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A 8 terms
API Gravity Fossil fuels
American Petroleum Institute (API) gravity — a measure of how heavy or light a crude oil is relative to water. Higher API number = lighter, less dense crude. Light crude: API >31° (flows easily, yields more petrol per barrel). Medium: 22–31°. Heavy: <22°. Light, sweet crude (high API, low sulphur) commands a premium price. Ghawar produces Arab Light crude at approximately 34° API.
Source: American Petroleum Institute · SPE-PRMS
Annual Energy Production (AEP) General
The total electrical energy a wind turbine or solar plant produces in one year, measured in MWh or GWh. Calculated by convolving the turbine's power curve with the site's wind speed distribution (for wind) or by multiplying capacity × capacity factor × 8,760 hours. A 3 MW turbine at 35% capacity factor produces: 3 × 0.35 × 8,760 = 9,198 MWh/year.
Source: IEA Wind · IRENA
Anaerobic Digestion (AD) Bioenergy
A biological process in which bacteria break down organic matter (food waste, manure, sewage) in sealed tanks without oxygen. Produces biogas (55–65% methane, CH₄) and digestate (fertiliser). AD is the basis for biogas plants, sewage treatment biogas capture, and India's Gobar Dhan programme. Typical retention time: 20–40 days.
Source: IEA Bioenergy · IRENA
Auction / Contract for Difference (CfD) Economics
A government mechanism for procuring renewable electricity. Developers bid a "strike price" (the minimum they need per MWh). If the market price falls below the strike price, the government pays the difference. If the market price rises above, the developer pays back the difference. This gives developers revenue certainty, allowing lower financing costs. The UK CfD programme and India's SECI auctions use this structure.
Source: UK DESNZ · SECI India
Agrivoltaics Solar
A land use system combining solar photovoltaic electricity generation with agricultural production on the same land. Solar panels are mounted high enough for crops, livestock, or beehives to exist beneath them. Benefits: shared land use reduces land-use conflicts, crops can benefit from shade and reduced water evaporation. Growing rapidly in Germany, Japan, France, and India.
Source: NREL Agrivoltaics Research · Fraunhofer ISE
Anthracite Coal
The highest-rank coal — 86–97% carbon content, energy density 26–33 MJ/kg. Hard, shiny, black, burns with almost no smoke. Very rare (<1% of world coal reserves). Not used for electricity generation — too valuable. Used for metallurgy, water filtration, and high-efficiency domestic heating. Major deposits: Pennsylvania (USA), South Wales (UK), Vietnam, Siberia.
Source: World Coal Association · USGS
ANERT India
Agency for Non-conventional Energy and Rural Technology — Kerala's state-level agency responsible for renewable energy promotion. Promotes solar, biomass, biogas, and small hydro in Kerala. Equivalent agencies exist in all Indian states (RRECL in Rajasthan, GEDA in Gujarat, TEDA in Tamil Nadu).
Source: MNRE India · Government of Kerala
Avoided Emissions Climate
The reduction in greenhouse gas emissions that results from using a cleaner energy source instead of a dirtier alternative. For example, if a 100 MW solar plant generates electricity that would otherwise have been generated by coal, the avoided emissions are calculated as: (coal carbon intensity − solar carbon intensity) × electricity generated. This concept underpins carbon credit markets and corporate net-zero claims. Not the same as negative emissions.
Source: IPCC AR6 · Gold Standard carbon methodology
B 9 terms
Baseload Grid
The minimum level of electricity demand over a given period, met by power plants that run continuously at near-maximum output. Baseload plants typically have high capital costs but low operating costs — nuclear, coal, large hydro, and geothermal are classic baseload sources. Contrast with "peaking plant" which runs only at peak demand. As solar and wind grow, the concept of fixed baseload is evolving.
Source: IEA · IRENA
BECCS — Bioenergy with Carbon Capture and Storage Bioenergy
A technology combining biomass electricity generation with carbon capture and storage. Plants absorb CO₂ as they grow; when burned for electricity, that CO₂ is captured at the plant and injected underground permanently — making the system carbon-negative (net removal of CO₂ from the atmosphere). IPCC AR6 includes BECCS in 1.5°C scenarios. The world's largest proposed BECCS project is at Drax Power Station, Yorkshire, UK (53.73°N 1.04°W), targeting 8 Mt CO₂/year removal. Highly contested due to land use requirements.
Source: IPCC AR6 WG3 · Drax Group · IEA
Betz Limit Wind
The theoretical maximum efficiency of any wind turbine: 59.3% (16/27) of available wind kinetic energy. Proved by German physicist Albert Betz in 1919. If a turbine extracted 100% of the wind's energy, the air behind would stop moving and block the turbine. The Betz limit defines the physics-based maximum — no engineering improvement can exceed it. Modern wind turbines achieve approximately 45–50% efficiency in ideal conditions.
Source: Betz, A. (1919) "Schraubenpropeller mit geringstem Energieverlust" · NREL
Bifacial Solar Panel Solar
A solar panel that captures sunlight on both the front and rear surfaces. The rear side captures reflected light from the ground or roof (albedo). In ideal conditions (light-coloured rooftop, desert ground, snow), bifacial panels generate 5–30% more energy than equivalent monofacial panels. Increasingly common in utility-scale solar plants. Works best with ground-mounted panels elevated above reflective surfaces.
Source: NREL · IEA Solar PV
Biomethane Bioenergy
Biogas that has been upgraded to remove CO₂, water vapour, and other impurities until it is approximately 97–99% methane — the same composition as natural gas. Can be injected directly into the gas grid, used in gas vehicles, or liquefied as bio-LNG. India's SATAT scheme targets 5,000 compressed biomethane plants. Also called "renewable natural gas" (RNG) in North America.
Source: IEA Bioenergy · MNRE India SATAT
BWR — Boiling Water Reactor Nuclear
A type of nuclear reactor where water boils directly inside the reactor vessel and the resulting steam drives the turbine directly — unlike the PWR which uses two separate water loops. Simpler design but lower pressure (75 bar vs 155 bar for PWR) and the turbine is exposed to slightly radioactive steam. Used in USA, Japan, Sweden. The Fukushima Daiichi reactors (Japan) were BWRs; the accident (2011) was caused by loss of cooling after the tsunami disabled backup generators.
Source: IAEA PRIS · World Nuclear Association
Barrel of Oil (bbl) Oil
The standard unit of measurement for crude oil. 1 barrel = 42 US gallons = 158.99 litres. The term originates from the wooden barrels used to transport oil in the 1860s when Drake's well first struck oil in Pennsylvania. Global oil consumption is approximately 100 million barrels per day. Proved reserves are expressed in billions of barrels (Gbbls) or trillions (Tbbls).
Source: API · US EIA
Battery Energy Storage System (BESS) Storage
A grid-scale battery installation that stores and releases electricity. Key specifications: power (MW — rate of charge/discharge) and energy (MWh — total storage capacity). The ratio determines how many hours of discharge are available (e.g., 100 MW / 400 MWh = 4 hours). BESS responds in milliseconds — much faster than any thermal plant. Primary uses: frequency regulation, renewable integration, peak shifting. Global installed BESS: ~50 GWh (2023), growing rapidly toward IEA's target of 1,500 GWh by 2030.
Source: IEA Batteries 2024 · BloombergNEF
Blue Hydrogen Hydrogen
Hydrogen produced from natural gas (steam methane reforming, SMR) with the CO₂ by-product captured and stored (CCS). "Blue" indicates the carbon is captured but the feedstock is still fossil fuel. Lifecycle emissions depend heavily on CCS capture efficiency — typically 85–95% capture rates, leaving 5–15% CO₂ emitted. Considered a bridging technology between grey hydrogen (no CCS) and green hydrogen (electrolysis from renewables). Cost typically $1.50–2.50/kg.
Source: IEA Future of Hydrogen 2023 · BloombergNEF
C 10 terms
Capacity Factor General
The ratio of a power plant's actual electricity output over a period to its theoretical maximum output if it ran at full capacity continuously. Expressed as a percentage. A 100 MW plant at 35% capacity factor generates 35 MWh/hour on average. Typical capacity factors: nuclear 85–95%, geothermal 90%+, coal 50–60%, gas (baseload) 40–60%, onshore wind 25–45%, offshore wind 35–55%, utility solar 15–35% (varies by location). Capacity factor determines how much electricity you actually get per MW of investment.
Source: IEA · IRENA · US EIA
Carbon Capture and Storage (CCS) Climate
Technology that captures CO₂ from power station flue gases or industrial processes, compresses it, and injects it into underground geological formations (depleted oil and gas fields, saline aquifers) for permanent storage. Three approaches: post-combustion capture (amine scrubbing of flue gas), pre-combustion capture (gasification then CO₂ removal), and oxyfuel combustion. Capture efficiency: 85–95%. Energy penalty: 15–25% of plant output. Operational CCS at power stations: Boundary Dam (Canada, 110 MW, 2014), Sleipner offshore (Norway, since 1996 — natural gas with CO₂ injection).
