Impacts of underground climate change on urban geothermal potential: Lessons learnt from a case study in London
Impacts of underground climate change on urban geothermal potential: Lessons learnt from a case study in London
复制标题
地下气候变化对城市地热潜力的影响：伦敦案例研究的经验教训
DOI：
10.1016/j.scitotenv.2021.146196
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发表时间：
2021
影响因子：
9.8
通讯作者：
Soga, Kenichi
中科院分区：
文献类型：
--
作者：
Bidarmaghz, Asal;Choudhary, Ruchi;Narsilio, Guillermo;Soga, Kenichi
虽然城市地下越来越多地被用于各种目的，但关于城市地下气候变化，应该解决两个问题：i)由于地下加热空间(如隧道和地下室)的热释放，有多少能量储存在城市地下；ii)一个城市或地区的热需求中，有多少可以通过收集地下累积的热能来供应。然而，我们对地面温升和城市地下地热潜力的了解仍然有限。本文通过考虑由于热量持续排入地下而引起的地面温度的时空变化，以及地热提取能力的影响，对伦敦市中心一个12平方公里人口稠密区的地热潜力进行了量化。建立了场地大尺度瞬变半三维地热地下模型，模拟了地下供热空间、地热能提取系统与地面和地下水的热相互作用。计算了地下的同时排热和抽热过程，从而确定了地下对其地热势影响最大的参数。结果显示，该行政区总供热需求的50%可以通过地热设施提供，从而减少了约33%的二氧化碳排放。砂石中的地热开采效率主要取决于地面条件，如渗透层的厚度和地下水流动状况。然而，在粘土等不透水的土地上，地下建筑环境，如供暖空间，已显示出对提高地热开采效率有重大影响。
While urban underground is being increasingly used for various purposes, two concerns should be addressed with respect to the urban underground climate change: i) how much energy has been stored in urban subsurface due to the heat rejection from underground heated spaces (such as tunnels and basements) and ii) how much of the thermal demand of a city or district can be supplied by harvesting this accumulative thermal energy in the ground. However, our understanding of the temperature rise in the ground and of the geothermal potential of urban subsurface is still limited. This paper quantifies the geothermal potential for a 12 km2densely populated borough in central London by considering the spatio-temporal temperature variation in the ground owing to continuous rejection of heat into the ground, coupled with the effect of geothermal extraction capacity. A large-scale transient semi-3D geothermal subsurface model of the site is developed, and the thermal interaction between underground heated spaces, geothermal energy extraction systems and the ground and groundwater are simulated. The concurrent heat rejection and extraction processes in the subsurface are computed so that the most influencing parameters of the subsurface on its geothermal potential are identified. Results show that up to 50% of the borough's total heat demand can be supplied via geothermal installations leading to around 33% reduction in CO2emission. The geothermal extraction efficiency in sand and gravel primarily depends on the ground conditions such as the thickness of the permeable layer and the groundwater flow regime. In impermeable ground such as clay, however, the underground built environment such as heated spaces have shown to have a significant impact on improving the geothermal extraction efficiency.