The key role of sufficiency for low demand-based carbon neutrality and energy security across Europe

The study addresses how Europe can achieve a 1.5 °C-compatible, climate-neutral energy system by emphasizing demand-side sufficiency alongside efficiency and renewables. It responds to the prevailing focus of energy scenarios on least-cost, technology-centric decarbonisation that often overlooks broader environmental and social consequences, such as resource extraction and dependency on energy imports. The concept of energy sufficiency—reducing absolute consumption of end-use products and services via changes in social practices and infrastructure to stay within planetary boundaries while securing decent living standards—frames the analysis. Prior work suggests large potential for demand reduction compatible with well-being (e.g., 60% global final energy reduction while maintaining decent living standards; 40% global reduction to meet 1.5 °C without negative emissions). Building on this, the paper introduces the Collaborative Low Energy Vision for the European Region (CLEVER) scenario for EU30 (EU27 plus UK, Norway, Switzerland), designed to: achieve rapid demand reductions to limit cumulative emissions; fairly distribute the remaining carbon budget; enhance energy/materials security and resilience; uphold deep sustainability across planetary boundaries; and strengthen intra-European collaboration. The scenario targets a 2020–2050 EU30 CO₂ budget of 30–32 GtCO₂ (≈6% of global, equal per-capita allocation), phases out nuclear by 2050, avoids CCS, and prioritizes technologies with TRL ≥7 to ensure realism. It promotes convergence toward equitable energy service levels across countries, explicitly incorporating sufficiency strategies beyond efficiency to meet multiple sustainability objectives.

The paper situates its contribution within a growing literature on demand-side solutions and sufficiency. Foundational studies indicate large reductions in energy needs consistent with decent living standards (Millward-Hopkins et al.) and 1.5 °C pathways without negative emissions (Grubler et al.). A UK case study (Barrett et al.) shows ~52% demand reduction by 2050 via combined sufficiency and efficiency while improving quality of life. Broader reviews emphasize the multi-dimensional sustainability benefits of demand-side measures and the underrepresentation of sufficiency in mainstream techno-economic optimization models. Comparative discussion later in the paper aligns CLEVER with other low-demand scenarios (e.g., LED global scenarios, UK Transform, France négaWatt, Germany RESCUE GreenSupreme), which converge around 50–55% final energy reductions and avoid reliance on CCS.