Source: IEA CCS · Global CCS Institute
CCGT — Combined Cycle Gas Turbine Natural gas
A highly efficient gas power station using two thermodynamic cycles. First: natural gas burns in a gas turbine (like a jet engine) producing electricity directly. Second: the hot exhaust gases (still 500–600°C) pass through a heat recovery steam generator (HRSG) to produce steam, which drives a steam turbine for additional electricity. Thermal efficiency: 55–65% (vs ~40% for simple open cycle). The most efficient large-scale technology for burning fossil fuels. LCOE approximately $60–100/MWh (Lazard 2024).
Source: IEA · Lazard LCOE 2024
Carbon Intensity (grid) Climate
The average CO₂ equivalent emitted per unit of electricity consumed from a grid, expressed in g CO₂/kWh. It reflects the mix of generation technologies on the grid at any given time. Typical values: France (~85 g/kWh, mainly nuclear), UK (~233 g/kWh, 2023), Germany (~400 g/kWh), USA (~380 g/kWh), India (~700 g/kWh, mainly coal), Norway (~10 g/kWh, mainly hydro). Used to assess the emissions impact of electric vehicles, heat pumps, and other electrified end uses.
Source: Ember Global Electricity Review 2024 · IEA
CapEx / OpEx Economics
CapEx (Capital Expenditure): One-time spending to build or acquire a power plant — engineering, procurement, construction (EPC). Expressed as $/kW or $/kWp installed. For solar: ~$700/kWp (utility, 2024). For nuclear: ~$7,000–12,000/kW (Western markets, 2024). OpEx (Operational Expenditure): Annual costs to run the plant — fuel, maintenance, staff, insurance. For solar/wind: OpEx dominates because there is no fuel cost. For gas: fuel is the dominant cost.
Source: Lazard LCOE 2024 · IEA
Coking Coal (Metallurgical Coal) Coal
A grade of bituminous coal with low volatile matter and ash that, when heated without air, forms coke — a porous carbon material essential for conventional steel production. In blast furnaces, coke simultaneously provides heat and acts as a reducing agent (removing oxygen from iron ore). Approximately 600–800 kg of coking coal are needed per tonne of steel. Cannot be substituted by thermal coal in a conventional blast furnace. Australia's Bowen Basin is the world's largest coking coal export region.
Source: World Coal Association · IEA Iron and Steel
Curtailment Grid
The deliberate reduction of a power plant's output below its potential because the grid cannot absorb all the electricity it could produce. Happens most commonly to solar and wind plants during periods of high generation and low demand. A sign of insufficient grid storage, interconnection, or demand flexibility. India curtailed significant renewable energy in 2023 due to transmission bottlenecks and demand patterns. Curtailment represents wasted clean energy and lost revenue for generators.
Source: CEA India · IRENA
Crude Oil Benchmarks (Brent, WTI, Arab Light) Oil
Standard reference crude oils used for global oil pricing. Brent Crude: North Sea blend, ~38° API, low sulphur (sweet), the global reference for approximately 70% of crude oil trading. WTI (West Texas Intermediate): ~40° API, very sweet — the main US benchmark. Arab Light: Saudi Aramco's main export crude, ~34° API, medium-sour — widely traded in Asian markets. Price spreads between benchmarks reflect quality differences and logistics.
Source: S&P Global Platts · US EIA
CAES — Compressed Air Energy Storage Storage
A form of energy storage in which off-peak electricity compresses air into underground caverns (salt caverns, aquifers, depleted gas fields). When electricity is needed, the compressed air is released, heated, and expanded through a turbine to generate power. Long-duration capability (hours to days). Two operational plants: Huntorf, Germany (321 MW, 1978 — the world's first) and McIntosh, Alabama, USA (110 MW, 1991). Adiabatic CAES (A-CAES) stores the heat of compression for reuse, eliminating the need for gas on discharge.
Source: IEA Storage · NREL
Clean Energy General
Energy from sources that produce little or no greenhouse gas emissions during operation. The IEA defines clean electricity as that from solar, wind, hydro, nuclear, biomass (sustainable), geothermal, and fossil fuels with CCS. Note: "clean" typically refers to climate impact (CO₂ and other GHGs), not to other environmental or health impacts. Nuclear electricity is "clean" in terms of CO₂ but produces radioactive waste. Air quality (particulate matter, NOx, SOx) is a separate dimension.
Source: IEA · IPCC
D 4 terms
Dispatchable Grid
A power source that can be turned on or off, or have its output controlled, on demand by a grid operator. Coal, gas, nuclear, hydro (with reservoir), and battery storage are dispatchable. Solar and wind are not dispatchable — their output depends on weather. As renewable penetration increases, the ability to balance variable supply with demand increasingly relies on dispatchable sources, storage, and demand response.
Source: IEA · IRENA
Degradation Rate (solar panels) Solar
The annual percentage decline in a solar panel's power output. Caused by UV exposure (darkening of encapsulant), thermal cycling, potential-induced degradation (PID), and contact corrosion. Typical rate: approximately 0.5% per year for silicon panels; approximately 0.35% per year for First Solar CdTe thin-film. Most manufacturers warrant 80% of rated output after 25 years (implying ≤0.7%/year average degradation). This means a panel rated at 400W today would produce approximately 320W after 25 years.
Source: NREL Long-Term PV Performance Studies · First Solar technical documentation
DISCOM (Distribution Company) India grid
In India's electricity sector, DISCOMs (Distribution Companies) are the state-owned or private utilities responsible for distributing electricity to end consumers — homes, businesses, and factories. They purchase electricity from generators (NTPC, IPPs, renewable developers) through Power Purchase Agreements (PPAs) and sell it to consumers at regulated tariffs. Many Indian DISCOMs are financially stressed due to below-cost tariffs, high transmission and distribution (T&D) losses (~20%), and subsidy gaps.
Source: CEA India · Ministry of Power, India
Dry Steam (geothermal) Geothermal
The simplest type of geothermal power plant. Steam comes directly from underground reservoirs and drives the turbine without any intermediate flash or heat exchange. Requires a rare geological configuration where the reservoir naturally produces dry steam. The world's first geothermal plant (Larderello, Italy, 1904) and the world's largest geothermal complex (The Geysers, California, 725 MW) use dry steam.
Source: IRENA · ThinkGeoEnergy
E 5 terms
Energy Density General
The amount of energy stored per unit mass (specific energy, MJ/kg) or volume (volumetric energy density, MJ/L). Higher energy density = more compact fuel storage. Key values: uranium 3,900,000 MJ/kg, hydrogen 142 MJ/kg (HHV), diesel 45 MJ/kg, coal 24–32 MJ/kg, Li-ion battery 0.9 MJ/kg. Energy density explains why aviation and shipping use liquid fuels (not batteries) and why nuclear submarines can operate for decades without refuelling. See the Codex compare page: thecodex.expert/energy/compare/energy-density/
Source: World Nuclear Association · US EIA · NREL
EGS — Enhanced Geothermal Systems Geothermal
Technology that creates artificial geothermal reservoirs in hot dry rock by hydraulically fracturing the rock and circulating water through it. Unlike conventional geothermal (which requires natural hydrothermal systems), EGS can potentially access geothermal energy anywhere on Earth where hot rock exists (typically 3–10 km depth). Fervo Energy's Project Red (Utah, USA, 2023) was the first commercial EGS plant to deliver power to the US grid. Key challenge: induced seismicity from hydraulic fracturing requires careful management.
Source: US DOE FORGE · Fervo Energy · IEA
Ember Data source
An independent energy think tank specialising in the global electricity transition. Publishes the Global Electricity Review annually — tracking electricity generation by source for approximately 90 countries. Their data is cited throughout the Energy Codex for current electricity generation statistics, including CO₂ displacement from solar and wind. Ember's data is publicly available and used by IEA, BloombergNEF, and major media. Website: ember-climate.org
Electrolysis (for hydrogen) Hydrogen
The process of splitting water (H₂O) into hydrogen (H₂) and oxygen (O₂) using electricity. The central technology for "green hydrogen." Two main types: PEM (Proton Exchange Membrane): fast response, suitable for variable renewable electricity, expensive membrane. Alkaline: mature technology, lower cost, slower response. SOEC (Solid Oxide Electrolysis Cell): high temperature, highest efficiency. System efficiency approximately 65–80% (electrical energy to hydrogen energy). Current green hydrogen cost: ~$4–8/kg. Target by 2030: $1–2/kg.
Source: IEA Future of Hydrogen 2023 · IRENA
ENTSO-E Grid
European Network of Transmission System Operators for Electricity. The organisation coordinating the operation of the Continental European synchronous grid — approximately 900 GW across 35 countries, 545 million customers. The largest synchronously interconnected AC grid on Earth. Operates at 50 Hz. Maintains real-time frequency balance across all interconnected members. Publishes transparency platform data on generation by source, cross-border flows, and demand.
Source: ENTSO-E Transparency Platform
F 4 terms
Flash Steam (geothermal) Geothermal
The most common type of geothermal power plant. High-pressure hot water (>180°C) from underground is brought to the surface where it rapidly "flashes" (partly vaporises) to steam as pressure drops. The steam drives a turbine; remaining water is re-injected. Used in Iceland, Philippines, New Zealand, Kenya, Mexico. More common than dry steam because high-enthalpy hot water reservoirs are more widely distributed than dry steam fields.
