chapter5.pdf

part II

energy resources and technology options

CHAPTER 5

energy resources

Hans-Holger Rogner (Germany)

LEAD AUTHORS: Fritz Barthel (Germany), Maritess Cabrera (Philippines), Andre Faaij

(Netherlands), Marc Giroux (France), David Hall (United Kingdom), Vladimir Kagramanian

(Russian Federation), Serguei Kononov (Russian Federation), Thierry Lefevre (France),

Roberto Moreira (Brazil), R. Nötstaller (Austria), Peter Odell (United Kingdom), and Martin Taylor

(United States and United Kingdom)

ABSTRACT

A comprehensive account of the

world’s energy resource endowment

is essential for any long-term energy assessment.

Energy resources exist in different forms—

some exist as stocks and so are exhaustible,

others exist as flows and are inexhaustible,

and a third form is based on exhaustible

stocks that can be leveraged to resemble

renewables. Most important, energy resources

evolve dynamically as a function of human

engineering ingenuity, driven by the desire

to supply affordable and convenient energy

services. Although the term stocks suggests

finiteness (which is ultimately correct), the

accessible portion depends on technology and

on the future demand for that resource.

Resources not demanded by the market are

‘neutral stuff’. Demand plus advances in

technology and knowledge turn neutral stuff

into reserves that are replenished upon use

by further advances in technology and

knowledge, enabling humans to tap into

resources previously beyond reach. But for

stocks there will eventually be a limit.

In contrast, resources based on annually

recurring flows are distinctly different from

stocks: harvested prudently, they are renewable.

But resources are not an end in themselves,

and their attractiveness must be seen in the

context of societies’ energy service needs, of

the technologies that convert resources into

energy services, and of the economics associated

with their use. This chapter assesses whether

long-term energy resource availability could

impede sustainable development and, based

on a dynamic technology concept, provides a

comprehensive account of the world’s energy

resource endowment.

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WORLD ENERGY ASSESSMENT: ENERGY AND THE CHALLENGE OF SUSTAINABILITY

Chapter 5: Energy Resources

his chapter reviews fossil,

nuclear, and renewable energy

resources. The reserve and resource

volumes presented here cover the ranges

considered robust by most of the lead

authors. The main controversy yet to be resolved

concerns the different views on the roles of technology

and demand in the long-term availability of a particular resource.

Subject to debate is the extent to which reserves can be converted

from additional conventional resources with lower geological

assurance and from unconventional resources lacking economic

attractiveness given current markets and technologies. Natural flows

are immense for renewable resources, but the level of their future

use will depend on the technological and economic performance of

technologies feeding on these flows as well as on possible constraints

on their use. The long-term availability of energy resources will likely

become more an issue of the degree to which future societies want

to balance environmental and economic tradeoffs, control greenhouse

gas emissions, and internalise externalities, or of the technological

and economic performance of different clean energy conversion

technologies, than a question of resource existence.

This chapter examines long-term energy resource availability primarily

Hydrocarbon occurrences

become resources only if there is

demand for them and appropriate

technology has been developed

for their conversion

and use.

from the perspectives of theoretical

maximums, or ultimately recoverable

resources. Admittedly, it can be argued

that an analysis based on ultimately

recoverable resources is irrelevant—hydro-

carbon occurrences or natural flows become

resources only if there is demand for them and

appropriate technology has been developed for their conversion

and use. Indeed, energy resources generally should not be scrutinised

without reference to the chain extending from the extraction of resources

to the supply of energy services—that is, along all the conversion

steps to the point of what consumers really want: transportation,

communication, air conditioning, and so on. But the assessment in this

volume has been structured so that each link of the chain is explored

separately. Energy conversion technologies are discussed in chapters

7 (renewable energy technologies) and 8 (advanced fossil and nuclear

energy technologies), as well as in chapter 6 (energy efficiency).

Definitions and units

A variety of terms are used to describe energy reserves, and different

authors and institutions have different meanings for the same terms.

Meanings also vary for different energy sources. The World Energy

FIGURE 5.1. PRINCIPLES OF RESOURCE CLASSIFICATION

Identified resources

Undiscovered resources

Demonstrated

Inferred

Probability range

Measured

Indicated

Hypothetical

Speculative

Economic

Reserves

Resources

Sub-economic

Resources

Other

Unconventional and low-grade materials

occurences

Increasing geological assurance

Source: Based on McKelvey, 1967.

