Clean Energy from First Principles

Clean Energy from First Principles

Examining clean energy technologies through a common lens: what gradient exists in nature, and what limits its conversion to useful work?

Primordial heat + radioactive decay

Hydrothermal Geothermal Energy

Extracts heat from naturally occurring underground reservoirs where hot water or steam has been heated by proximity to hot rock, converting thermal energy to electricity via steam turbines or binary cycle systems.

  • Thermal intermediate (heat engine)

Solar-derived

Ocean Current Energy

Extracts kinetic energy from continuous, unidirectional ocean currents driven by global wind patterns and thermohaline circulation.

  • Mechanical intermediate

Concentrated Solar Thermal

Uses mirrors to concentrate direct solar radiation onto a receiver, heating a working fluid to drive a heat engine that generates electricity.

  • Thermal intermediate (heat engine)

Photovoltaics

Converts solar photon energy directly to electricity using semiconductor p-n junctions that generate and separate electron-hole pairs.

  • Direct electrical conversion

Solar Heating

Absorbs solar radiation to produce low-grade thermal energy for domestic hot water, space heating, and industrial process heat without concentration.

  • Thermal intermediate (heat engine)

Thermophotovoltaics

Converts thermal radiation from a hot emitter (1000-2500°C) to electricity using narrow-bandgap photovoltaic cells with photon recycling.

  • Direct electrical conversion

Biomass and Biofuels

Converts solar energy stored in organic matter via photosynthesis into heat, electricity, or liquid fuels through combustion, fermentation, or thermochemical processes.

  • Chemical intermediate

Hydropower

Converts gravitational potential energy of elevated water to electricity via turbines, with water elevated by the solar-driven hydrological cycle.

  • Mechanical intermediate

Ocean Thermal Energy Conversion (OTEC)

Exploits the temperature difference between warm tropical surface seawater and cold deep seawater to drive a heat engine for electricity generation.

  • Thermal intermediate (heat engine)

Wave Energy

Extracts kinetic and potential energy from ocean surface waves created by wind (itself driven by solar heating) using various converter technologies.

  • Mechanical intermediate

Wind Energy

Converts kinetic energy from atmospheric air motion into electricity via aerodynamic lift on rotating turbine blades coupled to generators.

  • Mechanical intermediate

Gravitational (Earth-Moon-Sun)

Tidal Barrage

Captures gravitational potential energy from the vertical displacement of water caused by tides using a dam-like structure with low-head turbines.

  • Mechanical intermediate

Tidal Stream Energy

Extracts kinetic energy from horizontal tidal currents using underwater turbines, functioning like underwater wind turbines in the ocean.

  • Mechanical intermediate

Nuclear binding energy

Nuclear Betavoltaics

Converts kinetic energy of beta particles from radioactive decay directly into electricity using semiconductor junctions, providing microwatt-scale power for decades to millennia.

  • Direct electrical conversion

Nuclear Fission

Releases energy by splitting heavy atomic nuclei (uranium, plutonium), converting mass to energy via E=mc² with ~3 million times the energy density of fossil fuels.

  • Thermal intermediate (heat engine)

Nuclear Fusion

Releases energy by combining light atomic nuclei (hydrogen isotopes) into heavier ones, the process powering the Sun, with ~4× higher mass-energy conversion than fission.

  • Thermal intermediate (heat engine)

Radioisotope Thermoelectric Generator

Converts heat from radioactive decay (primarily Pu-238) directly into electricity via the Seebeck effect, providing decades of reliable power with no moving parts.

  • Direct electrical conversion