Source: IRENA · IEA
Flywheel Energy Storage Storage
A mechanical energy storage device that stores energy as the kinetic energy of a spinning mass (rotor). Modern flywheels spin at 20,000–50,000 RPM in a vacuum using magnetic bearings. Can respond in milliseconds, complete millions of cycles without degradation. Best suited for short-duration applications: frequency regulation, smoothing wind/solar output, UPS for data centres. Not suited for long-duration storage (>several hours) due to energy losses. Commercial example: Beacon Power Stephentown, New York (42.55°N 73.50°W, 20 MW, 200 flywheel units).
Source: NREL · Beacon Power · IEA
FAME — Faster Adoption of Manufacturing of Hybrid and Electric Vehicles India
India's government scheme to subsidise and promote electric vehicles. Phase I launched 2015; FAME-II launched 2019 with ₹10,000 crore outlay, targeting 1 million electric two-wheelers, 500,000 three-wheelers, 55,000 four-wheelers, and 7,090 electric buses. India's target: 30% of private car sales and 70% of commercial vehicle sales to be electric by 2030. Managed by Ministry of Heavy Industries.
Source: Ministry of Heavy Industries, Government of India · IEA Global EV Outlook 2024
Firm Power / Capacity Grid
Electricity generation capacity that can be relied upon to deliver power on demand, regardless of weather conditions. Coal, gas, nuclear, hydro (with reservoir), and storage are "firm." Solar and wind are not firm on their own — they generate only when the sun shines or wind blows. As renewable penetration grows, ensuring adequate firm capacity during peak demand becomes increasingly important. The IEA identifies the "firm capacity gap" as a key challenge for energy transitions.
Source: IEA WEO 2024 · IRENA
G 4 terms
Green Hydrogen Hydrogen
Hydrogen produced by electrolysis of water using electricity from renewable sources (solar, wind, hydro). Zero direct carbon emissions. Currently less than 1% of global hydrogen production (2024) but the fastest-growing segment. Current cost: approximately $4–8/kg (compared to grey hydrogen at $1–2/kg). IEA target for competitiveness with grey hydrogen: under $2/kg in sunny/windy locations by 2030. India's National Green Hydrogen Mission targets 5 million tonnes/year production by 2030.
Source: IEA Future of Hydrogen 2023 · MNRE India
Grid Frequency Grid
The number of complete AC cycles per second in the electricity grid, measured in hertz (Hz). India and most of the world: 50 Hz. USA, Canada, parts of Japan: 60 Hz. Grid frequency is the real-time signal of supply-demand balance: frequency rises if generation exceeds demand; frequency falls if demand exceeds generation. Grid operators maintain frequency within ±0.2 Hz. Significant deviation triggers automatic load shedding (emergency demand disconnection). As synchronous generators are replaced by solar and wind (connected via inverters), providing grid inertia and frequency response requires new technologies.
Source: POSOCO India · IEA Grid Report 2023
Grey Hydrogen Hydrogen
Hydrogen produced from natural gas via steam methane reforming (SMR) without carbon capture — the dominant production method globally (~96% of current production). Releases approximately 9–10 kg CO₂ per kg H₂ produced. Cheap ($1–2/kg) but carbon-intensive. Most industrial hydrogen (fertilisers, refinery operations) is grey. IEA, IRENA, and most government hydrogen strategies seek to replace grey hydrogen with green or blue hydrogen.
Source: IEA Future of Hydrogen · IRENA
GWp — Gigawatt-peak (solar) Solar
The rated peak output of a solar installation under Standard Test Conditions (STC: 1,000 W/m² irradiance, 25°C cell temperature, AM1.5 spectrum). Used as the standard measure of solar PV capacity. "Peak" capacity is important because actual output is lower most of the time — a 1 GWp solar park in India might average 250 MW actual output (25% capacity factor). Also written as GW (without the 'p') in casual usage.
Source: IEA · IRENA · IEC 61724 standard
H 4 terms
HVDC — High Voltage Direct Current Grid
A system for transmitting electricity over very long distances or under the sea using direct current at very high voltage (typically 320–1,100 kV). Advantages over HVAC for long distances: lower losses (~3% per 1,000 km vs ~7% for AC), ability to connect asynchronous grids (different frequencies), better control. China operates 1,100 kV UHVDC lines transmitting up to 12 GW from Xinjiang to coastal cities over 3,000+ km — the highest voltage ever used commercially. Used for submarine cables (e.g., NordLink between Norway and Germany, 623 km).
Source: State Grid Corporation of China · ABB HVDC Reference Projects
Hydraulic Fracturing (Fracking) Oil & gas
A technique for extracting oil or gas from tight rock formations (shale, tight sandstone) by pumping water, sand, and chemicals at high pressure into the rock, creating fractures through which hydrocarbons can flow to the well. Enabled the "shale revolution" in the USA — US oil production grew from 5 Mbbl/day (2010) to 13+ Mbbl/day (2024), making the USA the world's largest oil producer. Also used in Enhanced Geothermal Systems (EGS) to create artificial reservoirs. Controversial due to potential groundwater contamination, induced seismicity, and local air quality impacts.
Source: US EIA · SPE
Head (hydraulic) Hydro
In hydropower, the vertical height difference between the water surface at the inlet and the turbine level. Power available = ρ × g × Q × H × η (where Q is flow rate, H is head, η is efficiency). Higher head = more power per unit of water flow. Three Gorges Dam: approximately 80 metres head. A pumped storage plant increases head by pumping water uphill. High-head plants (Pelton turbines) operate at several hundred metres head; low-head run-of-river plants (Kaplan turbines) may operate at 5–20 metres.
Source: IHA — International Hydropower Association
HRSG — Heat Recovery Steam Generator Natural gas
The boiler in a combined cycle gas turbine (CCGT) plant that recovers heat from the gas turbine's exhaust gases (500–600°C) to generate steam for a secondary steam turbine. The HRSG is the component that makes CCGT plants significantly more efficient than simple open-cycle gas turbines — CCGT efficiency 55–65% vs OCGT 35–42%. Sometimes called a "waste heat boiler." The hot exhaust would otherwise be vented to atmosphere (wasting energy).
Source: IEA · Siemens Energy
I 4 terms
ITER Fusion
International Thermonuclear Experimental Reactor. The world's largest fusion experiment, under assembly at Cadarache, France (43.69°N 5.77°E). A 35-nation project (EU, USA, Russia, China, India, Japan, South Korea) costing approximately $22 billion. ITER aims to demonstrate Q=10 (produce 10 times the energy input) — producing 500 MW of fusion power from 50 MW of heating. Will not generate electricity — purely a scientific experiment. First plasma target: 2025 (revised); full fusion demonstration: 2035+. If successful, the follow-on DEMO plant will attempt commercial fusion electricity.
Source: ITER Organisation
IPP / PPA — Independent Power Producer / Power Purchase Agreement Economics
IPP: A private company that builds and operates power plants and sells electricity to utilities or directly to large consumers. Most renewable energy projects in India are IPPs. PPA: The long-term contract (typically 20–25 years) between an IPP and a buyer (DISCOM, government entity, large industrial consumer) fixing the price per kWh of electricity. PPAs provide revenue certainty, allowing IPPs to secure financing at lower interest rates. India's solar auctions determine the PPA price for projects.
Source: CEA India · Ministry of Power, India · IEA
IRENA — International Renewable Energy Agency Institution
An intergovernmental organisation headquartered in Abu Dhabi, UAE, established 2009. IRENA is the primary international institution for renewable energy statistics, policy analysis, and capacity building. Publishes: Renewable Capacity Statistics (annual), Renewable Power Generation Costs (annual — the most cited source for LCOE data), World Energy Transitions Outlook, and numerous technology reports. As of 2024, IRENA has 168 member countries.
Source: IRENA About
Inertia (grid) Grid
The resistance of a power system to sudden changes in frequency, provided by the rotational kinetic energy of large synchronously spinning generators (turbines). Inertia acts as a natural "buffer" — if generation suddenly drops, the kinetic energy of spinning turbines supports the frequency for a few seconds while other generators ramp up. Solar panels and wind turbines connected via inverters do not provide natural inertia — a growing concern as they replace synchronous generators. "Synthetic inertia" from inverter-connected sources is now provided by advanced power electronics in some grids.
Source: ENTSO-E · IEA Grid Report 2023
K 2 terms
Kerogen Oil & gas
The solid, waxy organic material found in sedimentary rocks, formed from the remains of ancient organisms. It is the precursor to oil and gas. When buried to sufficient depth (typically 2–4 km, the "oil window"), heat causes kerogen to "crack" into liquid crude oil. Further burial and higher temperatures crack the oil into natural gas. Shale formations contain large amounts of kerogen — "oil shale" technology attempts to extract this directly.
Source: AAPG — American Association of Petroleum Geologists
kWh — Kilowatt-hour Units
The standard unit of electrical energy consumption. 1 kWh = the energy consumed by a 1,000-watt appliance running for one hour. A typical Indian household consumes approximately 50–100 kWh per month. A 1 MW solar plant at 25% capacity factor generates approximately 2,190 MWh (2.19 million kWh) per year. 1 MWh = 1,000 kWh; 1 GWh = 1,000 MWh; 1 TWh = 1,000 GWh. Electricity tariffs are priced per kWh (e.g., ₹4–8/kWh in India).
