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国立環境研究所

地球システム領域

n et al.: The 5 arcmin resolution annual HaNi dataset from 1860 to 2019ǰśæĆƠɌ ǣ 52 Ł ɄƱ 26 ț02014 ț16 Ğ33

単位面積あたりの窒素投入 (gN/m2/年 )news & views

AMMONIA SYNTHESIS

Recycling fertilizer






AMMONIA SYNTHESIS


/1
%+.

Efforts to electrochemically
produce ammonia have mainly focused on dinitrogen as a feedstock.
Now, an *
electrocatalyst
composed of Cu embedded in an organic molecular solid is designed, which efficiently and nitrate ions to ammonia, paving a way to nutrient recovery and recycling.
selectively converts



Furthermore, most metallic surfaces
supplies. This nitrate, long considered to bemmonia is
critical to global food
facilitate conversion to N2 rather thana toxic water contaminant, is also a possible
security due
to its application as a
resource to be recovered and used to produce NH3. Lu, Wang and colleagues have madefertilizer. In
the future, it may also
ammoniabyelectrochemical
reductionfind use as an energy
carrier.
However,significant
strides in these two challengesnews & views

Recycling fertilizer

韓国&日本

Efforts to electrochemically produce ammonia have mainly focused on dinitrogen as a feedstock. Now, anelectrocatalyst composed of Cu embedded in an organic molecular solid is designed, which efficiently andselectively converts nitrate ions to ammonia, paving a way to nutrient recovery and recycling.

Lauren F. Greenlee

A34

農耕地当たりの窒素投入量
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農耕地当たりの窒素投入量

Lauren F. Greenleesupplies. This nitrate, long considered to bemmonia is critical to global fooda toxic water contaminant, is also a possible
security due to its application as aresource to be recovered and used to produce
fertilizer. In the future, it may alsoammonia by electrochemical reduction
find use as an energy carrier. However,(Fig. 1). However, there has been only limited
energy-efficient and environmentally
success in controlling reaction pathways tofriendly alternatives to the Haber–Boschfavour ammonia production over competingproduction of ammonia remain a critical
reactions such as hydrogen evolution.
need. Low-temperature electrochemical
GDPper capita(USドル/年)
Writingin Nature Energy,
Jun Lu, Haihui
approaches powered by renewable energy
could eliminate the use of fossil fuels and the Wang and colleagues in China, Germany anddischarge of CO2 emissions during ammonia the USA now report an electrode-supported
crystalline Cu–ligand electrocatalyst
production. To date, electrochemicalthat produces NH3 from nitrate at a highproduction of ammonia has mainly focusedon direct synthesis from N2. However, thisproduction rate and selectivity, effectivelysuppressing hydrogen production1.
approach is challenging because breaking
the triple bond in N2 is difficult and because
Typically, the practical voltages
needed for nitrate reduction on metallic
most electrocatalysts more easily promote
heterogeneous electrocatalysts are more
the hydrogen evolution reaction.
negative than the voltages needed for the
Anthropogenic forcing of nitrogen intohydrogen evolution reaction, causing low
the environment through crop fertilization
Faradaic efficiencies for nitrate reduction.
results in nitrate (NO3–) in our water

Furthermore, most metallic surfaces
facilitate conversion to N2 rather thanNH3. Lu, Wang and colleagues have madesignificant strides in these two challenges
through their electrocatalyst design,demonstrating Faradaic efficiencies
between 60% and 86% and NH3 production
rates between approximately 400 and
900 μg h–1 cm–2, as a function of applied
voltage. Electrochemical hydrogen evolution
is suppressed to less than 0.5% of theFaradaic current. In comparison, recent
work on Li-mediated conversion of N2 toNH3 achieved a Faradaic efficiency of 35% ata production rate of 1,836 μg h–1 cm–2 (ref. 2).
Lu, Wang and colleagues design acatalyst that features Cu embedded35
in acrystalline organic molecular solid. The
coordinated Cu active site can reduce nitrate
at more positive potentials than hydrogen
evolution. The positive potential reduces

