z jJoJ sgn(j)Pjdj (14) the sign of index j (j*O), i.e., = 1 if j>0 if j<O. -1 Thus adding (12) for each iI={R,L), our objective function can be given as follows: Minimize Z cixi ieM + jeN djyj + leL ewi - Z . sgn(j)Pjdij. i IjJ The negative of the above objective function can be (15) interpreted as maximizing the demand cost less supply cost, while meeting the future energy demand requirements. Hence the optimization problem corresponds to finding the economic equilibrium point economic surplus. 11 maximizing The probabilistic aspects of our energy model are as follows: many energy supplying countries are somewhat politically and economically availabilities to the unstable. Hence, right hand side values bi in denoted by b q, distributions bin, and which correspond random variables. availability of some and parameters the random lower bounds are are integers b variable has p the densityfunction: (b-bm) f(b) upper whose Then supply overseas supply region to Japan whose and respectively. followingprobability are bound of the total primary energy resources from the follow beta (1) that assume of the primary energy resources Suppose that the upper and we P = - (b-b) q- 1 bm , K where K is a constant. When parameters b p and q are b integers, (16) K is given by K(p))r(q) r(p+q) =(bM-bm)P+q- t (p+q-1) t 12 (17) where r(-) is a Gamma function co r(p) Suppose e-xxP = parameters - ldx. p>l and q>1, then p and q satisfy variable b has the following mean , variance 2, the and mode m. bmq-+bp A = random (18a) p + q C2 pq(bM - bm) (p+q) 2 2 (p+q-1) 2 (18c) bm(q-l) + b(p-l) m= (18c) p+q-2 Computational Method Our energy formulated model described in a vector-matrix to form as follows: (19) A2x = b2 (20b) A3X 2 b3 + Kd (20c) d (20d) 5 b4 > (20e) 0 where the unknown variable yj, be (20a) x, (xi, can Aix : bi d variables section cx - pd Minimize subject in the previous vectors Zk, Wi) and (dij), 13 x and d consist respectively. Here, of the p and d are price and commodity vectors, whose elements are given by and sgn(j)d'j (20c) are in (14), respectively. the resource Constraints availability (20a), constraints, Pj (20b) and balancing equations and demand requirement constraints, respectively. (20d) indicates the variables (dk j ). bounding constraints in (9) for the demand We define our resource supply cost minimization submodel as follows: csxs Minimize subject to A s ix (21) s bsi (22a) AS2Xs = bS2 (2 2b) AS3Xs (2 2c) L bS3 (2 2d) Xs a 0 A 5 i, where bSi submatrices and cS i=1,2,3, subvectors of the c and x in the original i=1,2,3, by (19)-(20). imply for that The our submatrices resource and xs are, corresponding respecti vely, Ai, b; for linear programming problem given and supply subvectors submodel described consists components related to crude oil and coal only, above of the than the soluti on, for rather whole supply model. Let the th e shadow price, demand resource requirement ie I be i.e., the optimal dual constraint r'i. Then the (22c) equil i brating of primary condition energy for our MP/EE energ:y model can be written as follows: w'i = gi(Di' + - Z d'j jEJ+ 14 Z d i 'j) jeJ - (23) where gi indicates the i-th component of the demand g(q), corresponding to the primary energy resource iI. function Die and di'j indicate the standard energy demand for the resource iIl and an optimal solution for the demand variable dj, respec tively. The optimization problem given by (19)-(20) surplus maximization problem. A general problem cannot always be transformed into maximization problem. the In order possible, the demand function e.g. Hurwicz [153). demand function has for to be the an economic equilibrium economic surplus transformation be i.e., to integrable Jacobian symmetric, an market g(q) needs to Therefore, is matrix the be (see of cross the price elasticities between two different commodities must be symmetric. In our energy model, cross price elasticities commodities were assumed between different to be zero, and thus our Jacobian matrix is symmetric. Let us look at a computational economic equilibrium point in procedure our energy for obtaining model. Firstly, sequence of random numbers with a beta distribution (beta assigned and to the corresponding by (1). Then the linear each pair of these numbers right side in the constraints programming solved to obtain an optimal energy economic flow equilibrium meeting demand. The computational method in our MP/EE model a random numbers) are generated. Two sequences of beta random numbers generated simultaneously, an are is given model is future energy analysis is presented in the flow chart of Figure 3. Solving our MP/EE energy 15 a is model iteratively part principal algorithm are given details of the solution our of in Figure 4. The correcting process at the t-th iteration, given energy prices pt and supply costs c, 1 pt+I 2 = C Cst+l + ('t + The analysis. primary as follows: is written t) (24) Cst (25) where AcSt = A(*Ot - cS), 0 A 1. (26) of this iterativ e computation The convergence is attained when the shadow price of each primary energy resource of crude oil and coal equals that corresponding obtained to optimal the from approximate demand curve commodi ty demand. Numerical Results Assumptions and Input Data We define the year 1983 as