Source: SI units · IEA
L 4 terms
LCOE — Levelised Cost of Energy Economics
The average cost per unit of electricity ($/MWh or ₹/kWh) over the entire lifetime of a power plant, accounting for all capital costs, fuel costs, operation and maintenance, and financing. Calculated as: LCOE = (Sum of all discounted costs) ÷ (Sum of all discounted electricity generation). Allows fair comparison across technologies with very different upfront vs. running cost profiles. Key 2024 values (Lazard, USA, new plants, unsubsidised): solar $24–96/MWh, onshore wind $27–73/MWh, gas (CCGT) $60–100/MWh, coal $65–166/MWh, nuclear $141–221/MWh. Important limitation: does not capture when electricity is generated (intermittency).
Source: Lazard LCOE Analysis 2024
LNG — Liquefied Natural Gas Natural gas
Natural gas (predominantly methane) cooled to approximately −162°C, at which point it liquefies and reduces to approximately 1/600th of its gaseous volume. Enables natural gas to be transported by ship (LNG tankers) across oceans where pipelines are impractical. Major LNG exporters: Qatar, USA, Australia. Major importers: Japan, China, India, South Korea, Europe. India imports approximately 25–30 MTPA of LNG. The LNG supply chain: liquefaction terminal → LNG tanker → regasification terminal → gas pipeline → consumer.
Source: IEA Gas Market Report 2024 · PPAC India
Lifecycle Emissions / LCA Climate
The total greenhouse gas emissions from an energy system across its complete life — from raw material extraction through manufacture, construction, operation, and decommissioning. Expressed as g CO₂eq per kWh of electricity generated. The IPCC AR6 WG3 Annex II provides the authoritative global compilation. Critical for comparing technologies fairly: coal looks cheap operationally but very costly in lifecycle emissions; solar has no operational emissions but has manufacturing-stage emissions. For the full comparison table see: thecodex.expert/energy/compare/carbon-footprint/
Source: IPCC AR6 WG3 Annex II · ISO 14040/44
LFP — Lithium Iron Phosphate (battery) Storage
A lithium-ion battery chemistry using lithium iron phosphate (LiFePO₄) as the cathode material. Key advantages over NMC (nickel manganese cobalt): no cobalt (cheaper, no supply security concerns), longer cycle life (2,000–5,000 cycles vs 500–1,000 for NMC), more thermally stable (safer, less prone to thermal runaway). Disadvantage: lower energy density (~120–160 Wh/kg vs ~250 Wh/kg for NMC). Dominant in Chinese EVs (BYD's Blade battery), grid storage, and e-bikes. CATL announced sodium-ion cells in 2023 as an even cheaper alternative for low-range applications.
Source: CATL Annual Report 2023 · BloombergNEF
M 3 terms
MW / GW / TW — Megawatt, Gigawatt, Terawatt Units
Units of power (rate of energy transfer): 1 MW = 1,000 kW = 1,000,000 W. Used to express the rated capacity of power plants. 1 GW = 1,000 MW; 1 TW = 1,000 GW. India's total electricity capacity: ~250 GW. Global solar capacity: ~1.6 TW. Global nuclear capacity: ~395 GW. A 1 MW solar plant in good conditions generates approximately 1,500–2,000 MWh of electricity per year. Note: capacity (MW) is not the same as generation (MWh).
Source: SI units · IEA · CEA India
Monocrystalline vs Polycrystalline (solar) Solar
Monocrystalline: Solar cells made from a single crystal of silicon. Uniform black appearance. Higher efficiency (20–24%) because the uniform crystal structure allows electrons to flow more easily. More expensive to manufacture (Czochralski crystal growing process). Dominant technology by 2020s. Polycrystalline (multicrystalline): Made from multiple silicon crystals melted together. Blue speckled appearance. Slightly lower efficiency (15–17%) due to grain boundaries disrupting electron flow. Lower manufacturing cost historically. Being replaced by monocrystalline in new installations.
Source: NREL Cell Efficiency Chart · IEA Solar PV
MNRE — Ministry of New and Renewable Energy (India) India
The Government of India ministry responsible for policy, research, and development of renewable energy. Responsible for India's 500 GW renewable target by 2030, the PLI scheme for solar manufacturing, the National Green Hydrogen Mission, FAME (EV subsidies), and Gobar Dhan (biogas). Manages the Solar Energy Corporation of India (SECI) and National Institute of Wind Energy (NIWE). Website: mnre.gov.in
Source: MNRE Government of India
N 4 terms
NZE — Net Zero Emissions (2050 scenario) Climate policy
The IEA's most ambitious energy scenario in which global energy-related CO₂ emissions reach net zero by 2050 — consistent with limiting global warming to approximately 1.5°C above pre-industrial levels. The NZE scenario requires: no new coal plants, no new oil and gas fields (beyond those already approved), massive deployment of solar and wind (~620 GW solar per year by 2030), near-complete decarbonisation of electricity by 2040, and carbon capture for hard-to-abate sectors. Used throughout the Energy Codex as the reference "ambitious transition" scenario.
Source: IEA Net Zero by 2050 (2021)
NDC — Nationally Determined Contribution Climate policy
A country's self-determined climate action plan under the Paris Agreement (UNFCCC). Each country submits an NDC describing what it will do to reduce emissions and adapt to climate change. NDCs are updated every 5 years and are expected to become progressively more ambitious. India's 2022 updated NDC targets: achieve about 45% reduction in emissions intensity of GDP by 2030 (vs 2005 levels), reach 50% cumulative electric power installed capacity from non-fossil fuel sources by 2030, and create an additional carbon sink of 2.5–3 Gt CO₂ equivalent through forest cover.
Source: UNFCCC NDC Registry · Government of India Updated NDC 2022
NTPC — National Thermal Power Corporation (India) India
India's largest power generation company, a Government of India enterprise. Operates approximately 75 GW of installed capacity (2024) — predominantly coal, but rapidly expanding into solar, wind, and green hydrogen. India's largest coal power stations (Vindhyachal STPS 4,760 MW) are NTPC plants. NTPC Renewable Energy Ltd (NTPC REL) is developing large solar and green hydrogen projects. CMD: Gurdeep Singh. BSE/NSE listed.
Source: NTPC Annual Report 2023-24
Net Metering Solar
A billing mechanism allowing rooftop solar owners to feed surplus electricity into the grid and receive credit against their electricity bills. When the rooftop solar produces more than the home consumes, the surplus flows to the grid and the meter "runs backwards" (or a credit is issued). When the home consumes more than the solar produces, it draws from the grid. Net metering makes rooftop solar economically viable by allowing the grid to act as a "virtual battery." India's net metering regulations are set by CERC and state electricity regulatory commissions.
Source: CERC India · MNRE India Rooftop Solar Programme
O 3 terms
OCGT / Peaker Plant Natural gas
An Open Cycle Gas Turbine (OCGT) burns natural gas in a single turbine cycle (no steam recovery), achieving approximately 35–42% efficiency. Higher capital cost per MWh than CCGT but can start in minutes vs hours for CCGT. Used as "peaker plants" — operating only during periods of peak electricity demand. High LCOE ($107–175/MWh, Lazard 2024) because high capital costs are recovered over few operating hours. Being replaced by battery storage for very short-duration peak services in some markets.
Source: Lazard LCOE 2024 · IEA
ONGC — Oil and Natural Gas Corporation (India) India
India's largest oil and gas producer. Founded 1956. Government of India majority enterprise. Operates Mumbai High offshore field (19.07°N 71.45°E) — India's largest oil field. Total oil production: approximately 20 MT/year. Also exploring for oil in onshore fields (Rajasthan, Gujarat, Assam). Increasingly investing in renewable energy and green hydrogen. NSE/BSE listed.
Source: ONGC Annual Report 2023
Offshore Wind Wind
Wind turbines installed in the sea, typically 5–50 km from shore. Key advantages: stronger, more consistent winds offshore (higher capacity factors, 35–55% vs 25–45% onshore); no land use conflicts; closer to coastal population centres. Disadvantages: significantly higher construction and maintenance cost ($2,500–4,500/kW vs $900–1,400/kW onshore). The world's largest offshore wind farm: Hornsea Two, UK (53.9°N 1.6°E), 1,386 MW, operated by Ørsted. Dogger Bank (UK, under construction) will be 3,600 MW.
Source: GWEC Global Wind Report 2024 · Ørsted
P 5 terms
PPA — Power Purchase Agreement Economics
See IPP / PPA entry above. A long-term contract (20–25 years) between a power generator and a buyer at a fixed price. The backbone of renewable energy finance in India and globally — provides revenue certainty enabling low-cost financing. India's largest renewable PPAs are between SECI (Solar Energy Corporation of India) and state DISCOMs. Corporate PPAs (direct between large consumers and generators) are growing globally.
Source: SECI India · IEA
Photovoltaic Effect / PV Solar
The generation of electric current in a material when light photons strike it. Discovered by Edmond Becquerel in 1839. In a silicon solar cell, photons knock electrons from the valence band to the conduction band, and the p-n junction directs these electrons to create direct current (DC). The DC is converted to alternating current (AC) by an inverter. "PV" is shorthand for "photovoltaic" — any solar technology that directly converts light to electricity (distinct from solar thermal, which converts light to heat).
