In this modified scenario, the initially available non-recoverable natural resources are doubled to make them last longer. This is a reasonable assumption, as indeed, the projections of available resources have repetitively been raised during recent decades. Consequently, industry is able to grow unabatedly for 20 more years, before the increasing extraction cost finally puts a damper on its further growth. Also postulated in this scenario are advances in resource extraction technology that make it cheaper and more efficient to produce the available resources.
References:
In order to accomplish this change, you need to modify the initial value of the natural resources as follows:
parameter Real nr_resources_init(unit="ton") = 2e12 "Initial available non-recoverable resources";,
you need to modify the table P_Fr_Cap_Al_Obt_Res_2 that describes the fraction of capital allocated to obtaining resources:
parameter Real p_fr_cap_al_obt_res_2[:] = {1,0.1,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05,0.05} "Non-renewable resource fraction remaining";,
and finally, you need to reset one of the switching times in the model:
parameter Real t_fcaor_time(unit="yr") = 2002 "Year of capital allocation to resource use efficiency";.
Simulate the model from 1900 until 2100, and display the same variables as in the book Limits to Growth: The 30-Year Update at page 173: