Glossary

Glossary This is a glossary proposed by the Our energy Futures project team It presents a commonly accepted definition of some concepts that are used in this website. However, those definition do not intend to be considered as the only valid one for each concept. Nevertheless, they have been considered good enough according to the scope of this website.


Agro-biofuels

Biofuels generated by agricultural crops. The most common agro-biofuels are ethanol (alcohol generated by fermentation of crops such as corn or sugarcane) and biodiesel (diesel fuel derived from crops such as soybean, rapeseed, sunflower and from palm oil). Second generation biofuels will be produced using biomass growing on marginal areas (switch-grass or fast growing trees) and therefore not competing with food production.

Backstop Technologies

A concept introduced by economists to assume "by default" the unlimited ability of human ingenuity to fix any problem with technology (a technical name for "silver bullet"). It is based on the assumption that, when the price of some scarce item or resource becomes very high, humans will find a series of technical processes, which combined, will result in them being capable of meeting the demand requirement, without facing any constraint in terms of resource consumption. This is a different version of the belief in perpetual motion, since the first law of thermodynamics rejects the possibility of generating a backstop technology in the event of there being a shortage of Primary Energy Sources!

Biofuels

Liquid fuels generated from biomass.

Dissipative Systems

All natural systems of interest for sustainability (e.g. complex biogeochemical cycles on this planet, ecological systems and human systems when analyzed at different levels of organization and scales above the molecular one) are "dissipative systems". That is they are self-organizing, open systems, operating away from thermodynamic equilibrium. This concept has been introduced and investigated by the Nobel Prize Winner Ilya Prigogine and his school.

Endosomatic Metabolism

Physiological conversions of different types of energy inputs (food) into end-uses that take place inside the human body.

Energetics

A systemic analysis of the set of energy transformations associated with the maintenance and reproduction of metabolic systems such as the biosphere, ecosystems, human societies, and organisms. There are general principles of energetics that dictate a set of expected features of metabolic patterns, and hence they can be used to study the characteristics of socioeconomic systems which are based on the expression of these metabolic patterns.

Energy Carriers

Various forms of energy inputs required by the various sectors of a society to perform their functions. Energy carriers are produced by the Energy Sector of a society by using Primary Energy Sources. Examples of energy carriers include liquid fuel in a furnace, gasoline in a pump, electricity used in a factory, and hydrogen in a tank of a car. The distinction between "Energy Carriers" and "Primary Energy Sources" is extremely important since these two labels refer to energy forms of different quality. Like for the concept of money, "US dollars", "European €" and "Chinese Yuans" are different forms of money. However, it is not possible to sum a given quantity of US$ to a given quantity of EU€ and Chinese Yuans, without applying conversion factors. In the same way, 1 kWh of electricity (3.6 MegaJoules of Energy Carriers) cannot be summed to 3.6 MJ of oil (a Primary Energy Source). This implies that every time we perform a quantitative analysis dealing with energy accounting we must specify first of all the energy form of reference: MJ of Energy Carriers are not the same as MJ of Primary Energy Sources!

Energy End-uses

This expression refers to the useful tasks/works performed by the various sectors of society that convert energy carriers into applied power. Examples of end-uses include moving goods, melting iron, building a road, and air-conditioning of a room.

Energy Sector

The specialized economic sector of a society having the goal of delivering the required mix of energy carriers to society using Primary Energy Sources. The mix of energy carriers supplied by the energy sector has to match in quantity and quality the demand of the various other economic sectors of the society.

EROI

Energy Return on Energy Invested (EROI) is one of the most important concepts in relation to the study of the quality of alternative energy sources, but also one of the most controversial. The concept of Economic Return on Investment – which inspired EROI – is an accounting valuation method used to assess the potential profit of a financial investment. In financial analysis this concept addresses at least two issues:

  1. the pay-back time of the investment; and
  2. the size of the required investment (input), which the investor must be able to handle.

However, very often, in energy analysis, the EROI is considered just as an output/input ratio determining a net surplus of energy, without considering the time dimension or the power level at which the flows are invested and supplied.
EROI is a semantic concept, useful for evaluating the quality of Primary Energy Sources. However, to implement this semantic definition one has to use a set of indicators and not just a simple ratio. In particular two factors should be considered when using EROI as an accounting evaluation method:

  1. the energetic burden associated with the conversion of a Primary Energy Source (PES) into a net supply of Energy Carriers (EC). This burden depends on the overall loss associated with two conversions: (a) PES to Gross EC and (b) Gross EC to Net EC, where the second conversion refers to the consumption of energy carriers in the production of energy carriers; and
  2. the power level at which energy carriers can be invested into the process of exploitation of PES. This is a crucial factor determining the final intensity of the net supply of net energy carriers to society.

Exosomatic Metabolism

Technical conversions of different types of energy inputs (in the form of Energy Carriers) into end/uses that take place outside the human body, but under direct human control.