Source: NREL · Becquerel (1839) historical records
Perovskite Solar Cell Solar
A next-generation solar cell using a synthetic crystal structure with the chemical formula ABX₃ (typically methylammonium lead halide) as the light-absorbing layer. Laboratory efficiency exceeds 33% — surpassing single-junction silicon (limited to ~29% in practice). Not yet commercially deployed at scale due to durability challenges (degradation in moisture and UV). Tandem cells combining perovskite with silicon have achieved >33% efficiency in laboratory conditions. Significant global R&D investment — potentially the next major solar technology revolution.
Source: NREL Cell Efficiency Chart 2024 · Nature Energy
POSOCO — Power System Operation Corporation of India India grid
The national and regional grid operator for India's electricity system. Manages real-time balance of supply and demand across India's national grid (ISTS). Operates five Regional Load Despatch Centres (RLDCs) and one National Load Despatch Centre (NLDC). Responsible for grid frequency management, grid security, and scheduling of inter-state electricity transmission. Published daily reports on India's electricity generation mix, renewable energy share, and grid events. Now merged with PowerGrid Corporation under CERC regulations.
Source: POSOCO Annual Report · CEA India
PHWR — Pressurised Heavy Water Reactor Nuclear
A nuclear reactor that uses heavy water (deuterium oxide, D₂O) as both its moderator and coolant. Key advantage: can use natural uranium fuel (no enrichment needed), making it energy-independent of enrichment technology. Canada's CANDU (Canadian Deuterium Uranium) and India's indigenous INDU design are PHWRs. India's entire domestic nuclear programme (Stage 1) is built on PHWRs for this reason — India can use its own uranium without enrichment infrastructure. 49 PHWRs operating globally (IAEA PRIS 2024).
Source: IAEA PRIS · NPCIL India · Atomic Energy of Canada Limited
Q 1 term
Q Factor (fusion) Fusion
The ratio of fusion power output to heating power input in a fusion experiment. Q=1 means the fusion reaction produces exactly as much energy as was put in to heat the plasma ("breakeven"). Q=10 is ITER's target — producing 500 MW of fusion power from 50 MW of heating input. No fusion experiment has yet demonstrated Q>1 in sustained operation (NIF's 2022 experiment achieved Q>1 momentarily in inertial confinement fusion). For commercial power plants, Q must be significantly greater than 1 to overcome the inefficiencies of converting fusion heat to electricity.
Source: ITER Organisation · US National Ignition Facility
R 3 terms
Run-of-River Hydropower Hydro
Hydropower plants that use the natural flow of a river without large reservoir storage — they divert some or all of a river's flow through a canal or penstock to turbines and return it downstream. Lower environmental and social impact than reservoir hydropower (no large flooded area, minimal displacement of communities). Output varies with river flow — high during monsoon, low in dry season. Switzerland and Austria have extensive run-of-river systems on Alpine rivers. India is building several run-of-river projects on Himalayan tributaries.
Source: IHA International Hydropower Association · IEA
RED — EU Renewable Energy Directive EU policy
The European Union's framework legislation setting binding renewable energy targets for member states. RED I (2009) set a 20% renewables target by 2020. RED II (2018) set 32% by 2030. RED III (2022) raised the target to 42.5% by 2030. RED III also sets strict sustainability criteria for biomass used for energy — minimum greenhouse gas savings of 70–85% vs fossil fuels, restrictions on using forest biomass, and controls on agricultural land use for energy crops. The most comprehensive renewable energy legislation globally.
Source: European Commission · EU Renewable Energy Directive 2022/2414
Reserves (proved, oil and gas) Oil & gas
Proved reserves are quantities of oil and gas that geological and engineering data demonstrate with reasonable certainty (typically 90% confidence — "1P" in SPE-PRMS terminology) to be commercially recoverable under current economic conditions and technology. The SPE-PRMS (Society of Petroleum Engineers — Petroleum Resources Management System) is the international standard. Reserves grow as technology improves and prices rise — which is why "X years remaining" figures have been roughly constant for decades despite consumption. Different from resources (which include technically recoverable but not yet economic).
Source: SPE-PRMS · BP Statistical Review 2024
S 6 terms
SMR — Small Modular Reactor Nuclear
Nuclear reactors with output below 300 MW, designed for factory manufacturing and modular assembly on-site. Key designs: NuScale VOYGR (USA, 77 MW modules), Rolls-Royce SMR (UK, 470 MW), BWRX-300 (GE Hitachi, 300 MW), Kairos KP-FHR (molten salt, 140 MW). Potential advantages: factory manufacturing (cost reduction via scale), shorter construction timelines (3–4 years), deployment in smaller grids and remote locations. Ontario Power Generation's BWRX-300 at Darlington, Canada, is the world's first commercial SMR project, targeting 2034. India's NPCIL is developing indigenous SMR designs. Economic case not yet proven at commercial scale.
Source: IAEA · World Nuclear Association · NPCIL India
Solar Irradiation / GHI Solar
The amount of solar energy received per unit area per day, measured in kWh/m²/day. GHI (Global Horizontal Irradiation): Total solar energy on a horizontal surface — relevant for flat-mounted PV. DNI (Direct Normal Irradiation): Energy from the direct beam of the sun only — relevant for concentrating solar (CSP) and tracking panels. India's GHI: most of India receives 4–7 kWh/m²/day, with Rajasthan and Gujarat at 5.5–6.5 kWh/m²/day — among the highest in the world. UK average: 2.5–3.0 kWh/m²/day. The solar irradiation of a site is the single biggest factor in determining the LCOE of a solar plant.
Source: NIWE India · NREL Solar Resource Data · Solargis
Steam Methane Reforming (SMR) Hydrogen
The dominant industrial process for producing hydrogen. Natural gas (CH₄) reacts with steam at high temperature (700–1,000°C) over a nickel catalyst: CH₄ + H₂O → CO + 3H₂ (steam reforming), then CO + H₂O → CO₂ + H₂ (water-gas shift). Produces approximately 95% of global hydrogen — but releases approximately 9–10 kg CO₂ per kg H₂. When CO₂ is captured (CCS), the product is "blue hydrogen." Energy efficiency: approximately 65–75%. Large SMR plants produce 50,000–300,000 Nm³ H₂/hour.
Source: IEA Future of Hydrogen 2023 · SPE
STEPS — Stated Policies Scenario (IEA) Climate policy
One of three main scenarios in the IEA's World Energy Outlook. STEPS reflects the energy policies that governments have already enacted or formally committed to — it is the "current policies trajectory." Contrast with NZE (Net Zero Emissions by 2050, the most ambitious scenario) and APS (Announced Pledges Scenario, which assumes all government pledges are met). STEPS typically projects continued fossil fuel use declining only gradually, with climate warming of approximately 2.5°C by 2100. Used throughout the Energy Codex to represent "realistic current policy trajectory."
Source: IEA World Energy Outlook 2024
Sweet vs Sour Crude Oil Oil
Classification of crude oil by sulphur content. Sweet crude: Less than 0.5% sulphur content. Easier and cheaper to refine to meet clean fuel standards. Commands a price premium. Examples: Brent, WTI. Sour crude: More than 0.5% sulphur. Requires hydrogen desulphurisation (hydroprocessing) in the refinery — additional capital cost and operating cost. Examples: Arab Medium, Dubai/Oman, Venezuelan heavy crude. Most Middle East crudes are medium-sour. The "sweet premium" is an important pricing factor in global crude markets.
Source: API · S&P Global Platts · US EIA
Supercritical / Ultra-Supercritical (coal power) Coal
Refers to the steam conditions in a coal power plant boiler. Subcritical: Steam <220°C and <22 MPa pressure. Efficiency ~33–36%. Supercritical: Steam >374°C and >22 MPa. Efficiency ~38–41%. Ultra-Supercritical (USC): Steam ~600°C and >30 MPa. Efficiency ~42–46%. Advanced USC: >700°C (requires nickel superalloys). Efficiency ~48–52%. Higher efficiency = less coal burned and less CO₂ emitted per kWh. India and China are deploying USC and supercritical plants for new coal capacity.
Source: IEA Clean Coal Technologies · NREL
T 3 terms
Tip Speed Ratio (TSR) Wind
The ratio of the speed of the blade tip to the actual wind speed. TSR = ω × R / v (where ω is rotational speed, R is rotor radius, v is wind speed). For maximum efficiency (approaching the Betz limit), 3-blade HAWT turbines should operate at TSR of approximately 6–8. At lower TSR, the rotor turns too slowly; at higher TSR, turbulence from one blade interferes with the next. Variable-speed modern turbines use power electronics to maintain optimal TSR across varying wind speeds.
Source: NREL · Burton et al., Wind Energy Handbook (Wiley)
Tariff / Feed-in Tariff (FiT) Economics
A regulated price at which electricity is sold. Feed-in tariff (FiT): A guaranteed price paid to renewable energy producers for each unit of electricity fed into the grid — typically above market price to incentivise early deployment. Germany's Erneuerbare-Energien-Gesetz (EEG) FiT programme drove the initial rapid deployment of solar and wind in Germany. India used FiTs for early solar deployment, later transitioning to competitive auctions (lower prices, more efficient). FiTs have mostly been replaced by auction/CfD systems in most large markets.
