Sustainable Development
Concepts on the Contribution of Chemistry to a Sustainable Development: Renewable Raw Materials
Jürgen O. Metzger, University of Oldenburg, Germany September 28, 2007, Basel http://www.chemie.uni-oldenburg.de/oc/metzger
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable global energy supply - Conclusion
Sustainable Development Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Brundtland Report 1987
Sustainable Development
UNITED NATIONS CONFERENCE ON ENVIRONMENT AND DEVELOPMENT Rio de Janeiro, 3 -14 June 1992 RIO DECLARATION AGENDA 21 JOHANNESBURG DECLARATION and Plan of Implementation , World Summit on Sustainable Development, Johannesburg, September 2002 http://www.un.org/esa/sustdev/
Agenda 21 PREAMBLE Agenda 21 addresses the pressing problems of today and also aims at preparing the world for the challenges of the next century.
It
reflects
a
global
consensus
and
political
commitment at the highest level on development and environment cooperation…This process marks the beginning of a new global partnership for sustainable development. The „Conservation and management of resources for development“ are the main focus of interest.
Some Important Topics of Agenda 21 - Changing consumption patterns (Chapter 4) - Protection of the atmosphere (Chapter 9) - Integrated approach to the planning and management of land resources (Chapter 10) - Programs to combat desertification (Chapter 12; see also ‘United Nations Convention to Combat Desertification’) and deforestation (Chapter 11, see “Statement of Principles for a Global Consensus on the Management, Conservation and Sustainable Development of all Types of Forests”, Rio Conference, 1992) - Protection of the oceans... Rational use and development of their living resources (Chapter 17) - Protection of the quality and supply of freshwater resources (Chapter 18)
Agenda 21 Chapter 35 SCIENCE FOR SUSTAINABLE DEVELOPMENT
35.2 There is a need for the sciences constantly to reassess and promote less intensive trends in resource utilization, including less intensive utilization of energy in industry, agriculture, and transportation. Thus, the sciences are increasingly being understood as an essential component in the search for feasible pathways towards sustainable development.
angew
M. Eissen, J. O. Metzger, E. Schmidt, U. Schneidewind, 10 Years after Rio – Concepts on the Contribution of Chemistry to a Sustainable Development, Angew. Chem. Int. Ed. 2002, 41, 414 – 436.
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable Global Energy Supply - Conclusion
Agenda 21 Chapter 4 CHANGING CONSUMPTION PATTERNS
…encouraging the environmentally sound and sustainable use of renewable natural resources.
Gross Energy Requirements of Important Base Chemicals Acetaldehyde
Process energy Feedstock
Adipic acid
Acetone Adipic acid Ammonia from natural gas
Acetic acid
Benzene Acetic acid Ethylbenzene
Ethylene oxide
Ethylene from naphtha Ethylene oxide Methanol from natural gas
Propylene oxide
n-Butanol
Propylene oxide
Ethanol from naphtha
Rape seed oil
Ethanol from corn Rape seed oil 0
20
40
60
GER / GJ t
GER Gross energy requirement of fossil energy M. Patel, 1999
-1
80
100
Propylene Oxide ¾6 Mt/a Propylene oxide (2006) ¾Gross energy requirement (GER) 104 GJ/t Polyether polyoles (for polyurethanes)
70%
Propylene glycol (for polyesters)
22%
Feedstocks of the Chemical Industry in Germany (2003) Petroleum 15 Mio. t 76%
“Most products obtainable from renewable raw materials may at present not be able to compete with the products of the petrochemical industry, but this will change as oil Natural gas becomes scarcer and oil prices rise. 2 Mio. t 10% The German Chemical Society calls Coal Renewables 0.4 Mio. t 2.3 Mio. t on governments to step up 2% 12% promotion of the necessary basic research and to create frame conditions that encourage the kind of private-sector research that would make sustainable substitute processes and products ready in good time.” Position paper of the GDCh presented to the governments of the countries participating in the World Summit on Sustainable Development in Johannesburg, 2002.
