JP3891544B2 - Hydrogen fermentation bioreactor with built-in fuel cell - Google Patents

Hydrogen fermentation bioreactor with built-in fuel cell Download PDF

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JP3891544B2
JP3891544B2 JP2001082208A JP2001082208A JP3891544B2 JP 3891544 B2 JP3891544 B2 JP 3891544B2 JP 2001082208 A JP2001082208 A JP 2001082208A JP 2001082208 A JP2001082208 A JP 2001082208A JP 3891544 B2 JP3891544 B2 JP 3891544B2
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hydrogen
fuel cell
bioreactor
gas
phase part
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JP2002280045A (en
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嘉之 上野
昌浩 多田羅
雅史 後藤
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Kajima Corp
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Kajima Corp
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    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12MAPPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M21/00Bioreactors or fermenters specially adapted for specific uses
    • C12M21/04Bioreactors or fermenters specially adapted for specific uses for producing gas, e.g. biogas
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12MAPPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M21/00Bioreactors or fermenters specially adapted for specific uses
    • C12M21/02Photobioreactors
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12MAPPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M43/00Combinations of bioreactors or fermenters with other apparatus
    • C12M43/08Bioreactors or fermenters combined with devices or plants for production of electricity
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E50/00Technologies for the production of fuel of non-fossil origin
    • Y02E50/30Fuel from waste, e.g. synthetic alcohol or diesel

Description

【0001】
【発明の属する技術分野】
本発明は燃料電池組込み型水素発酵バイオリアクターに関し、とくに発電を行うと共に微生物の水素生成効率を向上させることができる燃料電池組込み型水素発酵バイオリアクターに関する。
【0002】
【従来の技術】
水素は、燃焼した場合にも炭酸ガスを放出しないクリーンなエネルギー源であるばかりでなく、単位重量あたりの発熱エネルギーが石油の三倍もあり、燃料電池に供給することにより電気エネルギーとすることもできる。燃料電池は、ガスタービンやガスエンジンに比し発電効率が高いので、その分二酸化炭素の発生が少ない。また燃料電池は、NOx、SOx、煤塵の発生が殆どなく騒音、振動も少ない発電システムであり、環境対策のうえから普及が期待されている。
【0003】
図3を参照して、燃料電池の原理を本発明の理解に必要な程度において説明する。燃料電池10は、基本的には水素極(又は燃料極)15と酸素極(又は空気極)16とにより電解質17を挟持した構造であり、水素と酸素とを電気化学的に反応させて直流電力を発生する。交流電流を取り出す場合は、直流電力を交流電力に変換する電力変換装置を設ける。同図は、電解質17としてリン酸水溶液を用いたリン酸型燃料電池における電気化学反応の原理を示す。水素極15は通気性を有し、水素極15の電解質17と反対側面にある水素吸入口11から供給された水素は水素極15内を拡散して電解質17側に到達する。水素極15の電解質側面には白金粉末が分散されており、白金の触媒作用により水素ガスは下記(1)式に示すように水素イオン(H+)と電子(e-)とになる。電解質17は、イオンを通すが電子を殆ど通さない性質を有するものである。このため、水素イオンは電解質17を通過して酸素極16へ向かうのに対し、電解質を通過できない電子は外部回路18を介して酸素極16へ向かう。供給した水素のうち水素極15で未反応のものは、未反応水素排出口13から放出される。
【0004】
酸素極16も通気性を有し、電解質側面に白金の触媒層が設けられている。酸素極16の電解質17と反対側面にある酸素吸入口12から供給された酸素(又は空気)は、酸素極16内を拡散して白金触媒層に達し、白金の触媒作用により、電解質通過後の水素イオン及び外部回路通過後の電子と結合して水(H2O)となる((2)式)。供給した酸素のうち酸素極16で未反応のものは、未反応酸素排出口14から放出される。燃料電池の全体の反応は(3)式のように表すことができる。実際の燃料電池では、大きな電圧を得るため、図3に示す構造の最小単位のセル(単セル)をセパレータにより直列に積層したスタック(stack)として用いる。リン酸型燃料電池のほか、溶融炭素塩型燃料電池、固体酸化物型燃料電池、固体高分子型燃料電池等が開発されているが、これらの燃料電池の構造も原理的には図3と同様のものである。
【0005】
【化1】
水素極での反応 H2→2H++2e- ……………………………(1)
酸素(空気)極での反応 2H++(1/2)O2+2e-→H2O ……………(2)
全体の反応 H2+(1/2)O2→H2O ……………………(3)
【0006】
燃料電池に用いる水素は、ナフサの熱分解や水の電気分解等により製造することができる。しかし、この水素製造方法は製造過程において化石燃料を消費するため環境汚染を招く問題がある。また、化石燃料の使用は削減することが強く望まれている。
【0007】
化石燃料に依存しない水素生産方法として、微生物を利用した水素生産が注目されている。その一例は、メタン発酵によってメタンガスを生成し、生成したメタンガスを改質器に通して水素に改質するものである。メタン発酵は、複数の異なる微生物群(以下、メタン発酵微生物群ということがある。)による共同作業で有機性基質をメタンガスに変換するものであり、各種の有機性廃水や生ごみ等を材料とすることができる。但し、メタン発酵で生成したメタンガスを水素に改質する改質反応は吸熱反応であり、改質器内の加熱に外部からのエネルギー供給を必要とするため、省エネルギーの観点から問題点を残している。
