Effect of temperature on the electrochemical oxidation of ash free coal and carbon in a direct carbon fuel cell

Duc-Luong Vu,이충곤 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.5

The present study proposes the application of ash-free coal (AFC) as a primary fuel in a direct carbon fuel cell (DCFC) based on a molten carbonate fuel cell (MCFC). AFC was produced by solvent extraction using microwave irradiation. The influence of AFC-to-carbonate ratio (3 : 3, 3 : 1, 3 : 0 and 1 : 3 g/g) on the DCFC performance at different temperatures (650, 750 and 850 oC) was systematically investigated with a coin-type cell. The performance of AFC was also compared with carbon and conventional hydrogen fuels. AFC without carbonate (AFC-to-carbonate ratio=3 : 0 g/g) gave a comparable performance to other compositions, indicating that the gasification of AFC readily occurred without a carbonate catalyst at 850 oC. The ease of gasification of AFC led to a much higher performance than for carbon fuel, even at 650 oC, where carbon cannot be gasified with a carbonate catalyst.

초청정 석탄의 석탄연료전지 응용기술

최호경(Hokyung Choi),김상도(Sangdo Kim),유지호(Jiho Yoo),임정환(Jeonghwan Lim),임영준(Youngjoon Rhim),이시훈(Sihyun Lee) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.40

This paper describes the potential application of ash-free coal to direct carbon fuel cell (DCFC). DCFC can be made of typical fuel cell components and generates the electric energy by direct electrochemical oxidation of carbon, replacing hydrogen with solid carbon fuel. Carbon is mostly originated from coal, which is readily available, easily transportable, and economical. However, employing coal as a carbon source has been excluded, mainly due to its high ash content. The ash-free coal, produced by solvent extraction of combustibles from raw coal, can be applicable as carbon fuel to DCFC. The successful adaption may cut the fuel cost to one third of usual hydrogen fuel cells. In addition, 80% of power generation efficiency can be achieved and CO₂ emission from the conventional coal-fired power plant can be reduced by 90%.

Ammonia as an efficient CO_X-free hydrogen carrier: Fundamentals and feasibility analyses for fuel cell applications

Cha, Junyoung,Jo, Young Suk,Jeong, Hyangsoo,Han, Jonghee,Nam, Suk Woo,Song, Kwang Ho,Yoon, Chang Won Elsevier 2018 APPLIED ENERGY Vol.224 No.-

<P><B>Abstract</B></P> <P>A CO<SUB>X</SUB>-free 1 kW-class hydrogen power pack fueled by liquid ammonia is presented. For applications in a practical-scale hydrogen production system in conjunction with a polymer electrolyte membrane fuel cell, Ru catalysts supported on La-doped alumina (Ru/La(x)-Al<SUB>2</SUB>O<SUB>3</SUB>) were pelletized by varying the lanthanum doping content (x mol%) to control catalytic activities. An optimized Ru(1.06 wt%)/La(20)-Al<SUB>2</SUB>O<SUB>3</SUB> pellet catalyst presents a >99.7% conversion efficiency at 500 °C under a gas hourly space velocity of 5000 mL g<SUB>cat</SUB> <SUP>−1</SUP> h<SUP>−1</SUP>. Various materials were screened to remove residual ammonia from the product stream, and the X zeolite was chosen as a highly capable adsorbent. Based on the synthesized catalyst and screened adsorbent, a power pack consisting of a dehydrogenation reactor, an adsorbent tower, and a 1 kW-class polymer electrolyte membrane fuel cell was designed and manufactured. The as-integrated system can convert 9 L min<SUP>−1</SUP> of ammonia into 13.4 L min<SUP>−1</SUP> of hydrogen, powering a 1 kW-class fuel-cell continuously for >2 h without any performance degradation. To achieve autothermal and CO<SUB>X</SUB>-free operations, heat required for ammonia dehydrogenation was provided by unutilized hydrogen from the fuel cell, drastically increasing the overall efficiency of the system to >49% while removing the external heat source, isobutane. Finally, a drone tethered to the system was operated, demonstrating the feasibility of an elongated flight time of >4 h, much longer than 14 min with Li-polymer battery loaded on the drone. The system is expected to meet the United States Department of Energy’s 2020 gravimetric and volumetric hydrogen storage targets of 4.5 wt% and 30 gH<SUB>2</SUB> L<SUP>−1</SUP> at system weights of 43 kg and 50 kg, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pelletized Ru/La-Al<SUB>2</SUB>O<SUB>3</SUB> catalysts have superior NH<SUB>3</SUB> dehydrogenation activity. </LI> <LI> The CO<SUB>x</SUB>-free H<SUB>2</SUB> generator is integrated to produce hydrogen on demand from NH<SUB>3</SUB>. </LI> <LI> The H<SUB>2</SUB> generator powers a 1 kW-class fuel cell without performance degradation. </LI> <LI> Reformer efficiency of >84% is achieved by recirculating H<SUB>2</SUB> from a fuel cell. </LI> <LI> A potential H<SUB>2</SUB> storage density of the system is ca. 7.0 wt% (system based). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

