Electrification of heating: the role of heat pumps

Electrification is seen as an important global contributor to mitigation of climate change, because low carbon electricity can, in theory, replace current fossil fuel use in buildings and surface transport. Heat pumps are the key technology for delivering electrification of heating. This paper focuses on the role of heat pumps in heating the residential sector, with both a global and UK perspective. The UK perspective is used to discuss detailed issues around scenarios, technologies, infrastructures, social factors, policies and barriers to adoption. The global focus necessarily excludes a lot of this detail, but shows how heat pump adoption would affect electricity demand, and particularly peak demand, at this much larger scale. A number of UK low carbon scenarios are summarised. Heat pumps are a key technology in many, expected to deliver up to 90% of heating energy. However, the future role of heat pumps has been reduced recently in some influential scenarios, due to greater recognition of the cost and complexity of this transition. Nevertheless, there is a huge gulf between annual UK sales of 21,000 heat pumps, and the Committee on Climate Change's revised projection of 4 million heat pump installations by 2030. UK analysis illustrates the challenges for heat pumps – economic, technical and social – at a variety of scales. A key issue at national and international scale is the effect of heat pumps on peak electricity demand in countries with cold winters. This is explored by developing a model of global heating energy use. This geographical model uses historical population-weighted temperature data, and assumptions about heating energy use and the efficiency of heat pumps to give peak instantaneous demand, calculated at three-hourly time steps. Results show that heating energy need is dominated globally by China, which is responsible for almost 40% the total. For the UK, a 100% use of heat pumps would increase national electricity demand by 25%, and peak electricity demand by 65%. The peak: mean electricity ratio would change from the current 1.58 to 4.1. Globally, 100% heat pump adoption would require 11% of current world electricity use and increase peak demand by 65%. This peak electricity capacity is unlikely to be delivered, given the huge costs entailed. The challenges of delivering electrification of heating, suggest policy makers should also encourage alternative options including deep efficiency retrofits, biomass, biogas and renewable district heating systems. There are also options for reducing the peak: mean ratio, including international interconnection, and using backup heating systems at times of extreme cold, which can be further investigated. The key research question emerging from this work is: does the peak issue set a limit on the percentage of residential heating demand that can be met by heat pumps, and if so, what is it