【0008】
これに対し、光合成微生物や嫌気性微生物等の水素生成微生物によって、改質の必要がない水素ガスを直接生成する方法が開発されている。光合成微生物は、光エネルギーを原料に光合成を行い、そこで得られる還元力を用いて水の分解を行い水素を発生するものである。また嫌気性微生物は、主に発酵で生じる還元力により水素ガスを発生するものであり、純粋菌を使用する場合とミクロフローラ(以下、混合微生物群ということがある。)を使用する場合とがある。水素生成微生物による水素生成と燃料電池との組み合わせによる発電は、化石燃料に依存せず、しかも二酸化炭素を発生させない、環境対策の面からは究極の発電方法といえる。
【0009】
【発明が解決しようとする課題】
しかし、従来の微生物による水素生成は、必ずしも安定的・効率的に水素を生産することが難しい問題点がある。水素生成効率を下げる原因の一つは、微生物による水素生成効率が、微生物の種類に関わらず、菌体外部における水素分圧により影響を受けることにある。すなわち、微生物による水素生成では反応が進行するに従って気相及び液相の水素分圧が徐々に上昇するが、菌体外部の水素分圧が高くなると水素生成微生物の水素発生能力は著しく低下してしまう。微生物による水素生成は、菌体内に生成した還元力が酵素ヒドロゲナーゼによってプロトンを還元した結果、水素ガスとして放出されることにより起こる。水素分圧が高い状態では、この還元力が水素以外の他の還元的物質の生産に利用されてしまうため水素生成効率が低下する。具体的には、純粋菌の場合は菌の代謝自体が水素生成からエタノールや乳酸などの他の還元的物質の生成に反応が移行してしまう。また混合微生物群の場合は、エタノールや乳酸などの生産菌の優先化を引き起こし、これらの生成菌による水素消費により外部に取り出せる水素の生成効率が低下する。
【0010】
逆に、水素分圧が低い場合は、何れの微生物の場合も反応が水素の放出に傾くため、水素生成効率は増加する。この微生物の代謝に関する説明は、図4に示す一般的な代謝マップを用いることで説明することもできる。乳酸やエタノールの生成は還元力の消費であり、これらの生成は結果的に水素生成の妨げとなる。図4の代謝マップから、水素分圧が水素生成反応の進行に影響する重要な因子であることが示される。
【0011】
従来、水素発酵バイオリアクターの気相及び液相の水素分圧を下げて水素生成の効率を高めるため、バイオリアクターの気相からの水素の除去、アルゴンガス等の不活性ガスのリアクター液相中への連続的バブリング等の方法等が行われている。しかし従来の方法は何れも、水素分圧を下げるためにエネルギーや不活性ガス等の物質を供給する必要があり、コストが嵩む問題点がある。また、外部からのエネルギー供給は、微生物による水素生成と燃料電池との組み合わせによるシステム全体の発電効率の点からも問題がある。
【0012】
そこで本発明の目的は、燃料電池の水素消費を利用してバイオリアクターの水素分圧を低く保つ方式の燃料電池組込み型水素発酵バイオリアクターを提供することにある。
【0013】
【課題を解決するための手段】
図1の実施例を参照するに、本発明の燃料電池組込み型水素発酵バイオリアクターは、水素生成微生物が接種された液相部3と液相部3で生成された水素ガスが集まる気相部2と液相部3を攪拌する攪拌装置6とを有するバイオリアクター1、水素ガス26と酸素27とを吸入して発電する燃料電池10、バイオリアクター1の気相部2と燃料電池10の水素吸入口11とを連通する燃料流路22、及び燃料電池10の酸素吸入口12に接続した送気器20を備え、電力負荷に応じて消費される酸素27を送気器20により燃料電池10へ供給し、燃料電池10における水素ガス26の消費に応じた水素吸入口11の水素分圧の低下によりバイオリアクター1の気相部2から燃料電池10へ水素ガス26を吸入し、燃料電池 10 の出力電力を攪拌装置6及び/又は送気器 20 に供給してなるものである。
【0014】
好ましくは、燃料電池10を固体高分子型燃料電池とする。更に好ましくは、燃料流路22に脱硫器23を設ける。
【0015】
【発明の実施の形態】
図1に示すバイオリアクター1は、メタン発酵微生物群が接種され、有機性基質を前記微生物群中の水素生成微生物の増殖時間より長く且つ前記微生物群中の水素消費微生物の増殖時間より短い水理学的滞留時間に亘り滞留させつつ通過させ、前記有機性基質の通過に抗してバイオリアクター中で増殖する微生物群により水素ガスを生成させるものである。メタン発酵では、先ずメタン発酵微生物群中の水素生成微生物により有機性基質が酸化されて有機酸、水素、二酸化炭素等にまで分解されることが知られている。しかし、生成された水素はメタン生成菌等の他の水素消費微生物によって直ちに消費される中間代謝産物であり、通常のメタン発酵では水素ガスが系外へ放出されることはない。本発明者は、メタン発酵微生物群を接種したバイオリアクターにおける有機性基質の水理学的滞留時間(以下、HRTということがある。)を短くすることにより、水素ガスを取り出せることを実験的に見出した。
【0016】
図2は、完全攪拌混合型のバイオリアクター1の液相部3にメタン発酵微生物群を接種し、有機性基質のHRTを徐々に短くしていきながら単位容積あたりのメタンガス(CH4)、有機酸及び水素ガス(H2)の生成量を計測した実験結果を示す。同図に示すように、HRTを短くしていくとメタン生成菌がリアクター外へ流出し、有機酸生成量と共に水素の生成量が増加する。但し、メタン発酵微生物群中にはメタン生成菌以外にもホモ酢酸菌等の水素消費微生物が存在するので、生成した水素はそれらの水素消費微生物によって消費されてしまい、回収できる水素ガスの量はまだ少ない。更に有機性基質のHRTを短くし、メタン発酵微生物群中の水素生成微生物の増殖時間より長いが該微生物群中の水素消費微生物の増殖時間より短くすることにより、メタン発酵微生物群中の水素消費微生物をその増殖前にバイオリアクター1の外へ流出させ、バイオリアクター1内に水素生成微生物のみが増殖可能な環境を作り出し、単位容積あたりの水素ガス生成量を有機酸生成量より大きくすることができる。すなわち、HRTの短縮により液相部3における水素消費を最小限に抑え、気相部2において水素ガスを効率的に回収できる水素発酵バイオリアクター1とすることができる。水素生産に適するHRTは有機性基質の組成等により変り得るが、好ましくはHRTを0.01〜3.0日程度にまで短縮する。
【0017】
本発明は、バイオリアクター1の気相部2と燃料電池10の水素吸入口11とを燃料流路22により連通する。従って、バイオリアクター1内の水素発酵が進み、気相部2の水素分圧が燃料電池10の水素吸入口11の水素分圧に比し相対的に高くなると、燃料流路22を介して気相部2から水素吸入口11へ水素ガス26が流入する。燃料電池10をリン酸型燃料電池とした場合は、前記(1)式に示すように、水素吸入口11から進入した水素ガス26が水素極15内を拡散して電解質17側に到達し、水素イオンと電子とになる。更に水素イオンは電解質17を通過して酸素極16に至り、前記式(2)に示すように、酸素極16から電解質17に到達した酸素と結合して水になる。この水生成反応により、気相部2から流入した水素ガス26が消費される。
【0018】
従って、電力負荷に応じて送気器20から燃料電池10の酸素吸入口12へ酸素(又は空気)を送り込むことにより、前記式(3)に示す水生成反応を連続的に起こし、燃料電池10の水素吸入口11の水素分圧をバイオリアクター1の気相部2に比し低い状態に保ち、気相部2から燃料電池10へ水素ガス26を連続的に吸入することができる。また、外部回路18から電力を継続的に取り出すことができる。よって、バイオリアクター1の気相部2における水素分圧の上昇を抑え、気相部2の水素分圧を低く保つことができる。気相部2のガス分圧の低下は、液相部3のガス分圧の低下を引き起こし、液相部3に存在する水素生成微生物の水素生成を促進し、バイオリアクター1における高い水素生成効率を維持することができる。
