Intensive Sea Weed Aquaculture: A Potent Solution Against Global Warming


Turan G.

Seaweeds and their Role in Globally Changing Environments. , Alvaro Israel,Joseph Seckbach,Rachel Eiliav, Editör, Springer, London/Berlin , İzmir, ss.357-372, 2010

  • Basım Tarihi: 2010
  • Yayınevi: Springer, London/Berlin 
  • Basıldığı Şehir: İzmir
  • Sayfa Sayıları: ss.357-372
  • Editörler: Alvaro Israel,Joseph Seckbach,Rachel Eiliav, Editör

Özet

1.   Introduction

 

Based on current understanding of the relationship between climate change and energy policy, development of an effective and multi-structured renewable energy sector is crucial, as acknowledged in the United Nations Framework Convention on Climate Change, UNFCCC, and the fourteenth Conference of the Parties, COP-14, held December 2008 in Ponzan-Poland. The worldwide energy demand is increasing rapidly as many industries and populations are rapidly expanding. Since fossil fuels are finite resources and their combustion leads to a further increase of greenhouse gases, such as CO2, SO2 and NOx, their continued use is not sustainable. Today, renewable energy sources supply 14% of the total global energy demand. Some expect that in 2040 50% of the world energy supply will come from renewables sources (Demirbas, 2008). Additional efforts and further research and development on biofuels, toward environmentally and economically sustainable processes, are essential for the full exploitation of this given market opportunity.

The substitution of conventional fuels by biofuels can reduce pollution and support sustainability. First generation biofuels, such as biodiesel and bioethanol derived from biomass, have their environmental benefits related to carbon-neutral energy. However, increasing biofuel production from land crops strains the global food supply. Due to these limitations, second generation (bio) fuels- from biomasses that generate carbon neutral energy without competing with food production- have been developed. These can be produced from the residual non-food parts of current crops, as well as novel energy crops, such as seaweeds.

The culture of seaweeds has unique characteristics, which make it different and in many ways attractive in comparison with other biofuel sources. Seaweeds, also known as “marine macroalgae”, "aquatic plants" or “sea vegetables”, are autotrophic organisms that produce biomass using sunlight and extracting from the water dissolved inorganic nutrients, including carbon. Several seaweed species are perhaps the most attractive of all CO2 removal and biofuel aquatic crops, thanks to high yields and low cost of production. Therefore, efficient production of biodiesel and bioethanol from seaweeds has been considered (Bird and Benson, 1987; Flowers and Bird, 1987; Hanisak and Ryther, 1986; Morand et al., 1991; Gao and Mckinley, 1994; Kelly and Dworjanyn, 2008). Seaweeds can be viewed as miniature biochemical factories, photo-synthetically efficient and effective CO2 fixers. Many species of seaweed are rich in oil or sugars that can be converted into biofuels; as a result the biofuel productivity of seaweeds per unit area can be much higher than conventional farm crops, such as wheat and maize. Producing a ton of dry algal biomass utilizes approximately 360 kg carbon, 63 kg nitrogen and 8.6 kg phosphorus (Sinha, et al., 2001).Utilization of anthropogenic CO2 as an industrial by-product for seaweed production holds great promise not only as a carbon sink, but also as a source of food, fodder, fuel and pharmaceutics. The recent Algal Biomass Summit (Seattle, October 08) stressed the importance of algae to deliver such a mix of energy, feed and industrial products. From an ecological point-of-view, generation of biomass should not aim to a single application, treating the remainder as a 'waste', but towards a comprehensive solution to several challanges, including bio fuel, carbon sequestration, waste remediation and natural production of food and biochemicals. The goal therefore should be the integration of the processes. Mass balance and energy balance, complemented by exergy analysis, can guide the optimisation of the technologies and economics of using seaweeds, regarding carbon sequestration, waste remediation, biofuel production and generation of seaweed products. Additional attractive characteristics of seaweed based biofuels include (a) some saweeds are rich in oil, others in processable carbohydrates and proteins, (b) seaweeds of different species can be grown anywhere, in marine, brackish and fresh water and in most climates, (c) seaweed can grow well on liquid domestic and industerial wastewaters  and on streams polluted by agriculture, reducing pollution as they grow, (d) seaweed biomass  is desirable and valuable for a diverse array of commercial purposes, depending on species, quality and quantity.

