The Way to a Zero Emission SocietyYoichi Kaya
Research Institute of Innovative
Technology for the Earth (RITE)
2016.2.10
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Contents
1. Basic target in addressing climate change and CO2 zeroemission
2. Future revision of energy systems from view point ofdemand side
3. Primary energy of hydrogen
4. Decarbonization of fuels for power generation
5. CCS and its role
6. How to respond to requirement of future large scale
power demands
7. Closing remarks
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Basic target in addressing climatechange
Stabilization of global surface temperature
We should achieve this target regardless ofwhat temperature we set as the limit oftemperature rise in future⇒ How do we achieve this target ?

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Greenhouse effect of GHGs
1. Main 3 GHGs (CO2, CH4, N2O)
See next page
2. Montreal gases
Developed countries: scheduled not to use
these by 2020
Developing countries: scheduled not to use
these by 2030
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Greenhouse effect ofthe constant emission of GHGs
The amount remaining in the air
𝐴 exp −ɤ𝑡 =𝐴ɤ

１ − exp(−ɤＴ )𝐴→ ɤ (constant value)

The above result indicates that GHGs of shorter
life time will saturate at constant level
earlier andincrease in GHG effect → increase in temperature
will become to zero.
5About 3 main GHGs
1. Life time in the air
CO2 20~30% several thousand years
CH4
12 years
N2O 114 years
2. Their impacts on the global temperature
CH4, N2O: become zero unless large increasein their emissions
CO2: keeps the impact of temperature increasein the long run
CO2 zero emission is indispensable→
for stabilization of the global temperature in the long run
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Fig. Relation between cumulative CO2 emission and the rise inglobal surface temperature

Source: IPCC AR5 WG1, SPM, 2013

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Stabilization of the global surface temperatureand zero emission - suggestion by IPCC -Cumulative total emission of CO2 and global meansurface temperature response are approximately
linearly related( IPCC AR5 WG1 SPM p.27)⇒ To Stabilize the temperature requires to makeCO2 emission approximately zero.
Note: In the past anthropogenic absorption of CO2 wasalmost zero, so only CO2 emission was mentioned here.
If CO2 absorption is taken into account the target is tomake net anthropogenic emission of CO2 to be zero.
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CO2 anthropogenic absorption(1)-past exampleThe amount of CO2 absorption by forest（Kyoto protocol）
country

Amount of CO2 recognized ratio to the totalemission

Russia３３Mton CO2 /y

４．０％

Japan

３２

３．９

Canada１２

７．３

Note: only countries of which the recognized amount ofCO2 by forest absorption are larger than 1Mton/y9CO2 anthropogenic absorption (2)- actual measures being planned In IPCC scenarios satisfying 2 degree target
BECCS ( Biomass CCS) or AR (Afforestation)
will be introduced by 2100.
amount: 3.3 Gton C.
→ land area required: 380 ~ 700 Mha*(*source: Smith, P. et al: Nature C.C. vol.6,2016)
This is 30~50% of the entire arable land areain the world.
・・・low realizability due to competition with foodproduction
10Desirable direction of the world1.

Except CCS for fossil fuel use it is hard to realize large
anthropogenic absorption of GHGs in future.
↓2. Make efforts for realizing
zero anthropogenic emission of CO2↓
3. Make efforts for realizing zero emission of CO2
from fossil fuels( Regardless of how much the temperature target is )Note: CCS of CO2 from fossil fuels is to be included in the efforts for
reduction in CO2 emission.

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Structure of energy demand, Japan(2013)energy demand

non-E ind.

non-E transp.
non-E comm.
E and others。

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Details of non-electric energy
demands of Japan (2013)
ratio to the total demand
１．Industrial demand
35 ％２．Transportation demand 24
automobiles
airplanes
Ships
３．Residential andcommercial demand
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Note: demands for airplanes and ships are only those for domestictransportation. International transportation demand, particularly of
Ships are relatively large.