A(Fig. 1). However, there has been only limited through their electrocatalyst design,energy-efficient and environmentally
100200300
400 0 500
200400500
600
success
in controlling100
reaction pathways
to300 demonstrating
friendly alternatives to the0 Haber–Bosch
Faradaic efficiencies
favour ammonia production over competingproduction of ammonia remain,)!$a critical[YWVZX 60% and 86% and NH3 productionbetween
kg N/hareactions such as hydrogen evolution.
need. Low-temperature electrochemical
rates between approximately 400 and–1ƨ byŸɯƿƧŅXȝĊW<BjțTțXǱǊ¢XWriting
in Nature
Energy,JunLu,Haihuiapproaches powered
renewable energy
900 μg h=țɄċǫT
cm–2, as a function of applied
China, Germany
and voltage.
could eliminate the use offossil fuels
and the Wang and colleagues inElectrochemical hydrogen evolutionțXǱǊȅȘʂXȓɧ0OECD
EnvironmentalDatabase,2013 Ed.=hŕȴ1discharge of CO2 emissions during ammonia the USA now report an electrode-supported
is suppressed to less than 0.5% of thecrystalline Cu–ligand electrocatalyst
Faradaic current.
comparison, recent
production. To date, electrochemical
西尾In(2014)
that produces NH3 from nitrate at a highwork on Li-mediated conversion of N2 to
production of ammonia has mainly focusedon direct synthesis from N2. However, thisproduction rate and selectivity, effectively
NH3 achieved a Faradaic efficiency of 35% at
1suppressing hydrogen production
approach is challenging
because breaking
a productionrate of 1,836 μg h–1 cm–2 (ref. 2).
.
rVUSYɬƝǱǊʂ>!1X±ǕY)  țW<BjǱǊ
the triple bond in N2 is difficult and because
Typically, the practical voltages
Lu, Wang and colleagues design a
ɜɚTVOR9j*ȅȘʂn)ȭʀ)Âǰ\oșTKXǛW
needed for nitrate reduction
on metallic
catalyst that features Cu embedded36
in amost electrocatalysts
more easily promote
heterogeneous electrocatalysts are more
crystalline organic molecular solid. The
the hydrogen evolution
reaction.
ɂBLȓɧnūFR9j*KXǛYŸW
negative than the voltages needed for thecoordinated Cu active site can reduce nitrate
Anthropogenic forcing of nitrogen into
2$%ÄÅÇhydrogen evolution reaction,
causing low
at more positive potentials than hydrogen
the environmentÃɕǒWgjđǲǱǊĪǺS8j*
through crop fertilization
Faradaic
efficiencies
fornitratereduction.
evolution. The positive potential reduces
results in nitrateaIǳɥEkjXY)(NO3–) in our water  țXɬƝǱ ɔÏ)Ï)..ÏćVUŸ

Figure 12. Relationships between total N inputsTian(excludingdeposition; a–c) or the N input rate (d–f) and GDP per capita on cropland,
et al.N(2020)pasture, and rangeland, respectively, within each of 18 regions during the period from 1961 to 2019. The lines were fitted using the generalized
additive models. For visual clarity, not all region names are shown in each panel. The 18 regions are as follows: the USA (USA), Canada(CAN), Central America (CAM), northern South America (NSA), Brazil (BRA), southwestern South America (SSA), Europe (EU), Northern
Africa (NAF), Equatorial Africa (EQAF), Southern Africa (SAF), Russia (RUS), Central Asia (CAS), the Middle East (MIDE), China (CHN),
Korea and Japan (KAJ), South Asia (SAS), Southeast Asia (SEAS), and Oceania (OCE).

下水の反応性窒素リサイクル
Fossilfuels

CO2N2NH3

下水の反応性窒素リサイクル
Ǌʂ>  nǷ;j)íŅ)uW.¡ XɔȦɂX¸ïfr¢ǁ¢)Ȗɖ)x.SY)Âǰ\oFossilVUXŅőÅǁXºǃ>ƥŃ¿F)KXfuels

