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Sustainable Development
C H A P T E R
12.3 Sustainable Development Philippe Girardon Air Liquide, Paris, France
12.3.1 CARBON DIOXIDE AND LIFE ON EARTH First of all, let us restate the carbon dioxide gas (CO2) cycle, which is necessary for life. CO2 is the key to the ecosystem of the planet. It is the organic raw material used by plants for photosynthesis. The conversion to carbon dioxide gas through the breathing of living beings and their final decomposition is also a basic process of life. Carbon exchanges between the Earth and the atmosphere are more intense than those between the oceans and the atmosphere. In addition, a much larger fraction of carbon is stored in the ground than at the bottom of the oceans, and it is quickly returned to the atmosphere. Flows are expressed in billions of tons per year. It is estimated that only 1%–2% of the CO2 available on the Earth is contained in the atmosphere, a figure that results from the difference between consumption and production. The concentration of CO2 went from 283 ppm in 1839 to 390 ppm volume in 2010, an increase of 36% in 170 years.
12.3.2 THE GREENHOUSE EFFECT AND ITS IMPACT ON THE CLIMATE Carbon dioxide, water vapor, and other gases such as ozone, methane, nitrous oxide, and halogenated carbons in the atmosphere are the source Gases in Agro-food Processes https://doi.org/10.1016/B978-0-12-812465-9.00028-1
of the greenhouse effect, without which the temperature on Earth would be an average of 18°C instead of +15°C. The greenhouse effect reduces heat losses by radiation from the terrestrial surface. These gases work as absorbers of the infrared radiation reflected from the terrestrial surface. Their absorbent capacities, called GWP (global warming potential), vary; however, CO2 is the standard and is set to 1. For example, the GWP of methane is 23, that of nitrous oxide 296, and that of certain halogenated carbons 22000. Lastly, water vapor alone is responsible for two-thirds of the greenhouse effect. Human activities (combustion of fossil fuels, deforestation) are very likely the cause of climate change and are subject to public debates within the international organizations that specialize in this area (e.g., Intergovernmental Panel on Climate Change (IPCC) reports and other reports from 168 different organizations at this date). The consequences of this, which have been modeled, forecast rises in temperature of from 1 to 4°C that will lead to a rise in sea levels as well as increased violence and frequency of tornadoes and other cyclones along with changes to agricultural models. The 160 countries that signed the Kyoto protocol in 1997 are committed to reducing emissions of the gases mentioned to reach emission levels of 5.2% less than that of 1990 over the period 2008–12.
669
# 2019 Elsevier Inc. All rights reserved.
670
12.3. SUSTAINABLE DEVELOPMENT
12.3.3 THE CARBON DIOXIDE GAS INDUSTRY ORIGIN It has been several hundred years since humans (JB Van Helmont in 1648) discovered the existence of carbon dioxide gas by burning carbon. Since then, its unique physicochemical properties have been put to good use in many ways in daily life and in industry. As an example, the English chemist Joseph Priestley in 1772 poured sulfuric acid onto chalk, producing carbon dioxide that when dissolved in water made it the first sparkling water. The invention taken on by Johan Jacob Schweppe gave birth to the first soda company in 1790 in London, known by the name of Schweppes. Coming from nature or from different industrial or biological processes, CO2 is usually present in diluted form with other gaseous or liquid components. Its commercial use requires a purification process in order to be delivered in the refrigerated-liquefied form, the compressedgas form, or the solid form known as dry ice. CO2 was liquefied for the first time in 1823 by Humphrey Davy and Michael Faraday. In 1834, Charles Thilorier discovered that pressurized liquid CO2, when undergoing a rapid drop in pressure, produced solid “carbon dioxide snow.”
