@article{NakatenKempka2019,
  author    = {Nakaten, Natalie Christine and Kempka, Thomas},
  title     = {Techno-Economic Comparison of Onshore and Offshore Underground Coal Gasification End-Product Competitiveness},
  series = {Energies},
  volume    = {12},
  journal   = {Energies},
  number    = {17},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1996-1073},
  doi       = {10.3390/en12173252},
  pages     = {28},
  year      = {2019},
  abstract  = {Underground coal gasification (UCG) enables utilization of coal reserves, currently not economically exploitable due to complex geological boundary conditions. Hereby, UCG produces a high-calorific synthesis gas that can be used for generation of electricity, fuels, and chemical feedstock. The present study aims to identify economically-competitive, site-specific end-use options for onshore- and offshore-produced UCG synthesis gas, taking into account the capture and storage (CCS) and/or utilization (CCU) of produced CO2. Modeling results show that boundary conditions favoring electricity, methanol, and ammonia production expose low costs for air separation, low compression power requirements, and appropriate shares of H-2/N-2. Hereby, a gasification agent ratio of more than 30\% oxygen by volume is not favorable from the economic and CO2 mitigation viewpoints. Compared to the costs of an offshore platform with its technical equipment, offshore drilling costs are marginal. Thus, uncertainties related to parameters influenced by drilling costs are negligible. In summary, techno-economic process modeling results reveal that air-blown gasification scenarios are the most cost-effective ones, while offshore UCG-CCS/CCU scenarios are up to 1.7 times more expensive than the related onshore processes. Hereby, all investigated onshore scenarios except from ammonia production under the assumed worst-case conditions are competitive on the European market.},
  language  = {en}
}
@misc{NakatenKempka2019,
  author    = {Nakaten, Natalie Christine and Kempka, Thomas},
  title     = {Retraction: Techno-Economic Comparison of Onshore and Offshore Underground Coal Gasification End-Product Competitiveness. (Retraction of Vol 10, art no 1643, 2017)},
  series = {Energies : open-access journal of related scientific research, technology development and studies in policy and management},
  volume    = {12},
  journal   = {Energies : open-access journal of related scientific research, technology development and studies in policy and management},
  number    = {17},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1996-1073},
  doi       = {10.3390/en12173253},
  pages     = {1},
  year      = {2019},
  language  = {en}
}
@misc{MaLiKuehnetal.2018,
  author    = {Ma, Jianli and Li, Qi and K{\"u}hn, Michael and Nakaten, Natalie Christine},
  title     = {Power-to-gas based subsurface energy storage},
  series = {Renewable and Sustainable Energy Reviews},
  volume    = {97},
  journal   = {Renewable and Sustainable Energy Reviews},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {1364-0321},
  doi       = {10.1016/j.rser.2018.08.056},
  pages     = {478 -- 496},
  year      = {2018},
  abstract  = {The Renewable energy power generation capacity has been rapidly increasing in China recently. Meanwhile, the contradiction between power supply and demand is becoming increasingly more prominent due to the intermittence of renewable energies. On the other hand, on the mitigation of carbon dioxide (CO2) emissions in China needs immediate attention. Power-to-Gas (PtG), a chemical energy storage technology, can convert surplus electricity into combustible gases. Subsurface energy storage can meet the requirements of long term storage with its large capacity. This paper provides a discussion of the entire PtG energy storage technology process and the current research progress. Based on the comparative study of different geological storage schemes for synthetic methane, their respective research progress and limitations are noted. In addition, a full investigation of the distribution and implementation of global PtG and CO2 capture and storage (CCS) demonstration projects is performed. Subsequently, the opportunities and challenges of the development of this technology in China are discussed based on techno-economic and ecological effects analysis. While PtG is expected to be a revolutionary technology that will replace traditional power systems, the main issues of site selection, energy efficiency and the economy still need to be adequately addressed. Additionally, based on the comprehensive discussion of the results of the analysis, power-to-gas and subsurface energy storage implementation strategies, as well as outlook in China are presented.},
  language  = {en}
}
@misc{KuehnLiNakatenetal.2017,
  author    = {K{\"u}hn, Michael and Li, Qi and Nakaten, Natalie Christine and Kempka, Thomas},
  title     = {Integrated subsurface gas storage of CO2 and CH4 offers capacity and state-of-the-art technology for energy storage in China},
  series = {Energy procedia},
  volume    = {125},
  journal   = {Energy procedia},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1876-6102},
  doi       = {10.1016/j.egypro.2017.08.039},
  pages     = {14 -- 18},
  year      = {2017},
  abstract  = {Integration and development of the energy supply in China and worldwide is a challenge for the years to come. The innovative idea presented here is based on an extension of the "power-to-gas-to-power" technology by establishing a closed carbon cycle. It is an implementation of a low-carbon energy system based on carbon dioxide capture and storage (CCS) to store and reuse wind and solar energy. The Chenjiacun storage project in China compares well with the German case study for the towns Potsdam and Brandenburg/Havel in the Federal State of Brandenburg based on the Ketzin pilot site for CCS.},
  language  = {en}
}