the base year, and then the year 1990 as our future target. average annual growth rates of final energy we Firstly, demand look assume between base year and the target year are 2.0%, 3.0%, 2.0% and industry, residential commercial, transportation transfer, respectively. Final energy demands given in Table 1. Supplies of primary energy 16 and 2.0% at that the for stockpile- in 1983 and 1990 are resources in the base year and the target year are shown Table, Other Middle East Region denotes Table in 2. In Middle o il-exporting the the East countries excluding Saudi Arabia, i.the. U,Iran, Iraq, Bahrein, U nited Kuwait, Neutral Region, Qatar, Oman and the The South Region consists mainly of such as Indonesia, crude oil includes and Nigeria. Algeria The The Region Other Other coal- exporting countries for such countries oil-exporting African Pacific Southern Brunei and A ustralia. Arab Emirates. as incl udes Region South Africa, China, and Soviet Union. Upper bound availabilities of primary 1990 are estimated from the Middle East import In estimating upper bound upper based is of 4.0% between increase 1990. as follows. The resources energy upon for an for coal 1 year target from import oil an nua average se year 1983 and the bounds crude in the Southern Region, North-South America and Other Region, an ave:rage annual increase Estimates 4.0% is assumed. from the Other Middle East Region, crude oil and LNG North-South America Region, crude oil the Other all based on the average annual LNG from the Reg ion, gas and stockpile-transfer crude oil, coal, natural domestic from of supplies for increase 1983 to 1990. The upper bound availability are 2.0 - 4.0% from of hydro-nuclear p ower rates is estimated according to an average annual increase of 4.0 - 5.0 % from the base year. CIF prices of primary energy resources from regions in 1983 in Table 3. and their estimates Crude oil prices for the year 1990 in 1983 indicate 17 various are 'average' su pply g iven pr ices in oil-exporting countries in the region. For example, the oil price in Saudi Arabia is that of Arabian light, price in Other Middle East Region is based Emirates Murban. Prices in the on Southern the Blend, from 1983 data by assuming an average annual except that the increase oil Arab North-South Indonesian Sumatra respectively. Crude oil price estimates for the target year 1990 4.0%, the United Region, America Region and Other Region are those of Light, Mexican Isthmus and Algerian Sahara and crude are price obtained increase rate is 5.0% for Other as Middle East Region. Coal prices material in 1983 are the weighted mean of steam coal from each supply region. Coal prices Region and North-South America Australian and the Region's coal price United is Region States, the weighted are based annual Natural gas and LNG prices mean of increase South Region, and Alaskan for on coal South of Other African, prices in of 5.0% from 1983. and North-South and those The South in 1983 are those LNG for the Middle East Region, Brunei the respectively. Chinese and Russian coals. Estimates for future 1990 are based on an average in coal of Abu Indonesian America Dhabi for the Region. LNG price estimates for the target year 1990 are obtained from 1983 data by assuming an average annual increase of 4.0x. Transformation costs for petroleum products, coal and secondary energy (electricity and Table 4. Costs for fuel oil, city kerosine-gas naphtha are weighted means minus fuel costs. 18 products, gas) are given in oil, and gasoline- The other petroleum products' transformation cost is basically the LPG price, and the coke transformation cost is the coke price minus coal price. Electricity transformation costs for the material both industry and transportation are the capital costs in the electricity for industry, and those for residential-commercial capital costs in the rate for residences. costs are the capital costs in the are rate also the City gas transformation industrial and residential- commercial city gas rates. Upper and lower bounds respect to variables for constraints (5) and wi, are presented Zk Lower bounds for petroleum those whose consumption and coal products is relatively small, and (6) in Tables 5 and 6. are either the consumption 0.0 for or the amount of the base year's consumption when they are large. The upper either with of the base year or a 50% bound increase added when they are relatively small. The average annual increase is assumed from 1983 to large. Lower bounds 1990 for for those electricity whose and 4.0% consumption city gas is is are the consumption in the base year. Upper bounds are obtained from the base year's consumption by assuming an average annual increase of 5.0%. The upper and lower bounds for given in Table 7 are based petroleum on the assumptions products' that yields demand for light petroleum products such as kerosine, gas oil, gasoline naphtha will increase in the future, while demand for and heavy petroleum products such as heavy fuel oil will decrease. The main sources of Japanese 19 energy data used in our model analysis are Energy Statistics [23], Handbook of Industry [7], Industrial Statistics Statistics and bm and b the for maximum, estimates for the future Parameters [24], and Power Petroleum [8]. Parameters minimum Table Electric the availability future distribution respectively, p and q are determined equal to the expected beta indicating of crude oil extreme and coal. so that mean values are availability of these the are nearly resources. These parameters are presented in Table 8. Beta random numbers are generated by transformation method to uniformly applying distributed the inverse random numbers. Random numbers following uniform distribution between 0 and 1 are generated by using the square method. random number generation, see e.g. (For more Fishman information [93, Bratley, et on al [3].) Approximate demand curves for imported crude are based upon their price elasticity own and cross price oil elastic ity ij, i,je{R:crude oil, L:coal), and coal The data. represents the decrease (%) of commodity i's demand corresponding to a unit commodity j's price increase. According analysis in Oyama [22], own and cross primary energy resources in 1980 are 0.69, LL=-0. 7 4 . Hence that in Japan crude of RL price ERR=-0.07, oil is rather price and the translog e are substitutes ERL=O.04 , LR. 20 can insensitiv e compared each mlode1 lasticitie: from the above data on s;j 's we coal, and these resources positivity to of o ther from of L R= say with the An Optimal Energy Supply and Demand Structure We wrote a FORTRAN computer program model. to our analyze The program consists of nearly 3800 statements, which (around 80X) comprise the product form simplex solving the linear programming problem. histgrams and (including 17 xi's, 14 yj's, 28 Zk'S, variables) and 51 a second output 5 contains of CPU time on requiring about 140 pivots if for random formatting 121 we variables dij's and 33 (excluding bounding is obtained for each iteration IBM 3033 compu ter system, start from phase of the simplex technique. In order to 24 wi'S, constraints constraints). An optimal solution within method of and so on. The linear programming MP/EE model slack most Others relate to number generation, iterative procedures, for figures, MP/EE obtain an 1 the eq ui 1 ibrium economic point for each pair of resource availability constraints , necessary to solve 4 - 6 linear programming problems ternating al between the MP/EE energy model and the supply submode 1 Since the latter model Hence, solving is rather simple the MP/EE energy model time. We generated it problems. it can be sol ved quickly. takes up most 250 pairs of beta random numbers. of the So, a CPU total of 250 cases of these economic equilibrium problems are solved about is in 12 CPU minutes by the IBM 3033 system. An optimal Tables solution 9 and 10. Total and 72.016x101 3 for one of these 250 cases is import availabilities kcal for crude oil and coal, shown are 266.137x10 respectively. 1 3 in kcal The obtained economic equilibrium point implies an optimal supply and 21 resource supply total primary energy be 483.6 7 x10' demand structure under the given primary energy constraints. As presented supply to Japan in in Tables 1990 9 and 10, the is expected I equivalent), (5 14.54 xl 0 6 kl oil from 1983 to 1990. in crease a 22% 1990 ar e while those shares coal and hy dro-nuclear should increase by around 3%, crude consumes oi 1 will be unchanged. al 1 the available t hat are role in meeting Equilibrium pric es of crude oil and Yen/10 4 kcal and iterations. The se equilibrium Yen/104 kcal, and coal the Japan I n m odel 's and energy are given respectively, for that th at first, chosen LNG-natural gas plays a marginal 24.99 wh ile implies from cost criteria crude oil and coal 1983 in crude oil and coal supplies. MP/EE model we can recognize structure The solution gas 59.4%, The sh are s were 59.2%, 18.9%, 8.2% and 13.7%, respectively. of kcal LNG-natura 1 in Japan in the year 3.1% and 15.5%, respectively, 3 during seven years coal, Shares of crude oil, and hydro-n uclear supplies 22.0%, to our then demand. by 69.38 six after prices show that crude oil prices rise around 44% from 1983 to 1990, while coal prices go up by 26% during the same period. In the year 1990, production ratios of fuel oil, kerosine- gas oil, naphtha-gasoline and other petroleum products are 43.6%, 19.7%, 24.1% and 12.6%, respectively. that principal heavy volume of our refinery fuel oil to light gasoline that our refinery From the solution output and kerosine. system will be adjusted 22 is know changing Thus, to meet we a we from expect demand for more light petroleum products and less heavy in ones the near future. We can also see consumption of secondary energy of electricity and city gas increases about 40% from 1983 to 1990. especially in These our shadow constraints (10), we has a and that prices for that shadow price and will play major energy the demand industrial transportation shadow prices transportation than the demand industrial former demand sectors consume in the the constraints The expensive demand and demand This (electricity and city gas) than the latter. tell us that energy conservation energy residential- constraints one. more requirement Yen/lO04 kcal 59.51 4 kcal. both have shadow prices of 90.45 Yen/lO0 commercial and roles commercial demand sectors. note residential- commercial results energy resources residential Looking at constraint from have is