【0019】
[実験例1]
バイオリアクター1の気相部2と燃料電池10の水素吸入口11とを燃料流路22で連通した場合におけるバイオリアクター1の水素生成効率を確認するため、図1に示す嫌気性バイオリアクター(連続反応装置)を用いて実験を行った。本実験では、メタン発酵微生物群として他のメタン発酵槽から採取したメタン発酵汚泥を用い、蒸留水1リットル中にKH2P04 1.5g、Na2HP04・H20 4.2g、NH4Cl 0.5g、MgCl2・6H20 0.18g、酵母エキス 5g、及びセルロースパウダー 10gが含まれる人工廃水を、有機性基質取入口4から連続的に流入させた。図中の符号5は処理液排出口を示す。バイオリアクター1の液相部3におけるセルロース含有量、C2〜C8の低級脂肪酸、TOC(全有機炭素)をそれぞれ経時的に測定し、生成したガスはpH3以下の水を用いた水上置換法で定量して組成をガスクロマトグラフTCD法で分析した。
【0020】
バイオリアクター1をpH7.4、温度60℃に保ち、先ずHRTを5日としてメタン発酵を行ってメタンガスの安定的な生成を確認したのち、HRTを徐々に短くしていったところ、HRTを0.5日とすることにより水素の生成が顕著に認められ、リアクター容積1リットルあたり30ミリモル/日(30mmol/l-reactor/day)の水素ガスを連続して生産することができた。発生したガスの組成は水素80%、二酸化炭素20%であった。この状態におけるセルロースから水素への変換効率(水素生成効率)はヘキソース1モルあたり約1モル(1mol/mol-hexose)であった。
【0021】
水素の連続的生産を確認した後、バイオリアクター1の気相部2に設けた水素取出口21と固体高分子型燃料電池ユニット10の水素吸入口11とを燃料流路22で接続し、燃料電池10の酸素吸入口12に接続した例えばポンプである送気器20により空気を吹き付けたところ、燃料電池10で発電が起こった。燃料電池10の発電時における水素生成効率は、ヘキソース1モルあたり約2モル(2mol/mol-hexose)となり、燃料電池10を接続する前のヘキソース1モルあたり約1モルに比し水素生成効率の向上を確認できた。また、水素の生成に伴い、バイオリアクター1の液相部3中に副成していたエタノールの量の減少を確認できた。このエタノール量の減少は、図4の代謝マップに示すように、バイオリアクター1中の液相部3中の水素分圧低下によるものと考えられる。なお、送気器20の駆動電力は燃料電池10の発電で賄うことができる。
【0022】
予備的に、バイオリアクター1の気相部2に連通するガスホルダー31を設けたところ、ガスホルダー31に数%の水素ガスを含む二酸化炭素が蓄積することを確認できた。ガスホルダー31に接続して水酸化ナトリウム溶液を蓄えたシール瓶32を設け、気相部2のガスを水酸化ナトリウム溶液経由で収集したところ、二酸化炭素をトラップすることができ、ガスホルダー31に蓄積されていたガスは燃料電池で反応しきれなかったと思われる微量の水素ガスのみとなった。このことから、気相部2の水素ガス26のほとんどが燃料電池10の発電に利用されていることが確認できた。
【0023】
こうして本発明の目的である「燃料電池の水素消費を利用してバイオリアクターの水素分圧を低く保つ方式の燃料電池組込み型水素発酵バイオリアクター」の提供を達成できる。
【0024】
なお、図示例の燃料流路22には、気相部2中に含まれる硫黄分を除去する脱硫器23を設けている。改質器を用いる場合は、硫黄分が改質器の触媒を劣化させるため、改質器へ送入する前にガス中の硫黄分を取り除く必要がある。また、硫化水素(H2S)等は燃料電池の膜を不活化し効率を低下させるおそれがある。但し、本発明は改質器を必要としないので、気相部2中に含まれる硫黄分が高濃度でない限り、脱硫器23は必須のものではない。
【0025】
また図示例では、バイオリアクター1に液相部3の攪拌装置6を設けている。攪拌装置6で液相部3を攪拌することにより、液相部3の溶存水素ガスを気相部2へ効果的に移行させ、液相部3における水素生成の一層の効率化を図ることができる。攪拌装置6の駆動電力を燃料電池10の出力電力で賄うことも可能である。
【0026】
【実施例】
図1のバイオリアクター1で用いる有機性基質としては、微生物の培養に常用される炭素源、ミネラル、ビタミンその他からなる人工基質のほか、農産物加工工場、ジュース工場、食品工場等の各種製造工場から排出される有機性廃水、下水、屎尿等有機性の各種廃水、スラリー化した生ごみ等を使用できる。これらの基質は、必要に応じて希釈、混合、粉砕したり、必要な成分を添加して、水素の生成や廃水の処理がスムーズに行われるよう適宜調製することができる。
【0027】
また前記実験例1では、混合微生物群であるメタン発酵微生物群を液相部3に接種したバイオリアクター1を用いたが、水素生成可能な他の嫌気性微生物又は光合成微生物を利用したバイオリアクターと燃料電池とを組み合わせることにより、バイオリアクター中の水素分圧の低下を図り、水素生成効率が高い本発明の水素発酵バイオリアクターとすることが可能である。また、嫌気性微生物を純粋菌の系で利用する場合は、バイオリアクターにおけるHRTを短くすることにより、水素生成効率を高めることができる。
【0028】
[実験例2]
製糖工場廃水にクロストリジウム(Clostridium)属に属する水素生成嫌気性微生物を接種し、温度30℃に保たれたバッチ式バイオリアクターに投入して水素発酵を行った。その結果、培養72時間で培地1リットルあたり約2800ミリリットル(約2800ml/l-culture)のガスが生成した。ガスの組成は水素60%、二酸化炭素40%であった。製糖工場廃水中の炭水化物分解量から水素生成効率を計算したところ、その水素への変換効率はグルコース1モルあたり約1.8モル(1.8mol/mol-glucose)であった。この状態で、実験例1と同様の固体高分子型燃料電池ユニット10の水素吸入口11とバイオリアクターの気相部2とを接続して送気器20により酸素を供給したところ、燃料電池10で発電が起こり、炭水化物から水素への変換率はグルコース1モルあたり約2.6モル(2.6mol/mol-g1ucose)にまで増加した。即ち、クロストリジウム属の純粋菌を用いたバイオリアクターにおいても、燃料電池と組み合わせることにより、水素生成効率を向上できることが確認できた。なお、この実験における高分子型燃料電池での発電効率は約40%であり、生成した水素ガスを燃焼した場合の約40%の熱量を電気エネルギーとして回収できた。
【0029】
[実験例3]
乳酸1g/リットルを電子供与体とした合成培地に、光の照射下で水素生成可能な紅色非硫黄細菌Rhodobacter sp.を接種し、その細菌による水素生成に必要とされる条件、例えば強度の光の照射手段を設けたバイオリアクターに投入して、窒素制限下でタングステンランプにより10,000ルックスの光を照射しながら光水素発酵を行った。培養24時間目以降に水素ガスの生成が認められたので、実験例1と同様の固体高分子型燃料電池ユニット10の水素吸入口11とバイオリアクターの気相部2とを接続して送気器20により酸素を供給したところ、水素発生に伴う発電をその後4日間に亘り続けることができた。この実験における水素ガスによる燃料電池の発電効率は約50%であった。
【0030】
固体高分子型燃料電池は、常温での発電ができるので起動停止が容易であり、出力密度が高いため小型・軽量化、低コスト化が可能である等の特徴を有するので、比較的容易にバイオリアクター1との組み合わせることができる。但し、本発明に適用可能な燃料電池はこの例に限定されず、リン酸型燃料電池、溶融炭素塩型燃料電池、固体酸化物型燃料電池等を用いて本発明のバイオリアクターとすることが可能である。
