ESSO EASTERN INC. P O. 80X 1415 HOUSTON. TE XAS 77OOI NATUtlA PR,;JEL 8 I /iisrC\\ PHC:ir r , EXLCUIIVt February Mr. G. A. Northington Exxon Research & Eng'ineering Florham Park, N.J. Co. ETR 3, l98l 8I.I C02 Em'iss i ons Natuna Gas Project FILE: 68-4-1 -5 Dear Gene: to me a rough calculation you had made regarding the potential level of total emissjons of C02 from producing Natuna Gas and subsequent burn'ing of the LNG manufactured from the gas relative to what would be emitted if Natuna gas were not produced and-coal was burned as a replacement for the LNG. Your calculation (attached) indicates that the total C02 emissions from producing Natuna gas and burning the LNG would be no higher than what would be emitted by burning an amounl of coal equivalent 'in heating value to the LNG. This result is reflective of the fact that: i]) tfre C02 emitted per unit of heating value js higher for coal than for LNG because of the highgr.carbon content of coal (oi conversely the lower hydrogen content), and (2) producing LNG at Natuna will result in the release of a significant amount of C02 because of the high C02 content of the raw gas. Sometime ago you passed I have made a brief, independent analysjs of the relative release of C02. A copy of the calculat'ion is attached. In the calculations, I have attempted to be somewhat more rigorous, firstly, in simulating the chemical, ash and moisture content and the heating value-6f Coat illety"to b. burned in Japan (the properties used reflect a composite of some typical Australjan coals) and, secondly, 'in reflecting, in a gross sense, ttre ibtat.ive heat release from burn'ing coal or LNG in a commercial boiler. The calculations jnd'icate that the total release of C02 from producing Natuna gas and burning of the LNG manufactured from thE gas wbuld be ilmost twjce that emitted.by burning an-equivalent amount of coil. The c02 released from burning coal is calculated to be almost twjce that frbm burning LNG (this result'is cons'istent with the generalized data presented 'in Table I of s. Knisely's memorandum on ,,controil inq the cOe Concentration in the Atmosphere," 'issued by Exxon en6ineerin6,s petroleum Department, dated 0ctober 16, l9z9); but pioducing tiis volurie-or LNG at Natuna releases near'ly 40% more C02 than is releaied from burning coal. .\ Mr. G. A, Northington -2- February 3 , l98l Based on these calculations, the C02 content of the raw gas at Natuna would have to be around 50% for the total C02 emi ss i ons to be equivalent. It appears to me that there are two major reasons for the differing results two calcu'l ations. First, you assumed coal to be 1001 carbon, but the heating value you used for coal (.l0,750 BTU/Lb) represents an ,,as-received,, coal with some level of moisture and ash. The heating value of pure carbon is 14,]00 BTU/Lb. This resulted in an overstatement of the amount of coal required, and thus the amount of C02 emitted, for a given level of heat release, Second, you used a C02 content of raw Natuna gas of 63%, v{hereas the nominal level we have been using for planning purposes is 71.8fl. Adjusting your calculations for these two factors would bring the results of both calculations into close agreement. of the Both of these calculations are, of course, very rough approximations. To get a more accurate evaluation one would need to determine more precisely the relative heat liberated by both fuels in a cofimercjal boiler, which would, of course, involve a determination of relative stack temperatures, excess air, etc.; and the ener^gy consumed in the producing (or mining), manufactuning, shipping and terminalling of each fuel. It is also like1y that the relative release of C02 could vary significantly, depending on the specific coal considered. Nhile the boiler efficiency would probably favor LNG, I would guess that coal would probably have the advantage in terms of the overal1 energy consumed in getting the fuels out of the ground and to the market. This would seern to be particularly true in the case of Natuna, where fuel requirements will be higher than jn conventional LNG projects because of the need to either vent or reinject the C02 recovered from the raw gas. For example, including transportation and rEceiving losses, as well as fuel requirements for producing and l iquefaction, around 'I .6 times as much hydrocarbon wjll need to be produced as will finally be received at the boiler burner. llJhile the enery requirements for coal mining, etc. are undoubtedly substantial also, I doubt they wjll be this hi9h. to have one of your engineers look over these calculations to any additional light can be shed on this subject. However, I doubt any extensive additional work is justified. You may want see if that Very GRG: jdh/mkf Attachments cc: 0405N R. L. Preston G. J. L ook ab au gh truly yours, G A NoRn{rNGrcrJ / . fl(. T @,tc C t I C Ac- c,.. AI -F.nc xt.q a/ffi+r; ottv - 6 u,-tz;a /// lL ,,t-.1 <-J z.^' Jttr')'r, z c-/ z F (/ I L ) ( /c-',25u n, -/t L+.1g tLq.zzu rl zo o7 l1-l / ,oo o,-rtL , 12 q*c-+r,/!'l:u::' r l2p.7r> I;:;' ( l4c7/i//4 /i,. 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