탄소중립을 위한 암모니아 연소기술의 연구개발 필요성 - Part Ⅰ 연료 암모니아의 보급확대 배경과 경제성

이후경(Hookyung Lee),우영민(Youngmin Woo),이민정(Min Jung Lee) 한국연소학회 2021 한국연소학회지 Vol.26 No.1

Along with a global carbon neutral basis, the development of combustion technologies for greenhouse gas reduction is essential. Transitional technologies that are easy to commercialize within a relatively short period of time are required for the reinforced environmental pollutant reduction regulations and fulfillment of the promise with the international community. As a carbon-free fuel, ammonia is expected to play a important role through hydrogen energy carriers and direct use technology. This paper examines the history of the energy and resource sectors up to the formation of a carbon-neutral system in Korea, and also investigates the necessity of using ammonia to advance to a hydrogen economy. In order to secure the technical feasibility of ammonia combustion, this article discusses related domestic and foreign policies, the current state of the life cycle technology development from fuel ammonia production process to utilization, the characteristics of fuel ammonia, and the possibility of application as a combustion technology. This paper is divided into two parts, and in Part 1, we will discuss the background and economic feasibility of expanding the supply of fuel ammonia.

The feasibility of ammonia as marine fuel and its application on a medium-size LPG/ammonia carrier

Muammer Akturk,서정관 한국마린엔지니어링학회 2023 한국마린엔지니어링학회지 Vol.47 No.3

The study investigated the feasibility of using ammonia as a marine fuel and its application on a medium-size LPG/ammonia carrier. The study included a comprehensive literature review of existing research on ammonia as a marine fuel and further research on industrial developments in the field to gain insights into the practical challenges and opportunities associated with using ammonia as a marine fuel. The study found that ammonia has several advantages as a marine fuel, including its high energy density, low emis-sions profile, and potential for production from renewable sources. However, there are also significant technical, economic, and safety challenges associated with using ammonia, particularly in the design and operation of marine engines and fuel systems, particularly due to ammonia’s combustion characteristics. The study also demonstrated that the application of ammonia on a medium size LPG/Am-monia carrier is feasible but requires investment and technical expertise. The findings of this study have important implications for the shipping industry's efforts for decarbonization and suggest that ammonia could play a significant role in a carbon-free maritime future. In conclusion, the study provides a comprehensive analysis of the feasibility of ammonia as a marine fuel and highlights its potential application on a medium size LPG/Ammonia carrier.

무회분탄 연료의 촉매 가스화에 의한 직접탄소연료전지의 성능 향상

진선미(Sunmi Jin),유지호(Jiho Yoo),이영우(Young Woo Rhee),최호경(Hokyung Choi),임정환(Jeonghwan Lim),이시훈(Sihyun Lee) 한국청정기술학회 2012 청정기술 Vol.18 No.4

탄소가 다량 포함된 석탄을 직접탄소연료전지(direct carbon fuel cell, DCFC) 연료로 사용 시 무기물인 회분은 반응 후 남아 접촉계면을 물리적으로 덮어 연료전지 성능을 저하시킨다. 본 연구에서는 회분이 제거된 무회분탄(ash-free coal, AFC)을 제조하고 이를 증기 가스화 촉매와 함께 도입한 후 DCFC 연료로써의 특성을 알아보았다. 고체산화물 연료전지(solid oxide fuel cell, SOFC) 기반의 DCFC에 무회분탄과 가스화 촉매인 탄산칼륨을 연료로 도입한 경우와 무회분탄만을 도입한 경우를 비교하였다. 열분해 반응 조건에서는 두 경우의 전력밀도 차이가 크지 않으나, 증기 가스화 조건에서는 촉매가 도입된 무회분탄이 상대적으로 높은 전력밀도 상승을 나타냈다. 이것은 증기 가스화 반응이 촉매에 의해 활성화되어 더 많은 양의 수소가 생산되었기 때문이다. 촉매 유무에 따른 수소 생성양의 차이를 가스크로마토그래피(gas chromatography, GC)로 정량 분석한 결과, 탄산칼륨첨가는 수소 생산 속도를 증가시킴을 확인하였다. 시간 경과에 따른 전력밀도의 감소는 촉매가 첨가된 연료에서 더 빠르게 나타났는데, 이는 촉매의 칼륨성분이 전해질과 반응하여 이성질 화합물을 형성하기 때문으로 생각된다. 얇은 두께의 전해질(30 μm) 도입에 의해 전력밀도가 향상되었다. Carbon-rich coal can be utilized as a fuel for direct carbon fuel cell (DCFC). However, left-behind ash after the electrochemical oxidation may hinder the electrochemical reactions. In this study, we produced ash-free coal (AFC) by thermal extraction and then tested it as a fuel for DCFC. DCFC was built based on solid oxide electrolyte and the electrochemical performance of AFC mixed with K2CO3 was compared with AFC only. Significantly enhanced power density was found by catalytic steam gasification of AFC. However, an increase of the power density by catalytic pyrolysis was negligible. This result indicated that a catalyst activated the steam gasification reactions, producing much more H2 and thus increasing the power density, compared to AFC only. Results of a quantitative analysis showed much improved kinetics in AFC with K2CO3 in agreement with DCFC results. A secondary phase of potassium on yttria-stabilized zirconia (YSZ) surface was observed after the cell operation. This probably caused poor long-term behavior of AFC with K2CO3. A thin YSZ (30 μm thick) was found to be higher in the power density than 0.9 mm of YSZ.