CO2N2NH3 țW2ȝet al., 2006). According to Herridge et al. (2008), thetions in fertilizer application
rate at farm-level Ÿ¯>ȝĊS8jCT=h)and subnaǜA)=P)KXǛXǱǊXÞł>)Â
ĊøĨXƙŝWgjºǃ=hXƩėXɉ1 inglobal legume crop BNF90億kg-N
was aroundtional scales. A continuous
survey of crop-specificfertilizerǰ\oșǱǊʂWȬFRƓE9CTS8ĮWìHjÛɿɶŦËšʆ30¤¾2ƙin 21.5US Tg N yr
90億kg-Nin USj*CkYÂǰȊƬXÞłWɕǒǭXÞŝšʆ3Tɺ÷1>ǺdhkL
*
2005. As the HaNi dataset was developed to serve as inand manure use at subnationalscale, developmentof dył>ƓE9CTnȧµFR9j*¯bW ƙŝšʆWƈāFR)ÁɣŅY)Ʃű
namic global land use data, and crop rotation maps with moreputs for terrestrial biosphere models, N components likeÂǰ\oșǱǊWȬFRKXǛǱǊXÞ¢z.~¢nƽǮF)ƙ
precise regional patterns
are important for improving
the resBNF, which are simulated using different mechanisms
ł>ŀ9)u.p)u.ŝºǃTȺ¶ɰ¿0pu|XȢƵVU1>ƵGR9j=)KX<KkX8jǭ¾olution and accuracy p)pv)r)t|ĄʊŅ)of geospatial fertilizer and manuredata.
by models, were not included. Nevertheless, a related
Additionally, considering fertilizer and manure2 application
agricultural BNF database will be very meaningful for
deepening our understanding of global N cycling andtiming in the data is also important for agricultural nutrientinon
US
24億kg-N in US
ding N deposition; a–c)serving
or the Nasinput
rate (d–f)for
andecosystem
GDP24億kg-N
per capita
cropland,management, which relies on the efforts and investigations
a benchmark
models.
Toacions during the period from1961 to2019.
Thefuture,lines wereusing
generalized
complish
this,in themorefitted
efforts
are therequired
inregarding the fertilizer and manure application behavior atFig. 1 | Existing and possible future nitrogen cycles for ammonia production and nutrient recovery. Ammonia nitrogen is produced synthetically through theFig. 1 | Existing and possible future nitrogen cycles for ammonia production and nutrient recovery. Ammonia nitrogen is produced synthetically through theare shown in eachpanel.
The
18
regionsareas
follows:
theUSA(USA),
Canadamultiple spatial
scales.
developing long-term spatial and temporal distribution
Haber–Bosch process and used for crop fertilization. Nitrogen in crops then feeds livestock, feeds humans or is lost through runoff (yellow arrows). These
Haber–Bosch process and used for crop fertilization. Nitrogen in crops then feeds livestock, feeds humans or is lost through runoff (yellow arrows). Thesenitrogen sources could be recovered during water and wastewater treatment (black arrows). With a Cu–ligand electrocatalyst design, researchers have made anitrogen sources could be recovered during water and wastewater treatment (black arrows). With a Cu–ligand electrocatalyst design, researchers have made aa (NSA), Brazilsignificant(BRA),
southwesternSouth
America(SSA),
Europe(EU),Northern
maps
ofvarious
crops
such
as
cover
crops
andlegumeGreenlee(2022)
inNature
EnergyGreenlee(2022)
advance toward electrochemical nitrate reduction to ammonia, which could allow recovery of nutrients.
significant advance toward electrochemical nitrate reduction to ammonia, which
could allow recoveryof nutrients.in Nature Energya (SAF), Russia (RUS), crops,Centralwhich
Asia (CAS),
theMiddle
East(MIDE),China(CHN),
are currently, to our knowledge, not avail5 Data availability
ia (SEAS), and Oceaniaable(OCE).
at the global scale.
The History of anthropogenic Nitrogen inputs (HaNi) dataset
For future data improvements, we call for advanced NșǱǊXȅȘʂ>ȭʀǱǊT_`ȌG=Recovered N resources

Recovered N resources

N2

N2Crops

Crops

Lost N resources+Nutrient recovery throughelectrocatalytic reduction:
NH3
NO3–Water andwastewater
treatment

