[1] Electricity generation emissions 

Total global GHG emissions, around 55 Gt CO2eq: Our World in Data, “Greenhouse gas emissions” and UN environment programme, Emissions Gap Report 2022 (page 6, table 2.1). 

Share of global GHG emissions from power sector, around 14 Gt CO2eq, or 26%: International Energy Agency, “CO2 emissions in 2022”, and  Bill Gates, “How to avoid a climate disaster” 

Distribution of CO2eq emissions from coal-fired power plants (around 10 Gt), gas-fired power plants (around 3 Gt) and other sources of power generation: This was computed combining power generation data from Our World in Data, “Electricity production by source” and emission-intensity data from the 5th IPCC report, Annex III, “Technology-specific Cost and Performance Parameters”. Value for coal validated in IEA, “Coal-Fired Electricity”. 


[2] Electrical power system growing and transforming 

Data on historical electricity production by source: Our World in Data, “Electricity production by source” 

Data on predicted future electricity production by source: IEA, “Net zero by 2050” (net zero scenario, page 115) 


[3] Solar and wind fluctuations and the need for flexibility 

Graph generated using data from the Spanish electrical grid for the year 2022, when wind and solar reached 37% of total generation, and clean sources overall (including hydropower and nuclear) reached 63%. The “Projected clean sources” area was computed by adding extra wind and solar generation on top of current clean generation, to substitute all non-clean electricity, such that average clean generation equals average demand. The “Shortage” area represents the difference between demand and generation at specific times, and can be avoided with flexibility tools, such as long duration energy storage (LDES), in which generation surplus is stored and used to fill in the gaps. The electricity demand curve corresponds to unmodified data. 


[4] Flexibility tools 

Categories and applications of different flexibility tools: LDES Council, “Net-zero power” (Exhibit 6, page 6) 


[5-6] LDES families and technologies characteristics 

Own elaboration of infographic and technology tables, based on interviews with LDES technology developers and researchers. 

Clearly defining LDES is not a straightforward task, as there is yet no absolute consensus. The definition we provide, “LDES includes any storage technology that can supply energy continuously, at rated power, for at least 10 hours in a row”, is based on recommendations from the NREL report, “The Challenge of defining Long-Duration Energy Storage”.


[7] Recommendations 

Own elaboration, based on interviews with LDES innovators and on the results of a series of workshops on LDES market design co-hosted with Breakthrough Energy and EASE.