Carbon Dioxide Recycling
For Prevention of Global Warming and
Global Sustainable Development
by Renewable Energy
Koji Hashimoto
Koji[at]imr.tohoku.ac.jp
(Please replace [at] to @)
July 2020
Preface
Since prehistoric times to the industrial revolution the atmospheric carbon dioxide concentration was about 280 ppm. Human beings have increased it with industrial development. In particular, the atmospheric carbon dioxide concentration has risen remarkably in the past 50 years, exceeding the level in 3.5 million years ago when the temperature was 2-3°C higher than the pre-industrial level. The COP 21 held in 2015 adopted the Paris Agreement which sets out a global framework to avoid dangerous climate change by limiting global warming to well below 2°C above pre-industrial levels and pursuing efforts to limit it to 1.5°C.
The world now prevents global warming by stop of fossil fuel combustion to avoid carbon dioxide emission, and advances to maintain the global sustainable development by renewable energy. There are superabundant renewable energy sources on our planet, and we have various technologies to convert the renewable energy to the electricity.
The major electricity sources are intermittent and fluctuating wind and solar power. We need to supply sufficient amounts of stable high quality electricity supplementing the intermittent and fluctuating electricity generated directly from renewable energy by the surplus electricity saved.
Since 1980s we have studied the hydrogen production by water electrolysis using the electricity generated from renewable energy, and the methane production by the reaction of hydrogen and carbon dioxide captured.
This leads for us to save a surplus of the electricity generated from renewable energy in the form of methane that is the same as natural gas, and to be able to use methane for natural gas power generation as the synthesized natural gas. We can supply the high quality electricity supplementing the intermittent and fluctuating electricity generated directly from renewable energy by the electricity generated by a synthesized natural gas power plant, the operation and stop of which are easy.
Koji Hashimoto, summarizing the background of global warming, current situation, their research and development, international trend and the future view, published a book entitled “Global Carbon Dioxide Recycling, For Global Sustainable Development by Renewable Energy” in June 2019 from Springer Nature, and its Japanese version in February 2020 from Tohoku University Press Sendai.
This describes the main points of the books.
Contents
Preface
1. Reckless Action of Human Beings
2. World History of Energy Consumption
3. Complete Exhaustion of All Fossil Fuel and Uranium Reserves by the Middle of this Century
4. Responsibility of Developed Countries
5. Renewable Energy Sources that Cannot Be Used Up
6. Dream of the Hydrogen Fuel
7. Storage of Surplus Electricity from Renewable Energy in the Form of Methane
8. Stable Electricity Supply by Carbon Dioxide Recycling only from Renewable Energy
9. Key Materials for Methane Production from Renewable Energy
9-1. Cathode and Anode for Water Electrolysis
9-2. Catalysts for Methane Production by the Reaction of Carbon Dioxide and Hydrogen
10. Prototype Plant
11. Stable Power Supply by Supplementing Intermittent and Fluctuating Electricity Generated from Renewable Energy by Saved Energy
12. World Trend
13. Japan in the future
14. Power Generation and Supply from Local Regions
15. Concluding Remarks
Acknowledgement
References
1. Reckless Action of Human Beings
Atmospheric carbon dioxide concentration in the past 1 million years:
About 280ppm in interglacial periods and About 180ppm in glacial periods.
The current atmospheric carbon dioxide concentration exceeds 400 ppm
that is higher than the level in 3.5 million years ago.
Historical change in atmospheric carbon dioxide concentration investigated by a joint work of Tohoku University and National Institute of Polar Research gives one of the most important data on global warming [1]. Figure 1 shows the atmospheric carbon dioxide concentrations obtained by analyses of the ice core and the atmosphere on Antarctica [1] and those in a rural fisherman area, Ryori, Iwate, Japan [2].
Fig. 1 Historical carbon dioxide record in the ice core in Antarctica at 70 km
north from East Ongul Island and atmospheric carbon dioxide concentration
in Antarctica, reproduced from http://caos.sakura.ne.jp/tgr/observation/co2 [1]
with permission from Trace Gas Research Group Center of Atmospheric and
Oceanic Studies, Tohoku University, and atmospheric carbon dioxide
concentration in Ryori, Japan [2].