The study develops a bottom-up, country-scale scenario (EU30) through a collaborative, harmonized approach centered on the Sufficiency–Efficiency–Renewables (SER) framework. Key elements: - SER framework: First rescale energy service levels via sufficiency (individual and collective actions, modal shifts, avoidance of unnecessary consumption), then apply efficiency to reduce energy required for adjusted services, and finally substitute renewables to displace fossil fuels rapidly and limit cumulative emissions. - GHG targets and budget: Aim to meet or exceed EU targets for 2030 and 2050 and achieve climate neutrality as early as possible on a 1.5 °C pathway. Global carbon budget corridor (500–550 GtCO₂ median) is allocated per capita, assigning ~6% to EU30. Territorial accounting is applied; international flights included, international maritime excluded for comparability with EU targets; all GHGs (CO₂e) considered. - Collaborative bottom-up national trajectories: 26 organizations from 20 countries contributed country-specific pathways using standardized dashboards covering activity levels, sufficiency indicators, technologies, efficiencies, carriers, and sectoral balances. For countries without active partners, conservative normalized trajectories were developed and iteratively reviewed with experts. - Common sufficiency indicators: Sector working groups (transport, buildings) defined measurable sufficiency indicators (dimensional, service-related, organizational). Target corridors were set using literature, observed ranges and rates of change, partner expertise, and EU policy context, with convergence toward equitable service levels above decent living standards to account for within-country inequalities. Table 1 summarises main indicators (e.g., passenger-km/cap, active/collective transport shares, car occupancy; domestic freight tkm/cap and rail share; residential floor area m²/cap, hot water and specific electricity kWh/cap; industrial production and FEC indices; diet-related indicators for meat and dairy). - Industry modelling: Due to cross-border integration and limited detailed national models, industry was modelled top-down across countries with three levers—sufficiency (scale down material demand), circularity (optimize product lifecycle), and efficiency (reduce energy intensity). Energy-intensive materials (steel, cement, pulp/paper, glass, ammonia and high-value chemicals) were guided by corridors informed by detailed national studies (e.g., French sufficiency scenario) and adapted to each country; historical production/consumption ratios maintained. - AFOLUB and bioenergy: A top-down physical model (Couturier et al.) guided agriculture, forestry, land-use and bioenergy, aiming at (1) sectoral emissions mitigation, (2) fossil substitution, and (3) sequestration. Assumed diet shifts, substantial livestock reductions, and 100% agroecology; biomass use follows a cascading hierarchy. Domestic sustainable bioenergy potential rises from ~1500 TWh (2015) to ~2290 TWh (2050), with two-thirds of the increase from biogas (manure, cover crops, residues, biowaste). Biofuel potentials capped (first-gen ~150 TWh, second-gen ~50 TWh, third-gen ~20 TWh). Wood energy remains stable; other solid biomass grows via by-products, waste, agroforestry. - Renewable potentials and technology readiness: PV and wind potentials start from JRC ENSPRESO but adjusted downward by country experts for acceptability and deployment pace. Hydropower remains stable; solar thermal, ocean, CSP, deep geothermal, and waste heat contribute smaller shares. Technologies with TRL <7 are not assumed for large-scale deployment by 2050. PtX prioritized for aviation, international shipping, high-temperature industry, and long-duration storage; syngas production capped (~350 TWh/y EU27; ~214 TWh/y realized given biomass priorities). - Harmonisation and supply–demand matching: Iterative EU synthesis compared aggregates to EU targets, then balanced carriers within sectoral corridors considering technical constraints, materials limits (e.g., lithium, copper), and prioritizing hard-to-abate demands first. Corridors for carrier shares by subsector provided in project documentation. - Power system flexibility: Adequacy not simulated via hourly dispatch; instead, a conservative dispatchable production corridor of ≥14% of final electricity demand per country is assumed, totaling ~18% for EU27 including hydro reservoirs. Flexibility from methane/hydrogen plants, hydropower (reservoir/pumped), batteries, and cross-border transmission. Detailed grid modeling and hourly power flow were not performed. - Data, code, and sources: Historical data from Eurostat and ODYSSEE-MURE; population from Eurostat projections. Input/output datasets and code (SEPIA tool) available on Zenodo; supplementary Excel provides country-sector assumptions and ~100 policy instruments.

- Emissions trajectory and neutrality: Net GHG emissions fall by ~50% by 2030 and ~90% by 2040 relative to 2019 (3.9 GtCO2e). Net zero is reached by 2046 without nuclear or CCS. Residual 2050 emissions (~0.3 GtCO2e), primarily from industry and agriculture, are offset by natural sinks via land and forestry management (~0.5 GtCO2e). The trajectory fits an EU30 per-capita share of a 1.5 °C-compatible carbon budget (30–32 GtCO₂ for 2020–2050). - Demand reduction: Total final energy consumption (Eurostat definition; excluding ambient heat, maritime bunkers, energy sector, non-energy uses) declines 50.3% from 13,250 TWh (2019) to 6,590 TWh (2050). Per-capita reductions range from 27% to 72% across countries, with the largest cuts in higher-consuming Western European countries. At least 40% of the overall demand reduction is attributable to sufficiency measures. - Service-level convergence and equity: Scenario applies fairness-based convergence of energy service levels. Residential average floor space ~42 m²/cap (EU30) is 2.1–2.8 times decent living minima, allowing for within-country inequality (implied floor-space Gini 0.36–0.48). Surface transport averages allow a passenger-km Gini up to ~0.38 relative to decent living standards. - Industry: Demand reductions in energy-intensive subsectors arise from sufficiency (e.g., lower new construction reducing cement and steel needs), efficiency, and circularity. Circularity generally lowers unit energy consumption; classification as sufficiency vs efficiency depends on systemic scope. - Supply transformation: Renewables scale from 3,096 TWh/y (2019) to 8,837 TWh/y (2050). Contributions in 2050 include: solar PV 1,683 TWh/y (≈+1046% capacity vs 2019), onshore wind 1,782 TWh/y (≈+384%), offshore wind 1,697 TWh/y (≈+2183%). Bioenergy contributes: solid biomass primary demand ~1,296 TWh/y (~+9%), biogas ~619 TWh/y (~+213%), liquid biomass ~205 TWh/y (~+7%). Other sources (marine, geothermal, hydro, solar thermal, ambient and waste heat) provide ~1,539 TWh; petroleum ~104 TWh; non-renewable waste ~17 TWh and renewable waste ~16 TWh. - Energy security and imports: Extra-EU energy imports drop roughly tenfold, from 10.5 PWh (2019) to 0.1 PWh (2050). Only ~104 TWh of petroleum imports remain in 2050 as olefins feedstock. Local primary energy production supplies nearly all needs, supported by intra-European electricity and hydrogen exchange. - Infrastructure and interconnections: High power and hydrogen exchanges within Europe enable resource complementarity and reduce external dependencies; grid scaling is needed but is limited compared with alternative scenarios. - Policy implications: Although costs are not modeled, lower demand reduces required renewable and storage capacity, avoids CCS, and likely lowers system costs and materials needs. The scenario compiles ~100 policy measures and shows that comprehensive sufficiency policy mixes (regulatory, fiscal, information) are required in all sectors to achieve the sufficiency corridors.

