Development of CO2 Fixation Technology by Seaweed Bed Formation Using Steelmaking Slag

Transcription

1 Development of CO2 Fixation Technology by Seaweed Bed Formation Using Steelmaking Slag Coastal Environment Restoration Using Recycled Materials August 30, 2011 Akio Hayashi, Fellow JFE Steel Corporation Steel Research Laboratory 0

2 Contents 1. Absorption of CO2 by Coastal Ecosystem: Blue Carbon 2. Development of Coastal Environment Restoration Technology Using Steelmaking Slag 3. Experiment of Coastal Environmental Restoration & CO2 Fixation Demonstration in Kawasaki Port 1

3 1. Absorption of CO2 by Coastal Ecosystem : Blue Carbon 2

4 Coastal ecosystems such as seaweed beds, etc. are an important CO2 sink. (870 million ~ 1.65 billion tons-co2 /Yr.) Due to development, coastal ecosystems are decreasing. Decrease of approximately 30% from the 1940 s to present. Stopping this decrease is one effective countermeasure against global warming. Under the name of Blue Carbon (Blue Carbon Dioxide Sink), all countries are called on to make efforts to protect coastal ecosystems. 3

5 2. Development of Coastal Environment Restoration Technology Using Steelmaking Slag 1) Use of recycled material containing iron (by-product of Steelmaking) 2) Restoration of coastal environments (seaweed bed formation, etc.) 3) CO2 absorption by seaweed 4

6 What is Steelmaking Slag? Ironmaking Process Steelmaking Process Blast furnace Converter Blast Furnace Slag Generated in the process of producing pig iron by pouring iron ore (sintered ore) & coke into the blast furnace. Steelmaking Slag Generated in the process of producing steel from pig iron in the converter. 5

7 Properties of Steelmaking Slag Granulated blast furnace slag 1cm Air-cooled blast furnace slag 1cm Steelmaking slag 1cm Appearance Chemical properties Particle density g/cm 3 2.6~ ~ ~3.6 Unit weight kg/l ~ ~2.4 Hydraulic property *1 ph of leachate (leached water) Others Large Medium to small Medium (solidified dredged soil ) ph=10 (approx.) ph=10-11 ph=12 (approx.) P, S adsorption & swelling *1: solidification at the contact with water. Chemical Composition of Slags (Source: Brochure of Nippon Slag Association) SiO2 CaO Al2O3 T-Fe MgO TiO2 MnO S Blast furnace slag Steelmaking slag Andesite (reference)

8 Advantages of Using Steelmaking Slag Steelmaking Slag 1. Composition Main components are friendly to marine environment Overcomes Typical Problems CaO Fe 1. Difficulty to obtain sea sand SiO 2 2. Availability in Japan 10 million tons/year 3. Accessibility Generated at oceanfront steel works: advantageous for marine transportation 2. Difficulty to obtain materials on land 3. Difficulty to use imported sand 7

9 Recent Developments of Technology for Effective Utilization of Steelmaking Slag in Coastal Areas by Industry-Academia- Government Cooperation Government Industry Academia Source: Japan Iron and Steel Federation 8

10 PO 4 -P qu (kn/m 2 ) Result: Improved Technology for Mixing Steelmaking Slag & Dredged Soil Dredged soil [qu=0kn/m 2 ] Increase in Strength Ca in slag Mixing ratio 10% Mixing ratio 30% Mixing ratio 50% Si and water in dredged soil C-S-H Curing time Mix Steelmaking slag [high f-cao] Reduction of ph ph=8.7 Immersion of mixture into seawater Adsorption of phosphate/sulfide Shaking for 30min (amplitude 5cm, 200rpm) White turbidity ph=11.8 No mixture (slag only) Result of Laboratory Experiment Slag mix Sand mix Dredged soil only Expansion of applications by mixing dredged soil & converter steel slag Source: Japan Iron and Steel Federation 9

11 Restoration of Coastal Environment Artificial seaweed bed & shallow bottom Eel grass (Zostera marina) bed Submerged dike Seaweed settlement base Brown algae (Ecklonia cava) grown thick on Seaweed settlement block Steelmaking slag + Dredged soil Soil improvement Form seaweed beds, shallow bottoms & tidal flats which serve as a cradle for fish and shellfish. 10