The increasing pattern of the atmospheric carbon dioxide concentration in Japan is almost the same as that measured in Antarctica. The numerical difference between Japan and Antarctica is only 3-4 ppm. This fact indicates that once carbon dioxide is emitted to the atmosphere it is well mixed in all over the surface of our planet. No one is allowed to say that I am not responsible for global warming induced by the sharp increase in the atmospheric carbon dioxide concentration. The whole world needs to cooperate to solve global warming.
We had lived in the atmosphere containing about 280 ppm carbon dioxide until the industrial revolution since the prehistory when we burnt only firewood. After the industrial revolution that began in the late 1700s, the fossil fuel combustion led to an increase in the atmospheric carbon dioxide concentration. In particular, since 1970 the increasing rate of the atmospheric carbon dioxide concentration has significantly risen, because carbon dioxide emissions by developed countries were too high to be treated on our planet, and carbon dioxide accumulated in the atmosphere with a very high rate of about 1.85 ppm every year. After 2007 it has been increasing at a much faster rate of about 2.28 ppm every year, because of the economic development of developing countries in addition to high industrial activities of developed countries. The atmospheric carbon dioxide concentration reached 419 ppm in 2020.
According to Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report: Climate Change 2007 [3,4], such a high atmospheric carbon dioxide concentration dates back to 3.5 million years ago in Pliocene Epoch, in spite of the fact that our Homo Sapiens appeared only 200 thousand years ago. Atmospheric carbon dioxide concentrations in the Pliocene were between 360 to 400 ppm. Mean global temperatures were about 2 degrees to 3 degrees Celsius above the pre-industrial level, and the sea level was at least 15 to 25 m above the modern levels.
In the history of our planet a variety of creatures appeared, because the climate of that time was most suitable for their life. However, most of them died out because they were not able to adapt to the climate change.
Our ancestor parted from the ancestors of chimpanzee and bonobo about 7 million years ago. The bipedalism begun at about 4 million years ago. The time of 3.5 million years ago was far earlier than the appearance of the first Homo Erectus, Homo Habilis which used stone flakes to butcher and skin the animals in 2.4 million years ago. Thus, we cannot imagine the time travel to the era when Bipedal ape men mainly ate a leaf, a root, fruit and a nut, and did not yet find to eat the meat of the leftover by other animals.
Such climate change will threaten the survival of many of the current living things. All current living things can live because of the climate in the current interglacial period lasting 11,000 years.
Under the leadership of European countries the COP 21 of the UNFCCC in Paris on December 12, 2015 adopted the Paris Agreement to hold the global average temperature to well below 2 degrees Celsius above the pre-industrial level and to pursue efforts to limit the temperature increase to 1.5 degrees Celsius above the pre-industrial level.
Homo-Sapiens was big and inferior in the athletic capability. It was, thus, difficult to survive unless we helped each other. It is said that we are only the creature that the cooperation is printed in our DNA. We developed language to help each other and prospered by sharing wisdom. We human beings induced global warming. Just like the fight to the virus COVID-19, we should cooperate without fighting each other for prevention of global warming by the responsibility of the human beings. We have to perform the Paris Agreement, the promise that we must never break but keep for all creatures including us.
Nevertheless, the current atmospheric carbon dioxide concentration continuously increases over the value in 3.5 million years ago when the atmospheric temperature was 2-3 degrees higher than the pre-industrial level. We have to understand how we need to work hard to realize the Paris Agreement.
2. World History of Energy Consumption
Figure 2 [5] shows the history of the world primary energy consumption in the past 37 years.
Fig. 2 World history of primary energy consumption for 37 years [5].
In 2017 the fossil fuel consumption was 85.1%. Hydro-electric power generation and the electricity from other renewable energy were 6.8 and 3.9%, respectively. Nuclear power generation was only 4.2%. Those relative amounts were not largely changed during this history, and the total amount increased continuously except for the periods of the world economic depression. The world primary energy consumption on an average between 1980 and 2017 increased by a factor of 1.0187 every year since 1980.
3. Complete Exhaustion of All Fossil Fuel and Uranium Reserves by the Middle of this Century
Figure 3 [5,6] shows the history and future of the world primary energy consumption.
Fig. 3 History and future of the world primary energy consumption [5,6].