Renewable Feedstocks of the Chemical Industry, Germany 2002
Starch 640.000 t 24%
Fats and Oils 3
1.150x10 t 44%
Cellulose 320.000 t 12%
Pulp
2.4x106
t
(22x106 t
EU)
Biodiesel 1.3x106 t (2.7x106 t EU)
Othe rs 291.000 t 11%
Sugar 240.000 t 9%
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable Global Energy Supply - Conclusion
Transesterification of Fats and Oils O O O
O + 3 CH3OH
O
O
O H3CO
OH [cat]
OH OH
+
H3CO H3CO
O O
Biodiesel Production in Germany 1991-2005
Tonnen/Jahr 1.800.000
1.800.000 1.600.000
1.050.000 800.000
200 5.000
1.400.000 1.200.000 1.000.000 800.000
550.000 400.000 340.000 125.000 100.000100.000 60.000 10.00025.00045.000
600.000 400.000 200.000 0
year
1991
1993
1995
1997
1999
2001
2003
EU: 3.1 Mill. t (2005); capacity > 6.0 Mill. t (2006) Worldwide: 12.5 Mill. t (2006), 18-20 Mill. t (2007) J. Connemann, Leer/Germany
2005
tonnes/year
Glycerol Glycerol = 10 weight % of biodiesel production - about 1000 applications - present world consumption appr. 1 million tonnes - with increasing biodiesel production new outlets for glycerol have to be found - production of bulk chemicals.
Epichlorohydrin and 1,2-Propanediol + Cl2
Cl
H2 O2
O
Propene
Allylchloride
Propylene oxide
1. + HOCl
+H2O/Cat.
2. + Ca(OH)2
O
OH Cl OH
Epichlorohydrin (1.2 Mt/a)
+H2O
1,2-Propanediol (1.6 Mt/a)
+ Base
- HCl Cl
OH
OH
+ H2/Cat.
+HCl + OH
Cl
-H2O Cl
Cl
1,3-Dichloro-2-propanol 2,3-Dichloro-1-propanol
Solvay, Dow
OH
Glycerol
OH
ADM, Cargill and Ashland, Dow, Senergy Chemical, and Huntsman Corp.
Glycerol, a platform chemical O O
O
OH
O
Cat.
Glycidol Glycerol carbonate
+H2
OH
HO
OH
1,3-Propanediol
OH OH
O
OH Cl
1,2-Propanediol
Epichlorohydrin OH
OH
OH O
HO O O
Acrolein Glyceric acid O
OH
OH
O O
tert-Butylethers
O
OH
OH
Tartronic acid
O
OH
Acrylic acid
Unsaturated fatty acids
9
COOH COOH 6
13
12
OH
9
9
COOH
COOH
COOH 10
COOH
U.Biermann, W.Friedt,S.Lang,W.Lühs, G.Machmüller, J.O.Metzger, M.Rüsch gen. Klaas, H.J. Schäfer, M.P. Schneider, Angew.Chem.Int.Ed. 2000, 39, 3675-3677.
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable Global Energy Supply - Conclusion
Biomass and Energy Supply Biomass can provide a significant but nevertheless limited amount of energy that is inadequate to sustain our modern society’s needs. G. A. Olah, A. Goeppert, G. K. Surya Prakash, Beyond Oil and Gas: The Methanol Economy, 2006. Availability of arable land will constrain biofuel production. U. Stridbaek, International Energy Agency, Paris
World Marketed Energy Use by Fuel Type, 1980-2030
57% increase over the projection period.
Energy Information Administration / International Energy Outlook 2007
Development of Global Population Billion
10
9
8
7
6
Developing Transition OECD
5
4
3
2
1
0 1995
2025
2050
Year
Our Common Journey, a transition toward Sustainability, NRC,1999
Prof. Pimentel: 3.7 Billion people are malnourished.