higher because energy the resources These shadow prices residential-commercial demand sector is almost 50% more effective than that in industry, from the point of total energy system cost reduction. Let us look at shadow prices constraints given by (1). constraint of the decrease corresponding to a unit supply availability. the The shadow price imported interpreted as the for resource of the increase We know that from formula: 23 7r (104 region kcal) shadow the ieM supply can function of price supply availability for objective resource availability constraint for the given by the following supply the 7i region be value resource from the iM is xi = + (EP - CSi) + CT, isM. In the above formula, which holds for resource, 7a indicates the shadow (27) each primary energy for domestic energy price production constraint (i.e., the price for the stockpile-transfer constraint is equal to The ,W). value Yen/10 4 kcal for crude oil and 59.505 Yen/10 an equilibrium price of the primary 4 of energy of primary energy constant respectively. resource term given CSi 57.495 resources EP is obtained Yen/104 kcal 24.992 is the respective from each supply region for each primary energy 1.216 Yen/l0 4 kcal and 0.0 Yen/10 4 kcal for is kcal for coal. from the model, i.e., 69.379 Yen/104 kcal and for crude oil and coal, xn ieM. resource, crude cost CT is that oil and a is, coal, respectively. As mentioned as a "benefit" before, the shadow price obtained from increasing resource availability by a unit amount (104 can conclude that a unit amount (104 oil or coal availability i can be the kcal). interpreted corresponding Therefore kcal) of increase can basically produce The why coal is a little more beneficial than crude oil is directly latter needs to be transformed to the demand to other types petroleum products, electricity and city gas. 24 crude a benefit of Yen or 59.5 Yen, respectively, to our energy system. former can be transfered of we 57.5 reason that the sector, while the of energy, i.e., Stability Probability and EquiliIbrium Prices As shown in Figure 3, we N(=250) so lved our MP/EE model for cases. For some combinations of beta random numbers the model may be infeasible insufficient since either crude oil or coal supplies be pair of to meet our future final energy demand. Figure 5 shows model feasibility results for beta may random numbers. In Figure 5, the each vertical coordi nate indicates the availability of imported coal, while the horizo ntal coordinate indicates the availability of imported crude oil. For each combination of these energy resources' availability, an F or I indicates whether Let the number Ni. Then we define energy the model is feasible of infeasible or infeasible. cases among total the "supply stability N probability" system by the ratio of the feasible cases cases be (Ps) of our to the t otal number of cases. Ps = N - Ni (28) N Our energy probability system can be understood Ps and "unstable" with Ps and 1-Ps as stability and to be "stable" the probability instability with 1-Ps. We probabilities the call of our energy system, respectively. Our numerical experiments show that the stability instability probabilities of Japan's energy system in the year 1990 can be presented as follows: 25 and target 205 45 1-Ps = = 0.82, = Ps 250 We should consider that an extremely probability the instability difficult of 0.18 unless - = 0.18. 250 probability situation our (29) energy implication as an may occur system with the structurally is changed. An infeasibility result may be changed into a "feasible" case by adding more infrastructure to our energy sy stem, transforming our energy system into a more flexible one it can meet variable final energy by demands or so by that promoting substitution among primary and secondary energy reso urces. Let us examine objective function the 'stable' values for cases these in more detail. cas es (N-NI) The have the frequency distribution shown in Figure 6. This distr ibution shows rather higher This frequencies in the lower part of the cost is because the objective function value is dominated cost of crude.oil, so if crude oil is abundant low, the objective function value imported crude oil availability is rather and its range. by price 'stable', of crude oil prices The above availability upper the argument has a distribution range, so its price lower range, as also be with its peak Figure 26 8. Coal is a cases. applied will be distributed in if is low, its price goes up rapidly in the feasible can is but and objective function value becomes much higher. Figure 7 histgram the to coal. frequency with has its in peak higher Coal the in own price elasticities than crude oil, that availability solution, of imported the amount of crude coal oil used is, dominates is Since IELLI>IRRI. the subject to optimal crude availability. Furthermore since the own price elasticity of is rather large, the price extremity, thus splitting prices, of coal can the frequency quickly to distribution coal either of coal as in Figure 8. Figure 9 is obtained in Figure 5 with the crude oil and coal. by combining equilibrium into nine parts equilibrium the prices' feasibility results The figure first divides into feasible and infeasible divided move oil areas. depending