The blue broad curve on the right side is the extrapolation of the world primary energy consumption which increases by a factor of 1.0187 every year. For instance, the world average primary energy consumption per person in 2050 will be estimated by dividing the estimated world primary energy consumption in 2050 on the blue curve by the world population in 2050 estimated. The world average primary energy consumption per person in 2050 thus obtained is only 58.9 % of 192.11 G J that is the primary energy consumption per person in OECD country people in 2017.
Thus, the blue curve in Figure 3 is the significant underestimation. Nevertheless, if we supply fuels following the history until 2017, responding to this underestimated energy demand, the world petroleum reserves in 2016, that is 1.652 Tera barrels [5], will be completely exhausted by 2049. If we continue to supply the remaining fuels following this demand, the world reserves of natural gas [5], uranium [6] and coal [5] will be successively exhausted. This will happen in response to the underestimated energy demand.
It is clear that if we continue to consume fossil fuel and uranium as we have done, all of those reserves will be completely exhausted until the middle of this century. The complete exhaustion of world fossil fuel will induce intolerable global warming which will be much more serious than the current situation.
However, the world can survive if we decide to use only renewable energy without emitting carbon dioxide, because there are superabundant renewable energy sources on our planet.
As can be seen in Figure 3 we cannot expect the future to fossil fuel and uranium resources on our planet. However, fossil fuel is the feedstocks of the organic materials and we are not allowed to convert completely remaining fossil fuel to carbon dioxide. The descendant needs organic raw materials.
Let’s consider about the nuclear power generation. The nuclear power generation has been carried out by developed countries as the national policy for nearly 70 years. The annual total amount of the nuclear power generation by 31 countries in the world is only the level of 4 % of the annul world primary energy consumption, and it is not increased. Thus, the nuclear power generation is the useless technique from the world point of view. As an industry, in comparison with the fossil fuel power generation, the nuclear power generation is less efficient and more costly and requires more manpower. For the fixed amount of power generation the fossil fuel power generation is significantly more effective than the nuclear power generation even only from the view point of the cost effectiveness. Thus, nuclear power generation did not spread in the world.
In Japan power companies wish to operate stopping plants again. There are no absolutely safe industrial plants. Even if how much safety countermeasures are carried out, everybody knows that there are no absolutely safe human made things. There are no nuclear power plants installed near big cities. The plants are installed as far as possible from big cities. This is the big difference from the fact that fossil fuel power plants are constructed in big cities.
Once the accident of a nuclear power plant occurs hundreds of thousands of people should evacuate for several tens of years. Many children and working people inevitably suffer cancer. Chernobyl’s accident resulted in unbelievable number of victims. WHO reported 20 years after the accident, in 2006, that the dead persons of radiation victims suffered cancer were 9,000 [7]. Furthermore, in Chernobyl’s accident, the area contaminated with the most dangerous cesium 137 more than 40,000 becquerels per square meter exceeded 200,000 square kilometers, about 71% of which were in Belarus, Russia and Ukraine [8]. The area of the 71% corresponds to 62% of the area of the main island of Japan, Honshu. Even if the nuclear power plant is installed as far as possible from big cities, its big accident will lead not only to many people to die but also to disappearance of the place where people can live in the island country, Japan. It is too silly to hold such risky and useless nuclear power plants.
Such an industry is not allowed to exist. We have a variety of safer technologies for power generation.
4. Responsibility of Developed Countries
Developed countries induced global warming by continuous emission of large amount of carbon dioxide. Developed countries are responsible for development of technologies to maintain global sustainable development by renewable energy and for spread of these technologies to the whole world. It is not the time to do selfish nuclear power generation that is useless and exposes a large number of people to danger.
5. Renewable Energy Sources that Cannot Be Used Up
We need to restrict the carbon dioxide emission to the preindustrial level for prevention of further global warming, by the use of only renewable energy without fossil fuel combustion.
There is super quantity of renewable energy sources on our planet so that the world cannot consume. The world consumed 613.53 Exa J of the primary energy in 2017 [5]. Let’s consider the generation of this quantity of energy in the form of electricity by solar cell operation with 20 % energy conversion efficiency under sunlight of 1000 W per square m for 8 hours every day on deserts. The necessary desert area is 0.2923 G square m, which corresponds to only 1.29% of 22.69 G square m of the main desert area on our planet. We can generate the total quantity of energy consumed in the whole world in 2017 by solar cell in this small area.
