報告書番号

Y94004

タイトル（和文）

世界エネルギー・土地利用モデルによるバイオマス利用可能量の分析

タイトル（英文）

ANALYSIS OF BIOMASS PRODUNCTION POTENTIAL WITH GLOBAL ENERGY AND LAND-USE MODEL

概要 （図表や脚注は「報告書全文」に掲載しております）

本研究では，土地利用，人工増加，生活水準の向上，森林破壊，ＣＯ２の排出などを総合的に評価し，土地利用制約下でのバイオマス利用の制約を明らかにするため，ＳＤ（システム・ダイナミクス）の手法を用いて，世界エネルギー・土地利用モデルを開発した。そして，バイオマス需要や森林保護の指標をパラメータとするシミュレーションを行い，以下の結論を得た。１）途上地域の森林資源は，強力な森林保護対策を早急に実施しない限り，２１００年頃までにほとんど枯渇してしまう。２）耕地で生産する新型エネルギー作物の供給は，食料生産との競合を考慮すると，考慮しない場合の１／２以下に留まる。３）新型エネルギー木材を大規模に導入すると，森林破壊が加速されるが，バイオマスエネルギーで化石燃料を代替出来るため，全体としてはＣＯ２排出量を削減出来る。

概要 （英文）

BIOMASS ENERGY WILL BECOME A KEY ENERGY RESOURCE FOR SUSTAINABLE GLOBAL DEVELOPMENT. HOWEVER,BIOMASS IS NOT AN INFINITE ENERGY RESOURCE. THE LAND AREA AVAILABLE FOR BIOMASS PRODUCTION ISLIMITED AND SOME BIOMASS MUST BE RESERVED FOR FOOD AND MATERIALS. THE AMOUNT OF BIOMASS CONSUMED FOR NON-ENERGY PURPOSES WILL INCREASE WITH POPULATION AND ECONOMIC GROWTH IN DEVELOPING COUNTRIES. FURTHERMORE,FORESTS ARE DECREASING DUE TO INCOMPLETE REFORESTATION AND SLASH-AND-BURN FARMING IN DEVELOPING COUNTRIES. WE EVALUATED THE GLOBAL BIOMASS ENERGY POTENTIAL AND ASSOCIATED CO2 EMISSIONS BY DEVELOPING A GLOBAL ENERGY AND LAND-USE MODEL USING THE SD (SYSTEM DYNAMICS) TECHNIQUE. THE MODEL CONTAINS TWO SECTORS:THE ENERGY SECTOR AND THE LAND USE-SECTOR,AND DESCRIBES COMPETITION BETWEEN VARIOUS USES FOR BIOMASS SUCH AS ENERGY,FOOD,AND TIMBER. WE OBTAINED THE FOLLOWING RESULTS. (1)ALL EXISTING FORESTS INDEVELOPING REGIONS WILL BE EXHAUSTED BY 2100 IN THE BASE CASE. IN THISCASE,THE PARAMETERS OF BIOMASS DEMAND AND FOREST PROTECTION IN DEVELOPED REGIONS WILL STAY AT 1990 LEVELS,AND THE PARAMETERS IN THE DEVELOPING REGIONS WILL GRADUALLY REACH THE PARAMETERS IN THE DEVELOPED REGIONS BY 2100. (2)IF IT IS ASSUMED THAT THE AREA OF ARABLE LAND REMAINS CONSTANT IN THE FUTURE,A SHORTAGE OF ARABLE LAND AND FOOD PRODUCTION WILL OCCUR AND THERE WILL BE NO ROOM FOR MODERN ENERGY CROPS*. EVEN IF WE ADAPT THE DATA OF JOHANSSON ET AL. WHO ESTIMATE THAT THERE WILL BE ADDITIONAL ARABLE LAND,MODERN ENERGY-CROP PRODUCTION IS LIMITED TO 29 EJ IN 2050,WHICH CORRESPONDS TO ONLY A FOURTH OF THE POTENTIAL ESTIMATED BY JOHANSSON ET AL. THIS RESULT OCCURS BECAUSE ARABLE LAND IS USED PRIMARILY FOR FOOD PRODUCTION IN OUR MODEL. (3)IF THE SHARE OF MODERN ENERGY WOODS* REACHES 50% OF ALL BIOMASS PRODUCTION FROM FORESTS BY 2050,THE CHANGEIN ACCUMULATED CO2 EMISSIONS BY 2100 COMPARED TO THE BASE CASE WILL BE54 BILLION TONS-C FROM DEFORESTATION,AND MINUS 230 BILLION TONS-C FROMTHE DECREASE IN FOSSIL-FUEL CONSUMP

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