The GEC supply modelling relies on estimates of the remaining technically recoverable resource, rather than the (often more widely quoted) numbers for proven reserves. Resource estimates are subject to a considerable degree of uncertainty, as well as the distinction in the analysis between conventional and unconventional resource types.

Overall, the remaining technical recoverable resources of fossil fuels remain similar to those in the World Energy Outlook 2023. All fuels are at a level comfortably sufficient to meet the projections of global energy demand growth to 2050 in all scenarios. Remaining technically recoverable resources of US tight oil (crude plus condensate) total more than 210 billion barrels.

Natural gas resource numbers remain broadly similar to those of last year. Most of the proven reserves lie in the Middle East and Eurasia. World coal resources are made up of various types of coal: around 80% is steam and coking coal and the remainder is lignite. Coal resources are more available in parts of the world without substantial natural gas and oil resources, notably in Asia.

Overall, the gradual depletion of resources (at a pace that varies by scenario) means that operators have to develop more difficult and complex reservoirs. This tends to push up production costs over time, although this effect is offset by the assumed continuous adoption of new, more efficient production technologies and practices.

Major contributors to the levelised cost of electricity (LCOE) include: overnight capital costs; capacity factor that describes the average output over the year relative to the maximum rated capacity (typical values provided); cost of fuel inputs; plus operation and maintenance. Economic lifetime assumptions are 25 years for solar PV, and onshore and offshore wind.

Weighted average cost of capital (WACC) assumptions reflect market data and survey information provided through the Cost of Capital Observatory, updating analysis for utility-scale solar PV in the World Energy Outlook 2020, with a range of 4‑7%, and for offshore wind analysis from the Offshore Wind Outlook 2019, with a range of 5‑8%. Onshore wind was assumed to have the same WACC as utility-scale solar PV. A standard WACC was assumed for nuclear power, coal- and gas-fired power plants (8‑9% based on the stage of economic development).

The value-adjusted levelised cost of electricity (VALCOE) incorporates information on both costs and the value provided to the system. Based on the LCOE, estimates of energy, capacity and flexibility value are incorporated to provide a more complete metric of competitiveness for power generation technologies. The method is explained in the detailed GEC Model documentation.

Fuel, CO₂ and O&M costs reflect the average over the ten years following the indicated date in the projections (and therefore vary by scenario in 2023).

Solar PV and wind costs do not include the cost of energy storage technologies, such as utility-scale batteries.

The capital costs for nuclear power represent the “nth-of-a-kind” costs for new reactor designs, with substantial cost reductions from the first-of-a-kind projects.

All costs represent fully installed/delivered technologies, not solely the module cost, unless otherwise noted. Installed/delivered costs include engineering, procurement and construction costs to install the module. Iron-based steel production costs display a range considering technology and regional differences and differentiate between conventional and innovative production routes. Conventional routes are blast furnace-basic oxygen furnace (BF‑BOF) and direct reduced iron-electric arc furnace (DRI‑EAF). The innovative routes are BF‑BOFs with carbon capture, utilisation and storage (CCUS), DRI‑EAF with CCUS, and 100% electrolytic hydrogen-based DRI‑EAF.

Electrolyser costs reflect a projected weighted average of installed electrolyser technologies (excluding China, where the modelled costs are lower), including inverters.

Fuel cell costs are based on stack manufacturing costs only, not installed/delivered costs. The costs provided are for automotive fuel cell stacks for light-duty vehicles.

Utility-scale stationary battery costs reflect the average installed costs of all battery systems rated to provide maximum power output for a four-hour period.

The GEC Model also integrates innovative technologies and individual technology designs that are not yet available on the market at scale by characterising their maturity and expected time of market introduction. For each sector and technology area, new project announcements and important technological developments are tracked in databases that are regularly published.

The modelled scenarios are informed by such detailed technology tracking process. For instance, the project planning financing status is an important consideration for whether projects are reflected in STEPS or rather in APS. For technology development progress and the time to bring new technologies to markets, the scenarios assume different pace of progress as the support and degree of international cooperation on clean energy innovation increases with the ambition in decarbonisation.

The following databases are particularly relevant for the definition of the different scenarios:

• Clean Technology Guide: interactive database that tracks the technology readiness level (TRL) of over 550 individual technology designs and components across the whole energy system that contribute to achieving the goal of net-zero emissions. The Guide is updated every year.
• Clean Energy Demonstration Projects Database, launched in 2022 and updated every year, this provides more detailed tracking of the location, status, capacity, timing and funding, of over 500 demonstration projects across the energy sector.
• Tracking Clean Energy Progress: annual tracking of market deployment and techno-economic performance metrics for over 50 components of the energy system that are critical for clean energy transitions and their progress towards short-term 2030 milestone along the trajectory of the Net Zero by 2050 Scenario.
• Hydrogen Production Projects Database: covers all projects commissioned worldwide since 2000 to produce hydrogen for energy or climate-change-mitigation purposes.
• Global EV Outlook: annual publication that identifies and discusses recent policy and market developments in electric mobility across the globe. It is developed with the support of the members of the Clean Energy Ministerial Electric Vehicles Initiative (EVI).