We do not need to settle solar cell on the desert area, but we can do solar power generation everywhere on the roof of buildings. There is the super quantity of renewable energy sources such as solar power, wind power, biomass and others. We have various technologies for conversion of renewable energy to electricity.
6. Dream of the Hydrogen Fuel
There are super abundant renewable energy sources on our planet. We should establish technologies to maintain the global sustainable development only using renewable energy, and spread those technologies to the whole world.
In the early 1970s we dreamed to supply hydrogen to the whole world. We will generate the power by solar cell on a raft floating on the sea and produce hydrogen by seawater electrolysis using the electricity on the raft. However, there are no spread technologies and infrastructures for storage, transportation and combustion of hydrogen in the whole world.
The fuel supplied to the world in substitution for fossil fuel must be used readily in poor countries as well as in rich countries. We understood that a surplus of the electricity generated from renewable energy should be converted to the fuel for which technologies and infrastructures for storage, transportation and combustion spread widely.
7. Storage of Surplus Electricity from Renewable Energy in the Form of Methane
The conversion of a surplus of the electricity generated from renewable energy in the form of currently used fuel means synthesis of organic fuel. Hydrogen can be produced by water electrolysis using the surplus electricity from renewable energy. We have studied synthesis of organic fuel by the reaction of the electrolytic hydrogen and carbon dioxide since 1980s.
We were lucky to produce currently used fuel from renewable energy. We tailored effective catalysts for rapid synthesis of methane by the reaction of hydrogen and carbon dioxide with nearly 100% selectivity for methane production without forming other substances [9]. Methane is the main component of natural gas for which effective infrastructures of storage, transportation and combustion exist in the whole world.
8. Stable Electricity Supply by Carbon Dioxide Recycling only from Renewable Energy
The main renewable energy sources are intermittent and fluctuating wind and solar energy. The world must live by 100% renewable energy sources. Supply of the stable high quality electricity responding to variable energy demand requires the storage of a surplus of the electricity generated from renewable energy and the supplement of directly generated power by the stored electricity.
Battery storage and other current technologies can be used for short-term storage like several hours or a day. We, however, need to store several months [10], if we consider seasonal variation of power generation and energy demand. Daily adjustment of power supply by current power companies is carried out by natural gas power generation, the operation and stop of which are easy. Our synthesized methane can be used directly for natural gas power generation.
The storage of surplus electricity in the form of methane and the supplement of the intermittent and fluctuating electricity generated directly from renewable energy by the electricity from the natural gas power generation using stored methane will realize stable supply of the high quality electricity. Carbon dioxide in the exhaust gas of natural gas power generation is used repeatedly, and hence it is unnecessary to bring carbon dioxide captured elsewhere.
9. Key Materials for Methane Production
from Renewable Energy
Key materials are active cathode and anode for hydrogen and oxygen production by water electrolysis, and effective catalysts for methane production by the reaction of carbon dioxide and hydrogen. We call them green materials and have studied them since 1980s.
9-1. Cathode and Anode for Water Electrolysis
The water electrolysis is
4H2O → 4H2 + 2O2 (1).
The rates of hydrogen and oxygen production are determined by the current in the water electrolysis. For the industrial electrolysis for hydrogen and oxygen production we wish to pass 6000 amperes on 1 square meter of electrodes, by which we can produce 2.5 cubic meter of hydrogen on a 1 square meter cathode for 1 h. Energy saving electrolysis requires the low applied potential at 6000 amperes per square meter. Thereby, we needed to tailor active electrodes.
Figure 4 [11] shows the relationship between applied current density and potential on various metals and alloys for electrolytic hydrogen production. Less active conventional metals such as Ni and Fe require high applied potential for rapid production of hydrogen.
Fig. 4 The relationship between current density and potential for
electrolytic hydrogen production on some metals and alloys
in 8 M NaOH at 90°C. Reproduced with permission from [11].
Copyright 2000. The Electrochemical Society
In contrast, Ni-Fe-C alloys which we tailored using simple electroplating technology have the highest activity from the mechanistic point of view of hydrogen production. On the other hand, Ni, Fe and Ni-Fe alloys have the lowest activity from the mechanistic point of view of hydrogen reaction.
The active alloying elements with high corrosion resistance as the anode for water electrolysis are Ni and Co.
The practical water electrolyzers are available at an engineering company where many graduates are performing the research, development and construction of electrolyzers.