GHG emissions and overall environmental impact
Values are relative to fossil reference petrol. The green area means both lower GHG emissions and lower overall environmental impact than petrol. Rainer Zah
Biomass to Liquid (BtL): Karlsruhe Process Lignocellulose 100% (Energy content) Fast Pyrolysis, 550°C Condensate + Char = Slurry, 90%
Biomass to Liquid (BtL) Lignocellulose 100% (Energy content Fast Pyrolysis, 550°C Condensate + Char = Slurry, 90% Gasification with Oxygen, 1200 °C CO + H2 Synthesis Gas, 78%
Biomass to Liquid (BtL) Lignocellulose 100% (Energy content Fast Pyrolysis, 550°C
70 000 t/a unit Investment $15 million
Condensate + Char = Slurry, 90%
64 units ($960 million)
Gasification with Oxygen, 1200 °C CO + H2 Synthesis Gas, 78% Fischer-Tropsch
1 Mt/a BtL unit Investment $500 Million
Biofuels 40% + valuable chemicals 5-10% + steam + electrical energy Methanol 55%
Investment ≈ $1450 million
Global primary energy supply and global final energy consumptions assumed in 2030
Area needed to fulfil the energy demand in 2030 assuming an annual growth of wood of 15 t/ha amounts to about 3.48 billion ha.
Terrastat database, http://www.fao.org/ag/agl/agll/terrastat/#terrastatdb
Globally Available Land Globally, the area prone to desertification is estimated to 6 105 Mha being 68.8% of the agricultural and forest area. 800 Mha very severe human-induced degradation 2 700 Mha severe human-induced degradation 3 500 Mha should be available and suited for afforestation and to use the biomass continuously for the production of the necessary energy, fuel, materials and chemicals.
Afforestation of Degraded Areas How can it be possible to plant trees at the rim of the desert or other critical lands where at present no tree will grow? The soils are supplemented with hydrogels, which store the rain water and deliver it to the trees (Hüttermann, 1999, Ma and Nelles-Schwelm, 2004).
A. Hüttermann, Göttingen
Hydrogels, Superabsorbents
Superabsorbents are capable of absorbing large quantities of aqueous fluids spontaneously and rapidly. The aqueous fluid is strongly retained and is not released mechanically. While swelling they essentially keep their original shape. They only change in their dimensions and rheological behavior: a brittle solid material becomes a gel.
M. Frank, Superabsorbents, Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH,
Afforestation in the Hot Dry Valleys ofin the Aufforstungsversuche den Upper Hot DryJangtse Valleys Watershed 100 90 80
Ü b e rle b e n (% )
70 60 50 40 30 20 10 0
Eriobetrea japonica
Leucaena leucocephala
Melia toosendon
Controls, no Hydrogel Ma and Nelles-Schwelm, 2004
Acacia confusa Ziziphus mairei
Azadirachta indica
Sinobambusa latiflorus
Survival with Hydrogel 40g/pit
Some examples of trees showing an annual growth rate of about 20 t/ha.
The IEA estimated the cost of avoided CO2 emissions – when fully commercialised – in all countries, including developing countries to be not more than $25 per tonne (1). The annually avoided CO2 emissions of up to 40420 Mt – generated in the Reference Szenario in 2030 – would sum up – when fully commercialized – to $1 trillion per year, enough to make the reforestation of degraded areas profitable and economically feasible. Moreover, Stern estimated that the social cost of carbon is of the order of $85 per tonne of CO2, in summa $2.2 trillion in 2004. (1) International Energy Agency (2006) Energy technology perspectives - scenarios & strategies to 2050 (OECD/IEA, Paris); http://www.iea.org.
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable Global Energy Supply - Conclusion
World energy related CO2 emissions by fuel type and by region
Σ1990-2004: 360 Gt Σ2005-2030: 910 Gt
Sequestration of CO2
Some Important Topics of Agenda 21 - Changing consumption patterns (Chapter 4) - Protection of the atmosphere (Chapter 9) - Integrated approach to the planning and management of land resources (Chapter 10) - Programs to combat desertification (Chapter 12; see also ‘United Nations Convention to Combat Desertification’) and deforestation (Chapter 11, see “Statement of Principles for a Global Consensus on the Management, Conservation and Sustainable Development of all Types of Forests”, Rio Conference, 1992) - Protection of the oceans... Rational use and development of their living resources (Chapter 17) - Protection of the quality and supply of freshwater resources (Chapter 18)
Acknowledgement
I thank Prof. A. Hüttermann, Göttingen, for valuable discussions.