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Characteristics of energy demand
１．Demand can be divided into electric and non-electric demands.
２．More than 99% of non-electric demand are covered by fossil fuels.
３．CO2 in energy sector is emitted from fossil fuels.
４．Therefore CO2 zero emission should be covered by either of thefollowing three measures.
１）Coverage of non-electric demand by non-fossil fuels
２）Substitution of fossil fuels for power generation by non-fossilfuels
３）introduction of CCS into fossil fuel fired power plants５．Fossil fuels occupy more than 80% of the world primary energy.
Since realization of CO2 zero emission is a drastic revolution ofenergy systems, we have to expect that it takes a long time.
⇒ necessity of step by step approach ( to be described later )14

Non-fossil fuels substituting fossil fuels
Candidates are:１）bio-fuels
First generation ーfood based
Second generationーnon-food based（cellulose)２）hydrogen３）electric power
2) 3) are secondary energies, therefore what are
their primary energies is the key concern.
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Investigation of non-electric industrial
demand
1. Non-electric industrial demands are mainly
direct heating,steam and/or hot water generation and etc.
Temperature ranges between several tens andseveral thousands degrees in Celsius.
2. These demands may be covered by electric power,hydrogen or bio-fuels. Which is appropriate depends
upon demands ( and processes ) and further
investigation is indispensable.

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Future non-electric transportation fuels
1. Automobiles
Electric power（EV), hydrogen（FCV) are applicable to automobiles.
First generation biofuels are already utilized . ( Their neat use is still a matterof investigation )About second generation biofuels are to be investigated including thetransformation into hydrogen.
2. Airplanes
1) Application of second generation biofuels are now at the stage of R&D.
2) Electric power: may be limited due to available batteries.
3) Hydrogen: may be applicable but to be investigated.
3. Ships
1) Biofuels: may be utilized but to be investigated.
2) Electric power: limited due to available batteries.
3) Hydrogen: probably not applicable due to the size of turbines.

17Future treatment of non-electric
residential and commercial demands
1.Non-electric demands are the following types.
1)air conditioning 2)water heating 3) cooking
２．The temperature range of air conditioning andwater heating is lower than 100℃, and they can besupported by heat pumps operated by electricpower.
３．Theoretically cooking can be managed byelectric power including IH(Inductive Heater).
However how to deal with traditional cooking suchas those using blaze are to be investigated.
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On primary energy for hydrogen
１．There are 3 choices.
１）Electrolysis of water２）Thermo-chemical cracking of water via nuclear
heat ( high temperature gas reactor )３） Use of fossil fuels for cracking of water with CCS
２．There are various constraints in choices 2) and 3).
Rather we should choose 1) with the condition ofutilizing low carbon electric power.
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＜Future of hydrogen production＞
Electrolysis of waterElectrolysis of water
By small PV

Utilization of renewables inremote area(→Ｅ．Ｐｏｗｅｒ）→hydrogen ( longdistance transportation)

Artificial photosynthesis (R&D)

Promotion of use ofsmall PV for electrolysis

Promotion of thesystemwater cracking
directly bysunlight20

Non fossil fuels for power generation(1)- basic understanding 1. About 70% of fuels for power generation are fossil fuels.
2. For decarbonization of fossil fuel plants introduction of
CCS is indispensable.
3. At present the following non carbon energies are used:
1) nuclear power2) renewables
4. Expansion of nuclear power more than several tens % of
the total power is not easy in most countries, and thechoice is then mostly expansion of renewables.

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Non fossil fuels for power generation(2)- expansion of renewables 1.Irregular fluctuation of outputs taken into
account either of the following choices areindispensable.
choice 1: introduction of fossil fuel power plants with CCS
choice 2: introduction of large scale storages
2. Taking the limitation of introducing CCS into account we shouldmake more efforts for R&D of choice 2 .
1) large scale batteries ( NaS batteries etc.)
2) development of chemical storage systems
Ex. Dimethyl ether (DME) : total efficiency 50~60%
energy density: almost 10 times larger than those of batteriessource: Gencer,E. et al, Energy Policy, 88, Jan 201622

Fossil fuel fired plants and CCS
1. Introduction of huge amount of renewables
into the power grid requires the facilities toadjust demand-supply balance of electricpower.
Fossil fuel fired plants and power storages
have the ability for this adjustment.
2. In the future zero emission society fossil fuelfired plants can be utilized only with CCS.
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CCS（CO2 capture and storage)
1. History of CCS
１）It has been utilized in the form of EOR(Enhanced Oil Recovery )mainly in USA.
２）In 1996 CO2 accompanied by natural gas fromSleipner gas field in North sea was stored in
the underground of sea bottom. ( 1Mton CO2/year)
2. Future direction
CO2 captured at fossil fuel fired power plants→stored in the underground.
This will make the plants to be zero emission plants.
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The structure of CCS system
Trans.