9-2. Catalysts for Methane Production by the Reaction
of Carbon Dioxide and Hydrogen
The reaction of carbon dioxide and hydrogen for methane production is
4H2 + CO2 → CH4 + 2H2O (2).
The use of conventional catalysts for the reaction of carbon dioxide and hydrogen was very slow and generally form carbon monoxide as shown in the following reaction.
H2 + CO2 → CO + H2O.
Such a carbon monoxide formation must never take place.
Fig. 5 Analytical results of conversion of carbon dioxide by passing a gas mixture
of 4 volumes of H2 and 1 volume of CO2 at a flow rate of 0.9 L/h on 1 g of Ni-
ZrO2, Co-ZrO2, Fe-ZrO2, Ni-TiO2, Ni-Nb2O3 or Ni-T2O3 catalysts.
Reproduced with permission from [9]. Copyright 1993, The Electrochemical
Society.
Carbon dioxide and hydrogen adsorb on the catalyst surface for reaction. Figure 5 [9] shows carbon dioxide conversion by the reaction of four volumes of H2 and one volume of CO2 on catalysts composed of various metallic elements. Catalysts formed from Ni-Zr alloy precursors show the highest activity for carbon dioxide conversion.
Figure 6 [9] shows analytical results of reaction products.
Fig. 6 Analytical results of reaction products after passing a gas
mixture of 4 volumes of H2 and 1 volume of CO2 at a flow rate of
0.9 L/h on 1 g of Ni-ZrO2 and Fe-ZrO2 catalysts. Reproduced with
permission from [9]. Copyright 1993, The Electrochemical Society.
More than 99% of products on the catalyst formed on Ni-40Zr alloy precursor, was methane and less than 1 % was ethane. The products are ideal. Other alloys such as Fe-Zr alloy are useless as the catalyst precursor because the main product is carbon monoxide in addition to slow reaction.
The catalyst and preparation method of the catalyst were improved. The practical methane production plants are available at an engineering company where graduates are performing their research, development and construction.
10. Prototype Plant
We received a special budget based on the study of these green materials in the autumn of 1995. Graduates at engineering companies constructed a prototype plant of global carbon dioxide recycling on the rooftop of a building at Institute for Materials Research, Tohoku University as shown in Figure 7 [12]. It was the spring of 1996. This was the world’s first Power-To-Gas Plant.
Fig. 7 Prototype plant for carbon dioxide recycling built on the rooftop of
Institute for Materials Research, Tohoku University in March 1996.
The operation of the plant consisted of power generation by solar cell, hydrogen production by water electrolysis, methane formation by the reaction of hydrogen and carbon dioxide, methane combustion and carbon dioxide return to the carbon dioxide methanation system.
The methane combustion is
CH4 + 2O2 → CO2 + 2H2O (3).
In the prototype plant the methane combustion furnace was previously filled with carbon dioxide, and methane combustion was carried out by injection of stoichiometric quantity of oxygen necessary for reaction (3). After cooling of steam to water in the exhaust gas, the remaining carbon dioxide returned for methane formation by the reaction with hydrogen.
11. Stable Power Supply by Supplementing Intermittent and Fluctuating Electricity Generated from
Renewable Energy by Saved Energy
A water electrolyzer and a carbon dioxide methanation plant are installed together with a natural gas power plant. In this setup, in addition to hydrogen and oxygen production by reaction (1) and methane production by reaction (2), oxygen can be diluted with carbon dioxide in the exhaust gas and can be used for methane combustion as shown in (3)’.
CH4 + 2O2 + 8CO2 → 9CO2 + 2H2O (3)’
The exhaust gas does not contain nitrogen as in the case of methane combustion with air. When the steam is removed by cooling to water in the exhaust gas the remaining carbon dioxide can be used directly for methane formation by reaction (2) and dilution of oxygen formed by reaction (1) to be used for reaction (3)’. In this setup, carbon dioxide and water can be recycled repeatedly.
In contrast, when methane combustion is carried out in air, the air includes nitrogen 4 times as large as oxygen, and the practical reaction can be written as (4).
CH4 + 2O2 + 8N2 → CO2 + 8N2 + 2H2O (4)
The exhaust gas contains nitrogen 8 times as large as carbon dioxide. For the use of carbon dioxide again to form methane, the capture of carbon dioxide separating from nitrogen requires some sophisticated technologies after removal of the steam from the exhaust gas by cooling.