RunoffLivestock

NO3

Nutrient recovery throughelectrocatalytic reduction:
NH3NO3–NH3

HumansWater andwastewater
treatment

RunoffLivestock

Sources of N

NATURE ENERGY | VOL 5 | AUGUST 2020 | 557–558 | www.nature.com/natureenergy

Lost N resources+––NO3

NH3

Humans

Sources of N557

NATURE ENERGY | VOL 5 | AUGUST 2020 | 557–558 | www.nature.com/natureenergy

557

仁科一哉

国立環境研究所

第6次エネルギー計画: NH3燃焼利用

37

第6次エネルギー計画: NH3燃焼利用38

Type20

Import (for Fuel)
ImportDomestic production

CanadaBlue Ammonia

50Saudi Arabia
15排出10NOx
NH3latDomestic NH3 consumption [Tg-N/Year]25

地球システム領域

US

火力発電＋CCS

Oman
05South Africa

Green Ammonia
再生可能エネルギー

Australia−50020192030
Year

2050

色々なアンモニア？！

0100

200300long39

水質改善：瀬戸内海の事例

ブラウン/グレイ 化石燃料で製造
イエロー

原子力エネルギーで製造

ブルー

化石燃料+CCS（低炭素）で製造グリーン

再生可能エネルギーで製造

ホワイト

リサイクル回収されたアンモニア

神戸新聞NEXT

Hayashi et al. (2021) in EP仁科一哉

国立環境研究所

地球システム領域

環境の保全と創造に関する条例

下水処理場の季節別運転の採用

先進・ユニーク条例

表と生物の関係はて︑海域の全窒素濃度及び
全基 水 あ る (2020)
限 水 り
素 プ のし 月 号 県 /L /L自治体法務研究
ん・ ロ 栄 ま ま 25 ︵ 告 と ︑ に 産 り こ 値 質 濃
全 セ 養 た し 日 令 示 定 全 全 用 ︑ と ︶ 目 度
り 全国（世界？）初の環境基準の下限値
ス 塩 ︑ た ︶ 和 第 め り 窒 水 そ が を 標 にん ︑ の 海 ︒
で 元 ５ ︑ ん 素 基 の 必 設 値 関濃 全 循 域 ︵公 年 １ 兵 0.02 0.2 準 値 要 定 ︵ し表度 窒 環 で ︶ 布 10 ３ 庫 ㎎ ㎎ を を で す 下 ︑望ましい濃度の範囲（水質目標値（下限値）と環境基準値との間の濃度）︵処 転 に しい 工 陸 ま 本 し
４１
本日の発表のまとめ理 ︶ 排 て 家 ︶ま 場 か す 県 ︑ 条場
で本運用を実施しています︒
今後︑こを行っており︑本県の播
磨灘
では３
下
水

物
が育ち︑棲むりん
などの栄
養

水の窒
素
濃度を引き上げる
運
転︵管理
運いる
下
水処
理
場
では︑11月〜４
月の冬
季

庭等の生
活に伴い排出される
汚水を処理す︒
︵図５︶

・
事業場
︑
︵３︶
農地・山林に着目してらの供給源として︵︑１︶
下
水処
理場
︵︑２︶

︒
瀬戸
内
海で窒
素やりんを増やす
ための給源として農地

降雨等により︑源﹂と比べると
コ

では︑主に以下３つの取組を検討してい

豊
かで美し
い
瀬
戸
内
海を再生
す
る
た
めに人
為的に
制御︵３︶
農地
・山林

例
改
正により
定め
ら
れ
た
水
質
目
標を達
成

政策/開発が必要とされている。

豊かで美し
い

５課
題と展

待されます︒

ることで豊かでます︒
森
里
川
海組を促す
施
策
を等をまとめましました︒
豊かな生
態
系を維持す
る
た
めに︑一に実施していきます︒

質
目
標
値を定め︑それに向けた施策を順応
的が生息できる
栄
養塩
濃度を維持す
る
た
めに水す
な
わ
ち︑
海域の水質を保全しつつ︑
生
物

供給のた
めの基給に係る
ガ
イ
ド

昨
年度
︑
﹁
工場・供給される
方法

条
例
改
今後、日本も廃棄窒素削減にむけた取り組正をみを加速させる必要がある。
基にそのために反応性窒素負荷または環境リスした取クを効率的に逓減させるための窒素管理の組
下
水処
理場
での管理
運転の拡
大定の窒素・りん濃度を保つための仕組みとしその濃度が保持されるよう努めるものと定め保す
る
上で望ましい栄
養塩類の濃度を定め︑好な水質を保全し︑かつ︑
豊かな生
態系を
確の実
施に当たり︑
瀬戸
内
海の海域におけ
る
良

豊かで美し
い
瀬戸
内
海の再生に向けた施策︵切 ４な ︶管 瀬
すでに条例に先立って
理 戸
内︵
冬季に下水放流水の窒素・第 海リンの除去を行わず栄養塩の１ の４ 海不足を補うといった下水終０ 域
条 に末処理場の「季節別運転管の お理」が試みられていた。
５ け︶ る栄
養塩
類 時事通信記事よりのhttps://www.jiji.com/jc/article?k=2020102400413&g=soc&p=20201024ax07S&rel=pv
適反映
するものとしています︒

究を行い︑これにより得られた
知
見を施
策にる
栄
養
塩類の適
切
な
管理に関す
る
調
査
及び
研

関す
る
研
究︑
その他の瀬戸内
海の海域におけ

栄
養
塩類の実
態の調
査
︑
生物に与える
影
響に関係
機
関と連携
し︑
瀬戸
内
海の海域における

複雑であり︑未解
明な
要
素もある
ことから︑

水から
有
害物
質事
業場があり
ま海を埋め
立て︵２︶
工
場
・事
業

域への栄
養分のの管理運
転実施