12.3.4 THE DIFFERENT SOURCES OF CARBON DIOXIDE GAS Where is carbon dioxide gas found? Large quantities are available in nature and as a result of human activity. It is recovered in both cases by industry, but this only represents a very small proportion of what escapes into the atmosphere. Indeed, the choice of sources is based on technical and economic constraints (purity and proximity of sources), which in the end represent less than 0.07% of the emissions from combustion, for example. In Europe, 80% of the CO2 recovered comes from chemical industry “waste” that, without this CO2 recovery industry, would be released
into the atmosphere. Due to the 98% purity of the CO2 emitted, these sources are preferred. Examples are the production of ammonia and the reforming of methane and ethylene oxide. Due to the low concentration and necessary purification of the CO2 from combustion fumes, its recovery is not economic when compared with the other channels mentioned. The anaerobic metabolism of yeasts during alcoholic fermentation on a large scale is also a preferred channel with regard to breweries and in the production of alcohol for industrial uses such as fuels. These latter sources are especially used in Brazil and the United States. Europe has also begun building plants of this type in France and Austria. For Asia, see the chapter called “Utilization and application of carbon dioxide recovered from beer and ethanol industry in Vietnam.” Methanogenic bacteria also produce CO2 associated with the production of methane, which is captured from grass, discharges, or purification station sludges. The separation and purification of CO2 from these sources is now being studied. Lastly, pockets of CO2 from biological sources have been trapped in certain geological layers for millennia, for example in the United States, France, Hungary, Turkey, and Russia. The recovery of this CO2 is often carried out in conjunction with a mineral water source. CO2 in varying degrees of concentration is also associated with natural gas (methane) sources, particularly in Asia. The combustion of fossil fuel with the sole aim of producing CO2 should be avoided as far as possible when the sources described above are within reach. Nevertheless, cogeneration or trigeneration from natural gas combustion makes sense in some particular cases when all the energy and utility outputs are well balanced in proportion for simultaneous applications: electricity, steam, and CO2. This is true for vegetal production in greenhouses where lighting and heating are needed during nights and cold
12. MARKET TRENDS, PROSPECTIVES, SUSTAINABLE DEVELOPMENT, AND R&D PERSPECTIVES
12.3.5 APPLICATIONS OF CARBON DIOXIDE GAS
periods and CO2 is used during days and warmer periods. A similar trigeneration application is fruitful in the soft drink industry where the output utilities are servicing water carbonation, pasteurization steaming, and diverse electricity purposes such as water chilling, conveying, building lighting, etc.
12.3.5 APPLICATIONS OF CARBON DIOXIDE GAS By virtue of its numerous physicochemical properties, CO2 has many roles in daily life and in industry. When dissolved in an aqueous medium, it forms carbonic acid (H2CO3). In liquefied or solid form, it becomes a chilling agent mainly used in the food industry and for the transport of perishable foodstuffs. As a weak acid, CO2 may be used to adjust the pH of milk, swimming pool water, or drinking water to lower its hardness. It thus enables the lime in hard water to be dissolved and alkaline effluents from food industries or tanneries to be neutralized more effectively than with strong acids (sulfuric acid), which are tricky to handle. In the chemical industry, its properties as an inert and heavy-density gas are put to good use in avoiding any risk of inflammation of solvents or explosion of carbonaceous dusts. Likewise, many firefighting systems use CO2 to extinguish fires (extinguishers, automatic sprinkler systems in computer rooms and archives). In agriculture, the growth of vegetation results from photosynthesis, through which light energy from the sun is used as a source of energy to enable organic matter to be synthesized using atmospheric CO2. This phenomenon, which is accompanied by the production of oxygen by plants, may be chemically represented by the following formula: 6 H2 O + 6 CO2 + light energy ! C6 H12 O6 + 6 O2
671
This equation highlights the fact that CO2 is one of the three main factors that combines to produce the organic components necessary for building the structure of the plant. The chlorophyllous components assimilate the CO2 normally present in the air at an average volume concentration of 390 parts per million (ppm volume). If this value is less than the optimum needed for the growth of the plants, as is true in the case of hothouses (for example 120– 150ppm volume), photosynthesis stops. CO2 enrichment enables the minimum concentration to be reestablished, which stimulates photosynthesis and hence the growth of the vegetable matter. CO2 enrichment from 390 to about 800 ppm can increase the quality, quantity, and precocity of certain cultures (e.g., tomatoes, roses). Refer to the related chapter in this book. As a bacteriostatic and fungistatic agent, CO2 can increase the growth lag phase and reduce the speed of multiplication of bacteria and molds, particularly in the absence of oxygen. It is effective at concentrations greater than 20% in the surrounding atmosphere and does not have a stimulating effect on the pathogen bacteria. This property is widely used in protective atmospheres around fresh foods such as meat, fish, and ready-made meals. Refer to the chapter on modified atmosphere packaging. In solid form at 78°C, CO2 (snow or compacted dry ice) is a source of cold production used during the chilling of foodstuffs or for controlling the cold chain during industrial processes and logistics. It is used within special equipment (chiller units, linear or spiral tunnels). This built-in, self-contained cold source is put to good use in air and road transport (trucks, onboard aircraft, “last kilometer” logistics for delivering vaccines to pharmacies or perishable foodstuffs to the home). Developments are under way for the replacement of CFCs and HCFCs by CO2 in closed-circuit compression systems for cold production. Major distribution groups have started converting to such systems for the refrigeration of shop displays. Refer to chapters on refrigeration and transports.