The findings demonstrate that prioritizing sufficiency alongside efficiency and renewables can deliver a 1.5 °C-compatible pathway for Europe with earlier net zero and without reliance on nuclear or CCS. Compared with other low-demand scenarios at national and regional scales, CLEVER’s ~50% final energy reduction aligns with a consistent result: strong demand reduction decreases supply-side scale, infrastructure expansion, and dependency risks, while reducing residual emissions and avoiding expensive removal technologies. The approach enhances fairness by converging service levels and maintaining buffers above decent living standards to account for inequality. It also strengthens energy security by radically cutting extra-EU imports and limiting exposure to global resource markets. Realizing these potentials hinges on policy: sufficiency must be explicitly integrated into EU frameworks (e.g., National Energy and Climate Plans) via coherent, consistent, and comprehensive policy mixes emphasizing structural change (regulation, economic instruments, and education) over purely individual behavior nudges. Reinforced interconnections and coordinated European collaboration are essential to unlock synergies, especially for electricity and hydrogen exchanges. Additionally, common service-level indicators and improved statistics are needed to systematically include sufficiency in scenario work. Overall, sufficiency offers a multi-solving strategy: it raises the probability of meeting climate targets, reduces imports and externalization of impacts, lowers materials and land-use pressures, and supports a more just transition within Europe and globally.

The study provides a detailed, bottom-up EU30 pathway showing that deep demand reduction—anchored in sufficiency—can halve final energy use by 2050, enable 77% renewables by 2040 and 100% by 2050, reach net zero by 2046 without nuclear or CCS, and drastically reduce extra-EU energy imports. By converging energy service levels above decent living standards, the scenario enhances fairness while limiting cumulative emissions and supply-side risks. Key contributions include: a harmonized sufficiency-focused modelling language and indicator set across 30 European countries; an iterative supply–demand matching method constrained by deep sustainability (technology readiness, materials limits, bioenergy sustainability); and openly available data and code (SEPIA tool). Future research should: (i) perform high-resolution power system adequacy and grid flow modelling to refine flexibility and network needs; (ii) quantify investments and system costs; (iii) integrate consumption-based accounting to complement territorial emissions; (iv) assess intra-country inequality effects on access to energy services; and (v) evaluate potential rebound effects. Policymakers should explicitly integrate sufficiency into EU and national plans, develop common service-level indicators, and deploy robust regulatory and fiscal packages to realize the sufficiency corridor equitably.

- No hourly dispatch or explicit adequacy modelling; instead a conservative flexible generation corridor (≥14% per country; ~18% EU27 with hydro) is assumed. - Grid not explicitly modelled; transmission assumed available, with congestion ignored. A detailed hourly power flow and capacity expansion model would better quantify reinforcement needs. - No explicit investment or cost quantification; resulting energy mix may not be cost-optimal. - Policies are outlined qualitatively (~100 measures) but not endogenously modelled; lack of empirical links from specific policies to sufficiency indicators limits quantification. - Rebound effects (financial or time-use) are not modelled. - Emissions accounting is territorial; consumption-based emissions and embodied imports/exports of goods are not included, potentially understating global justice implications. - Technology deployment constrained to TRL ≥7; emerging technologies may change feasible options by 2050, while assumed potentials (e.g., PV/wind acceptance, bioenergy from sequential cropping) carry uncertainties.