In reaction (3)’ 8CO2 is unchanged before and after reaction, and hence, the real total reactions are (1), (2) and (3).
4H2O → 4H2 + 2O2 (1)
4H2 + CO2 → CH4 + 2H2O (2)
CH4 + 2O2 → CO2 + 2H2O (3).
In this system we do not need to add carbon dioxide and water as feedstocks, but carbon dioxide and water are just recycled. Carbon dioxide used for dilution of oxygen for reaction (3)’ is repeatedly used for dilution of oxygen.
In this manner, the surplus electricity is converted to methane on the spot. The operation of the power plant is carried out by combustion of methane, depending on the condition of the electricity generated directly from renewable energy and the energy demand.
The direct supply of the electricity generated directly from renewable energy will not be done in this system. This is the structure by which the stable high quality electricity without intermission and fluctuation will be supplied from renewable energy depending on the demand.
12. World Trend
In the world, particularly in Europe, many countries and cities intend to achieve 100% renewable energy sources. This always results in energy saving. The energy efficiency of coal and nuclear power generation is lower than 40 %, and more than 60 % of reaction energy is thrown away as the warm drainage. In contrast, there is no energy loss in power generation by renewable energy in addition to no emission of carbon dioxide.
In transportation, many countries and cities have declared to prohibit soon the entry and/or sale of gasoline and diesel vehicles because the energy efficiency of those vehicles is less than 15 % in addition to carbon dioxide emission. In contrast, the electric vehicles do not emit carbon dioxide and their energy efficiency is around 70 %. All world auto industry concentrates for development and improvement of the electric vehicle.
All buildings are nearly zero-energy buildings by power generation by themselves from renewable energy. All buildings increase the thermal insulation characteristics by triple window filled with thermal insulators and use an LED light for energy saving.
Consequently, countries and cities aiming 100% renewable energy sources consider that the primary energy consumption in the future will be about a half of that in around 2010.
For instance, if we consider about the primary energy consumption in Japan, the total electricity generated in 2017 was 1.056 TkWh [13] that was 18.5 % of the annual primary energy consumption of 20.552677 Exa J [5]. If this electricity was generated by coal power generation of 40% energy efficiency, the energy loss which was thrown away as warm drainage was 27.7% of the annual primary energy consumption of 20.552677 Exa J. In contrast, if we generate 1.056 TkWh from renewable energy which is not accompanied by any energy loss we can save 27.7 % of the annual primary energy consumption in addition to no carbon dioxide emission.
When gasoline and diesel vehicles with 15 % energy efficiency are substituted by electric vehicles with 70% energy efficiency, the energy consumption by electric vehicles becomes less than a quarter of the current energy consumption by gasoline and diesel vehicles.
The energy saving will be done in industry, business and civic life in the same manner.
We can, therefore, understand that the total energy consumption will become lower than a half of the current total energy consumption
13. Japan in the Future
When 100% renewable energy sources are realized in Japan, we will need to generate the electricity corresponding to a half of the current annual primary energy consumption, like as countries and cities in Europe intending 100% renewable energy sources.
Figure 8 shows the share of renewable energy sources for power generation in Japan [14].
Fig. 8 The share of the electricity from renewable energy sources
in the total power generation in Japan [14]
In Europe the main renewable energy sources are wind, solar light and biomass, and the efforts to expand these sources are actively made. In Japan the solar power generation is grown but the wind power generation is not so prosperous.
Japan repeatedly declares that the power will be supplied mostly by coal and nuclear power generation. Japan received the Fossil of the Day Award two times at United Nations Framework Convention on Climate Change, the Conference of the Parties COP 25 held in Madrid in December 2019.
Power companies own the transmission network. It is not easy to put the electricity generated from renewable energy on the network, and when the total electricity generated surpasses the demand, the power company orders to stop power generation from renewable energy.
The conversion to 100% renewable energy sources is the world trend. This is for the safety life of the whole world by prevention of global warming and to leave fossil fuel as the organic raw materials. Thus, the world makes efforts to stop fossil fuel and nuclear power generation as soon as possible. We need to concentrate to increase the electricity from renewable energy. Most of industry in Japan emits the voices of 100% renewable energy sources and zero emission of carbon dioxide. The industry in Japan, that must advance in the world, knows the world trend.