12. MARKET TRENDS, PROSPECTIVES, SUSTAINABLE DEVELOPMENT, AND R&D PERSPECTIVES
672
12.3. SUSTAINABLE DEVELOPMENT
Pressure
Solid
pe Su id flu
Liquid
al
itic
r rc
73.8 bar
Critical point
Gas
o
31.1 C
Temperature
FIG. 12.3.1
Mollier diagram of CO2.
The carbonation of mineral waters and soda mentioned above remains the most widespread application of CO2 around the world, and it is also used for drink draughting in bars. Highly pressurized CO2 in a supercritical state (see Fig. 12.3.1) is an excellent solvent for fragile active biological substances such as essential oils like spices, fragrances, active ingredients in cosmetics and pharmacology, hops for beer, and caffeine. This type of process is an alternative to the use of organic solvents by virtue of its harmlessness with regard to residues. Refer to the chapters “Supercritical CO2 in the food industry” and “Supercritical Carbon Dioxide Extraction of Bioactives – A Southeast Asia Perspective.” Many other applications aim to use CO2 in industry and in our daily lives.
12.3.6 OTHER ECOLOGICAL BENEFITS OF INDUSTRIAL GASES USE Not everybody is aware that industrial gases can participate in savings in materials and energy in the food industry.
An example is given when using small amounts of liquid nitrogen to pressurize delicate PET packages and aluminum cans to provide some internal pressure. This process allows to withstand during transit and handling and allows less packaging material. It also helps to extend the product shelf life. In hot fill applications, the use of liquid nitrogen in the headspace eliminates the vacuum effect that occurs during cooling. The most common applications are bottled still water, juice, tea, sport drinks, wine, beer, nuts, vegetable oil, and dairy products. The solution is described in detail in dedicated chapters. Onsite beverage dispensing and associated carbonation avoid water, glass, plastic, and metallic container logistics in bars, fast food restaurants, and any event locations. The replacement of chlorine in drinking water plants and in washing and sanitation operations in the food industry (e.g., floors, equipment surfaces, containers) by means of ozone is also a contribution to effluent pollution reduction. Note that water savings and consequently water recycling in agrofood processing is a major challenge for the future. Pure oxygen
12. MARKET TRENDS, PROSPECTIVES, SUSTAINABLE DEVELOPMENT, AND R&D PERSPECTIVES
12.3.7 CONCLUSION
and ozonation of fish pools can also contribute to restrict the use of veterinary drugs and subsequent pollution in discharge water.
12.3.7 CONCLUSION We have just seen that carbon dioxide gas is recovered from a number of sources and is used by industry even if its usages are low in relation to its availability. One of the con-
673
straints for a more extended role is the distance issue between recuperation sources and industrial applications. Indeed, a transport distance that is too long (several hundred Kms) cannot always place “sustainable” CO2 with a competitive advantage facing other technologies such as combustion or mechanical refrigeration. The use of industrial gases, not only CO2, in the future will participate more and more in carbon footprint reduction at a customer’s premises.
