Green energy: Which sources are the most sustainable?

Strategic Energy Transition & Carbon Goals

• Current global power generation relies on fossil fuels for 80% of supply, a sector responsible for the majority of greenhouse gas emissions.
• The primary objective is achieving a "zero carbon" or "net negative" greenhouse gas energy system, rather than relying solely on renewables.
• Nuclear energy is identified as a critical, virtually carbon-free source that could significantly aid net zero goals if its global share is maintained or increased.
• The limited adoption of nuclear power is driven primarily by political resistance and public trauma from accidents (Fukushima, Three Mile Island, Chernobyl), rather than technological or economic failures.
• Bioenergy has potential for net-negative emissions if implemented correctly, though current costs remain high.

Solar Efficiency & Storage Challenges

• While solar energy theoretically exceeds global annual consumption within hours of Earth's exposure, current conversion, capture, and distribution efficiencies remain extremely low.
• Improvements in solar technology require advancements in materials, chemistry, and transmission infrastructure to reduce distribution losses.
• Solar intermittency necessitates superior energy storage solutions, moving beyond current battery systems (hours of storage) to multi-season capacity.
• Hydrogen is highlighted as a promising energy carrier capable of long-term, multi-season storage to balance peak and off-peak grid demands.
• Global experiments are currently underway to test seasonal storage solutions using wind and hydro resources.

Biofuels, EVs, & Building Efficiency

• Widespread biofuel adoption is cautioned against due to the trade-off between food security and energy production, particularly in emerging markets.
• Agricultural subsidies for biofuels, such as US corn-based ethanol, are criticized for distorting food markets and creating suboptimal energy outcomes.
• Biofuels are deemed viable only for a limited role in global decarbonization strategies rather than a primary solution.
• Electric vehicles (EVs) are viewed as a necessary "leverage point" for zero carbon transport, even when plugged into coal-dominant grids, because the internal combustion engine offers no path to zero emissions.
• The long-term sustainability of EVs depends on the grid's eventual transition to zero-carbon power sources.
• Heat pumps offer a four-fold increase in energy efficiency compared to traditional heating and cooling systems.
• Building efficiency is identified as a critical factor, with recommendations focusing on better construction (e.g., triple-glazed windows) to reduce baseline energy demand rather than just optimizing heating systems.
• Housing stock in certain regions, such as Britain, is noted as among the least energy-efficient in Europe, highlighting a global issue in building design.