12 CO2 Absorption by Seaweed CO2 absorption by seaweed 55 ton-co2/ha/yr. Decrease of seaweed beds are in Japan in the past 30 years 80,000ha: 200,000ha 120,000ha After restoration + 80,000ha : 120,000ha 200,000ha 5 million tons of CO2 /yr. absorption is expected. 11

13 3. Experiment of Coastal Environment Restoration & CO2 Fixation Demonstration in Kawasaki Port 12

14 Purpose of the Experiment Demonstrate the effect of using mixture of Steelmaking slag & Dredged soil on seaweed growth To contribute to a low carbon society Targets of the Experiment Form artificial & viable seaweed beds using a mixture which supplies Fe ions. Quantify CO2 Capture & Storage (CCS) Assess the amount of biomass fuel 13

15 Organizations Involved Ministry of Economy, Trade and Industry (METI) Organizations Local companies IDEA Consultants Inc. JFE Steel Corporation JFE Mineral Co., Ltd. Tokyo Gas Co., Ltd. Universities University of Tokyo Institute of Industrial Science, University of Tokyo Tokyo University of Agriculture Yokohama College of Pharmacy Grants Research institutes National Institute for Materials Science (NIMS) Port and Airport Research Institute (PARI) Fisheries Research Agency (FRA) National Institute of Advanced Industrial Science and Technology (AIST) National Institute for Environmental Studies (NIES) Kagawa Prefectural Fisheries Experimental Station Cooperation Cooperating Entities Local governments, etc. Kawasaki City Kagawa Prefecture Ministry of Land, Infrastructure, Transport and Tourism (MLIT), Kanto Regional Development Bureau, Port and Airport Department Local companies Nippon Steel Corporation NPOs Act Kawasaki Liaison Center for Creation of Industry & Environment Kawasaki Marine History Preservation Society 14

16 Image of CO 2 Capture & Storage (CCS) by Seaweed in Formation of Seaweed Beds CO2 Conversion of biomass to fuel Seaweeds (grow 2-3 times faster than on natural materials) Increase in fish & shellfish Supply of Fe 2+ & other minerals Environmental improvement by suppressing leaching of H2S Recovery of dissolved oxygen (DO) Artificial stones made of Slag Construction of seaweed beds using mixture of Slag & Dredged soil 15

17 Location of Seaweed Bed Formation & Demonstration Tests Kawasaki Port Tunnel at Higashi-Ohgishima entrance 1 SYMBOLS Land for pier use Greenbelt Land for traffic functions Land for port related uses Land for other uses 16

18 Test Cases in Demonstration Tests Controlled area Mound E Mound F Large container 2m x 2m x 1m Slag area Mound A 11m x 5m x 1m Mound マウンド A A Mound マウンド B B Symbols 凡例 :: Slag スラグ混合材 mixture :: Slag mixture :: Slag mixture :: Natural 天然砂 sand :: Frontier フロンティアロック Rock :: Natural 天然石 stone :: Wakame ワカメ seaweed :: Kelp コンブ :: Brown アカモク seaweed Mound マウンド E Mound マウンド C C Mound マウンド F F Slag area Mound B Mound C Mound D Large container 2m x 2m x 1m Mound マウンド D 17

19 Flow of Demonstration Tests Supply of steel slag from steel works Supply of dredged soil from Port of Kawasaki Preparation of mixture Construction of seaweed beds in Port of Kawasaki Seaweed planting and growth test Site Monitoring Monitored items: Stability of seaweed beds Growth of seaweeds Fe concentration in seawater Calculation of CO2 reduction Demonstrate the viability of CO 2 fixation using the mixture of Steelmaking slag & Dredged soil 18

20 Timeline of Demonstration Tests August 2009 November 2009 December 2009 January 2010 March 2010 Preparing mixture of Steelmaking slag & Dredged soil Application of mixed material & construction of mounds (Mounds A F) Monitoring survey Planting of juvenile seaweed (Sargassum horneri) Planting of juvenile seaweed (wakame, kelp) Monitoring study (1 month after planting) Monitoring study (2 months after planting) Monitoring study (4 months after planting) 19

21 Table 1 Characteristics of the dredged soil sampled in Ukishima Moisture ratio w % Wet density t g/cm Dry density d g/cm Soil particle density s g/cm Liquid limit w L % Plastic limit w P % 39 Plasticity index I P % 70.7 Liquidity index (w-w P )/(w L -w P ) Proportion of particles under 75mm % 91.6 Total organic carbon % 1.2 Ignition loss %