12. MARKET TRENDS, PROSPECTIVES, SUSTAINABLE DEVELOPMENT, AND R&D PERSPECTIVES
12.3 Sustainable Development Philippe Girardon Air Liquide, Paris, France
12.3.1 CARBON DIOXIDE AND LIFE ON EARTH First of all, let us restate the carbon dioxide gas (CO2) cycle, which is necessary for life. CO2 is the key to the ecosystem of the planet. It is the organic raw material used by plants for photosynthesis. The conversion to carbon dioxide gas through the breathing of living beings and their final decomposition is also a basic process of life. Carbon exchanges between the Earth and the atmosphere are more intense than those between the oceans and the atmosphere. In addition, a much larger fraction of carbon is stored in the ground than at the bottom of the oceans, and it is quickly returned to the atmosphere. Flows are expressed in billions of tons per year. It is estimated that only 1%–2% of the CO2 available on the Earth is contained in the atmosphere, a figure that results from the difference between consumption and production. The concentration of CO2 went from 283 ppm in 1839 to 390 ppm volume in 2010, an increase of 36% in 170 years.
12.3.2 THE GREENHOUSE EFFECT AND ITS IMPACT ON THE CLIMATE Carbon dioxide, water vapor, and other gases such as ozone, methane, nitrous oxide, and halogenated carbons in the atmosphere are the source Gases in Agro-food Processes https://doi.org/10.1016/B978-0-12-812465-9.00028-1
of the greenhouse effect, without which the temperature on Earth would be an average of 18°C instead of +15°C. The greenhouse effect reduces heat losses by radiation from the terrestrial surface. These gases work as absorbers of the infrared radiation reflected from the terrestrial surface. Their absorbent capacities, called GWP (global warming potential), vary; however, CO2 is the standard and is set to 1. For example, the GWP of methane is 23, that of nitrous oxide 296, and that of certain halogenated carbons 22000. Lastly, water vapor alone is responsible for two-thirds of the greenhouse effect. Human activities (combustion of fossil fuels, deforestation) are very likely the cause of climate change and are subject to public debates within the international organizations that specialize in this area (e.g., Intergovernmental Panel on Climate Change (IPCC) reports and other reports from 168 different organizations at this date). The consequences of this, which have been modeled, forecast rises in temperature of from 1 to 4°C that will lead to a rise in sea levels as well as increased violence and frequency of tornadoes and other cyclones along with changes to agricultural models. The 160 countries that signed the Kyoto protocol in 1997 are committed to reducing emissions of the gases mentioned to reach emission levels of 5.2% less than that of 1990 over the period 2008–12.
669
# 2019 Elsevier Inc. All rights reserved.
670
12.3. SUSTAINABLE DEVELOPMENT
12.3.3 THE CARBON DIOXIDE GAS INDUSTRY ORIGIN It has been several hundred years since humans (JB Van Helmont in 1648) discovered the existence of carbon dioxide gas by burning carbon. Since then, its unique physicochemical properties have been put to good use in many ways in daily life and in industry. As an example, the English chemist Joseph Priestley in 1772 poured sulfuric acid onto chalk, producing carbon dioxide that when dissolved in water made it the first sparkling water. The invention taken on by Johan Jacob Schweppe gave birth to the first soda company in 1790 in London, known by the name of Schweppes. Coming from nature or from different industrial or biological processes, CO2 is usually present in diluted form with other gaseous or liquid components. Its commercial use requires a purification process in order to be delivered in the refrigerated-liquefied form, the compressedgas form, or the solid form known as dry ice. CO2 was liquefied for the first time in 1823 by Humphrey Davy and Michael Faraday. In 1834, Charles Thilorier discovered that pressurized liquid CO2, when undergoing a rapid drop in pressure, produced solid “carbon dioxide snow.”
