Energy balancing

The Global Calculator automatically matches the global supply and demand for energy at a yearly level. The user makes their choices on the global demand for energy and the global supply of energy, except for the supply of energy from fossil fuels, as this is driven by the model. The Calculator:

  • matches the supply of electricity to the demand for electricity. If the user does not supply enough electricity from renewables, nuclear and CCS, the Calculator automatically makes up the shortfall by supplying electricity from unabated power stations (either fuelled by fossil fuels or bioenergy depending on the user’s choice on bioenergy).
  • Supplies fossil fuels if the demand for hydrocarbons exceeds the supply from bioenergy and waste. For example, if the user demands more liquid fuels than supplied by bioenergy, the Calculator "extracts" oil, "refines" it and "distributes" it to end users.

However it should be noted by the user that we do not assume that the entire world’s population have access to electricity; this is a user choice and is driven by the "urbanisation" lever, which considers the range of electricity access that experts believe is possible.

Meeting peak demand

The Global Calculator models electricity demand at a yearly level. In the real world, the supply of electricity must meet the demand for electricity on a second-by-second basis on each independent electricity grid. Otherwise there are losses of power for electricity users. To ensure the viability of pathways, the Calculator ensures that there is enough generation capacity to meet peaks in electricity demand. The user chooses the size of the demand peak and the storage capacity (using the "storage and demand shifting" lever), and the Calculator "builds" enough backup gas power plants to meet the outstanding peak.

The Calculator does not capture the energy implications associated with balancing - it does not model the curtailment of generation technologies. This means that in extreme cases the Calculator may overstate the supply that is possible from intermittent technologies such as wind and solar, which in reality would be switched off if the following hold simultaneously: (a) their supply exceeds demand at any one point in time, and (b) there was insufficient storage capacity.

The Calculator does not model each grid in the world. This would make the model far too complex to be workable in an Excel workbook, which would prevent it from being open and user-friendly. Instead it models at a global level, and the user is asserting that their supply choices are located near enough to population hubs.

Finally, the Calculator cannot comment on the incidence of black outs or brown outs as these are driven by factors beyond the size of the electricity demand peak and the available electricity capacity. For example, black outs and brown outs depend on the system operator and on the incidence of shocks such as extreme weather events. These would be influenced by the climate, and this feedback loop is not taken into account within the model.