The Periodic Table of Energy

139 parts of the energy system, from natural sources to capture, transport, storage and use: how energy is held in nature, how much exists, and the materials each part needs.

Natural sources · Fossil stores

• Crude oil: Liquid fuel for most transport and plastics feedstock; its price moves inflation
• Natural gas: Methane piped or shipped as LNG for heat, power and fertiliser hydrogen
• Thermal coal: Steam coal burned in power stations; still the largest single source of electricity
• Coking coal: Metallurgical coal baked into coke for blast furnaces; hard to replace in steelmaking
• Methane hydrates: Ice-bound methane under seafloor and permafrost; vast but barely tapped

Natural sources · Earth, gravity and atoms

• Uranium: Nuclear reactor fuel, mined then converted, enriched and fabricated by few suppliers
• Tides: Sea rise and fall from the pull of Moon and Sun; the raw resource
• Earth's heat: Heat from Earth's interior, kept up by radioactive decay; the source behind geothermal
• Fusion fuels: Light atoms such as deuterium and lithium that release energy when fused
• Natural hydrogen: Hydrogen gas formed underground by rock reactions; newly found and still being studied

Conversion and use · Fuel processing

• Low-carbon hydrogen and e-fuels: Clean hydrogen made with little CO2 and fuels from it: green ammonia, e-methanol, e-SAF
• Refining and reforming: Refineries and reformers turning crude oil and gas into fuels and hydrogen
• Power-to-X: Clean electricity made into hydrogen, then e-fuels and chemicals; the conversion step

Capture · Bioenergy

• Bioethanol: Fuel alcohol fermented from cane, molasses, maize or other grains and blended into petrol
• Biodiesel (FAME): Vegetable oil or waste fat reacted with methanol and blended into diesel
• Renewable diesel and SAF: Hydrotreated fats made into drop-in diesel and jet fuel, unlike blended FAME
• Biogas and biomethane: Gas from digesting manure and waste, upgraded to pipeline grade as CBG in India
• Biomass combustion and CHP: Burning wood, residues and pellets in boilers for heat and power
• Thermochemical biomass conversion: Gasification and pyrolysis using heat to break biomass into gas, oil or char

Natural sources · Solar-derived flows

• Sunlight: Radiant energy from the Sun, the origin of almost every other energy source
• Wind: Moving air driven by uneven solar heating; the raw resource behind all wind tiles
• Water cycle: Sun-driven evaporation and rain that refill rivers, the natural resource behind hydropower
• Ocean waves: Wind energy passed into the sea surface; the resource that wave converters tap
• Ocean currents: Steady ocean flows driven by wind and differences in sea temperature and saltiness
• Ocean thermal gradient: Temperature gap between warm surface seawater and cold deep water, a resource for OTEC
• Salinity gradient: Energy released where fresh river water meets salty seawater, known as blue energy
• Biomass: Solar energy stored in wood, crop residues, dung and energy crops; the natural source
• Ambient heat: Low-temperature heat in air, ground and water that heat pumps can harvest
• Muscle power: Human and animal work fuelled by food, still vital for farming and carrying

Capture · Solar

• Solar photovoltaics: Panels of cells turning sunlight straight into electricity, from rooftops to utility parks
• Concentrated solar power: Mirrors focusing sunlight to raise steam for turbines, often with molten-salt storage
• Solar heat collectors: Collectors turning sunlight into hot water and process heat rather than electricity
• Passive solar and natural cooling: Building design that gathers or sheds heat and light without machines
• Solar fuels and photosynthesis: Sunlight stored as chemical energy, in crops or in fuels from artificial photosynthesis

Capture · Wind

• Onshore wind: Land-based horizontal-axis turbines, the main source of new wind power capacity
• Offshore wind: Turbines at sea on fixed foundations or floating platforms; costlier, steadier output
• Small, airborne and traditional wind: Rooftop turbines, airborne kites and windmills or sails using wind as motion

Capture · Water and ocean

• Hydropower dams: Large reservoirs releasing water through turbines; dispatchable power with storage
• Run-of-river and small hydro: River plants with little or no reservoir, down to village micro-hydro
• Wave energy converters: Devices turning the up and down motion of waves into electricity
• Tidal and ocean-current power: Barrages, lagoons and underwater turbines driven by tides and ocean currents
• OTEC and salinity power: Plants using ocean temperature or salt differences; some also make fresh water

Capture · Geothermal

• Geothermal power plants: Plants using natural underground steam or hot water to spin turbines
• Advanced geothermal: Enhanced and closed-loop wells reaching heat where no natural reservoir exists
• Geothermal direct use and ground-source heat pumps: Earth heat used directly for warmth, or shallow ground heat moved by heat pumps