Jürgen O. Metzger, University of Oldenburg, Germany September 28, 2007, Basel http://www.chemie.uni-oldenburg.de/oc/metzger
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable global energy supply - Conclusion
Sustainable Development Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Brundtland Report 1987
Sustainable Development
UNITED NATIONS CONFERENCE ON ENVIRONMENT AND DEVELOPMENT Rio de Janeiro, 3 -14 June 1992 RIO DECLARATION AGENDA 21 JOHANNESBURG DECLARATION and Plan of Implementation , World Summit on Sustainable Development, Johannesburg, September 2002 http://www.un.org/esa/sustdev/
Agenda 21 PREAMBLE Agenda 21 addresses the pressing problems of today and also aims at preparing the world for the challenges of the next century.
It
reflects
a
global
consensus
and
political
commitment at the highest level on development and environment cooperation…This process marks the beginning of a new global partnership for sustainable development. The „Conservation and management of resources for development“ are the main focus of interest.
Some Important Topics of Agenda 21 - Changing consumption patterns (Chapter 4) - Protection of the atmosphere (Chapter 9) - Integrated approach to the planning and management of land resources (Chapter 10) - Programs to combat desertification (Chapter 12; see also ‘United Nations Convention to Combat Desertification’) and deforestation (Chapter 11, see “Statement of Principles for a Global Consensus on the Management, Conservation and Sustainable Development of all Types of Forests”, Rio Conference, 1992) - Protection of the oceans... Rational use and development of their living resources (Chapter 17) - Protection of the quality and supply of freshwater resources (Chapter 18)
Agenda 21 Chapter 35 SCIENCE FOR SUSTAINABLE DEVELOPMENT
35.2 There is a need for the sciences constantly to reassess and promote less intensive trends in resource utilization, including less intensive utilization of energy in industry, agriculture, and transportation. Thus, the sciences are increasingly being understood as an essential component in the search for feasible pathways towards sustainable development.
angew
M. Eissen, J. O. Metzger, E. Schmidt, U. Schneidewind, 10 Years after Rio – Concepts on the Contribution of Chemistry to a Sustainable Development, Angew. Chem. Int. Ed. 2002, 41, 414 – 436.
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable Global Energy Supply - Conclusion
Agenda 21 Chapter 4 CHANGING CONSUMPTION PATTERNS
…encouraging the environmentally sound and sustainable use of renewable natural resources.
Gross Energy Requirements of Important Base Chemicals Acetaldehyde
Process energy Feedstock
Adipic acid
Acetone Adipic acid Ammonia from natural gas
Acetic acid
Benzene Acetic acid Ethylbenzene
Ethylene oxide
Ethylene from naphtha Ethylene oxide Methanol from natural gas
Propylene oxide
n-Butanol
Propylene oxide
Ethanol from naphtha
Rape seed oil
Ethanol from corn Rape seed oil 0
20
40
60
GER / GJ t
GER Gross energy requirement of fossil energy M. Patel, 1999
-1
80
100
Propylene Oxide ¾6 Mt/a Propylene oxide (2006) ¾Gross energy requirement (GER) 104 GJ/t Polyether polyoles (for polyurethanes)
70%
Propylene glycol (for polyesters)
22%
Feedstocks of the Chemical Industry in Germany (2003) Petroleum 15 Mio. t 76%
“Most products obtainable from renewable raw materials may at present not be able to compete with the products of the petrochemical industry, but this will change as oil Natural gas becomes scarcer and oil prices rise. 2 Mio. t 10% The German Chemical Society calls Coal Renewables 0.4 Mio. t 2.3 Mio. t on governments to step up 2% 12% promotion of the necessary basic research and to create frame conditions that encourage the kind of private-sector research that would make sustainable substitute processes and products ready in good time.” Position paper of the GDCh presented to the governments of the countries participating in the World Summit on Sustainable Development in Johannesburg, 2002.