【0031】
更に本発明では、燃料電池10の起電力をモニターすることでバイオリアクター1における微生物の水素生成量そのものをモニターすることができる。従来、水素発酵バイオリアクターにおける水素ガス発生量は、発生した水素ガスをガスホルダーに捕集するか、又はガスメータを用いて計量する必要があった。本発明では、燃料電池10の起電力から水素生成量をモニターできるので、ガスホルダーやガスメータを必要としない。
【0032】
【発明の効果】
以上説明したように、本発明の燃料電池組込み型水素発酵バイオリアクターは、バイオリアクターの気相部と燃料電池の水素吸入口とを燃料流路で連通し、電力負荷に応じて消費される酸素を送気器により燃料電池へ供給し、燃料電池における水素の消費に応じた水素吸入口の水素分圧の低下によりバイオリアクターの気相部から燃料電池へ水素を吸入するので、次の顕著な効果を奏する。
【0033】
(イ)バイオリアクターで生成した水素ガスを直接燃料電池に導くので、燃料ガスの改質を必要とせず、改質のためのエネルギー供給を必要としない。
(ロ)燃料電池の発電によってバイオリアクターの気相部水素分圧の低下を促進し、バイオリアクターにおける高い水素生成効率を維持できる。
(ハ)従来の水素発酵バイオリアクターをそのまま利用して、燃料電池を組み込むことにより、本発明の水素バイオリアクターに転用することができる。
(ニ)メタン発酵微生物群を用いて水素を発生させるバイオリアクターを利用することにより、メタン発酵微生物群が利用可能な有機性廃棄物等を原料とすることができ、水素の生成のみならず廃水処理の効率化を図ることができ、公害防止技術としての利用も期待できる。
(ホ)クリーンなエネルギー源である水素を安定的に高効率で生産できるので、環境を汚染しないエネルギー生産技術としての利用が期待できる。
【図面の簡単な説明】
【図1】は、本発明の一実施例の説明図である。
【図2】は、メタン発酵微生物群を液相部に接種した嫌気性バイオリアクターにおける、有機性基質の水理学的滞留時間(HRT)と、メタンガス( CH 4 )、有機酸及び水素ガス(H2)の生成量との関係を示すグラフである。
【図3】は、燃料電池の説明図である。
【図4】は、水素生成微生物における代謝マップの一例である。
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell built-in hydrogen fermentation bioreactor, and more particularly to a fuel cell built-in hydrogen fermentation bioreactor that can generate power and improve the hydrogen production efficiency of microorganisms.
[0002]
[Prior art]
Hydrogen is not only a clean energy source that does not release carbon dioxide when burned, but also has a heat generation energy per unit weight that is three times that of petroleum. it can. A fuel cell has higher power generation efficiency than a gas turbine or a gas engine, and therefore generates less carbon dioxide. The fuel cell is a power generation system that generates almost no NOx, SOx, and dust, and has little noise and vibration, and is expected to spread from the viewpoint of environmental measures.
[0003]
With reference to FIG. 3, the principle of the fuel cell will be described to the extent necessary for understanding the present invention. The fuel cell 10 basically has a structure in which an electrolyte 17 is sandwiched between a hydrogen electrode (or a fuel electrode) 15 and an oxygen electrode (or an air electrode) 16, and a direct current is obtained by electrochemically reacting hydrogen and oxygen. Generate power. When taking out alternating current, the power converter which converts direct-current power into alternating current power is provided. This figure shows the principle of an electrochemical reaction in a phosphoric acid fuel cell using an aqueous phosphoric acid solution as the electrolyte 17. The hydrogen electrode 15 has air permeability, and hydrogen supplied from the hydrogen suction port 11 on the side surface opposite to the electrolyte 17 of the hydrogen electrode 15 diffuses in the hydrogen electrode 15 and reaches the electrolyte 17 side. Platinum powder is dispersed on the electrolyte side surface of the hydrogen electrode 15, and hydrogen gas is converted into hydrogen ions (H + ) and electrons (e ) as shown in the following formula (1) by the catalytic action of platinum. The electrolyte 17 has a property of passing ions but hardly passing electrons. Therefore, hydrogen ions pass through the electrolyte 17 toward the oxygen electrode 16, whereas electrons that cannot pass through the electrolyte go to the oxygen electrode 16 via the external circuit 18. Of the supplied hydrogen, the unreacted hydrogen at the hydrogen electrode 15 is discharged from the unreacted hydrogen discharge port 13.