Capture · Fossil and nuclear

• Coal mining: Extracting coal from underground seams or open pits, the start of the coal chain
• Conventional oil and gas production: Onshore and offshore wells where oil and gas flow freely from reservoirs
• Unconventional oil and gas: Shale, tight, oil sands and coalbed methane, needing fracking or special methods
• Nuclear fission reactors: Reactors splitting uranium or thorium to make steam; steady, low-carbon baseload power

Capture · Emerging

• Fusion reactors: Experimental machines joining light atoms as the Sun does; not yet producing power
• Micro energy harvesting: Tiny power from motion, heat or radio waves for sensors and wearables
• Space-based solar power: Orbiting collectors that would beam solar power down to Earth; still experimental

Transport · Electricity

• AC transmission: High-voltage overhead AC lines moving bulk power across long distances
• HVDC links: Direct-current links with lower losses for long distances, undersea and between grids
• Distribution grids, mini-grids and interconnectors: Local power networks to homes and businesses, plus mini-grids and cross-border links
• Underground, submarine and superconducting cables: Buried and subsea power cables for cities, offshore wind and international links
• Railway electrification and wireless power: Overhead wires and third rails powering trains, plus wireless power transfer

Transport · Liquid and gaseous fuels

• Oil and product pipelines: Pipelines moving crude and refined products overland and under the sea
• Tankers, barges and fuel trucks: Ships, barges, rail cars and road tankers that move liquid fuels
• Gas pipelines and city gas: High-pressure trunk lines and low-pressure city gas mains carrying natural gas
• LNG chain: Gas chilled to liquid for shipping by sea, then regasified
• CNG, LPG and biogas distribution: Cylinders, cascades and tankers delivering compressed or liquefied gas to users
• Hydrogen and hydrogen carriers: Moving hydrogen by pipe, as liquid, or inside ammonia and other carriers

Transport · Solid and nuclear fuels

• Coal transport: Moving coal by rail rakes, bulk ships, barges, trucks and conveyors
• Firewood and charcoal supply: Informal supply of wood and charcoal by bag and head-load, mostly rural
• Nuclear fuel transport: Shielded, licensed containers and casks for fresh and spent nuclear fuel

Transport · Heat, motion and embodied energy

• District heating and cooling networks: Insulated pipe networks carrying hot water, steam or chilled water across towns
• Heat-transfer fluids and heat pipes: Thermal oils, molten salts, refrigerants and heat pipes that move heat
• Mechanical power transmission: Shafts, ropes, hydraulics and compressed air moving energy as motion or pressure
• Embodied energy trade: Energy exported inside metals, fertiliser and computing made where power is cheap

Storage · Electrochemical

• Lithium iron phosphate batteries: Safer, long-lived lithium chemistry dominant in grid storage and many cheaper EVs
• Nickel-rich lithium-ion batteries: Higher-energy nickel cathode lithium cells for longer-range EVs and electronics
• Next-generation lithium batteries: Solid-state and lithium-sulphur cells promising more energy; mostly still in development
• Sodium-ion batteries: Lithium-free cells using cheap, plentiful sodium; now entering the market
• Lead-acid batteries: Mature, recyclable cells for car starters, UPS units and home inverters
• Nickel-based batteries: Nickel-cadmium, nickel-metal hydride and nickel-iron cells, used in hybrids and rail
• Flow batteries: Liquid electrolytes in tanks, such as vanadium, so capacity scales with tank size
• High-temperature batteries: Molten sodium-sulphur and similar cells that run hot for grid storage
• Metal-air batteries: Cells that breathe oxygen from air; iron-air aims at multi-day grid storage
• Other and primary batteries: Zinc and other emerging rechargeables, plus single-use alkaline and lithium cells

Storage · Mechanical

• Pumped hydro storage: Water pumped uphill and released through turbines; the largest grid store in the world
• Gravity storage: Lifting heavy blocks or weights and lowering them to make power
• Flywheels and small mechanical stores: Spinning rotors, springs and hydraulic accumulators giving short bursts of power
• Compressed-air and CO2 storage: Air or CO2 compressed into caverns or domes, then expanded through turbines
• Liquid air storage: Air cooled to liquid, then warmed so it expands through a turbine

Storage · Thermal

• Sensible heat storage: Heat held by warming water, molten salt, sand, rock or bricks
• Latent heat and cold storage: Phase-change materials and ice stores that hold energy by melting or freezing
• Carnot batteries: Electricity stored as heat and cold, then turned back into electricity

Storage · Chemical

• Hydrogen storage: Compressed gas, liquid, salt cavern and metal hydride stores of hydrogen
• Ammonia, methanol and e-fuels: Synthetic molecules holding energy for months, burned or cracked back to hydrogen
• Fuel stocks and strategic reserves: Tanks, caverns and stockpiles of oil, gas and coal, including strategic reserves
• Biomass and biofuel stores: Energy kept in wood piles, pellets, charcoal, biofuels and stored biogas
• Thermochemical storage: Reversible reactions that absorb heat and release it later, with little loss
• Explosives and propellants: Chemical stores built to release energy very fast, for mining and rockets