Ministry of Economy, Trade and Industry, Japan has begun to say that 90 % of the low efficiency coal power generation will be stopped by 2030. The Minister said that this is for the decrease in carbon dioxide emission. However, the ministry considers the high efficiency coal power generation important, and accepts the construction of new coal power plants. The ministry expects that nearly 80% of total electricity will be generated by liquified natural gas, coal, nuclear and oil power in 2030. The Ministry does not promote the use of renewable energy for power generation and does not expect 4 % increase in the share of renewable energy in 2030 in comparison with that in 2019 shown in Figure 8. The ministry considers that people will carry out the power generation from renewable energy although the ministry does not promote. The disaster induced by global warming such as the heavy rain and flood becomes intense year by year in Japan, and causes the death of many people. However, they consider that the disaster is not for Japan to wrestle positively but the world problem. Thus, they do not recognize to decrease carbon dioxide emission in cooperation with world. The ministry does not understand at all that the world aims 100% renewable energy sources for prevention of global warming without emission of carbon dioxide at power generation.
Even if we are taught that the electricity will be supplied by coal and nuclear power generation, how long is Japan, that wants to look good in the world, able to continue the selfish behavior frowned and scorned by the world? The power generation technologies of the current power companies will become outdated sometime soon, and they cannot continue acting as the leading roles of the industry. For survival, the power companies need to change by themselves the direction to power generation from renewable energy and its transmission. It is not accepted in the world unless they explain that the current fossil fuel power generation is carried out because the power generated from renewable energy is not yet sufficient. They need to concentrate to increase the power generation from renewable energy in corporation with private enterprises of solar light and wind power generation.
For the use of only the electricity from renewable energy, we need to save a surplus of the electricity generated from renewable energy and to supply stable high quality electricity by supplementing the intermittent and fluctuating electricity generated directly from renewable energy by the saved electricity. We should establish such systems.
14. Power Generation and Supply from Local Regions
The power generation by renewable energy and stable power supply to the inside and outside will be performed in respective local regions as shown in Figure 9.
Figure 9 Illustration of power generation in a local region
and stable power supply to the inside and outside.
For the use of renewable energy, most of buildings and houses equip with own power generation system, in addition to power generation systems in the local area. EU agreed that Member States shall ensure that: by 31 December 2018, new buildings occupied and owned by public authorities are nearly zero-energy buildings, and by 31 December 2020, all new buildings are nearly zero-energy buildings [15].
For supply of the stable high quality electricity the system to supplement the intermittent and fluctuating electricity generated directly from renewable energy by the saved electricity will be established: hydrogen and oxygen are formed as much as possible by water electrolysis using a surplus of the electricity from renewable energy. Hydrogen thus formed is used to produce methane by the reaction with carbon dioxide of exhaust gas from the natural gas power plant which use synthesized methane as fuel. Oxygen will be used for combustion of methane for power generation at the natural gas power plant after diluted with carbon dioxide of the exhaust gas of the natural gas power plant.
This setup just corresponds to the substitution of the methane conversion furnace to the natural gas power plant in Figure 7. Hydrogen formed by water electrolysis reaction (1) using a surplus of the electricity from renewable energy is not stored but converted to methane by reaction (2). Gas reservoirs equipped are for methane, carbon dioxide and oxygen. The size of the oxygen reservoir is two times as large as the methane reservoir as seen in reactions (1) and (3). The oxygen reservoir is installed beside the power plant. Consequently, as far as the surplus electricity is given from renewable energy for water electrolysis, we can store the surplus electricity in the form of methane. We use methane for the necessary quantity of natural gas power generation to supplement the deficit of the intermittent and fluctuating power generated directly from renewable energy. We, thus, supply the stable high quality electricity responding to variable demand.
Water for production of hydrogen and oxygen, and carbon dioxide for methane formation are recycled as seen in three reactions (1), (2) and (3), and hence we do not need to bring them as feedstocks from somewhere, although water recycling may not need in Japan.
From this area the stable high quality electricity will be supplied to the inside and outside. The power generation from renewable energy will be done as much as possible, and the operation of the natural gas power plant is carried out considering the climate and weather forecast in addition to the electricity demand.