prices PR and PL. Then on of crude this imported whole the feasible the Note that the results region region oil and division is coal of the feasible region is not very accurate, since the equilibrium price of each primary energy resource can vary depending on the availability of the other. However, this partitioning supply helps us to know approximately how much each energy resource's equilibrium price will be changed by the degrees of supply availability. Summary During the years following the Arab oil embargo of 1973, there have been many energy policy debates throughout the world, including Japan. Energy policy debates concern various technical, environmental, social, economical, political problems. Energy policy modeling efforts have 27 and even increased military due to not only the necessity of such interdisciplinary also the greater availability of Hoffman [11 supply-demand proposed energy high energy network problems, approaches have been developed. [19, 20, 21], Modiano computers. systems various (See e.g. Manne, et al [17] for energy models. Oyama speed Also and Shapiro research, Since analyses systems see Shapiro and for analysis Charpentier [18], but [4] and [26, 28], Shapiro and White [29].) We investigated the Japanese electric power (see Energy Study Group to see what our energy supply and demand situation will be like in the year [6], Saito and Oyama [25]) system 2000. Many economic equilibrium models have also developed been which use linear and nonl inear programming techniques. Kennedy [16], Hogan Daniel and Goldberg [12], Griffin [5]. [10], Hogan See also Takayama price and resource allocation models.) and and Furthermore, Shapiro [277] Kuhn-Tucker optimality presents conditions Shapiro [141, [30] for disc usses [27] between 1 inear of energy planning moidels. the as Weyant Judge decomposition techniques to show the relationship programming and economet ric components (See e.g. interpretation an economic of the equili brium point for certain matheniatical programming models. However, in most of these modeling studies, demands and the availabi lity of given exogenously. that our future energy We believe primary energy future e nergy resources demand are and the availability of primary energy resources should be uncertain. In this analysis, we have 28 investigated the effects of constraints on Japan's primary energy resources' supply system. It is generally resource 's availability that true when a primary its commodity is high, price and vice versa. However, since we have considered primary energy resources simultan eously, el asticities price resources are supply analyse. a re constraints Through our MP/EE a mo del energy goes two down kinds their furthermore the price effects of more complex to econ omic little we obtain an equilibr ium point for each energy resource as shown in Figure However, the splitting based regions complica ted on because the comp utational of feasible the commodity pr,ices, as region in into the the equilibri um points may figu be re, depen, dent Hogan [12], and its main framework, procedur'es and some assumptions are different. assumed to be supply mapping our model mappings. existence MP/EE Hogan, et al [133; and Ahn and Hogan [2] for co nvergence arguments for in In the PIES continuo us ly except on that model, the special function and the while we existence solution. 29 for functions were po int-to-set and the uniqu enless of an equilibrium the was (inverse) as sumed The assumptionis of the PIES model guarantee only also Ahn i terative the demand differentiable, was a po in t-to-set mapping, assumes the a bout supply and demand functions that both supzpl y and demand model is method and its convergence criteria. PIES mod.el (see e.g. cases) 9. sma 11er Our computational technique is fundamentally similar to [1], of and dif ferent, very energy point, of an both the while our equilibrium Our iterative computational method worked very well, and could obtain an equilibrium point after all feasible cases. computational convergence Although the method is not given is guaranteed several convergence in this paper, by showing the fact iterations for proof our for we believe that the the shadow price of the demand requirement constraint (25c) is expressed the approximate demand function value we corresponding to by the optimal resource demand. We are presently working on this proof. Approximating a demand function is another problem. In paper we assumed the existence of nonzero own price for primary energy resources only, neglecting this elasticities cross price elasticities between two distinct primary energy resources. Both own and cross price elasticities can be simultaneously considered in our model analysis K matrix price of by incorporating (20c). elasticities The does this information consideration not make of solving into nonzero the the cross problem more difficult, but rather changes the problem formulation slightly by adding more nonzero elements in the coefficient matrix. Applying decomposition techniques should also be very effective in solving our MP/EE model in this case. The stability probability was defined to be the that the MP/EE model was feasible. random obtained numbers the as our stability import and We tried a single