Abstract: Water, energy, and agricultural infrastructure investments have important inter-relations fulfilling potentially competing objectives. When shaping investment plans, decision makers need to evaluate those interactions and the associated uncertainties.

We compare planning infrastructure under uncertainty with an integrated water-energy-food nexus framework and with sector-centered (silo) frameworks. We use WHAT-IF, an open-source hydroeconomic decision support tool with a holistic representation of the power and agriculture sectors. The tool is applied to an illustrative synthetic case and to a complex planning problem in the Zambezi River Basin involving reservoirs, hydropower, irrigation, transmission lines and power plant investments. In the synthetic case, the nexus framework selects investments that generate more synergies across sectors. In sector-centered frameworks, the value of investments that impact multiple sectors (like hydropower, bioenergy, and desalinization) are under- or overestimated. Furthermore, the nexus framework identifies risks related to uncertainties that are not linked to the investments respective sectors.

In the Zambezi river case, we find that most investments are mainly sensitive to parameters related to their respective sectors, and that financial parameters like discount rate, capital costs or carbon taxes are driving the feasibility of investments. However, trade-offs between water for irrigation and water for hydropower are important; ignoring trade-offs in silo frameworks increases the irrigation expansion that is perceived as beneficial by 22% compared to a nexus framework that considers irrigation and hydropower jointly. Planning in a nexus framework is expected to be particularly important when projects and uncertainties can considerably affect the current equilibrium.

Abstract: We explore potential impacts of global decarbonization on trends in light-duty vehicle (LDV) fleets from 2020-2050. Using an economy-wide multi-region multi-sector model, we project that the global EV fleet will grow from 5 million vehicles in 2018 to about 95–105 million EVs by 2030, and 585–823 million EVs by 2050. At this level of market penetration, EVs would constitute one-third to one-half of the overall LDV fleet by 2050 in different scenarios.

China, USA, and Europe remain the largest markets in our study timeframe, but EVs are projected to grow in all regions reducing oil use and emissions. EVs play a role in reducing oil use, but a more substantial reduction in oil consumption comes from economy-wide carbon pricing. Absent more aggressive efforts to reduce carbon emissions, global oil consumption is not radically reduced in the next several decades because of increased demand from other sectors, such as for heavy-duty transport and non-fuel uses. use of increased demand from other sectors, such as for heavy-duty transport and non-fuel uses. Overall, we find that EVs, along with more efficient internal combustion engine vehicles (ICEVs), represent a viable opportunity among a set of options for reducing global carbon emissions at a reasonable cost.