Renewable Feedstocks of the Chemical Industry, Germany 2002
Starch 640.000 t 24%
Fats and Oils 3
1.150x10 t 44%
Cellulose 320.000 t 12%
Pulp
2.4x106
t
(22x106 t
EU)
Biodiesel 1.3x106 t (2.7x106 t EU)
Othe rs 291.000 t 11%
Sugar 240.000 t 9%
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable Global Energy Supply - Conclusion
Transesterification of Fats and Oils O O O
O + 3 CH3OH
O
O
O H3CO
OH [cat]
OH OH
+
H3CO H3CO
O O
Biodiesel Production in Germany 1991-2005
Tonnen/Jahr 1.800.000
1.800.000 1.600.000
1.050.000 800.000
200 5.000
1.400.000 1.200.000 1.000.000 800.000
550.000 400.000 340.000 125.000 100.000100.000 60.000 10.00025.00045.000
600.000 400.000 200.000 0
year
1991
1993
1995
1997
1999
2001
2003
EU: 3.1 Mill. t (2005); capacity > 6.0 Mill. t (2006) Worldwide: 12.5 Mill. t (2006), 18-20 Mill. t (2007) J. Connemann, Leer/Germany
2005
tonnes/year
Glycerol Glycerol = 10 weight % of biodiesel production - about 1000 applications - present world consumption appr. 1 million tonnes - with increasing biodiesel production new outlets for glycerol have to be found - production of bulk chemicals.
Epichlorohydrin and 1,2-Propanediol + Cl2
Cl
H2 O2
O
Propene
Allylchloride
Propylene oxide
1. + HOCl
+H2O/Cat.
2. + Ca(OH)2
O
OH Cl OH
Epichlorohydrin (1.2 Mt/a)
+H2O
1,2-Propanediol (1.6 Mt/a)
+ Base
- HCl Cl
OH
OH
+ H2/Cat.
+HCl + OH
Cl
-H2O Cl
Cl
1,3-Dichloro-2-propanol 2,3-Dichloro-1-propanol
Solvay, Dow
OH
Glycerol
OH
ADM, Cargill and Ashland, Dow, Senergy Chemical, and Huntsman Corp.
Glycerol, a platform chemical O O
O
OH
O
Cat.
Glycidol Glycerol carbonate
+H2
OH
HO
OH
1,3-Propanediol
OH OH
O
OH Cl
1,2-Propanediol
Epichlorohydrin OH
OH
OH O
HO O O
Acrolein Glyceric acid O
OH
OH
O O
tert-Butylethers
O
OH
OH
Tartronic acid
O
OH
Acrylic acid
Unsaturated fatty acids
9
COOH COOH 6
13
12
OH
9
9
COOH
COOH
COOH 10
COOH
U.Biermann, W.Friedt,S.Lang,W.Lühs, G.Machmüller, J.O.Metzger, M.Rüsch gen. Klaas, H.J. Schäfer, M.P. Schneider, Angew.Chem.Int.Ed. 2000, 39, 3675-3677.
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable Global Energy Supply - Conclusion
Biomass and Energy Supply Biomass can provide a significant but nevertheless limited amount of energy that is inadequate to sustain our modern society’s needs. G. A. Olah, A. Goeppert, G. K. Surya Prakash, Beyond Oil and Gas: The Methanol Economy, 2006. Availability of arable land will constrain biofuel production. U. Stridbaek, International Energy Agency, Paris
World Marketed Energy Use by Fuel Type, 1980-2030
57% increase over the projection period.
Energy Information Administration / International Energy Outlook 2007
Development of Global Population Billion
10
9
8
7
6
Developing Transition OECD
5
4
3
2
1
0 1995
2025
2050
Year
Our Common Journey, a transition toward Sustainability, NRC,1999
Prof. Pimentel: 3.7 Billion people are malnourished.