[0004]
The oxygen electrode 16 also has air permeability, and a platinum catalyst layer is provided on the electrolyte side surface. Oxygen (or air) supplied from the oxygen inlet 12 on the side opposite to the electrolyte 17 of the oxygen electrode 16 diffuses in the oxygen electrode 16 and reaches the platinum catalyst layer. Combined with hydrogen ions and electrons after passing through the external circuit, it becomes water (H 2 O) (Equation (2)). Of the supplied oxygen, the unreacted oxygen at the oxygen electrode 16 is released from the unreacted oxygen outlet 14. The overall reaction of the fuel cell can be expressed as equation (3). In an actual fuel cell, in order to obtain a large voltage, a minimum unit cell (single cell) having a structure shown in FIG. 3 is used as a stack in which separators are stacked in series. In addition to phosphoric acid fuel cells, molten carbon salt fuel cells, solid oxide fuel cells, solid polymer fuel cells, and the like have been developed. The structure of these fuel cells is also shown in FIG. It is the same thing.
[0005]
[Chemical 1]
Reaction H 2 → 2H + + 2e in the hydrogen electrode - ................................. (1)
Oxygen reaction 2H + + (1/2) O 2 + 2e in (air) electrode - → H 2 O ............... (2 )
Overall reaction H 2 + (1/2) O 2 → H 2 O (3)
[0006]
Hydrogen used in a fuel cell can be produced by thermal decomposition of naphtha, water electrolysis, or the like. However, this hydrogen production method consumes fossil fuel during the production process, and thus has a problem of causing environmental pollution. In addition, it is strongly desired to reduce the use of fossil fuels.
[0007]
Hydrogen production using microorganisms has attracted attention as a hydrogen production method that does not depend on fossil fuels. One example is that methane gas is produced by methane fermentation, and the produced methane gas is passed through a reformer to be reformed into hydrogen. Methane fermentation is a process of converting an organic substrate into methane gas through joint work by a plurality of different microorganism groups (hereinafter also referred to as methane fermentation microorganism groups). can do. However, the reforming reaction that reforms methane gas produced by methane fermentation into hydrogen is an endothermic reaction, and it requires an external energy supply for heating in the reformer, leaving a problem from the viewpoint of energy saving. Yes.
[0008]
On the other hand, a method for directly generating hydrogen gas that does not require modification has been developed by hydrogen-producing microorganisms such as photosynthetic microorganisms and anaerobic microorganisms. A photosynthetic microorganism performs photosynthesis using light energy as a raw material, and generates hydrogen by decomposing water using the reducing power obtained there. In addition, anaerobic microorganisms generate hydrogen gas mainly by the reducing power generated by fermentation, and there are cases where pure bacteria are used and microflora (hereinafter, referred to as mixed microorganism group) is used. is there. Power generation by the combination of hydrogen generation by hydrogen-producing microorganisms and a fuel cell is the ultimate power generation method from the viewpoint of environmental measures that does not depend on fossil fuels and does not generate carbon dioxide.
[0009]
[Problems to be solved by the invention]
However, conventional hydrogen production by microorganisms has a problem that it is difficult to produce hydrogen stably and efficiently. One of the causes for lowering the hydrogen production efficiency is that the hydrogen production efficiency by microorganisms is affected by the hydrogen partial pressure outside the cells regardless of the type of microorganisms. That is, in hydrogen production by microorganisms, the hydrogen partial pressure in the gas phase and liquid phase gradually increases as the reaction proceeds. However, as the hydrogen partial pressure outside the cells increases, the hydrogen generating ability of the hydrogen-producing microorganisms decreases significantly. End up. Hydrogen generation by microorganisms occurs when the reducing power generated in the cells is released as hydrogen gas as a result of reducing protons by the enzyme hydrogenase. In a state where the hydrogen partial pressure is high, since this reducing power is used for the production of other reducing substances other than hydrogen, the hydrogen generation efficiency is lowered. Specifically, in the case of pure bacteria, the metabolism of the bacteria itself shifts from hydrogen production to production of other reductive substances such as ethanol and lactic acid. In the case of a mixed microorganism group, priority is given to producing bacteria such as ethanol and lactic acid, and the production efficiency of hydrogen that can be taken out decreases due to hydrogen consumption by these producing bacteria.
[0010]
On the other hand, when the hydrogen partial pressure is low, the reaction tends to release hydrogen in any microorganism, and the hydrogen generation efficiency increases. This explanation about the metabolism of microorganisms can also be explained by using a general metabolism map shown in FIG. Production of lactic acid and ethanol is a consumption of reducing power, and these production results in hindering hydrogen production. The metabolic map of FIG. 4 shows that the hydrogen partial pressure is an important factor affecting the progress of the hydrogen production reaction.
[0011]
Conventionally, in order to increase the efficiency of hydrogen generation by lowering the hydrogen partial pressure in the gas phase and liquid phase of the hydrogen fermentation bioreactor, removal of hydrogen from the gas phase of the bioreactor and in the reactor liquid phase of inert gas such as argon gas A method such as continuous bubbling is performed. However, any of the conventional methods has a problem that it is necessary to supply a substance such as energy or an inert gas in order to lower the hydrogen partial pressure, which increases the cost. In addition, the energy supply from the outside also has a problem in terms of the power generation efficiency of the entire system by the combination of hydrogen generation by microorganisms and a fuel cell.
[0012]
Accordingly, an object of the present invention is to provide a hydrogen fermentation bioreactor with a built-in fuel cell that uses the hydrogen consumption of the fuel cell to keep the hydrogen partial pressure of the bioreactor low.
[0013]
[Means for Solving the Problems]
Referring to the embodiment of FIG. 1, the hydrogen fermentation bioreactor with a built-in fuel cell of the present invention includes a liquid phase part 3 inoculated with hydrogen-producing microorganisms and a gas phase part in which hydrogen gas generated in the liquid phase part 3 collects. 2, a bioreactor 1 having an agitator 6 for agitating the liquid phase part 3, a fuel cell 10 for generating electricity by sucking hydrogen gas 26 and oxygen 27, a gas phase part 2 of the bioreactor 1, and hydrogen of the fuel cell 10 A fuel flow path 22 communicating with the suction port 11 and an air supply device 20 connected to the oxygen suction port 12 of the fuel cell 10 are provided, and oxygen 27 consumed according to the electric power load is supplied to the fuel cell 10 by the air supply device 20. The hydrogen gas 26 is sucked into the fuel cell 10 from the gas phase portion 2 of the bioreactor 1 by the decrease of the hydrogen partial pressure of the hydrogen inlet 11 according to the consumption of the hydrogen gas 26 in the fuel cell 10 , and the fuel cell 10 in which the composed output power is supplied to the stirring device 6 and / or insufflator 20 That.