supply instability probability sequence availability, and probabilities of of then our energy system. We know that if the substitutability between crude oil and coal increases, then the stability probability 30 will also increase, since there are more ways to meet the forecast energy demand. We can conclude that the Japanese energy system more flexible, so that it can structurally primary energy supply availability. For adjust example, needs to variations the (from 1979 to 1980). In another good example, of Japanese cement industry changed almost totally from fuel oil to one year be coal our in power industry is introducing mixed fuel thermal power plants consuming fuel oil, coal and LNG. If our energy system were well coal, it will greatly heighten organized the stability primary energy supply, and also lower cost. We would not have the to consume probability total to depend so heavily more of energy system on crude oil, which has higher supply uncertainty and instability. We must note coal transportation and storage infrastructure and countermeasures for SOx and NOx emissions and very important in the case where we consume a the that environmental burned ashes are great amount of coal. Thus, the substitutability among primary energy resources is a very important factor in our energy system's stability. In order to further elucidate the relationship between the stability probability and the energy resources substitutability, we need more numerical experiments, trying different values for lower and upper bounds of certain energy flows, and varying the yields and efficiencies of petroleum and coal products. The model described in Section 2 is a single 31 period static optimization model. a part of the right hand side in Letting apply could we variable, linear programming model be a random the probabilistic and stochastic analyses, obtaining supply stability and instability probabilities. We can and increasing the number of periods probability in the more distant add the estimating future. In this stability case, following difficulties occur: uncertainty with respect to primary energy variations of prices and final energy supply forecast availability and of the reliability of data. Obtaining the large scale structure linear programming model and computational to obtain an economic equilibrium point another difficulty. Therefore we believe representing techniques necessary will efficiently two future solutions, optimal justification of probability distribution, and the subsequent availability, and by analysis dynamic or three be stages, the next 10 - 15 years will be the largest time span we can deal with reasonably. We believe that the approach introduced in this paper can be useful to quantitatively analyse the energy system countries like Japan which depend heavily energy resources. We are considering further on stability imported primary modification of energy systems approach by incorporating dynamic terms modeling of national economic structures. 32 of and our more REFERENCES 1 B.H. Ahn, Analysis: The Computation Project of Market Equilibria Independence Evaluation for Policy System [PIES] Approach, Gorland Publishing, Inc., New York & London, 1979. 2 B.H. Ahn and W.W. Hogan, On Convergence for Computing Equilibria, Operations of the PIES Algorithm Research, Vol.30, No.2, 1982, pp.281-300. 3 P. Bratley, B.L. Fox and L.E. Schrage, A Guide to Simulation, Springer-Verlag, New York, 1983. 4 J.P. Charpentier, A review of energy International Institute for Applied models: Systems No.1, RR-74-10 Analysis, Schloss Laxenburg, Austria, 1974. 5 T.E. Daniel and H.M. Goldberg, Dynamic Equilibrium Modeling: The Canadian Balance Model, Operations Energy Research, Vol. 29, 1981, pp.829-852. 6 Energy Study Group, A long-range outlook for supply and demand of energy and electricity, Research Report, Central Research Institute of Electric Power Industry, Tokyo, Japan (in Japanese) 1979. 7 Federation of Electric Power Industry, Power Industry, Ministry Handbook of International Trade of Electric and Industry Tokyo, Japan (in Japanese), 1984. 8 Federation of Petroleum Industry, Petroleum Statistics, Petroleum Industry League, Tokyo, Japan (in Japanese), 1984. 33 9 Fishman, Concepts and methods in discrete G.S. event digital simulati on, John Wiley & Sons, U.S.A., 1973. Griffin, Long-run production modeling with pseudo 10 J.M. data: electric power generation, The Bell Journal of Economics, Vol.8, No.1, 1977, pp.112-127. 11 K. Hoffman, A unified framework for energy in Energy Modeling, M. Washington, 12 W.W. Searl(ed.), Resources D.C., U.S.A., system for planning, the Future, 1973. Hogan, Energy Policy Models for Project Independence, Computers and Operations Research, Vol.2, 1975, pp.251-271. 13 W.W. Hogan, J.L. Models in the Sweeney and National Energy M.H. Wagner, Outlook, TIMS Energy Policy Studies in the energy models, Management Sciences, Vol.10, 1978, pp.37-62. 14 W.W. Hogan and J.P. Weyant, Combined Discussion Paper E-80-02, Energy and Environmental Policy Center Harvard University, Cambridge, Mass., U.S.A., 1980. 15 L. Hurwicz, On the problem of integrability demand of functions, in the Preferences, Utility and Demand, J.S. C] hipman, L. Hurwicz, M.K. Richter and H.F. Sonnenschein (eds.), Harcourt Brace Jovanovich, Inc., 1971, pp.174-214. 