12.3.4 THE DIFFERENT SOURCES OF CARBON DIOXIDE GAS Where is carbon dioxide gas found? Large quantities are available in nature and as a result of human activity. It is recovered in both cases by industry, but this only represents a very small proportion of what escapes into the atmosphere. Indeed, the choice of sources is based on technical and economic constraints (purity and proximity of sources), which in the end represent less than 0.07% of the emissions from combustion, for example. In Europe, 80% of the CO2 recovered comes from chemical industry “waste” that, without this CO2 recovery industry, would be released
into the atmosphere. Due to the 98% purity of the CO2 emitted, these sources are preferred. Examples are the production of ammonia and the reforming of methane and ethylene oxide. Due to the low concentration and necessary purification of the CO2 from combustion fumes, its recovery is not economic when compared with the other channels mentioned. The anaerobic metabolism of yeasts during alcoholic fermentation on a large scale is also a preferred channel with regard to breweries and in the production of alcohol for industrial uses such as fuels. These latter sources are especially used in Brazil and the United States. Europe has also begun building plants of this type in France and Austria. For Asia, see the chapter called “Utilization and application of carbon dioxide recovered from beer and ethanol industry in Vietnam.” Methanogenic bacteria also produce CO2 associated with the production of methane, which is captured from grass, discharges, or purification station sludges. The separation and purification of CO2 from these sources is now being studied. Lastly, pockets of CO2 from biological sources have been trapped in certain geological layers for millennia, for example in the United States, France, Hungary, Turkey, and Russia. The recovery of this CO2 is often carried out in conjunction with a mineral water source. CO2 in varying degrees of concentration is also associated with natural gas (methane) sources, particularly in Asia. The combustion of fossil fuel with the sole aim of producing CO2 should be avoided as far as possible when the sources described above are within reach. Nevertheless, cogeneration or trigeneration from natural gas combustion makes sense in some particular cases when all the energy and utility outputs are well balanced in proportion for simultaneous applications: electricity, steam, and CO2. This is true for vegetal production in greenhouses where lighting and heating are needed during nights and cold
12. MARKET TRENDS, PROSPECTIVES, SUSTAINABLE DEVELOPMENT, AND R&D PERSPECTIVES
12.3.5 APPLICATIONS OF CARBON DIOXIDE GAS
periods and CO2 is used during days and warmer periods. A similar trigeneration application is fruitful in the soft drink industry where the output utilities are servicing water carbonation, pasteurization steaming, and diverse electricity purposes such as water chilling, conveying, building lighting, etc.
12.3.5 APPLICATIONS OF CARBON DIOXIDE GAS By virtue of its numerous physicochemical properties, CO2 has many roles in daily life and in industry. When dissolved in an aqueous medium, it forms carbonic acid (H2CO3). In liquefied or solid form, it becomes a chilling agent mainly used in the food industry and for the transport of perishable foodstuffs. As a weak acid, CO2 may be used to adjust the pH of milk, swimming pool water, or drinking water to lower its hardness. It thus enables the lime in hard water to be dissolved and alkaline effluents from food industries or tanneries to be neutralized more effectively than with strong acids (sulfuric acid), which are tricky to handle. In the chemical industry, its properties as an inert and heavy-density gas are put to good use in avoiding any risk of inflammation of solvents or explosion of carbonaceous dusts. Likewise, many firefighting systems use CO2 to extinguish fires (extinguishers, automatic sprinkler systems in computer rooms and archives). In agriculture, the growth of vegetation results from photosynthesis, through which light energy from the sun is used as a source of energy to enable organic matter to be synthesized using atmospheric CO2. This phenomenon, which is accompanied by the production of oxygen by plants, may be chemically represented by the following formula: 6 H2 O + 6 CO2 + light energy ! C6 H12 O6 + 6 O2
671
This equation highlights the fact that CO2 is one of the three main factors that combines to produce the organic components necessary for building the structure of the plant. The chlorophyllous components assimilate the CO2 normally present in the air at an average volume concentration of 390 parts per million (ppm volume). If this value is less than the optimum needed for the growth of the plants, as is true in the case of hothouses (for example 120– 150ppm volume), photosynthesis stops. CO2 enrichment enables the minimum concentration to be reestablished, which stimulates photosynthesis and hence the growth of the vegetable matter. CO2 enrichment from 390 to about 800 ppm can increase the quality, quantity, and precocity of certain cultures (e.g., tomatoes, roses). Refer to the related chapter in this book. As a bacteriostatic and fungistatic agent, CO2 can increase the growth lag phase and reduce the speed of multiplication of bacteria and molds, particularly in the absence of oxygen. It is effective at concentrations greater than 20% in the surrounding atmosphere and does not have a stimulating effect on the pathogen bacteria. This property is widely used in protective atmospheres around fresh foods such as meat, fish, and ready-made meals. Refer to the chapter on modified atmosphere packaging. In solid form at 78°C, CO2 (snow or compacted dry ice) is a source of cold production used during the chilling of foodstuffs or for controlling the cold chain during industrial processes and logistics. It is used within special equipment (chiller units, linear or spiral tunnels). This built-in, self-contained cold source is put to good use in air and road transport (trucks, onboard aircraft, “last kilometer” logistics for delivering vaccines to pharmacies or perishable foodstuffs to the home). Developments are under way for the replacement of CFCs and HCFCs by CO2 in closed-circuit compression systems for cold production. Major distribution groups have started converting to such systems for the refrigeration of shop displays. Refer to chapters on refrigeration and transports.
