Energy self-sufficient households with photovoltaics and electric vehicles are feasible in temperate climate

RESEARCH ARTICLE Energy self-sufficient households with photovoltaics and electric vehicles are feasible in temperate climate Ursin Gsto¨ hl*, Stefan PfenningerID* Climate Policy Group, Institute for Environmental Decisions, ETH Zu¨ rich, Switzerland * ugstoehl@student.ethz.ch; stefan.pfenninger@usys.ethz.ch Abstract The idea that households produce and consume their own energy, that is, energy self-suffi- ciency at a very local level, captures the popular imagination and commands political sup- port across parts of Europe. This paper investigates the technical and economic feasibility of household energy self-sufficiency in Switzerland, which can be seen as representative for other regions with a temperate climate, by 2050. We compare sixteen cases that vary across four dimensions: household type, building type, electricity demand reduction, and passenger vehicle use patterns. We assume that photovoltaic (PV) electricity supplies all energy, which implies a complete shift away from fossil fuel based heating and internal com- bustion engine vehicles. Two energy storage technologies are considered: short-term stor- age in lithium-ion batteries and long-term storage with hydrogen, requiring an electrolyzer, storage tank, and a fuel cell for electricity conversion. We examine technological feasibility and total system costs for self-sufficient households compared to base cases that rely on fossil fuels and the existing power grid. PV efficiency and available rooftop/facade area are most critical with respect to the overall energy balance. Single-family dwellings with pro-

found electricity demand reduction and urban mobility patterns achieve self-sufficiency most easily. Multi-family buildings with conventional electricity demand and rural mobility patterns can only be self-sufficient if PV efficiency increases, and all of the roof plus most of the facade can be covered with PV. All self-sufficient cases are technically feasible but more expensive than fully electrified grid-connected cases. Self-sufficiency may even become cost-competitive in some cases depending on storage and fossil fuel prices. Thus, if political measures improve their financial attractiveness or individuals decide to shoulder the neces- sary investments, self-sufficient buildings may start to become increasingly prevalent. Introduction Climate change mitigation requires eliminating fossil fuel emissions from the energy sector. Solar photovoltaics (PV) is not only one of the most promising technology options to play a major role in a clean energy system, but also opens up the possibility for a much more decen- tralized supply of electricity. It has led to the idea of energy self-sufficiency or energy autarky PLOS ONE | https://doi.org/10.1371/journal.pone.0227368 March 4, 2020 1 / 25 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Gsto¨hl U, Pfenninger S (2020) Energy self-sufficient households with photovoltaics and electric vehicles are feasible in temperate climate. PLoS ONE 15(3): e0227368. https://doi.org/ 10.1371/journal.pone.0227368 Editor: Chen Lv, Nanyang Technological University, SINGAPORE Received: September 17, 2019

Accepted: December 17, 2019 Published: March 4, 2020 Copyright: © 2020 Gsto¨hl, Pfenninger. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the manuscript and its Supporting Information files. Funding: SP acknowledges funding from the Swiss Competence Center for Energy Research − Supply of Electricity (SCCER SoE), contract number 1155002546. http://sccer-soe.ch/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors have declared that no competing interests exist.