The 2013 energy flow Sankey diagram from Lawrence Livermore National Laboratory visualizes how the United States sourced and consumed primary and secondary energy. This detailed map of energy pathways helps researchers, policymakers, and the public understand efficiency losses and transition opportunities.
By tracing energy from resource extraction through conversion, delivery, and end use, the diagram highlights where energy is lost as waste heat and where efficiency gains can have the largest impact. The visualization remains a foundational reference for energy system analysis and policy discussion.
| Energy Source | 2013 Input (Quads) | Pathway | Delivered to Sector (Quads) |
|---|---|---|---|
| Coal | 18.8 | Electricity generation, industrial heat | 9.2 |
| Petroleum | 18.9 | Transportation, industrial processes | 9.0 |
| Natural Gas | 24.4 | Electricity, industrial, residential, commercial | 10.7 |
| Nuclear | 8.4 | Electricity generation | 8.0 |
| Renewables | 7.6 | Electricity, biofuels, geothermal, hydro | 7.1 |
Energy Resource Extraction and Input Quantities
Primary Fuel Contributions
The diagram begins with primary energy resources, showing the magnitude of coal, petroleum, natural gas, nuclear, and renewables entering the U.S. energy system. Each resource band is scaled to reflect raw input in quadrillion British thermal units, making it easy to compare dominance and shifts in the fuel mix.
Conversion Losses and Efficiency Insights
Thermodynamic and Operational Losses
Conversion processes such as power plants and refineries lose a significant share of energy as waste heat. The Sankey bands visibly narrow at conversion nodes, illustrating where efficiency improvements would yield the greatest systemic savings across the energy economy.
Delivery and End-Use Distribution
Sectoral Consumption Patterns
After conversion, delivered energy splits across residential, commercial, industrial, and transportation sectors. The width of each final band reveals which end uses dominate demand, informing targeted strategies for electrification, combined heat and power, and load management.
Policy and System Planning Implications
Strategic Levers for Decarbonization
By mapping both losses and high-impact nodes, the diagram supports decisions on infrastructure investment, research priorities, and regulatory design. Planners can trace how changes in one sector propagate through conversion and delivery, improving system-wide planning and risk assessment.
Key Takeaways for Energy Analysts and Stakeholders
- Natural gas, coal, and petroleum supplied most primary input in 2013, with clear waste heat at conversion points.
- Electricity generation and transportation are the two largest delivered-energy sectors, guiding efficiency and decarbonization efforts.
- Identifying narrow flow bands highlights conversion technologies where innovation can unlock large system savings.
- Cross-sector interactions revealed by the flow paths support integrated planning for grid, buildings, and industry.
FAQ
Reader questions
How are losses represented in the 2013 Sankey diagram?
Losses appear as the vertical gaps between incoming resource bands and outgoing delivery bands, highlighting inefficiencies in conversion and end use.
What makes this visualization different from simple stacked bar charts?
The flow thickness captures both magnitude and direction, revealing transformation steps and quantifying where energy is discarded as waste heat.
Which sectors receive the largest share of delivered energy?
Transportation and industrial processes together absorb the majority of delivered petroleum and natural gas, while electricity dominates delivered natural gas and nuclear output. By clarifying where emissions-intensive conversions occur and which end uses are dominant, the diagram helps prioritize abatement technologies and grid upgrades.