Source: CERC India · German Federal Ministry for Economic Affairs
Tokamak Fusion
A doughnut-shaped (toroidal) magnetic confinement device used to contain plasma at temperatures of 100–200 million degrees Celsius for fusion research. The magnetic field is produced by superconducting coils. ITER uses a tokamak design — the largest ever built, with a plasma volume of 840 m³. The word "tokamak" is a Russian acronym from TOroidalnaya KAmera MAgnitnymi Katushkami. The tokamak design was first developed by Soviet physicists Andrei Sakharov and Igor Tamm in the 1950s. Alternatives to tokamaks include stellarators, inertial confinement (NIF), and field-reversed configurations (TAE Technologies).
Source: ITER Organisation · IEA Fusion Report
U 2 terms
Uranium Enrichment Nuclear
The process of increasing the proportion of uranium-235 (U-235) in uranium fuel. Natural uranium contains only ~0.7% U-235 (the fissile isotope) — the rest is mostly U-238. Light water reactors (PWR, BWR) need 3–5% U-235 to sustain a chain reaction. Enrichment is done by gaseous diffusion (old, energy-intensive — mostly replaced) or gas centrifuge (modern, 50× more efficient). HEU (highly enriched uranium, >20% U-235) for weapons is prohibited by the NPT for non-nuclear-weapon states. PHWRs (India's type) use natural uranium — avoiding the need for enrichment.
Source: IAEA · World Nuclear Association · NPCIL India
Ultra High Voltage (UHV) Transmission Grid
Electricity transmission at voltages above 800 kV AC or 800 kV DC. China operates the world's highest voltage commercial power lines at 1,100 kV UHVDC — transmitting 12 GW over 3,200 km from Xinjiang's wind and solar to coastal cities like Wuhan and Shanghai. UHV enables efficient long-distance renewable energy transport — connecting areas with abundant generation (Xinjiang, Inner Mongolia) to areas with high demand (Beijing, Shanghai, Guangzhou). India operates 765 kV AC lines (PowerGrid ISTS).
Source: State Grid Corporation of China · PowerGrid India
V 2 terms
V2G — Vehicle to Grid EV / Storage
Technology allowing electric vehicles to discharge their batteries back into the electricity grid during periods of peak demand. A global fleet of 40 million EVs represents approximately 2,000 GWh of battery capacity — 40× the world's installed grid-scale battery storage. V2G could transform EVs from pure consumers to flexible grid assets. Requires bidirectional charging equipment and smart grid coordination. Japan leads deployment — Nissan CHAdeMO standard supports V2G. Nissan Leaf owners powered homes after the 2011 earthquake.
Source: IEA Global EV Outlook 2024 · Nissan
VVER — Vodo-Vodyanoy Energetichesky Reaktor Nuclear
Russia's pressurised water reactor design (Водо-Водяной Энергетический Реактор = Water-Water Power Reactor in Russian). The most widely exported reactor type globally — Rosatom has contracts in 35+ countries. India's Kudankulam Nuclear Power Plant (8.17°N 77.72°E) uses VVER-1000 reactors (1,000 MW each). The latest design, VVER-1200, offers improved passive safety features. The AES-2006 and AES-2006+ projects (using VVER-1200) are operating in Finland, Egypt, Hungary, Turkey, Bangladesh, China, and elsewhere.
Source: Rosatom · IAEA PRIS · NPCIL India
W 3 terms
WACC — Weighted Average Cost of Capital Economics
The average rate a company or project must pay to all its capital providers (debt and equity holders) — expressed as a percentage. For renewable energy projects, WACC is a critical driver of LCOE: lower WACC = lower LCOE. Typical WACC: 3–5% in low-risk developed markets (OECD); 8–14% in higher-risk emerging markets (India, Africa). A 1 percentage point increase in WACC increases solar LCOE by approximately $5–10/MWh. Blended finance mechanisms (development bank concessional loans, guarantees) are used to reduce WACC in developing countries.
Source: IEA Finance for Clean Energy Transitions · Lazard LCOE 2024
Wind Shear Wind
The increase in wind speed with height above ground. Wind speed is typically higher at greater heights because friction from the ground surface slows down air at lower levels. Wind shear is described by the power law: v(h) = v(h₀) × (h/h₀)^α, where α (the wind shear exponent) depends on terrain roughness. Over flat terrain: α ≈ 0.14. Over rough terrain: α ≈ 0.20–0.30. This is why wind turbine hub heights have increased from 50–60m (2000) to 120–160m (2024) — taller towers access significantly more wind energy. A turbine at 120m hub height in rough terrain can generate 30–40% more energy than the same turbine at 80m.
Source: NREL Wind Resource Assessment · IEC 61400 standards
World Bank (energy role) Institution
The World Bank Group finances energy infrastructure in developing countries — one of the largest multilateral sources of energy project finance globally. The International Finance Corporation (IFC, the World Bank's private sector arm) financed Egypt's Benban Solar Park (24.42°N 32.73°E, 1,650 MW) — the largest solar park in Africa and the Middle East when built. The World Bank also published the ESMAP (Energy Sector Management Assistance Program) data on energy access globally. Has committed to align all financing with Paris Agreement goals.
Source: World Bank Energy Data
Z 1 term
Zero-Point Energy (ZPE) Quantum physics
The lowest possible energy state of a quantum mechanical system — the ground state energy that remains even at absolute zero temperature. Predicted by quantum mechanics and confirmed experimentally through the Casimir effect (1948 — measured by Lamoreaux 1997) and the Lamb shift. ZPE is real and measurable. No working device that extracts useful net energy from vacuum fluctuations has been demonstrated as of , despite numerous claims. The second law of thermodynamics imposes fundamental constraints on energy extraction from a system at thermal equilibrium with its environment.
Source: Lamoreaux (1997) Physical Review Letters · Casimir (1948) KNAW · IPCC AR6
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New Terms (Session 30 additions)
Carbon Budget Climate
Definition: The total cumulative amount of CO₂ that can be emitted globally while keeping warming below a specified temperature threshold with a given probability. The IPCC AR6 (2021) estimated approximately 500 Gt CO₂ remaining from January 2020 for a 50% probability of staying below 1.5°C. At ~37-40 Gt/yr current emissions, this budget was effectively exhausted by 2030. For 2°C (66% probability), approximately 1,150 Gt CO₂ remained from 2020.
Source: IPCC AR6 Working Group I Chapter 5 · Global Carbon Project 2024
CBAM (Carbon Border Adjustment Mechanism) Policy
Definition: The EU's Carbon Border Adjustment Mechanism — a charge on imports of carbon-intensive goods (steel, cement, aluminium, fertilisers, hydrogen, electricity) into the EU that reflects the carbon price paid at origin or the EU ETS price. Provisional phase from October 2023; fully operational from 2026. First carbon border tax at significant scale globally. Designed to prevent carbon leakage where EU industry relocates to less-regulated markets.
Source: European Commission CBAM regulation · ICAP 2024
Corium Nuclear
Definition: The lava-like mixture of nuclear fuel, fuel cladding, control rods, and reactor structural materials formed during a nuclear meltdown when the reactor core melts. The term combines "core" and "uranium." Corium from Fukushima Daiichi (approximately 880 tonnes) has collected at the bottom of three damaged reactor pressure vessels — its removal is the primary challenge of the decades-long Fukushima cleanup. Corium is intensely radioactive and thermally hot from decay heat.
Source: TEPCO Fukushima Decommissioning Status 2024 · IAEA Nuclear Safety
Crack Spread Fossil Fuels
Definition: The difference between the market price of refined petroleum products (petrol, diesel, jet fuel) and the market price of the crude oil used to produce them. Represents the gross refinery margin per barrel processed. High complexity refineries (Jamnagar NCI 21.1) earn higher crack spreads by converting cheap heavy sour crude into more valuable light products. Crack spreads are quoted as combinations (e.g., "3-2-1 crack spread" = 3 barrels crude → 2 barrels gasoline + 1 barrel distillate fuel oil).
Source: CME Group crack spread definition · BP Statistical Review 2024
DISCOM (Distribution Company) India Policy
Definition: State-owned electricity distribution companies in India responsible for purchasing wholesale electricity and selling it to retail consumers. India's approximately 50+ DISCOMs are in aggregate financial distress — aggregate losses approximately ₹75,000 crore/yr (Ministry of Power 2021-22) due to tariffs set below cost-recovery for agricultural consumers, 18% T&D losses, and delayed subsidy payments from state governments. The RDSS (Revamped Distribution Sector Scheme, 2021) targets reducing AT&C losses to below 12% by 2025.
Source: Ministry of Power India · CERC Annual Report 2024 · ICRA India
Dry Cask Storage Nuclear
Definition: A method of storing spent nuclear fuel that has already cooled in a spent fuel pool for at least 5 years. Fuel assemblies are placed in sealed welded stainless steel canisters, which are then either stored in thick-walled concrete casks or placed in horizontal concrete vaults. Cooling is achieved by passive natural air convection — no external power or water required. The industry's current "interim" storage solution while permanent repositories (Onkalo) are developed. Most spent fuel in the USA is in dry cask storage.