16 M. Kennedy, Journal of An economic Economics model and of the world oil Management market Sciences, Vol.5 Bell 9 1974, pp.540-577. 17 A.S. Manne, R.G. Modeling: A survey, Richels and Operations J.P. Weyant, Research, pp.1-36. 34 Energy Vol.27, Policy No.1 , 1979, 18 E.M. Modiano and J.F. of depletable No.1, 19 T. resources, Shapiro, A dynamic optimization model The Bell Journal of Oyama, Model analyses of energy policy Tokyo, Japan Oyama, (in Japanese), Energy debates, Research Electric Power Industry, 1980. policy Vol.2, No.2, 1983, pp.77-87 21 T. Vol.11, 1980, pp.212-236. Report, Central Research Institute of 20 T. Economics, modeling: A survey, Simulation, (in Japanese). Oyama, On the stability of Japan's energy primary energy supply constraints, Economic Research Series, Economic Planning Agency, system under the Research Institute Japan, No.40, 1983, pp.117-162 (in Japanese). 22 T. Oyama, Primary energy consumption change in Japan Institute Research and related technical A translog model analysis, Economic Research Series, Economic Planning Agency, Japan, No.40, 1983, pp.232-263 (in Japanese). 23 Resources and Energy Agency, Energy Statistics, International Trade and Industry, Tokyo, Japan Ministry (in of Japanese), 1985. 24 Research and Statistics Division, Industrial Statistics (Items), Ministry of International Trade and Table Industry, Tokyo, Japan (in Japanese), 1984. 25 T. Saito and T. Oyama, Outline of the Energy Model DEM-1, Research Memorandum, Central Research Institute of Electric Power Industry, Tokyo, Japan, 1980. 26 J.F. Shapiro, OR Models for Energy 35 Planning, Computers and Operations Research, Vol.2, 1975, pp.145-152. Shapiro, Decomposition methods for mathematical program- 27 J.F. -ming/economic equilibrium energy planning models, TIMS Studies in the Management Sciences, Vol.10, 1978, pp.63-76. 28 J.F. Shapiro, D.E. White and D.O. Wood, Sensitivity analysis of the Brookhaven energy system optimization model, MIT Operations Research Center Working Paper OR 060-77, 1977. 29 J.F. for Shapiro and D.E. integrating coal White, A hybrid supply and demand decomposition models, method Operations Research, Vol.30, No.5, 1982, pp.887-906. 30 T. Takayama and G.G. Judge, Spatial and Temporal Allocation Models, North-Holland, Amsterdam, 1971. 36 Price and Table 1. Final Energy Demand (1010 kcal) Sectors 1983 1990 211858 243358 Residential-Commercial 99465 122329 Transportation 56869 65324 Stockpile-Transfer 45844 52660 Industry Table 3. Energy Prices by Supply Region (106Yen/10'0kcal) Energy Supply Region 1983 Data 1990 Price Saudi Arabia 45.996 60.488 Other Middle East 47.437 66.749 South Region North-South America 48.964 47.398 64.433 62.373 Other Region 50.729 66.756 South Region 22.712 31.958 North-South America 19.184 26.994 Other Region 17.761 24.992 Middle East 48.072 63.259 Gas South Region 45.219 59.505 LNG North-South America 46.042 60.588 Crude Oil Coal Natural 1 Table 2. Primary Energy Resources by Supply Region (1018 kcal) Energy Crude Oil Supply Region 1983 Data Natural Suiply Saudi Arabia 59904 74100 Other Middle East 91649 113368 South Region North-South America 38882 9196 48096 11375 Other Region 13213 16344 447 588 Stockpile-Transfer 28531 37545 South Region North-South America 26890 21312 35385 28045 Other Region Domestic 8834 11173 11625 12834 Stockpile-Transfer 7197 8851 Middle East 2411 2965 23655 29093 Domestic Coal 1990 Avai1abil ty South Region Gas North-South America 1389 1708 LNG Domestic 2154 2474 Stockpile-Transfer 1335 1642 2 Table 4. Costs of Secondary Energy Resources Transformation (10'0 Yen/101 0kcal) Energy Transformation costs Resources Fuel Oil 2.01 Kerosine-Gas Oil 32.96 Naphtha-Gasoline 49.85 Other Petroleum Products 24.85 Coke Coke Gas-Blast 19.29 31.39 Furnace Gas Electricity(Industry, Electricity Transport) 215.52 (Residential) 284.42 City Gas (Industry) City Gas (Residential) Table 6. 71.95 106.57 Upper and Lower Bounds for Secondary Energy (101' kcal) Secondary Energy Energy Lower Bound Use Industry Electricity Upper Bound 101,500 120,500 60,000 70,000 Transportation Industry 4,000 2,400 5,500 3,500 Residential 9,500 13,500 Residential 3 Table 5. Upper and Lower Bounds for Petroleum and Coal Products (1010 kcal) Products Energy Crude Oil Fuel Oil Kerosine Gas Oil Naphtha Gasoline Lower Bound Use Electricity Stockpile 0.0 32,000 18,600 41,000 Electricity 32,000 41,200 Industry 37,000 49,400 Residential 0.0 12,600 Transportation 0.0 7,000 Industry 0.0 12,000 Residential 25,000 33,000 Transportation 13,500 17,600 Industry City Gas 22,000 0.0 29,000 1,400 Transportation 35,000 41,500 Electricity Petroleum Products Coke Coke Gas Upper Bound Industry Residential 2,600 3,500 12,500 16,500 0.0 9,500 Transportation 2,000 3,500 City Gas 2,000 2,900 Industry 32,000 42,500 0.0 Residential 50 Stockpile 1,300 1,800 City Gas 2,000 2,900 Electricity 4,200 5,600 0,300 14,500 Industry 1 4 Table 7. Upper and Lower Bounds for Petroleum Products Yields Upper Bounds Lower Bounds Petroleum Products Fuel Oil 0.40 0.55 Kerosine-Gas Oil 0.10 0.30 Naphtha-Gasoline 0.20 0.0 0.30 0.15 Other Petroleum Products Table 8. Parameters for Beta Distribution Parameters Energy Resource bm Crude Coal Oil