12. MARKET TRENDS, PROSPECTIVES, SUSTAINABLE DEVELOPMENT, AND R&D PERSPECTIVES
672
12.3. SUSTAINABLE DEVELOPMENT
Pressure
Solid
pe Su id flu
Liquid
al
itic
r rc
73.8 bar
Critical point
Gas
o
31.1 C
Temperature
FIG. 12.3.1
Mollier diagram of CO2.
The carbonation of mineral waters and soda mentioned above remains the most widespread application of CO2 around the world, and it is also used for drink draughting in bars. Highly pressurized CO2 in a supercritical state (see Fig. 12.3.1) is an excellent solvent for fragile active biological substances such as essential oils like spices, fragrances, active ingredients in cosmetics and pharmacology, hops for beer, and caffeine. This type of process is an alternative to the use of organic solvents by virtue of its harmlessness with regard to residues. Refer to the chapters “Supercritical CO2 in the food industry” and “Supercritical Carbon Dioxide Extraction of Bioactives – A Southeast Asia Perspective.” Many other applications aim to use CO2 in industry and in our daily lives.
12.3.6 OTHER ECOLOGICAL BENEFITS OF INDUSTRIAL GASES USE Not everybody is aware that industrial gases can participate in savings in materials and energy in the food industry.
An example is given when using small amounts of liquid nitrogen to pressurize delicate PET packages and aluminum cans to provide some internal pressure. This process allows to withstand during transit and handling and allows less packaging material. It also helps to extend the product shelf life. In hot fill applications, the use of liquid nitrogen in the headspace eliminates the vacuum effect that occurs during cooling. The most common applications are bottled still water, juice, tea, sport drinks, wine, beer, nuts, vegetable oil, and dairy products. The solution is described in detail in dedicated chapters. Onsite beverage dispensing and associated carbonation avoid water, glass, plastic, and metallic container logistics in bars, fast food restaurants, and any event locations. The replacement of chlorine in drinking water plants and in washing and sanitation operations in the food industry (e.g., floors, equipment surfaces, containers) by means of ozone is also a contribution to effluent pollution reduction. Note that water savings and consequently water recycling in agrofood processing is a major challenge for the future. Pure oxygen
12. MARKET TRENDS, PROSPECTIVES, SUSTAINABLE DEVELOPMENT, AND R&D PERSPECTIVES
12.3.7 CONCLUSION
and ozonation of fish pools can also contribute to restrict the use of veterinary drugs and subsequent pollution in discharge water.
12.3.7 CONCLUSION We have just seen that carbon dioxide gas is recovered from a number of sources and is used by industry even if its usages are low in relation to its availability. One of the con-
673
straints for a more extended role is the distance issue between recuperation sources and industrial applications. Indeed, a transport distance that is too long (several hundred Kms) cannot always place “sustainable” CO2 with a competitive advantage facing other technologies such as combustion or mechanical refrigeration. The use of industrial gases, not only CO2, in the future will participate more and more in carbon footprint reduction at a customer’s premises.
12. MARKET TRENDS, PROSPECTIVES, SUSTAINABLE DEVELOPMENT, AND R&D PERSPECTIVES