CaptureInjection
海上施設
より圧入

地上施設
より圧入分離・回収
パイプライン輸送

パイプライン輸送
大規模排出源

不透水層

CO2

不透水層
CO2

陸域
帯水層
海域
帯水層

Detailed picture of aquifer
CO2 is stored in the pore.

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Removed by CCS

エネルギー起源CO2排出量・削減量 [GtCO2/y]

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発電部門：CCS 17%

ベースライン排出量：
57GtCO2/yr

発電部門：再生可能14%50

発電部門：原子力 15%40
発電部門：効率向上、化石燃料間転換 11%30

発電以外のエネルギー転換部門 5%20

民生部門 12%
世界半減時排出量：
13GtCO2/yr

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運輸部門 9%
産業部門 17%

02010

2015

2020

2025

2030
西暦年

2035

2040

2045

2050

CO2排出量Fig. The scenario for halving CO2 emission by 2050
(via RITE DNE21+ model )26

CCS: merits and problems
１．meritCO2 zero emission plant can be realizable byemploying CCS.
２．problems１）At present CCS is relatively expensive：
several tens dollars/ton CO2 or more
→ power price will be elevated at leastby several cents / kWh.
２）Public acceptance around storage sites.
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Possibility of drastic increasein future electric power demand
As mentioned before non-electric power demands

will be in future covered by electric power,hydrogen, and/or biofuels.
It is highly probable that hydrogen will in future be
produced by electric power ( electrolysis of water ).
→ electric power demand +electric power replacing non electric demand +electric power producing hydrogen

Drastic increase in electric power demand in future28

Response to drastic increasein future power demand
1. Mid term future1) renewables + large-scale power storage2) large-scale concentrated solar power (CSP)
2. Long term future1) Space solar power systems (SPS)
2) Nuclear fusion systems

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Fig. Image of space solar system (SPS)30

Main features of space solar system(SPS)
１．Due to its location on stationary orbit of
38,000km far from the earth the relative location ofSPS and the rectenna on the earth is fixed.
２．Since the power from SPS will be transported by
microwave to the earth the power will be received
with little turbulence by clouds. (lower than 20GHz)
３．The key is how to reduce high costs of facilities,transportation by rockets and of construction ofthe system in the space.
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Fig. Principle of nuclear fusion

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Features of concentrated solar
power(CSP)
１．Power output can be stabilized due to heatstorage.
２．Basic technologies are already developed. More than 3 GW
plants are in operation around the world.
３．Power produced in desertsーdry area→
long distance transmission → demand area
Large scale power generation /transmission can be realized
in the above scheme.
Example：Dessertec plan imagined in the early stage of 21 century
Sahara desert CSP → DC transmission → Europe
In the plan about 1/15 of the total European demand will becovered. It was however suspended due to political instability
around Sahara area.

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Fig. The area to be covered by CSP：In case of Sahara desert（from Dessertec plan）

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MW36

< power generation technologies>
Fossil fuel/CSP
Development ofHigh eff. fossil
fuel fired plants

SPS
Basic R&D
Nuclear power

R&D of 4thGenerationreactors

Present

More use of CSP

Development of large
scale CSP
Utilization of desserts

Use of combined fossil fuelfired and CSP plants

Introduction of CCS

More CCS for fossil fuel firedplants

Realization of zero
emission plants with CCS

Experiment of space
Power transmission/R&D

Installment of SPS

Experiment of nuclear
fusionRealization of nuclear
fusion power plants

Realization ofNuclear fuel cycle

Broad use ofhigh breeder reactors

Low carbon stage（2015~2050)

Zero carbon stage37(2050~2100)

Final remarks
１．Ultimate goal in addressing climate change：
Achievement of net zero anthropogenic emission of CO2
２．We should make efforts for 1) decarbonization of nonelectric industrial demand, 2) decarbonization oftransportation demand , and 3) decarbonization of power
generation.
３．The road map from present to net zero emission stage via lowemission stage should be established.
４．Key middle term technologies include large scale renewables withlarge scale storage systems, the second generation biofuels and large
scale concentrated power systems (CSP).
５．Key long term, large scale technologies include space powersystems (SPS) and nuclear fusion which should be developed via
international collaboration.
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