bM p _q 200,000 300,000 4.0 2.0 45,000 135,000 2.0 4.0 5 Table 9. Optimal Primary Energy Supply (1010 kcal) Energy Supply Region Saudi Arabia Crude Oil Coal Natural Gas LNG 72,683 * * 111,200 47,176 * * 38,966 North-South America 11,157 30,884 * Other Region 16,031 12,802 * 600 12,900 2,550 37,600 8,950 1,750 296,447 104,502 15,283 Other Middle East South Region Domestic Stockpile-Transfer Total 6 10,983 I_ l oo a) (d * u · H - O O * * * f f H C * * * H * t OZ - VI 0 O m. O O r- ace a 0 L. c- L c * Cm d) c. C 0D CN1 * 0: o * N- 0 0) 0: C0 0) * - LO ** * C00 C 0IC C:) C) 0 0 1-4 a m ~H·O) C3~ CU a~~~~~~~C m in H· · ~C· · CD C/) = :: C ,!Ztl 00 CU C) C)C:) C C m C> C> 0000 C. Cw 010~0z0 m 0 00 0cc) m0)~C) o0 L0L 0) C ,!I C ~- t V - Cn -- Cg - -- C) Cl 0 te CY) II O O ** *- * O O ^* * * CN 0) 0 * * -4 -4 aQ) ce - a) S Ec LEQ) O O O 4-3= C a) _D C)0 _ C- L- 0 O C CO - C) c' C 0 44.· -* OC LO C9 O C1 C C a= Q~ 0 O o Q = E- o o l e 0 ¢ m CD :l C CZ o- - CD C 0 O CO O C] CD 0 0 C - Ln C m C5 Cm L i 0 C4 cs CD c LO -4 n C LL n L ) 0Qc- *-O0- a)n c> a) c4 O o ~ . 30 o _* ._- -( 5 a) 4-(rcsw* LQ) Z e b O O*-' SD O t) tC/) - L. 0 0 ) 43*-V) 't - 0O L -- L > = Vt -I a) Q U - 3 0O) ;V a n OO -4~ V Z O * : 0 - zd c CE - t 5 Co - CO O V) 0 0 LD CO O 0 cC CS a O Q - 0 -a ) [--4- V cT -rD .- X C V V) C (5 a) 0 1' (L) -0Qa $. (D [... P-2 P0 P1 P2 P3 d-3 Figure 2. d-2 d-i De di d2 Approximate demand function d3 and supply functions START I I1 Generate two sequences of beta random numbers Bl(i), B2(i), i=l,...,N. If For each pair of Bl(i), B2(i), i=l,...,N, solve the MP/EE model and obtain an economic equilibrium solution. w I r Obtain the probability of supply stability and distributions of total energy system cost, primary energy prices and their quantities. - Nr END Figure 3. Computational procedure for the model analysis START | II Initial p, q, p=Q(qo). t=O. I I IJE l l Solve the MP/EE model Optimal solution X't, Y't, and supply submodel. t. Yes i -- "Converged". Equilibrium point obtained t1No t+l - )t. Cst=cS+ACst Figure 4. pt=(' t+pt -)/2. ll END Algorithm for solving the MP/EEmodel U) '-4 x 0 0 0 . * * · 0 05 6 S 0 6 . 05o9 .. * L 4. 6 LL.. 6l 0 LI. L- LL LU : @ LL 0 . . L . . ILL . 6. L. ·* * LL. * LL L. U.. U; . U.LU. e o·eoeleio C- i 4 * 6* U. I A. L .L. LA. . · U LL . LA. A. L LA. LL, 4- . LL U. L ·L U. L LA. .L.. 6 6 .* U. A. LL ,* A. tL *r. U B IU UF * · · UL · U. 6 * UA.. L. 6* U -* . . U . . LL 0 L L ..... L UA. 0 : 0 ~.. * 0 r 0 U , LA.. .... A. LA. LLLL. L. · L. L... *U S l ... U Uw,. LA. 6* e . . . . . eefeeee·e U, .~LA .* L * e LL. ·. d 4 ·· *- . S LA. * U. & u L0 · * S 0 LA. o UA.. UA... tLA. . L . I A ~r~r···U, U BA..L , LA. U.. LLA.. . LL 5* *. * LA. LA.U . r .: C) · *· U. 0 *. L. * _ U. L · LA. * ,, · 0 . : * LL. iA. 4t 9: CN 0 Nr L.L. .LLU. U. LA LI. · I . U : L.. ** * L. LLA. LA. . S . LA .L. * L U.. LA. . la. 0 L .ULA. :U. .L * LL. . . LL u. LL UL U.. L · · . * L. U. L.. LA. · IL . I ,-LL . U. LA. * . U. LL 6 60**06 .A. L U. 0 * . U - ~ ~~~~ LA . LA. 0 · * .. * .* .9* . .. * 0* . ._ LL L . S : U. . U: U LA.. · eeeeeeell . r4 N1 B -~~~~~~ . BI _ .. I . *, ,d . . a6 ii . I LA. IL ,. . LA. ,e LA. 0 0 Im I. e, ·6 , o _ * LI . . .. · LL _ O 0 6 · 6 * L * . * 00 SO S . . ... . 0 5 . 6* 543 S .. . 0 I .. . . . .~ O 5t l, 0 _~~~ _i r . . * * * * * * * 0 ._ S 6 6 6 6 ,i · L · ~~~~· · . * 0 0 .d 0 0 0 00 "4 ,0 . . 0 . 0 0 C) CL) 0 0 0 O 0 00 0N r- 0 GO .I 0 o 0 * * I C 0 06E 0 e- : - o o C o s o 0 o N - 0 0 ue ** Figure 6. ** HISTGRAM 9.664583E+08 - Distribution of objective function values 0.667239E+08 - 0.665911E+08 0 .667239E+08 0.668567E+08 0.668567E+B - 0. 669895E+08 0.665911E+38 0.669895E+03 0.671223E+08 0.672551E+08 0.673880E+08 0.675208E+08 0.676536E+0O 0.677864E+D8 0.679192E+08 0.680520E+08 0.681848E+08 0.683176E+08 0.684504E+08 0.685832E+08 0.687160E+08 0.683488E+08 0.689817E+08 - 62) 22) 13) 9) 0.671223E+08 0.672551E+08 0.673879E+08 0.675208E+08 12) 0. 676536E+08 13) 0. 677864E+08 10) 8) 12) 8) 0.679192E+08 0.680520E+08 0.681848E+08 0.683176E+08 0.684504E+08 0.685832E+08 3) 0. 687160E+08 0. 688488E+08 3) 0.689816E+08 0.691145E+08 4) 6) 5) 7) 7) 0) 0) 1) T ~~~~~&*"~( L *rr -'-4-4.4. ****=~c I*4*4a I *4*4*4=l~C I 44*" .44 r4. 4 444*~C 4 I4*4*4 143~3 4. A. 4 ~I~~*" 7 Figure Distribution of crude oil prices. ** HISTGRAM 49.5565 - 55 .9771 - 52.7668 59. 1874 62.3977 65.6080 68. 8183 72.0286 75.2389 78. 4492 Figure 52.7668 55.9771 59. 1874 - 62.3977 65.6080 68.8 183 72.0286 75.2389 78.4492 1 54) ( 18) 1 8. 17) 60) ( I 1~~~*******~~~~f~~~ O) I 10) I~CS~ 6) 1 *******4~~*~** I***** 7) 8) 81 6595 - I ~~1~~~1~~~~~~~ I ~~**r;**8 25) Distribution coal prices. of *4 HlSTGRAM** 21. 2030 22. 8574 24. 5 118 26. 1662 27.8206 29.4750 22.8574 -24.5118 (11) I *:+*m* 1 57) I 26.166 2 1 -27.8206 -29.4750 *:*~*r*e******~** t?~ r~~?3~ 48) 0) 31.1294 31. 1294 32.7838 34.4382 -32.7833 36.G926 37.7470 0) 0) 34.4382 -36.0926 29) 21) 1 13) 26) it ^ I ****t***g*** I I I *******.... **a go* I rI**trt**^* I * .. 1 CC~ i, ******.r** 4 v * 4 * *** X in V v it o vI vII x A4 o (N .. . . . . . 9 9 . LL LL Li · 9 U. L LL LL L * . LU. . . * . . LL . .L LL 9 LL U tL U. · L. L U: LL.U UL U. Lt. UA. L. L 4- Z s · U. .U. t 4I . , U. U- " L i · L .1- U LL· . 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