十億立方英尺/天（BCFD）：用來定義天然氣容積率的標(biāo)準(zhǔn)單位。每天10億立方英尺的天然氣足以滿足全世界家庭使用天然氣的2%左右。每天60億立方英尺的天然氣相當(dāng)于每天約100萬桶石油當(dāng)量。英國(guó)熱量單位（BTU）：BTU是可用于測(cè)量任何類型能源的標(biāo)準(zhǔn)能量單位。一加侖汽油的能量含量約為12萬英熱單位?！癚uad”指的是一個(gè)萬億（1015）BTU。在2018年能源展望中，每種石油產(chǎn)品（如汽油、柴油、液化石油氣等）的BTU能量含量基于其比能量密度。傳統(tǒng)車輛：一種裝有內(nèi)燃機(jī)的輕型車輛，通常是汽油點(diǎn)燃式發(fā)動(dòng)機(jī)或柴油壓燃式發(fā)動(dòng)機(jī)。傳統(tǒng)的包括先進(jìn)技術(shù)的車輛，如渦輪增壓和“溫和的混合”功能，如停止-啟動(dòng)發(fā)動(dòng)機(jī)。焦耳：焦耳是一個(gè)標(biāo)準(zhǔn)單位，可以用來測(cè)量任何類型的能量。1埃焦耳=1018焦耳，大致相當(dāng)于1萬億BTU。發(fā)電效率：在一次能源發(fā)電中，有用能源的產(chǎn)出與能源的投入之比。發(fā)電效率通常因發(fā)電類型和地區(qū)而異，但風(fēng)、太陽能光伏和水力發(fā)電的效率假定為100%。混合動(dòng)力汽車：“全”混合動(dòng)力汽車是一種輕型汽車，它有電池（通常是金屬氫化物鎳）和電動(dòng)機(jī)，以及傳統(tǒng)的內(nèi)燃機(jī)。當(dāng)踩下制動(dòng)器時(shí)，移動(dòng)車輛的能量存儲(chǔ)在蓄電池中，可以在以后使用，從而節(jié)省燃料。氫燃料電池汽車：一種輕型汽車，其燃料為氫并儲(chǔ)存在車上。氫通過一個(gè)燃料電池，燃料電池為汽車提供電力。輕型車輛（LDV）：道路車輛的分類，包括轎車、輕型卡車和運(yùn)動(dòng)型多用途車（SUV）。摩托車不包括在輕型車隊(duì)規(guī)?；蛉加徒?jīng)濟(jì)性中，但摩托車使用的燃油包括在輕型運(yùn)輸需求中。液化天然氣：天然氣（主要是甲烷），經(jīng)過超冷處理后轉(zhuǎn)化為液態(tài)，便于運(yùn)輸。液化石油氣：碳?xì)淙剂系囊环N分類，包括丙烷、丁烷和其它類似的低分子量碳?xì)浠衔?。百萬石油當(dāng)量桶/天（MBDOE）：根據(jù)與典型石油桶相關(guān)的能源含量，針對(duì)不同類型能源（天然氣、煤炭等）的標(biāo)準(zhǔn)計(jì)量單位。每天100萬桶的石油當(dāng)量足以為當(dāng)今世界道路上約4%的輕型車輛提供燃料。MBDOE中所有能源類型的報(bào)告都是在石油當(dāng)量的基礎(chǔ)上完成的，石油產(chǎn)品除外，石油產(chǎn)品是以實(shí)物桶報(bào)告的。天然氣液體（NGL）：主要與天然氣一起產(chǎn)生的液體燃料。天然氣是天然氣的組成部分，在天然氣加工過程中，天然氣從氣態(tài)分離成液態(tài)。乙烷、丙烷、丁烷、異丁烷和戊烷都是ngl。經(jīng)濟(jì)合作與發(fā)展組織（經(jīng)合組織）：一個(gè)論壇，來自世界各地的約35個(gè)國(guó)家相互合作，并與更多的伙伴國(guó)家合作，以促進(jìn)將改善全世界人民經(jīng)濟(jì)和社會(huì)福祉的政策。插電式混合動(dòng)力汽車（PHEV）：一種輕型車輛，通常使用電動(dòng)機(jī)。與其他電動(dòng)汽車不同，PHEV也有一個(gè)傳統(tǒng)的內(nèi)燃機(jī)，可以在需要時(shí)使用石油燃料為其電池充電，在某些情況下為汽車提供動(dòng)力。購(gòu)買力平價(jià)：購(gòu)買力平價(jià)。一次能源：包括石油、天然氣、煤炭、核能、水力、地?zé)?、風(fēng)能、太陽能和生物能源（生物燃料、城市固體廢物、傳統(tǒng)生物量）。它不包括電力或市場(chǎng)熱，這是反映一次能源轉(zhuǎn)換/生產(chǎn)的二次能源類型。二次能源：從一次能源中獲得的能源類型，包括電力和市場(chǎng)熱。例如，電力是使用天然氣、風(fēng)能或其他一次能源產(chǎn)生的二次能源。萬億立方英尺瓦特：電功率的單位，等于一焦耳每秒。一座十億瓦的發(fā)電廠可以滿足美國(guó)50多萬戶家庭的用電需求。千瓦（kW）=1000瓦；千兆瓦（GW）=100000000瓦；兆瓦（TW）=1012瓦。瓦時(shí)：電能的單位。300太瓦時(shí)相當(dāng)于1萬億BTU（四倍）。千瓦時(shí)（kWh）=1000瓦時(shí)；千兆瓦時(shí)（GWh）=100000000瓦時(shí)；兆瓦時(shí)（TWh）=1012瓦時(shí)。

Billion cubic feet per day (BCFD): A standard unit used to define volumetric rates of natural gas.  One billion cubic feet per day of natural gas is enough to meet about 2 percent of the natural  gas used in homes around the world. Six billion cubic feet per day of natural gas is equivalent to about 1 million oil-equivalent barrels per day. British thermal unit (BTU): A BTU is a standard unit of energy that can be used to measure any type of energy source. The energy content of one gallon of gasoline is about 120,000 BTUs. “Quad” refers to a quadrillion (1015) BTUs. In the 2018 Outlook for Energy, energy content in BTUs for each oil product (e.g., gasoline, diesel, LPG, etc.) is based on its specific energy density. Conventional vehicle: A type of light-duty vehicle with an internal combustion engine, typically either a gasoline-fueled spark ignition engine or a diesel-fueled compression ignition engine. Conventional includes vehicles with advanced technologies such as turbocharging and “mild hybrid” features such as a stop-start engine. Exajoule: A joule is a standard unit that can be used to measure any type of energy. 1 exajoule = 1018 joules, roughly equivalent to 1 quadrillion BTUs. Generation efficiency: The ratio of useful energy output to energy input in the generation of electricity from primary energy sources. Generation efficiency typically varies by generation type and region, however wind, solar PV and hydro are assumed to be 100 percent efficient. Hybrid vehicle: A “full” hybrid is a type of light-duty vehicle that has a battery (usually a nickel metal hydride) and an electric motor, as well as a conventional internal combustion engine.  