[0014]
Preferably, the fuel cell 10 is a solid polymer fuel cell. More preferably, a desulfurizer 23 is provided in the fuel flow path 22.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The bioreactor 1 shown in FIG. 1 is inoculated with a methane-fermenting microorganism group and has an organic substrate that is longer than the growth time of hydrogen-producing microorganisms in the microorganism group and shorter than the growth time of hydrogen-consuming microorganisms in the microorganism group. Hydrogen gas is generated by a group of microorganisms that are allowed to pass through the residence time and propagate in the bioreactor against the passage of the organic substrate. In methane fermentation, it is known that an organic substrate is first oxidized by a hydrogen-producing microorganism in a methane-fermenting microorganism group and decomposed into an organic acid, hydrogen, carbon dioxide and the like. However, the produced hydrogen is an intermediate metabolite that is immediately consumed by other hydrogen-consuming microorganisms such as methanogens, and hydrogen gas is not released out of the system in normal methane fermentation. The inventor has experimentally found that hydrogen gas can be taken out by shortening the hydraulic residence time (hereinafter sometimes referred to as HRT) of an organic substrate in a bioreactor inoculated with a methane fermentation microorganism group. It was.
[0016]
Figure 2 is a fully agitated and mixed type were inoculated with methane fermentation microorganisms in the bioreactor 1 of the liquid phase 3, the organic substrate methane per unit volume while gradually shortening the HRT of (CH 4), organic shows the experimental results obtained by measuring the production amount of acid and hydrogen gas (H 2). As shown in the figure, when the HRT is shortened, methanogenic bacteria flow out of the reactor, and the amount of hydrogen produced increases with the amount of organic acid produced. However, in the methane-fermenting microorganism group, there are hydrogen-consuming microorganisms such as homoacetic acid bacteria in addition to the methanogen, so the produced hydrogen is consumed by these hydrogen-consuming microorganisms, and the amount of hydrogen gas that can be recovered is Still few. Furthermore, by shortening the HRT of the organic substrate and making it longer than the growth time of the hydrogen-producing microorganism in the methane fermentation microorganism group but shorter than the growth time of the hydrogen-consuming microorganism in the microorganism group, hydrogen consumption in the methane fermentation microorganism group microbial drained out of the bioreactor 1 before the growth of only the hydrogen-producing microorganism in the bioreactor 1 is out making capable of growing environments, hydrogen gas generation amount per unit volume greater than organic acid generation amount be able to. That is, the hydrogen fermentation bioreactor 1 capable of minimizing hydrogen consumption in the liquid phase part 3 and efficiently recovering hydrogen gas in the gas phase part 2 by shortening the HRT can be obtained. The HRT suitable for hydrogen production can vary depending on the composition of the organic substrate, etc., but preferably the HRT is shortened to about 0.01 to 3.0 days.
[0017]
In the present invention, the gas phase portion 2 of the bioreactor 1 and the hydrogen inlet 11 of the fuel cell 10 are communicated with each other through the fuel flow path 22. Therefore, when hydrogen fermentation in the bioreactor 1 progresses and the hydrogen partial pressure in the gas phase portion 2 becomes relatively higher than the hydrogen partial pressure in the hydrogen inlet 11 of the fuel cell 10, the gas passes through the fuel flow path 22. Hydrogen gas 26 flows from the phase portion 2 into the hydrogen suction port 11. When the fuel cell 10 is a phosphoric acid fuel cell, as shown in the equation (1), the hydrogen gas 26 that has entered from the hydrogen inlet 11 diffuses in the hydrogen electrode 15 and reaches the electrolyte 17 side, It becomes hydrogen ion and electron. Further, the hydrogen ions pass through the electrolyte 17 to the oxygen electrode 16, and combine with oxygen that has reached the electrolyte 17 from the oxygen electrode 16 to become water as shown in the above formula (2). By this water generation reaction, the hydrogen gas 26 flowing in from the gas phase portion 2 is consumed.
[0018]
Accordingly, by sending oxygen (or air) from the insufflator 20 to the oxygen inlet 12 of the fuel cell 10 according to the electric power load, the water generation reaction shown in the above formula (3) is continuously caused, and the fuel cell 10 The hydrogen partial pressure of the hydrogen inlet 11 can be kept lower than the gas phase portion 2 of the bioreactor 1, and the hydrogen gas 26 can be continuously sucked into the fuel cell 10 from the gas phase portion 2. Further, electric power can be continuously taken out from the external circuit 18. Therefore, an increase in the hydrogen partial pressure in the gas phase portion 2 of the bioreactor 1 can be suppressed, and the hydrogen partial pressure in the gas phase portion 2 can be kept low. The reduction in the gas partial pressure in the gas phase part 2 causes a reduction in the gas partial pressure in the liquid phase part 3, promotes hydrogen production of hydrogen-producing microorganisms present in the liquid phase part 3, and high hydrogen production efficiency in the bioreactor 1. Can be maintained.
[0019]
[Experimental Example 1]
In order to confirm the hydrogen generation efficiency of the bioreactor 1 when the gas phase portion 2 of the bioreactor 1 and the hydrogen inlet 11 of the fuel cell 10 are communicated with each other through the fuel flow path 22, an anaerobic bioreactor (continuous) shown in FIG. Experiments were performed using a reactor. In this experiment, methane fermentation sludge collected from other methane fermenters was used as a methane fermentation microorganism group, and KH 2 P0 4 1.5 g, Na 2 HP0 4 · H 2 0 4.2 g, NH 4 Cl in 1 liter of distilled water. Artificial wastewater containing 0.5 g, MgCl 2 · 6H 2 0.18 g, yeast extract 5 g, and cellulose powder 10 g was continuously introduced from the organic substrate intake 4. Reference numeral 5 in the figure denotes a processing liquid discharge port. The cellulose content in the liquid phase part 3 of the bioreactor 1, C2 to C8 lower fatty acids, and TOC (total organic carbon) are measured over time, and the generated gas is quantified by a water displacement method using water of pH 3 or lower. The composition was analyzed by gas chromatograph TCD method.
[0020]
Bioreactor 1 was maintained at pH 7.4 and temperature 60 ° C. First, methane fermentation was carried out using HRT for 5 days to confirm the stable production of methane gas, and when HRT was gradually shortened, HRT was reduced to 0.5. The production of hydrogen was remarkably observed by setting the day, and 30 mmol / l-reactor / day of hydrogen gas could be continuously produced per liter of reactor volume. The composition of the generated gas was 80% hydrogen and 20% carbon dioxide. The conversion efficiency from cellulose to hydrogen (hydrogen generation efficiency) in this state was about 1 mol (1 mol / mol-hexose) per mol of hexose.