Storage · Electrical and system

• Capacitors and supercapacitors: Devices storing charge in an electric field; very fast and very long-lived
• Superconducting magnetic storage: Energy held in the magnetic field of a superconducting coil; niche, very fast
• Demand response and vehicle-to-grid: Shifting when power is used: smart appliances, pre-cooling and parked EVs
• Natural reservoirs: Snowpack, lakes, glaciers, oceans and ground heat acting as nature's own stores

Conversion and use · Conversion devices

• Steam turbines and thermal power plants: Boilers raising steam to spin turbines in coal, nuclear, biomass and waste plants
• Gas turbines and combined cycle: Turbines burning natural gas for peaking, or paired with steam for high efficiency
• Internal combustion engines and gensets: Petrol, diesel and gas piston engines in vehicles, ships and backup generators
• Generators and alternators: Machines turning rotation into electricity in almost every power plant
• Electric motors and drives: Machines turning electricity into motion; they use about half the world's power
• Transformers and power electronics: Transformers, inverters and converters that change voltage and switch between AC and DC
• Fuel cells: Cells turning hydrogen or other fuels straight into electricity, with heat as by-product
• Electrolysers: Equipment using electricity to split water into hydrogen, or brine into chlorine
• Heat pumps, air conditioning and refrigeration: Compressor machines moving heat for space heating, air conditioning and refrigeration
• Electric heating: Resistance, induction, arc furnace and microwave heating driven by electricity
• Lighting and displays: Turning electricity into light, from LEDs and lasers to screens
• Boilers, furnaces and stoves: Fuel-burning industrial boilers, kilns, furnaces and household cooking stoves

Conversion and use · Transport systems

• Combustion road vehicles: Cars, trucks and buses running on petrol, diesel, CNG or LPG
• Electric and hybrid vehicles: Battery-electric and hybrid vehicles, the main new demand for lithium-ion cells
• Rail traction: Electric trains and metros on overhead wires, plus diesel-electric locomotives
• Aviation propulsion: Jet, turboprop and helicopter engines burning jet fuel or SAF
• Ship propulsion: Marine diesel and LNG engines, wind-assisted and nuclear ships moving world trade
• Rockets and human power: Chemical rockets and muscle-powered bicycles, the two extremes of transport energy

Conversion and use · Industry, buildings and farms

• Energy-intensive industry: Steel, cement, aluminium, ammonia and chlor-alkali, where energy dominates costs
• Energy in buildings: Cooking, water heating, cooling and appliances in homes and offices
• Data centres: Energy view of server halls turning electricity into computing and waste heat
• Energy in farming: Irrigation pumps, fertiliser and draught power: the energy it takes to grow food

Recovery and reuse · Heat to heat

• Recuperators and regenerators: Hot exhaust preheating combustion air in furnaces, kilns and glass melting
• Boiler heat recovery: Economisers and blowdown recovery reclaiming flue gas and hot water heat
• Heat exchangers and pinch integration: Passing heat between process streams, and pinch design to share hot and cold
• Waste heat for drying, water and food: Low-grade heat drying products, desalinating water and warming greenhouses

Recovery and reuse · Heat to power and cogeneration

• Waste-heat power (steam Rankine): Hot exhaust raising steam for power in cement, steel, glass and acid plants
• Organic Rankine, Kalina and sCO2 cycles: Special working fluids making power from lower-temperature heat than steam needs
• Engine exhaust recovery: Turbochargers and turbo-compounding that reuse engine exhaust energy
• Combined heat and power: Making electricity and useful heat, or cooling, from the same fuel
• Bagasse and black-liquor cogeneration: Sugar and paper mills burning bagasse or black liquor for own steam and power
• Steel plant energy recovery: Coke dry quenching, top-gas turbines and gas reuse inside steelworks

Recovery and reuse · Pressure, motion and waste fuels

• Pressure and flow recovery: Expanders and turbines turning surplus gas or water pressure into power
• Regenerative braking and motion recovery: Capturing energy as vehicles, lifts, cranes and motors slow down
• Flare and off-gas recovery: Capturing gas that oilfields and plants would otherwise flare or vent
• Waste-to-energy: Incineration, landfill gas and fuels recovering energy from rubbish and residues
• LNG cold and cryogenic recovery: Using the cold released when LNG or liquid air warms back into gas

Recovery and reuse · Shared heat and everyday recovery

• Industrial heat pumps and vapour recompression: Heat pumps and vapour recompression lifting waste heat to process temperatures
• Shared and district heat reuse: One site's waste heat warming others: data centres, sewers, metros and factories
• Building heat recovery: Ventilation heat recovery and drain heat reuse in homes, hotels and offices
• Electrical loss reduction: Power factor correction and efficient equipment that cut electrical losses