고압축비 SI 엔진의 순수 암모니아 연료 사용 가능성에 관한 연구

원현우(Hyun-Woo Won) 한국자동차공학회 2022 한국 자동차공학회논문집 Vol.30 No.11

Environmental concerns and attempts to reduce CO₂ emission due to greenhouse gas(GHG) include increased consumption of carbon-free fuel like hydrogen and its derivate(like ammonia) in the transportation sector. However, ammonia(NH₃), whose storage and carrier requirements suit the existent infrastructure and has better commercial viability, are less expensive in terms of cost per unit of energy and higher volumetric energy density compared to hydrogen. In this study, the potential of NH₃ as a sustainable fuel for spark ignition engines with a high compression ratio(CR: 16.5), based on a compression ignition engine architecture, is evaluated after considering NH₃ combustion and thermodynamic performance. The experimental results addressed combustion behavior and exhaust gases’ emissions as the possibility of using pure NH₃ as fuel on a conventional engine continues to be explored.

탄소중립 시대의 분야별 공기질 관리 기술 현황과 전망

한방우,조윤행,이정훈,권순박,김대성,이건희,홍기정,박인용,박대훈 한국대기환경학회 2023 한국대기환경학회지 Vol.39 No.5

As the average concentration of carbon dioxide (CO2) in the earth has continuously increased over 400 ppm, climate change caused by the global warming has become a critical global issue. Air pollutants are mostly reduced in the process of reducing carbon emissions, for example, by reducing operations of coal-fired power plants and fossil-fuel vehicles. However, nitrogen oxides, ammonia and other pollutants may actually increase during the processes of switching from fossilfuels to carbon-free fuels such as ammonia and hydrogen. Here, we take a look at what are the requirements to suppress air pollutants while reducing greenhouse gases. It is necessary to reduce directly non-exhaust fine particles from electric vehicles and also indirectly air pollutants during the process of recycling waste batteries from the electric vehicles. When a mixture of combustible wastes is used in industries as an alternative instead of bituminous coal, it is also needed to reduce air pollution emissions during its incineration. It becomes more important to develop a strategy for energy optimization by internet of things (IoT) monitoring and artificial intelligence (AI) prediction in the industrial sites and residential buildings. In addition, we have to investigate steadily the atmospheric aerosol itself from a climate change point of view. And it is also necessary to conduct a lot of field studies for removal of non-CO2 greenhouse gases and short-lived climate pollutants (SLCP).

탄소중립을 위한 암모니아 연소기술의 연구개발 필요성 - Part Ⅱ 연구개발 동향과 기술적 타당성 분석

이후경(Hookyung Lee),우영민(Youngmin Woo),이민정(Min Jung Lee) 한국연소학회 2021 한국연소학회지 Vol.26 No.1

Following the previously published Part 1, the Part 2 focuses on the basic combustion characteristics of fuel ammonia and research cases of applied combustion technology. In addition, we would like to review the items necessary for a large-scale demonstration of ammonia combustion technology. Most of the technologies for utilizing ammonia combustion are being carried out in Japan and are strongly promoted by policy. The results give a method of stabilizing flame and reducing nitrogen oxides when mixed burning of ammonia, and are applied to automobile engine, marine engine, gas turbine, coal-fired boiler, reheating furnace, and fuel cell. The co-burning rate, which is advantageous for stabilizing combustion and reducing nitrogen oxides, has been derived, and accordingly, the use of ammonia as a carbon-free fuel for the future is brightly expected.

A carbon-based fuel cell system operating in CO₂ atmosphere

Jong-Pil Kim(김종필),Chung-Hwan Jeon(전충환) 한국신재생에너지학회 2016 한국신재생에너지학회 학술대회논문집 Vol.2016 No.5