[0021]
After confirming the continuous production of hydrogen, the hydrogen outlet 21 provided in the gas phase part 2 of the bioreactor 1 and the hydrogen inlet 11 of the polymer electrolyte fuel cell unit 10 are connected by a fuel flow path 22 to produce fuel. When air was blown by an air supply device 20, for example, a pump connected to the oxygen inlet 12 of the battery 10, power generation occurred in the fuel cell 10. The hydrogen generation efficiency of the fuel cell 10 during power generation is about 2 moles per mole of hexose (2 mol / mol-hexose), which is higher than that of about 1 mole per mole of hexose before the fuel cell 10 is connected. The improvement was confirmed. In addition, a decrease in the amount of ethanol by-produced in the liquid phase part 3 of the bioreactor 1 was confirmed with the generation of hydrogen. This decrease in the amount of ethanol is considered to be due to a decrease in the hydrogen partial pressure in the liquid phase part 3 in the bioreactor 1 as shown in the metabolism map of FIG. Note that the driving power of the insufflator 20 can be covered by the power generation of the fuel cell 10.
[0022]
Preliminarily, when the gas holder 31 communicating with the gas phase portion 2 of the bioreactor 1 was provided, it was confirmed that carbon dioxide containing several percent of hydrogen gas was accumulated in the gas holder 31. A seal bottle 32 storing a sodium hydroxide solution is provided connected to the gas holder 31, and when the gas in the gas phase part 2 is collected via the sodium hydroxide solution, carbon dioxide can be trapped. The accumulated gas was only a small amount of hydrogen gas that could not be reacted by the fuel cell. From this, it was confirmed that most of the hydrogen gas 26 in the gas phase part 2 was used for power generation of the fuel cell 10.
[0023]
In this way, it is possible to achieve “the fuel cell-embedded hydrogen fermentation bioreactor of the type that keeps the hydrogen partial pressure of the bioreactor low by utilizing the hydrogen consumption of the fuel cell”, which is the object of the present invention.
[0024]
In the illustrated fuel flow path 22, a desulfurizer 23 that removes sulfur contained in the gas phase portion 2 is provided. When the reformer is used, the sulfur content deteriorates the catalyst of the reformer, and therefore it is necessary to remove the sulfur content in the gas before sending it to the reformer. Further, hydrogen sulfide (H 2 S) or the like may inactivate the membrane of the fuel cell and reduce the efficiency. However, since the present invention does not require a reformer, the desulfurizer 23 is not essential as long as the sulfur content contained in the gas phase portion 2 is not high.
[0025]
In the illustrated example, the bioreactor 1 is provided with a stirring device 6 for the liquid phase part 3. By stirring the liquid phase part 3 with the stirring device 6, the dissolved hydrogen gas in the liquid phase part 3 can be effectively transferred to the gas phase part 2, thereby further improving the efficiency of hydrogen generation in the liquid phase part 3. it can. It is also possible to cover the driving power of the stirring device 6 with the output power of the fuel cell 10.
[0026]
【Example】
The organic substrate used in the bioreactor 1 in FIG. 1 includes artificial substrates composed of carbon sources, minerals, vitamins, etc., which are commonly used for culturing microorganisms, as well as various manufacturing factories such as agricultural product processing factories, juice factories, and food factories. Organic wastewater discharged, various organic wastewater such as sewage and human waste, slurried garbage, etc. can be used. These substrates can be appropriately prepared so that hydrogen generation and wastewater treatment can be performed smoothly by diluting, mixing, and pulverizing as necessary, or adding necessary components.
[0027]
In the experimental example 1, the bioreactor 1 in which the liquid phase part 3 was inoculated with the methane fermentation microbial group which is a mixed microbial group was used. However, By combining with a fuel cell, the hydrogen partial pressure in the bioreactor can be reduced, and the hydrogen fermentation bioreactor of the present invention having high hydrogen production efficiency can be obtained. In addition, when anaerobic microorganisms are used in a pure fungal system, hydrogen production efficiency can be increased by shortening the HRT in the bioreactor.
[0028]
[Experiment 2]
Sugar production wastewater was inoculated with hydrogen-producing anaerobic microorganisms belonging to the genus Clostridium and charged into a batch-type bioreactor maintained at 30 ° C. for hydrogen fermentation. As a result, about 2800 milliliters (about 2800 ml / l-culture) of gas was produced per liter of culture medium in 72 hours of culture. The composition of the gas was 60% hydrogen and 40% carbon dioxide. The hydrogen generation efficiency was calculated from the amount of carbohydrates decomposed in the sugar mill wastewater, and the conversion efficiency to hydrogen was about 1.8 moles per mole of glucose (1.8 mol / mol-glucose). In this state, when the hydrogen inlet 11 of the polymer electrolyte fuel cell unit 10 similar to that of Experimental Example 1 and the gas phase part 2 of the bioreactor were connected and oxygen was supplied by the insufflator 20, the fuel cell 10 Power generation occurred, and the conversion rate from carbohydrate to hydrogen increased to about 2.6 mol / mol glucose (2.6 mol / mol-g1ucose). That is, it was confirmed that even in a bioreactor using a pure bacterium of the genus Clostridium, the hydrogen production efficiency can be improved by combining with a fuel cell. The power generation efficiency of the polymer fuel cell in this experiment was about 40%, and about 40% of the heat generated when the generated hydrogen gas was burned could be recovered as electric energy.
[0029]
[Experiment 3]
A synthetic medium containing 1 g / l of lactic acid as an electron donor is inoculated with a red non-sulfur bacterium, Rhodobacter sp. , Capable of producing hydrogen under light irradiation, and conditions necessary for hydrogen production by the bacterium, such as intense light Was put into a bioreactor equipped with the irradiation means, and photohydrogen fermentation was performed while irradiating light of 10,000 lux with a tungsten lamp under nitrogen limitation. Since generation of hydrogen gas was observed after 24 hours of culture, the hydrogen intake port 11 of the polymer electrolyte fuel cell unit 10 and the gas phase part 2 of the bioreactor were connected to supply air as in Experimental Example 1. When oxygen was supplied by the vessel 20, power generation accompanying hydrogen generation could be continued for 4 days thereafter. The power generation efficiency of the fuel cell using hydrogen gas in this experiment was about 50%.