Source: NRC Spent Fuel Storage · IAEA Nuclear Technology Review 2024
Dunkelflaute Renewable
Definition: German for "dark doldrums" — extended winter periods when both solar irradiance and wind speeds are simultaneously low in Central Europe, resulting in very low combined renewable electricity output. During Dunkelflaute, a high-renewable grid must rely entirely on dispatchable backup (gas, coal, hydro, imports). Events can last 5–15 days. Germany experienced a notable Dunkelflaute in December 2023 lasting approximately 10 days. A key challenge for 80–100% renewable grid design in Central Europe.
Source: Fraunhofer ISE Energy-Charts · Bundesnetzagentur Winter Adequacy Report 2024
Energy Poverty Access
Definition: The lack of access to modern, affordable, reliable, and clean energy services. Approximately 750 million people globally lack electricity access (IEA 2023, >80% in Sub-Saharan Africa) and approximately 2.3 billion lack clean cooking access (WHO 2023). In wealthy countries, "fuel poverty" or "energy insecurity" refers to households unable to afford adequate heating or cooling — approximately 3.2 million UK households (2023), 10.6% of EU households (Eurostat 2022). Addressed by UN SDG 7 (Affordable and Clean Energy).
Source: IEA World Energy Outlook 2024 · WHO Household Air Pollution 2023 · Eurostat Energy Poverty Observatory
Firming Capacity General
Definition: Electricity generation capacity that can reliably supply power on demand, regardless of weather or time of day. Includes nuclear, thermal (gas, coal), hydro with reservoirs, and batteries with sufficient storage duration. Opposed to "variable" or "intermittent" capacity (solar PV, wind). As renewable penetration increases, the value of firming capacity increases because it provides grid stability when solar and wind are insufficient. Energy storage, hydrogen fuel cells, and extended-duration batteries are emerging as firm renewable alternatives to fossil firming capacity.
Source: IEA Energy Storage 2023 · AEMO Integrated System Plan 2024 · MISO capacity adequacy guidelines
HPAL (High Pressure Acid Leach) Mining/Processing
Definition: High Pressure Acid Leach — a hydrometallurgical process for extracting nickel, cobalt, and other metals from laterite ores (oxidised nickel ore found in tropical regions). Ore is mixed with sulphuric acid at high temperature (250°C) and pressure (50 bar) — dissolving metals which are then extracted by solvent extraction and electrowinning. HPAL is used extensively in Indonesia's Morowali Industrial Park (2.53°S 121.63°E) to process Indonesian nickel laterite into battery-grade nickel sulphate for EV batteries.
Source: USGS Mineral Commodity Summaries 2024 · IEA Critical Minerals 2024 · Benchmarks Mineral Intelligence
Hydrogen Embrittlement Engineering
Definition: The process by which hydrogen atoms (H, not H₂ molecules) penetrate steel and other metals, collecting at grain boundaries and causing micro-cracking and loss of ductility. At high pressures, H₂ molecules dissociate to atomic H at the metal surface and diffuse into the lattice. High-strength steels are most susceptible. Hydrogen embrittlement is a key constraint on repurposing existing natural gas transmission pipelines for hydrogen — high-strength steel pipes require testing or replacement. Materials that resist embrittlement: austenitic stainless steel, aluminium, titanium, certain grades of carbon steel at low pressure.
Source: US DOE Hydrogen Pipeline Research · ASME B31.12 Hydrogen Piping Code
JETP (Just Energy Transition Partnership) Policy
Definition: A pledging framework where wealthy G7 nations and development banks commit financial support to help a major developing-country coal user accelerate its energy transition. "Just" refers to managing the social impacts on coal workers and communities. First JETPs: South Africa ($8.5 billion, COP26 2021), Indonesia ($20 billion, G20 Bali 2022), India (structured post-COP27), Vietnam ($15.5 billion). JETPs have been criticised for headline amounts that are mostly loans rather than grants, complex governance conditions, and slow disbursement. Source: JETP CIPP documentation · Climate Policy Initiative analysis 2024.
Source: IEA JETP analysis · Presidential Climate Commission South Africa · CPI Climate Finance
LCOH (Levelised Cost of Hydrogen) Economics
Definition: The cost per kilogram of hydrogen produced, including all capital costs (electrolyser, balance of plant), electricity costs, operating costs, and financing costs amortised over the project lifetime. Analogous to LCOE for electricity. Green hydrogen LCOH (2024): approximately $3–8/kg depending on location and electricity cost. Best locations (Middle East, Australia, Chile with $20-30/MWh solar): approaching $3/kg. IEA NZE target: below $2/kg by 2030, below $1/kg by 2050 in best locations. Grey hydrogen (from natural gas SMR, without CCS): approximately $1–2/kg.
Source: IEA Global Hydrogen Review 2024 · IRENA Green Hydrogen Cost Reduction 2024
LOHC (Liquid Organic Hydrogen Carrier) Hydrogen
Definition: A category of hydrogen storage and transport technology where hydrogen is chemically bonded (hydrogenated) to an organic carrier molecule — typically dibenzyltoluene (DBT) or methylcyclohexane (MCH) — at elevated temperature and pressure, converting it to a stable liquid that can be stored and transported at ambient conditions using conventional petroleum infrastructure. At the destination, hydrogen is released (dehydrogenated) by applying heat. Key advantage: no high-pressure cylinders, no cryogenic systems — the carrier liquid looks and handles like diesel. Key disadvantage: 20–30% energy loss in the hydrogenation/dehydrogenation process.
Source: Hydrogenious LOHC Technologies · IEA Hydrogen Storage 2023 · Chiyoda SPERA
Merit Order Electricity Markets
Definition: The sequence in which power plants are dispatched in a competitive electricity market — ranked from lowest to highest marginal cost (the variable cost of generating one additional MWh). Zero-marginal-cost sources (solar PV, wind) are dispatched first, followed by low-cost baseload (nuclear, must-run hydro), then gas peakers, then expensive oil plants. The last plant dispatched sets the market-clearing price for all generators. High renewable penetration causes the "merit order effect" — solar and wind push lower-cost generators earlier in the stack, suppressing wholesale prices. On very sunny days, wholesale prices can be zero or negative.
Source: CERC India Annual Report · FERC State of the Markets · Agora Energiewende merit order analysis
Nelson Complexity Index (NCI) Fossil Fuels
Definition: A measure of the investment intensity and capability of a petroleum refinery to process heavier, lower-value crude oils and produce higher-value products. Developed by W.L. Nelson in 1958. Calculated as the weighted sum of all processing unit capacities relative to crude distillation capacity. Simple topping refineries: NCI 1–3. Complex refineries (conversion): NCI 8–12. Very complex (deep conversion, hydrocracking, coking): NCI 12+. Jamnagar India (22.47°N 69.87°E): NCI ~21.1 — among world's highest. Higher NCI means more ability to profit from cheap heavy sour crude grades.
Source: Oil & Gas Journal · PPAC India · Reliance Industries Annual Report
PAYG (Pay-As-You-Go Solar) Renewable/Access
Definition: A business model for off-grid solar home systems in developing countries where customers pay in small mobile-money instalments (daily or weekly) rather than an unaffordable upfront sum. The solar system is remotely enabled/disabled based on payment status. When the full price is paid (typically 2–3 years), the customer owns the system outright. Pioneered by d.light, M-KOPA, BBOXX in Sub-Saharan Africa using M-Pesa mobile money. PAYG has provided first electricity to tens of millions of homes that could never afford upfront payment. Approximately 50 million solar home systems installed in Africa by 2023 (IRENA).
Source: IRENA Off-grid Renewable Energy 2023 · GOGLA Global Off-grid Solar Market Report 2024
Permafrost Climate/Arctic
Definition: Ground that has remained frozen for at least two consecutive years. Underlies approximately 25% of the Northern Hemisphere land area, predominantly in Siberia, Alaska, northern Canada, and Greenland. Contains approximately 1.5 trillion tonnes of organic carbon — nearly twice the atmospheric CO₂ pool. As climate change warms the Arctic (warming approximately 3–4× faster than global average), permafrost thaws and this carbon decomposes, releasing CO₂ and methane — a potentially self-reinforcing climate feedback. Also causes infrastructure failure: the 2020 Norilsk diesel spill (21,000 tonnes, 69.34°N 88.21°E) was caused by a fuel tank foundation sinking as permafrost thawed.
Source: AMAP Arctic Monitoring 2023 · IPCC AR6 Chapter 5 Permafrost
REBCO (High-Temperature Superconducting Tape) Nuclear/Fusion
Definition: Rare Earth Barium Copper Oxide — a high-temperature superconducting (HTS) material that achieves superconductivity at temperatures achievable with liquid nitrogen (~77K) rather than liquid helium (~4K). REBCO coated conductors (thin tapes with REBCO coating) can carry large currents with zero resistance at 20–30 Tesla magnetic field strengths. Commonwealth Fusion Systems (CFS) uses REBCO magnets in its SPARC tokamak design — achieving 20+ Tesla fields that would be impossible with conventional LTS (Low-Temperature Superconducting) magnets, allowing a much smaller tokamak to achieve fusion conditions.
