Techno-Economic Analysis Of Capturing CO₂ From Pyrolysis

Emerging negative emission technologies（NETs）are considered as effective measures to reduce carbon dioxide emissions to achieve the climate goal set by the Paris Agreement,and bioenergy with carbon capture and storage（BECCS）is one of the most important NETs.The"14th Five-Year Plan"and the Outline of Vision 2035 pointed out that carbon capture is the most important work of energy conservation and emission reduction.With the support of a series of policies,carbon capture and storage（CCS）technologies are booming.It will make a huge contribution to achieving the"carbon peak"and"carbon neutral".The development of CCS technology will provide the basis for the wide application of BECCS.The Comprehensive Work Plan for Energy Conservation and Emission Reduction in"14th Five-Year Plan"highlights the high carbon emissions of the transportation industry.Therefore,integrating CO₂ capture with biomass pyrolysis（PyrCC）is attracting increasing interest,such an integration as replacing fossil fuel with biooil produced through biomass pyrolysis is a crucial way for decarbonizing the transport sector.However,studies about the integration of CO₂ capture with biomass pyrolysis（PyrCC）are rare,especially on the technic and economic performance.Pyrolysis in different conditions integrated with different capture technologies will show different technic and economic performance.The lack of research data makes the selection and development of capture technologies difficult.Besides,the high cost of carbon capture technologies has become a barrier of technological development.This study aims to explore the technical and economic performance of integrating pyrolysis with different carbon capture technologies.This will provide a reference for the commercial application of PyrCC and promote the development of BECCS.This study analyzes the impact of different biomass feedstocks and reaction times on pyrolysis integrated with different carbon capture technologies by validated models.CO₂ purity,captured CO₂,energy penalty,exergy penalty and energy efficiency are used to assess technic performance.And levelized cost,net present value and payback time are used to estimating economic performance.Four capture technologies have been estimated,including ethanolamine（MEA）chemical absorption（MEA-CA）,temperature swing adsorption（TSA）,calcium looping（Ca L）and chemical looping combustion（CLC）.The main research conclusions are as follows:（1）The type of biomass and the reaction time have a great influence on the pyrolysis product;while the reaction temperature has a relatively small influence.Biomass with high ash content have higher gas and biochar yields.With the increase of reaction time,the yield of bio-oil gradually decreases;the yield of biochar gradually increases,and the yield of gas doesn’t change much.The CO₂ content in the gas phase increases gradually.（2）In terms of technical performance,CLC can realize the highest capture amount of CO₂ with the lowest energy penalty,requires minimal additional fuel and has minimal impact on energy efficiency.Ca L has the highest energy penalty and exergy penalty.The reaction time of pyrolysis also significantly affects the performance of the capture technology.With the increase of reaction time,the energy penalty and exergy penalty are significantly reduced,but the additional fuel needed and the impact on energy efficiency are both increased.（3）Both Ca L and CLC show the lowest levelized cost of CO₂（LCOC）,which are around56$/tCO₂,and the LCOC of MEA chemical absorption is the highest,about 83$/tCO₂.With the increase of reaction time,the LCOC of all assessed technologies decrease.Moreover,the net present value（NPV）and the payback time（PBT）are also estimated for different technologies.At the carbon price of 70.1$/tCO₂,MEA-CA and CLC show the longest and shortest payback time that are 5.9 years and 3.2 years respectively.（4）The current carbon price in China is too low to get economic benefits.However,if the carbon price can reach more than￥300/tCO₂,all capture technologies can get higher net present value and shorter payback time.（5）The type of biomass feedstock also has a significant effect on carbon capture performance.The captured CO₂ from pyrolysis of rice husks is more than that from pyrolysis of wood,and the energy penalty and exergy penalty are lower,while it has a greater impact on the energy efficiency of the system.The economic performance of CO₂ capture from pyrolysis of rice husks is better than that of wood,including the lower LCOC,higher NPV and shorter PBT.（5）Considering technical and economic performance comprehensively,whether wood or rice husk is used as biomass feedstock,CLC shows best capture performance,and the increase of reaction time can significantly reduce energy penalty and LCOC.If the carbon price is increased to 80$/tCO₂,the PBT of carbon capture technologies will be significantly reduced.