This chapter analyzes the current production of both commercially grown and wild-grown seaweeds, as well as their capacity for photosynthetically driven CO2 assimilation and growth. It is suggested that CO2 uptake by seaweeds can represent a considerable sink for anthropogenic CO2 emissions and that harvesting and appropriate use of seaweed primary production is a commercially-viable approach for the amelioration of greenhouse gas emissions and biofuel production.

 

 

1.   Introduction

 

Based on current understanding of the relationship between climate change and energy policy, development of an effective and multi-structured renewable energy sector is crucial, as acknowledged in the United Nations Framework Convention on Climate Change, UNFCCC, and the fourteenth Conference of the Parties, COP-14, held December 2008 in Ponzan-Poland. The worldwide energy demand is increasing rapidly as many industries and populations are rapidly expanding. Since fossil fuels are finite resources and their combustion leads to a further increase of greenhouse gases, such as CO2, SO2 and NOx, their continued use is not sustainable. Today, renewable energy sources supply 14% of the total global energy demand. Some expect that in 2040 50% of the world energy supply will come from renewables sources (Demirbas, 2008). Additional efforts and further research and development on biofuels, toward environmentally and economically sustainable processes, are essential for the full exploitation of this given market opportunity.

The substitution of conventional fuels by biofuels can reduce pollution and support sustainability. First generation biofuels, such as biodiesel and bioethanol derived from biomass, have their environmental benefits related to carbon-neutral energy. However, increasing biofuel production from land crops strains the global food supply. Due to these limitations, second generation (bio) fuels- from biomasses that generate carbon neutral energy without competing with food production- have been developed. These can be produced from the residual non-food parts of current crops, as well as novel energy crops, such as seaweeds.

The culture of seaweeds has unique characteristics, which make it different and in many ways attractive in comparison with other biofuel sources. Seaweeds, also known as “marine macroalgae”, "aquatic plants" or “sea vegetables”, are autotrophic organisms that produce biomass using sunlight and extracting from the water dissolved inorganic nutrients, including carbon. Several seaweed species are perhaps the most attractive of all CO2 removal and biofuel aquatic crops, thanks to high yields and low cost of production. Therefore, efficient production of biodiesel and bioethanol from seaweeds has been considered (Bird and Benson, 1987; Flowers and Bird, 1987; Hanisak and Ryther, 1986; Morand et al., 1991; Gao and Mckinley, 1994; Kelly and Dworjanyn, 2008). Seaweeds can be viewed as miniature biochemical factories, photo-synthetically efficient and effective CO2 fixers. Many species of seaweed are rich in oil or sugars that can be converted into biofuels; as a result the biofuel productivity of seaweeds per unit area can be much higher than conventional farm crops, such as wheat and maize. Producing a ton of dry algal biomass utilizes approximately 360 kg carbon, 63 kg nitrogen and 8.6 kg phosphorus (Sinha, et al., 2001).Utilization of anthropogenic CO2 as an industrial by-product for seaweed production holds great promise not only as a carbon sink, but also as a source of food, fodder, fuel and pharmaceutics. The recent Algal Biomass Summit (Seattle, October 08) stressed the importance of algae to deliver such a mix of energy, feed and industrial products. From an ecological point-of-view, generation of biomass should not aim to a single application, treating the remainder as a 'waste', but towards a comprehensive solution to several challanges, including bio fuel, carbon sequestration, waste remediation and natural production of food and biochemicals. The goal therefore should be the integration of the processes. Mass balance and energy balance, complemented by exergy analysis, can guide the optimisation of the technologies and economics of using seaweeds, regarding carbon sequestration, waste remediation, biofuel production and generation of seaweed products. Additional attractive characteristics of seaweed based biofuels include (a) some saweeds are rich in oil, others in processable carbohydrates and proteins, (b) seaweeds of different species can be grown anywhere, in marine, brackish and fresh water and in most climates, (c) seaweed can grow well on liquid domestic and industerial wastewaters  and on streams polluted by agriculture, reducing pollution as they grow, (d) seaweed biomass  is desirable and valuable for a diverse array of commercial purposes, depending on species, quality and quantity.

This chapter analyzes the current production of both commercially grown and wild-grown seaweeds, as well as their capacity for photosynthetically driven CO2 assimilation and growth. It is suggested that CO2 uptake by seaweeds can represent a considerable sink for anthropogenic CO2 emissions and that harvesting and appropriate use of seaweed primary production is a commercially-viable approach for the amelioration of greenhouse gas emissions and biofuel production.