22 Chemical composition of Steelmaking slag SiO2 Al2O3 CaO MgO MnO P2O5 Al2O3 Total-Fe Metal-Fe FeO

23 Preparing Mixture of Steelmaking Slag & Dredged Soil Steelmaking slag & Dredged soil are mixed by a backhoe on a soil hopper barge. Composition: Dredged soil 70%, steel slag 30% Curing time: 2 days 22

24 Preparing Mixture of Steelmaking Slag & Dredged Soil Solidified mixture after curing Compressive strength: 110 kn/m 2 23

25 Results of Water Quality Monitoring Survey Location of mounds Mound A Mound B Mound C Mound D Mound E Mound F Mound A Mound B - D Mound E, F Study (Slag & Dredged soil mixture) Control (Natural sand) 24

26 ph Monthly changes of water Acidity of seawater Mound A Mound B Mound C Mound D Mound E Mound F 7.7 Jul Aug Sep Nov Dec Jan Feb Mar 25

27 Monthly changes of dissolved Oxygen in seawater DO (mg/l) Mound A Mound B Mound C Mound D Mound E Mound F 0 Jul Aug Sep Nov Dec Jan Feb Mar 26

28 Content of total Nitrogen in seawater T-N (m g/l) Mound A Mound B Mound C Mound D Mound E Mound F 0.0 Jul Aug Sep Nov Dec Jan Feb Mar 27

29 Content of total Phosphorus in seawater T-P (m g/l) Mound A Mound B Mound C Mound D Mound E Mound F 0.00 Jul Aug Sep Nov Dec Jan Feb Mar 28

30 Content of Magnesium ion in seawater Mg (m g/l) Mound A Mound B Mound C Mound D Mound E Mound F 0 Jul Aug Sep Nov Dec Jan Feb Mar 29

31 Content of Ferrous ion in seawater Fe (m g/l) Mound A Mound B Mound C Mound D Mound E Mound F Jul Aug Sep Nov Dec Jan Feb Mar 30

32 Concentration of various hazardous heavy metals dissolved from Mound A after 180 days (mg/l) Element Mound A Bottom sediment standards Hg or Hg compound < Cd or Cd compound < Pb or Pb compound < Cr(Ⅵ) or Cr(Ⅵ) compound < Cu or Cu compound <0.1 3 Zn or Zn compound <0.1 2 Be or Be compound < Cr or Cr compound <0.1 2 Ni or Ni compound < V or V compound <

33 Juvenile Seaweed (Wakame =Undaria pinnatifida) Growth Test 3 cm Immediately after transplanting Max 200 cm After 120 days 32

34 Dry weight(g) Length(cm) Dry weight (g) Length of Seaweed (m) Length (a) & Dry weight (b) of Wakame in March from various mounds 29.3 g / 25.9 g = 1.13 Average (A~C) 29.3 g Average (E, F) 25.9 g Study area Control area 33

35 Juvenile Seaweed (Akamoku = Sargassum homeri) Growth Test 10 ~ 15 cm Immediately after transplanting Max 600 cm After 120 days 34

36 Dry weight(g) Length(cm) washed away washed away Length of individual (m) washed away Dry weight (g) washed away Length (a) & Dry weight (b) of Akamoku (Sargassum homeri) in March from various (a) (b) mounds 67.0 g / 31.8 g = 2.11 Average (B~C) 67.0 g Average (E, F) 31.8 g 0 A Artificial stone A Natural stone B Natural stone C Artificial stone C Artificial stone D Artificial stone E Artificial stone F Natural stone Study area(slag mixture) Controlled area 35

37 Presence of Organisms after Construction Inhibition of settlement by organisms was not observed in the areas of Slag mixture seaweed beds compared with those constructed of natural sand. 36

38 Conclusion The mixture of Steelmaking slag & Dredged soil can be transformed into viable seaweed beds 1. The mixture keeps the necessary strength of solidification. 2. The mixture supplies Fe ions which enhance growth of seaweed. 3. Seaweeds (Akamoku = Sargassum homeri) on Slag mixture seaweed beds grow 2 times bigger than those on natural sand. 4. Inhibition of settlement by organisms was not observed in the areas of Slag mixture seaweed beds 37

39 END Thank you very much for your kind attention. 38