General observations:

1. No energy is clean:

• Each source has risks & pollutions: their nature and intensity vary greatly from one source to another.

2. Remain critical on the words used:

• Renewable energy: sunlight is renewable over our time horizons, but the materials used to produce solar panels are not.
• Green energy: what does green mean?
• Energy transition: the really fast increase in energy consumption with a relatively constant mix with 80% fossil fuels

3. Always analyze the bigger picture and avoid the "Myopia Syndrome"

• Myopia Syndrome: comparing two elements within a too narrow perimeter,
• Example #1: consider natural gas as a "cleaner energy" because it emits marginally less CO2 than oil when used, while it emits massive quantities of CH4 over the value chain because of leaks.
• Example #2: calculate a wind turbine carbon intensity without integrating CO2 and CH4 emissions coming for the necessary use of natural gas to compensate the wind.
• Example #3: focus too much on the supply-production side of the energy market, without considering the demand side.

4. Complexity: integrate as many constraints as possible to develop realistic analyses.

Multiple Constraints:

National Energy Resources:

• Non-renewables: which reserves?
• Renewables: geographic and climatic potential.
• Energy infrastructures: value chain, technical knowledge, investment capacities?

Domestic Demand & Uses:

• Volume: how much energy is used today? In 20+ years ?
• Mix: what type of energy do we need?
• Developing countries: what aspirations for development to improve basic living conditions (and so increase energy consumption)

Environmental Objectives:

• Climate: how much CO2 do we emit? What carbon intensity? Aligned with the Paris Agreement?
• Other pressures on the environment: raw materials, water consumption, land-use, air and water pollutions, waste…

Geo-strategic Situation:

• Sovereignty: how much do we depend on other countries? On which countries do we rely?
• Risk exposure: how exposed are we to disruptions in the supply chain?
• Reliability: which back-up options do we have? How interconnected are we?