Mitigation potential of horizontal Ground Coupled Heat Pumps for current and future climatic conditions: UK environmental modelling studies

政策制定者的主要优先事项是减少化石碳的燃烧，从而减缓地球大气中二氧化碳浓度的增加。英国在调查风能、海洋和太阳能等可再生能源以及生物能源方面做出了相当大的努力。然而，与美国、瑞士和瑞典等其他国家相比，关于地源热泵系统(GCHP)的研究相对较少，这是一项在英国相对未得到充分利用的技术。简单地说，GCHP利用(土壤和空气之间的)温差来提供空间供暖，增加对低二氧化碳或非二氧化碳排放的替代能源的吸收，是冬季和夏季降温的一种方式。这是通过在地下放置塑料管(装满含有防冻剂的液体)来实现的，这样它们就可以与土壤交换热量，即所谓的热交换器。这种热能通过热泵为家庭或其他建筑供暖，从而提供一种可持续、可再生和可靠的能源。这些GCHP的性能取决于热交换器的设计和配置(例如，管道的长度、安装深度、管道之间的间距)。然而，与更昂贵的垂直钻孔系统相比，水平安装系统的性能也受到环境的相当复杂的影响。这里我们指的是土壤、植被和大气条件，这些条件将随着英国和时间的推移而显著不同(日变化、季节变化和年际变化)。这项建议中描述的研究旨在调查这些系统的长期(~50年，地源热电联产系统的平均寿命)性能在整个英国是如何变化的。我们的发现将成为向地方政府(和用户)建议这些系统依赖于地点的经济可行性及其减少碳排放的潜力的基础，同时明确考虑到我们的气候正在以显著的速度变化。此外，根据从地面带走和返回地面的热量之间的平衡，热交换器附近的土壤温度可能会下降或上升；与此相关的是土壤水分离开或朝向热交换器的运动。这些过程还将影响系统在其生命周期内的性能。土壤和地源热泵之间的这些错综复杂的相互作用可以通过计算机模型模拟，各种软件包可供地源热泵设计者和安装者使用。然而，这些类型的软件被开发为在逐个站点的基础上工作，而且它们简化了环境的影响。此外，它们仅针对较短的时间跨度(~1-3年)。在这项建议中，我们将使用一个详细的陆地表面模式，例如英国气象局用来预测天气的模式。首先，我们将对其进行改进，以确保考虑到地下热交换器和土壤之间的所有重要相互作用(热量和水分流动，包括地下水)。然后我们将对其进行测试，并随后使用生成的长期数据来驱动该模型，这些数据代表了整个英国的气候、土壤类型和植被(以及相关属性)。只有到那时，我们才能对全英国范围内的地源热泵系统的长期性能及其在减少二氧化碳排放方面的有效性获得可靠的估计。这使我们能够建议在英国的特定地区增加吸收，并指出对地源热泵系统设计和配置的具体改变(例如，管道类型和安装深度)如何能够改善性能，从而增加其减少二氧化碳排放的潜力。

the key priorities for policymakers in order to decrease combustion of fossil carbon, thereby slowing the increase of CO2 concentration in the Earth's atmosphere. A considerable amount of UK effort has gone into investigating renewable energy sources such as wind, marine and solar power, as well as into bio-energy. However, relatively little work has been undertaken on the topic of ground coupled heat pump systems (GCHP), a relatively underused technology in the UK, in contrast to other countries such as USA, Switzerland and Sweden. To put it simply, GCHPs use temperature differences (between soil and air) to provide space heating An increased uptake of alternative low- or non-CO2 emitting energy sources is one of in the winter and cooling in the summer. This is achieved by placing plastic pipes (filled with fluid containing anti-freeze) in the ground so that they can exchange heat with the soil, so called heat exchangers. This heat is 'upgraded' by a heat pump to heat homes or other buildings, thereby providing a sustainable, renewable and reliable source of energy. The performance of these GCHPs depends on the design and configuration of the heat exchangers (e.g. length of pipes, depth of installation, spacing between pipes). However, the performance of horizontally installed systems, as opposed to the more expensive vertical borehole ones, is also affected, in a rather complex way, by the environment. With this we mean soil, vegetation and atmospheric conditions, which will significantly differ over the UK and over time (diurnal, seasonal and inter-annual variation). The research described in this proposal aims to investigate how the long-term (~50 years, the average lifespan of GCHP systems) performance of these systems varies throughout the UK. Our findings would form the basis of recommendations to local governments (and users) on the location-dependent economic viability of these systems and their potential to reduce carbon emissions, while explicitly taking into account that our climate is changing at a significant rate. Also, depending on the balance between how much heat is taken away from and returned to the ground, the soil temperature in the neighbourhood of the heat exchangers may fall or rise; related to this is the movement of soil moisture away from or towards the heat exchanger. These processes will also affect the performance of the system during its life span. These intricate interactions between soil and GCHP can be mimicked by computer model simulations and various packages are available for use by GCHP designers and installers. However, these types of software have been developed to work on a site-by-site basis and moreover they simplify the effect of the environment. Also, they address short time spans only (~1-3 years). In this proposal we will use a detailed land surface model, such as the one used by the UK Meteorological Office to predict the weather. First we will improve it to ensure that all important interactions between the below-ground heat exchangers and the soil (heat and moisture flow, including groundwater) are taken into account. We will then test it and subsequently drive the model with long-term data, generated to represent the climate, soil type, and vegetation (and related properties) throughout the UK. Only then can we obtain reliable estimates about the UK-wide long-term performance of GCHP systems and their effectiveness in reducing CO2 emissions. This allows us to recommend increased uptake in specific UK areas as well as indicate how specific changes to the design and configuration of GCHP systems (e.g. type of tube and installation depth) can improve performance and hence increase its potential for reduction in CO2 emission.