Extended Peer Review

A process whereby, due to the complexity of its topic, the quality of a piece of scientific information is evaluated by an extended community of peers, including perhaps scientists from various different disciplines and/or laypersons from outside of scientific society (coined by the two philosophers of science, Silvio Funtowicz and Jerome Ravetz).

Fossil Fuels

Solid and liquid fuels (Energy Carriers) that are derived from fossilized energy. Fossilized energy is stored within organic material generated in pre-historic times and is generally found below the surface of the earth.

Kyoto Protocol

A protocol of the United Nations Framework Convention on Climate Change (UNFCCC or FCCC), aimed at fighting global warming. The Protocol was initially adopted on 11 December 1997 in Kyoto Japan, and entered into force on 16 February 2005, but has been ineffective in reducing the pace of energy consumption at the world level (which is still growing), let alone in reducing greenhouse gas emissions.

Net Energy Analysis

A theoretical approach introduced in the 1970s, pointing at the need to analyze the entire set of energy conversions associated with a given energy flow or energy form. For example, when dealing with a Primary Energy Source, what is relevant is the net supply of Energy Carrier that can be used by a society, not the total amount of Primary Energy Source that is consumed. Net Energy Analysis can be carried out, for example, by using the concept of Energy Return On the Investment (EROI). See also Energetics.

Peak Oil

This expression indicates a given point in time or a timeframe, when the world oil production rate reaches its maximum. After that point, it will not be possible to increase the amount of oil supplied to society. This situation arises because old oil fields, already under exploitation, decrease their supply over time, and the new production from new fields fails (or soon will fail) to offset this natural decline. It is important to understand that the issue of Peak Oil is very relevant not because we are running out of oil soon. The issue of Peak Oil is relevant, because after reaching a situation of Peak Oil, the total amount of oil available will begin to shrink. This means that it will no longer possible to increase oil based energy consumption at the world level (each time someone increases their consumption of energy, someone else will have to reduce their consumption proportion!). For more on this point see the story on Economic Addiction to Growth and the two additional relevant stories Fossil Fuel Resource Peaks and Implications of Peak Oil.

Price Inelasticity

An increase in prices results in no decrease of consumption or in a less than proportional one.

Primary Energy Source(s)

This expression refers to the energy forms required by the energy sector to generate the supply of energy carriers used by human societies. According to the laws of thermodynamics primary energy sources cannot be produced. They must be available, in order to make possible the production of energy carriers. Examples of Primary Energy Sources include below-ground fossil energy reserves (coal, gas, oil), blowing wind, falling water, sun, and biomass. The distinction between “Energy Carriers” and "Primary Energy Sources" is extremely important since these two labels refer to energy forms of different quality. Like for the concept of money, “US dollars”, "European €" and "Chinese Yuans" are different forms of money. However, it is not possible to sum a given quantity of US$ to a given quantity of EU€ and Chinese Yuans, without applying conversion factors. In the same way, 1 kWh of electricity (3.6 MegaJoules of Energy Carriers) cannot be summed to 3.6 MJ of oil (a Primary Energy Source). This implies that every time we perform a quantitative analysis dealing with energy accounting we must specify first of all the energy form of reference: MJ of Energy Carriers are not the same as MJ of Primary Energy Sources!

Shale Oil

A possible non-conventional supply of oil coming from the exploitation of oil shale (a sedimentary rock containing organic compounds – a solid form of "fossil energy"). The exploitation of oil shale requires using energy carriers to extract and liquefy the organic compounds found in the rocks. This internal loop of energy carriers, required to generate energy carriers, reduces the EROI of the process and represents the major draw-back of this non-conventional fossil energy source - see the explanation in the story Liquid Biofuels.

Tar Sands

A mixture of sand, water and bitumen (a very heavy and viscous form of oil). Like shale oil, tar sands are gaining attention as a possible non-conventional energy sources. However, they also share with shale oil the same problem of low EROI, when compared with conventional oil - see the explanation in the story of Liquid Biofuels. The most important production of oil from tar sand is taking place in the province of Alberta in Canada.

Technological Optimism

The belief that all problems and stumbling blocks preventing humans from achieving their wants can be effectively removed or overcome by humanly devised technologies. These enthusiastic ideas about technology are based on a modern European Enlightenment attitude: technology is inherently good and infinitely powerful, and its misuses are accidental.

The Hydrogen Economy

The idea of an economy that uses hydrogen derived from renewable resources as its main "fuel" or energy carrier. It is considered by many as the best possible solution in relation to the sustainability of the energy sector. Many experts of energetics, however, as sceptical about the possibility of establishing such an economy in the short to medium term.

URR

URR stands for ultimately recoverable reserves, also referred to as Total Recoverable Reserves or "Ultimate" or Estimated Ultimate Recovery (EUR used by BGR-Germany). It is the total amount of recoverable resource in the ground before production starts or in simpler terms the total quantity of a given resource that will ever be exploited. So for oil, per definition this includes oil consumed already, oil consumed in the future from existing wells and from those that are expected to be discovered still.

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