[0030]
Since the polymer electrolyte fuel cell can generate electricity at room temperature, it is easy to start and stop, and because it has high output density, it can be reduced in size, weight, and cost. Combination with bioreactor 1 is possible. However, the fuel cell applicable to the present invention is not limited to this example, and the bioreactor of the present invention may be formed using a phosphoric acid fuel cell, a molten carbon salt fuel cell, a solid oxide fuel cell, or the like. Is possible.
[0031]
Furthermore, in the present invention, the hydrogen production amount of microorganisms in the bioreactor 1 itself can be monitored by monitoring the electromotive force of the fuel cell 10. Conventionally, the amount of hydrogen gas generated in a hydrogen fermentation bioreactor has to be collected by collecting the generated hydrogen gas in a gas holder or using a gas meter. In the present invention, since the amount of hydrogen generation can be monitored from the electromotive force of the fuel cell 10, no gas holder or gas meter is required.
[0032]
【The invention's effect】
As described above, the hydrogen fermentation bioreactor with a built-in fuel cell of the present invention connects the gas phase part of the bioreactor and the hydrogen inlet of the fuel cell through the fuel flow path, and oxygen consumed according to the power load. Is supplied to the fuel cell by the air blower, and hydrogen is sucked into the fuel cell from the gas phase portion of the bioreactor due to the decrease of the hydrogen partial pressure at the hydrogen inlet according to the consumption of hydrogen in the fuel cell. There is an effect.
[0033]
(A) Since the hydrogen gas generated in the bioreactor is directly guided to the fuel cell, the fuel gas is not required to be reformed and energy supply for reforming is not required.
(B) It is possible to promote a reduction in the hydrogen partial pressure in the gas phase of the bioreactor by power generation of the fuel cell, and to maintain high hydrogen production efficiency in the bioreactor.
(C) By using a conventional hydrogen fermentation bioreactor as it is and incorporating a fuel cell, it can be diverted to the hydrogen bioreactor of the present invention.
(D) By using a bioreactor that generates hydrogen using methane-fermenting microorganisms, organic waste that can be used by methane-fermenting microorganisms can be used as a raw material. It is possible to improve the efficiency of the treatment and use it as a pollution prevention technology.
(E) Since hydrogen, which is a clean energy source, can be stably produced with high efficiency, it can be expected to be used as an energy production technology that does not pollute the environment.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an embodiment of the present invention.
FIG. 2 shows the hydraulic residence time (HRT) of an organic substrate , methane gas ( CH 4 ), organic acid and hydrogen gas ( in an anaerobic bioreactor inoculated with methane-fermenting microorganisms in the liquid phase. is a graph showing the relationship between the amount of H 2).
FIG. 3 is an explanatory diagram of a fuel cell.
FIG. 4 is an example of a metabolic map in a hydrogen-producing microorganism.

Claims (6)

水素生成微生物が接種された液相部と液相部で生成された水素ガスが集まる気相部と液相部を攪拌する攪拌装置とを有するバイオリアクター、水素ガスと酸素とを吸入して発電する燃料電池、前記バイオリアクターの気相部と前記燃料電池の水素吸入口とを連通する燃料流路、及び前記燃料電池の酸素吸入口に接続した送気器を備え、電力負荷に応じて消費される酸素を前記送気器により前記燃料電池へ供給し、前記燃料電池における水素ガスの消費に応じた水素吸入口の水素分圧低下により前記バイオリアクターの気相部から前記燃料電池へ水素ガスを吸入し、前記燃料電池の出力電力を攪拌装置及び/又は送気器に供給してなる燃料電池組込み型水素発酵バイオリアクター。 A bioreactor having a liquid phase part inoculated with hydrogen-producing microorganisms, a gas phase part where hydrogen gas generated in the liquid phase part gathers, and a stirrer that stirs the liquid phase part, and generates electricity by inhaling hydrogen gas and oxygen Fuel cell, a fuel flow path that connects the gas phase part of the bioreactor and the hydrogen intake port of the fuel cell, and an air supply device connected to the oxygen intake port of the fuel cell. The supplied oxygen is supplied to the fuel cell by the insufflator, and the hydrogen gas is supplied from the gas phase part of the bioreactor to the fuel cell by the reduction of the hydrogen partial pressure at the hydrogen inlet according to the consumption of the hydrogen gas in the fuel cell. A hydrogen fermentation bioreactor with a built-in fuel cell, in which the output power of the fuel cell is supplied to a stirrer and / or an air supply device . 請求項1のバイオリアクターにおいて、前記燃料電池を固体高分子型燃料電池としてなる燃料電池組込み型水素発酵バイオリアクター。2. The bioreactor according to claim 1, wherein the fuel cell is a solid polymer fuel cell. 請求項1又は2のバイオリアクターにおいて、前記燃料流路に脱硫器を設けてなる燃料電池組込み型水素発酵バイオリアクター。The bioreactor according to claim 1 or 2, wherein a desulfurizer is provided in the fuel flow path. 請求項1から3の何れかのバイオリアクターにおいて、前記バイオリアクターを、水素生成微生物を含むメタン発酵微生物群が接種され且つ有機性基質を連続的に流入させると共にその水理学的滞留時間を単位容積あたりの水素生成量が有機酸生成量より大きくなるように調節した完全攪拌混合型の嫌気性バイオリアクターとしてなる燃料電池組込み型水素発酵バイオリアクター。The bioreactor according to any one of claims 1 to 3, wherein the bioreactor is inoculated with a group of methane-fermenting microorganisms containing hydrogen-producing microorganisms and continuously infused with an organic substrate and its hydraulic residence time is measured in unit volume. A hydrogen fermentation bioreactor with a built-in fuel cell as a fully stirred and mixed anaerobic bioreactor adjusted so that the amount of hydrogen produced per unit is larger than the amount of organic acid produced . 請求項4のバイオリアクターにおいて、前記有機性基質を有機性廃棄物としてなる燃料電池組込み型水素発酵バイオリアクター。The bioreactor according to claim 4, wherein the organic substrate is an organic waste as a fuel cell-embedded hydrogen fermentation bioreactor. 請求項1から3の何れかのバイオリアクターにおいて、前記バイオリアクターを、光の照射下で水素を生成する光合成微生物が接種され且つ光合成微生物による水素生成に必要とされる条件の光の照射手段を有するものとしてなる燃料電池組込み型水素発酵バイオリアクター。In any of the bioreactors of claims 1 to 3, the bioreactor conditions photosynthetic microorganisms to produce hydrogen under irradiation with light is needed to hydrogen production by by and photosynthetic microorganisms inoculated irradiation means of light A hydrogen fermentation bioreactor with a built-in fuel cell.
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