GHG emissions and overall environmental impact
Values are relative to fossil reference petrol. The green area means both lower GHG emissions and lower overall environmental impact than petrol. Rainer Zah
Biomass to Liquid (BtL): Karlsruhe Process Lignocellulose 100% (Energy content) Fast Pyrolysis, 550°C Condensate + Char = Slurry, 90%
Biomass to Liquid (BtL) Lignocellulose 100% (Energy content Fast Pyrolysis, 550°C Condensate + Char = Slurry, 90% Gasification with Oxygen, 1200 °C CO + H2 Synthesis Gas, 78%
Biomass to Liquid (BtL) Lignocellulose 100% (Energy content Fast Pyrolysis, 550°C
70 000 t/a unit Investment $15 million
Condensate + Char = Slurry, 90%
64 units ($960 million)
Gasification with Oxygen, 1200 °C CO + H2 Synthesis Gas, 78% Fischer-Tropsch
1 Mt/a BtL unit Investment $500 Million
Biofuels 40% + valuable chemicals 5-10% + steam + electrical energy Methanol 55%
Investment ≈ $1450 million
Global primary energy supply and global final energy consumptions assumed in 2030
Area needed to fulfil the energy demand in 2030 assuming an annual growth of wood of 15 t/ha amounts to about 3.48 billion ha.
Terrastat database, http://www.fao.org/ag/agl/agll/terrastat/#terrastatdb
Globally Available Land Globally, the area prone to desertification is estimated to 6 105 Mha being 68.8% of the agricultural and forest area. 800 Mha very severe human-induced degradation 2 700 Mha severe human-induced degradation 3 500 Mha should be available and suited for afforestation and to use the biomass continuously for the production of the necessary energy, fuel, materials and chemicals.
Afforestation of Degraded Areas How can it be possible to plant trees at the rim of the desert or other critical lands where at present no tree will grow? The soils are supplemented with hydrogels, which store the rain water and deliver it to the trees (Hüttermann, 1999, Ma and Nelles-Schwelm, 2004).
A. Hüttermann, Göttingen
Hydrogels, Superabsorbents
Superabsorbents are capable of absorbing large quantities of aqueous fluids spontaneously and rapidly. The aqueous fluid is strongly retained and is not released mechanically. While swelling they essentially keep their original shape. They only change in their dimensions and rheological behavior: a brittle solid material becomes a gel.
M. Frank, Superabsorbents, Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH,
Afforestation in the Hot Dry Valleys ofin the Aufforstungsversuche den Upper Hot DryJangtse Valleys Watershed 100 90 80
Ü b e rle b e n (% )
70 60 50 40 30 20 10 0
Eriobetrea japonica
Leucaena leucocephala
Melia toosendon
Controls, no Hydrogel Ma and Nelles-Schwelm, 2004
Acacia confusa Ziziphus mairei
Azadirachta indica
Sinobambusa latiflorus
Survival with Hydrogel 40g/pit
Some examples of trees showing an annual growth rate of about 20 t/ha.
The IEA estimated the cost of avoided CO2 emissions – when fully commercialised – in all countries, including developing countries to be not more than $25 per tonne (1). The annually avoided CO2 emissions of up to 40420 Mt – generated in the Reference Szenario in 2030 – would sum up – when fully commercialized – to $1 trillion per year, enough to make the reforestation of degraded areas profitable and economically feasible. Moreover, Stern estimated that the social cost of carbon is of the order of $85 per tonne of CO2, in summa $2.2 trillion in 2004. (1) International Energy Agency (2006) Energy technology perspectives - scenarios & strategies to 2050 (OECD/IEA, Paris); http://www.iea.org.
- Introduction
- Base chemicals and renewable feedstocks - Fats and Oils as renewable feedstock - Sustainable Global Energy Supply - Conclusion
World energy related CO2 emissions by fuel type and by region
Σ1990-2004: 360 Gt Σ2005-2030: 910 Gt
Sequestration of CO2
Some Important Topics of Agenda 21 - Changing consumption patterns (Chapter 4) - Protection of the atmosphere (Chapter 9) - Integrated approach to the planning and management of land resources (Chapter 10) - Programs to combat desertification (Chapter 12; see also ‘United Nations Convention to Combat Desertification’) and deforestation (Chapter 11, see “Statement of Principles for a Global Consensus on the Management, Conservation and Sustainable Development of all Types of Forests”, Rio Conference, 1992) - Protection of the oceans... Rational use and development of their living resources (Chapter 17) - Protection of the quality and supply of freshwater resources (Chapter 18)
Acknowledgement
I thank Prof. A. Hüttermann, Göttingen, for valuable discussions.