Source: Commonwealth Fusion Systems technical documentation · Science 2021 CFS magnet paper
SAF (Sustainable Aviation Fuel) Bioenergy/Transport
Definition: Jet fuel produced from non-fossil feedstocks that is compatible with existing aircraft engines and infrastructure. Feedstocks include waste fats and oils (HEFA-SAF — Hydro-processed Esters and Fatty Acids), agricultural residues (AtJ — Alcohol-to-Jet), municipal solid waste (Fischer-Tropsch synthesis), and CO₂ + green hydrogen (e-SAF or power-to-liquid). Currently approximately 0.1% of global jet fuel. IATA targets 5% by 2030 and 65% by 2050. EU ReFuelEU mandates 2% from 2025, rising to 70% by 2050. Cost: approximately $1,500–3,000/tonne vs $700 for conventional jet fuel. Lifecycle CO₂ reduction: 50–90% vs fossil jet fuel depending on feedstock.
Source: IATA SAF Report 2024 · ReFuelEU Aviation regulation · IEA Aviation Decarbonisation
SAFSTOR (Safe Storage Decommissioning) Nuclear
Definition: One of three NRC-approved nuclear decommissioning methods. A defuelled nuclear reactor is maintained in a safe, monitored state (the "SAFSTOR") for 40–60 years, allowing short-lived radioactive isotopes to decay and reduce radiation levels, before the plant is dismantled. Lower worker radiation doses (and thus costs) during dismantlement. Many US nuclear plants have used SAFSTOR. The main alternative is DECON (immediate dismantlement within ~10 years of shutdown), preferred in Germany and by the UK NDA. ENTOMB (permanent encasement) is not approved by the NRC for civilian power reactors.
Source: NRC Decommissioning Guidance · IAEA Nuclear Decommissioning Standards
Scope 3 Emissions Climate Policy
Definition: The third category of greenhouse gas emissions accounting under the GHG Protocol. Scope 1 = direct emissions from owned/controlled operations. Scope 2 = indirect emissions from purchased electricity, heat, or steam. Scope 3 = all other indirect emissions in the value chain — both upstream (suppliers, raw materials) and downstream (use of sold products, end-of-life treatment). For oil and gas companies, Scope 3 is the largest category by far (combustion of sold fuels by customers). For energy transition: Scope 3 is why a solar panel manufacturer must account for the coal electricity used to smelt its aluminium frames, and why an EV manufacturer accounts for the mining of its battery minerals.
Source: GHG Protocol Corporate Standard · CDP Scope 3 guidance · TCFD recommendations
Shadow Fleet Geopolitics
Definition: The approximately 600–700 tankers (as of 2024) used to carry Russian crude oil outside the Western shipping services ecosystem — operating without Western insurance (P&I Clubs), classification by Western societies, or under Western flag states. These vessels carry Russian crude from Primorsk (60.37°N 28.75°E), Ust-Luga, and Novorossiysk to India, China, and Turkey, enabling Russia to evade the G7 price cap ($60/bbl) enforcement. Many are older vessels with opaque ownership structures registered in UAE, Hong Kong, Gabon, Palau, or under unknown flags. Represent a significant maritime safety risk from uninsured, poorly maintained tankers.
Source: US Treasury OFAC reports · Kpler shipping intelligence · IEA Oil Market Report 2024
Stranded Assets Finance/Policy
Definition: Assets that lose economic value before the end of their expected useful life due to changes in technology, policy, markets, or physical environment — in the context of energy transition, primarily fossil fuel infrastructure (coal plants, oil fields, gas pipelines) that become economically unviable as clean energy becomes cheaper and carbon policies tighten. The IRENA estimates approximately $1 trillion of fossil fuel assets could become stranded globally by 2030 in an aggressive energy transition. Stranded asset risk is a primary driver of coal plant retirement economics and a key concern for DISCOM debt management in India. Also applies to buildings (stranded by minimum EPC requirements) and ICE vehicles (stranded by EV mandates).
Source: IRENA Stranded Assets and Renewables 2017 · Carbon Tracker Initiative · Bank of England climate stress testing
VPP (Virtual Power Plant) Electricity Markets
Definition: A software-coordinated aggregation of many small distributed energy resources (household batteries, EV batteries, flexible loads, rooftop solar systems) that collectively behave as a single dispatchable power plant from the grid operator's perspective. The VPP software sends dispatch signals to individual units simultaneously — charging when electricity is cheap, discharging when it is expensive or grid frequency is low. Tesla's Virtual Power Plant in South Australia (33.87°S 151.21°E) aggregates approximately 4,000 Powerwall home batteries totalling approximately 50 MWh, participating in the AEMO frequency regulation market. VPPs can provide grid services 100× faster than gas turbines (respond in milliseconds).
Source: AEMO VPP trials · Tesla Virtual Power Plant South Australia · Rocky Mountain Institute VPP analysis
Vitrification (Nuclear) Nuclear
Definition: The process of immobilising liquid High-Level nuclear Waste (HLW) by mixing it with glass-forming materials (borosilicate glass) and heating to approximately 1,150°C, producing solid glass blocks containing the radioactive material locked in a durable matrix. Glass is chemically resistant and leaches very slowly — providing a stable waste form for transport, interim storage, and eventual disposal in a geological repository. Sellafield's Waste Vitrification Plant (WVP, 54.42°N 3.47°W) has vitrified thousands of m³ of liquid HLW into stainless steel canisters of borosilicate glass blocks. Each canister contains approximately 150 kg of glass.
Source: NDA UK Annual Report 2024 · IAEA Vitrification Safety Standards · Sellafield Ltd
Aneutronic Fusion Fusion
Definition: A fusion reaction that produces no high-energy neutrons — or greatly reduced neutron production — compared to the standard deuterium-tritium (D-T) reaction. The proton-boron fusion reaction (p + ¹¹B → 3⁴He) is the most attractive aneutronic candidate — producing three helium nuclei and no neutrons. Advantages: no neutron activation of reactor materials (eliminating the main source of radioactive waste), no need for tritium breeding, no radiation shielding requirements beyond what is needed for charged particles. Challenge: proton-boron fusion requires plasma temperatures of approximately 3 billion°C — 20× hotter than D-T fusion (~150 million°C). TAE Technologies (33.67°N 117.83°W) is the primary company pursuing this approach commercially.
Source: TAE Technologies technical documentation · Fusion Industry Association 2024 · Physics of Plasmas review
Arc7 (Arctic Ice Class) Transport
Definition: The highest commercial ice class under the Russian Maritime Register of Shipping classification — Arc7 vessels can independently navigate 2.1-metre-thick first-year ice without icebreaker assistance, year-round. The 15 LNG carriers serving Yamal LNG (73.50°N 67.50°E) are Arc7 class — the first ever ice-class LNG carriers. Built at South Korean Daewoo (DSME) and Russian Zvezda shipyards. In summer (June–October), Arc7 tankers take the Northern Sea Route east to Asia (~18 days to Japan). In winter they go west via the Barents Sea to Europe. Russia's Arctic LNG 2 (73.76°N 67.80°E) was blocked partly because Arc7 LNG carriers are built using Western technology under export controls.
Source: Novatek Yamal LNG Annual Report 2023 · IMO Ice Class standards · Kawasaki Shipbuilding
Green Hydrogen Hydrogen
Definition: Hydrogen produced by electrolysis of water using electricity from renewable energy sources — producing only hydrogen and oxygen with no direct CO₂ emissions. The electrolyser splits water (H₂O → H₂ + ½O₂) using DC electricity. Current production cost: approximately $3–8/kg (vs grey hydrogen from natural gas SMR at $1–2/kg). Target: below $2/kg by 2030 in best locations. Electrolyser types: PEM (Proton Exchange Membrane, responsive, 50–80 bar output), alkaline (most mature, lower cost), SOEC (Solid Oxide, high efficiency, high temperature). Colour code: grey (SMR, no CCS), blue (SMR + CCS), green (electrolysis + renewables), turquoise (methane pyrolysis, no CO₂). India National Green Hydrogen Mission targets 5 MT/yr by 2030.
Source: IEA Global Hydrogen Review 2024 · IRENA Green Hydrogen Cost Reduction 2024 · MNRE India Green Hydrogen Mission
Biogas Digester Bioenergy
Definition: A sealed vessel in which organic material (animal dung, agricultural waste, food waste, sewage) is broken down by anaerobic (oxygen-free) microorganisms, producing biogas — a mixture of approximately 60% methane (CH₄) and 40% CO₂. Biogas can be burned directly for cooking, heating, or electricity generation. The remaining solid digestate is a nutrient-rich biofertiliser. Fixed-dome digesters (buried concrete dome, developed for domestic use in China and Nepal) serve individual households. Nepal's Biogas Support Programme has installed approximately 400,000 household digesters. India's GOBAR-Dhan scheme promotes community-level digesters from cattle dung. Larger centralised biogas plants (hundreds to thousands of m³/day) operate on municipal waste and agricultural waste in Europe, India, and China.
Source: Nepal Biogas Support Programme · Clean Cooking Alliance · IEA Bioenergy 2023