When brakes are applied, the energy of the moving vehicle is stored in the battery and can be  used later, thus saving fuel.  Hydrogen fuel cell vehicle: A type of light-duty vehicle for which hydrogen is the fuel and is  stored onboard. This hydrogen is passed through a fuel cell that then provides electricity to  power the vehicle. Light-duty vehicle (LDV): A classification of road vehicles that includes cars, light trucks and  sport utility vehicles (SUVs). Motorcycles are not included in the light-duty vehicle fleet size or  fuel-economy, but the fuel used in motorcycles is included in light-duty transportation demand.  Liquefied natural gas (LNG): Natural gas (predominantly methane) that has been super-chilled  for conversion to liquid form for ease of transport. Liquefied petroleum gas (LPG): A classification of hydrocarbon fuel including propane, butane and other similar hydrocarbons with low molecular weight. Million oil-equivalent barrels per day (MBDOE): A standardized unit of measure for different types of energy sources (natural gas, coal, etc.) based on energy content relative to a typical barrel of oil. One million oil-equivalent barrels per day is enough energy to fuel about 4 percent of the light-duty vehicles on the world’s roads today. Reporting for all energy types in MBDOE is done on an oil-equivalent basis, with the exception of oil products, which are reported in physical barrels. Natural gas liquid (NGL): A liquid fuel produced chiefly in association with natural gas. NGLs  are components of natural gas that are separated from the gaseous state into liquid form during natural gas processing. Ethane, propane, butane, isobutane and pentane are all NGLs.  Organisation for Economic Co-operation and Development (OECD): A forum for about  35 nations from across the world that work with each other, as well as with many more partner nations, to promote policies that will improve the economic and social well-being of people  around the world.  Plug-in hybrid electric vehicle (PHEV): A type of light-duty vehicle that typically uses an electric motor. Unlike other electric vehicles, a PHEV also has a conventional internal combustion engine that can charge its battery using petroleum fuels if needed, and in some cases power the vehicle.  PPP: Purchasing power parity. Primary energy: Includes energy in the form of oil, natural gas, coal, nuclear, hydro, geothermal, wind, solar and bioenergy sources (biofuels, municipal solid waste, traditional biomass). It does  not include electricity or market heat, which are secondary energy types reflecting  conversion/production from primary energy sources. Secondary energy: Energy types, including electricity and market heat, that are derived from primary energy sources. For example, electricity is a secondary energy type generated using  natural gas, wind or other primary energy sources.  TCF: Trillion cubic feet Watt: A unit of electrical power, equal to one joule per second. A 1-gigawatt power plant can  meet the electricity demand of more than 500,000 homes in the United States. Kilowatt (kW) = 1,000 watts; gigawatt (GW) = 1,000,000,000 watts; terawatt (TW) = 1012 watts.  Watt-hour: A unit of electrical energy. 300 terawatt hours is equivalent to about 1 quadrillion BTUs (quad). Kilowatt-hour (kWh) = 1,000 watt-hours; gigawatt-hour (GWh) = 1,000,000,000 watt-hours; terawatt-hour (TWh) = 1012 watt-hours.