WORLD ENERGY ASSESSMENT: ENERGY AND THE CHALLENGE OF SUSTAINABILITY

137

Chapter 5: Energy Resources

Council defines resources as “the

occurrences of material in recognis-

able form“ (WEC, 1998). For oil, it is

essentially the amount of oil in the

ground. Reserves represent a portion of

resources and is the term used by the extraction

industry. British Petroleum notes that proven reserves

of oil are “generally taken to be those quantities that geological

and engineering information indicates with reasonable certainty can

be recovered in the future from known reservoirs under existing

economic and operating conditions” (BP, 1999). Other common

terms include probable reserves, indicated reserves, and inferred

reserves—that is, hydrocarbon occurrences that do not meet the

criteria of proven reserves. Undiscovered resources are what remains

and, by definition, one can only speculate on their existence. Ultimately

recoverable resources are the sum of identified reserves and the

possibly recoverable fraction of undiscovered resources and generally

also include production to date. Then there is the difference between

conventional and unconventional occurrences (oil shale, tar sands,

coalbed methane, clathrates, uranium in black shale or dissolved in

sea water), especially the rate at which unconventional resources

can be converted into conventional reserves.

To the extent possible, this chapter uses the McKelvey box, which

presents resource categories in a matrix with increasing degrees of

geological assurance and economic feasibility (figure 5.1). This

scheme, developed by the U.S. Bureau of Mines and the U.S.

Geological Survey (USGS, 1980), is to some extent also reflected in

the international classification system recently proposed by the

United Nations.

In this classification system, resources are defined as concentrations

of naturally occurring solid, liquid, or gaseous material in or on the

Earth’s crust in such form that economic extraction is potentially

feasible. The geologic dimension is divided into identified and

undiscovered resources. Identified resources are deposits that have

known location, grade, quality, and quantity or that can be estimated

from geologic evidence. Identified resources are further subdivided

into demonstrated (measured plus indicated) and inferred

resources, to reflect varying degrees of geological assurance. Reserves

are identified resources that are economically recoverable at the

time of assessment (see the British Petroleum definition, above).

Undiscovered resources are quantities expected or postulated to

exist under analogous geologic conditions. Other occurrences are

materials that are too low-grade or for other reasons not considered

technically or economically extractable. For the most part, unconventional

resources are included in ‘other occurrences’.

The boundary between reserves, resources, and occurrences is

current or expected profitability of exploitation, governed by the

ratio of market price to cost of production. Production costs of

reserves are usually supported by actual production experience and

feasibility analyses, while cost estimates for resources are often

inferred from current production experience adjusted for specific

geological and geographic conditions.

Technological improvements

are continuously pushing resources

into the reserve category by

advancing knowledge and

lowering extraction costs.

For several reasons, reserve

and resource quantities and related

supply-cost curves are subject to con-

tinuous revision. Production inevitably

depletes reserves and eventually exhausts

deposits, while successful exploration and

prospecting add new reserves and resources. Price

increases and cost reductions expand reserves by moving

resources into the reserve category and vice versa. The dynamic

nature of the reserve-resource relationship is illustrated by the

arrows in figure 5.1. Technology is the most important force in this

process. Technological improvements are continuously pushing

resources into the reserve category by advancing knowledge and

lowering extraction costs.

The outer boundary of resources and the interface to other

occurrences is less clearly defined and often subject to a much

wider margin of interpretation and judgement. Other occurrences

are not considered to have economic potential at the time of

classification. But over the very long term, technological progress

may upgrade significant portions to resources.

In 1992 the United Nations Economic Commission on Europe

(UNECE) launched an effort to define a generally applicable

resource classification scheme with a higher resolution of technical

and economic feasibility than the McKelvey box. By adding a third

dimension—the level of actual feasibility of extraction based on

geological engineering assessments—this new classification provides

a more accurate picture of the accessibility of resources. In 1997

the United Nations International Framework Classification for

Reserves/Resources—Solid Fuels and Mineral Commodities

(UNFC) was completed and recommended by the Economic and

Social Council (ECOSOC) for world-wide application. But it will take

time for the UNFC to be universally adopted by public and private

institutions and for fossil reserves and resources to be consistently

reported in compliance with the UNFC.

For renewable energy sources, the concepts of reserves, resources,

and occurrences need to be modified. Renewables represent annual

flows available, in principle, on an indefinite sustainable basis.

Fossil energy reserves and resources, although expanding over time,

are fundamentally finite quantities. In this context the annual natural

flows of solar, wind, hydro, and geothermal energy and quantities

grown by nature in the form of biomass (often referred to as

theoretical potentials) would correspond to occurrences. The

concept of technical potentials can be used as a proxy for energy

resources, while economic potentials correspond to reserves. The

distinction between theoretical and technical potentials reflects the

degree of use determined by thermodynamic or technological

limitations without consideration of practical feasibility or costs.

Thus the economic potential is the portion of the technical potential

that could be used cost-effectively. In terms of reserves, resources,

and occurrences of hydrocarbons, economic and technical potentials

are dynamically moving targets in response to market conditions

and technology availability and performance.

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WORLD ENERGY ASSESSMENT: ENERGY AND THE CHALLENGE OF SUSTAINABILITY

Chapter 5: Energy Resources

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