The stable electricity supplied from local areas will be collected for supply of the demand in industry, transportation, cities and others.
The energy efficiency of natural gas power generation is about 50 %. The remaining 50 % of energy in the discharge of the natural gas power generator will be used for agriculture, cattle breeding, cultivation, heating, etc. in that area.
15. Concluding Remarks
In the current interglacial period for about 11,000 years, human beings began agriculture and live stock farming. This interglacial period until the industrial revolution was the most safety time for all current living things. Nevertheless, we continued to emit a large amount of carbon dioxide as ignorance, and induced global warming which jeopardizes many creatures including human beings.
Now we reflect on our behavior and have begun efforts to hold the global average temperature to well below 2 degrees Celsius above the pre-industrial level.
We hope we can build the peaceful and safety world by the cooperation of the whole world, where we can supply sufficiently the necessary energy in the form of electricity from renewable energy.
Acknowledgement
The author expresses his appreciation to Prof. Eiji Akiyama, Institute for Materials Research, Tohoku University for his kind designing and preparation of this site.
References
[1] T. Nakazawa, T. Machida, M. Tanaka, Y. Fujii, S. Aoki, O. Watanabe: Atmospheric CO2
concentrations and carbon isotopic ratios for the last 250 years deduced from an Antarctic
ice core, H 15, Proceedings of Fourth International Conference on Analysis and Evaluation of
Atmospheric CO2 Data, Present and Past, pp.193 196(1993).
http://caos.sakura.ne.jp/tgr/observation/co2.
[2] Meteorological Agency of Japan
http://ds.data.jma.go.jp/ghg/kanshi/obs/co2_monthave_ryo.html.
[3] IPCC Fourth Assessment Report: Climate Change 2007: Working Group I: The Physical
Science Basis.
[4] A. M. Haywood, H. J. Dowsett, P. J. Valdes, D. J. Lunt, J. E. Francis, B.W. Sellwood:
Introduction. Pliocene climate, processes and problems, Phil. Trans. R. Soc. A 13 January
2009.doi: 10.1098/rsta.2008.0205.
[5] U.S. Energy Information Administration, 2019, http://www.eia.gov/tools/a-z/.
[6] World Nuclear Association, 2019, http://www.world-nuclear.org/
[7] E. Cardis et.al: Cancer Consequences of the Chernobyl Accident: 20 Years On,
J. Radiol. Prot., 26, [2], (2006) 127-140
[8] www.scj.go.jp/ja///member/iinkai/.../3-250325-1-mn.pdf
Environmental consequences of the Chernobyl Accident and their remediation: Twenty years of experiences.
Translated by Science Council of Japan
[9] H. Habazaki, T. Tada, K. Wakuda, A. Kawashima, K. Asami, K. Hashimoto: Amorphous iron
group metal-valve metal alloy catalysts for hydrogenation of carbon dioxide. In C. R. Clayton,
K. Hashimoto eds. Corrosion, Electrochemistry and Catalysis of Metastable Metals and
Intermetallics, the Electrochemical Society, pp.393-404 (1993).
[10] White Paper of Electrical Energy Storage, by International Electrotechnical Commission
2011,http://www.iec.ch/whitepaper/pdf/iecWP-energystorage-LR-en.pdf.
[11] S. Meguro, T. Sasaki, H. Katagiri, H. Habazaki, A. Kawashima, T. Sakaki, K. Asami, K.
Hashimoto: Electrodeposited Ni-Fe-C cathodes for hydrogen evolution, J. Electrochem.
Soc.,147 (2000) 3003-3009.
[12] Koji Hashimoto, Eiji Akiyama, Hiroki Habazaki, Asahi Kawashima, Kazuo Shimamura,
Mitsuru Komori and Naokazu Kumagai, Global CO2 Recycling, Zairyo-to-Kankyo (Corros.
Engng, Japan) 45, (1996) 614-620.
[13] The Agency for Natural Resources and Energy in the Ministry of Economy, Trade and
Industry, Energy White Paper 2019
[14]The share of renewable energy in the electricity supply and demand in 2019 [Prompt Report]
of Authorized NPO, Institute for Sustainable Energy Policies on Feb. 18, 2020
https://www.isep.or.jp/archives/library/12464
[15] DIRECTIVE 2010/31/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of
19 May 2010 on the energy performance of buildings
