The potential of renewable energy sources

Resources

and Conservation,

7 (1981)

Elsevier Scientific

Publishing

THE POTENTIAL

OF RENEWABLE

C.W.J.

17-35

Company,

17

Amsterdam

- Printed

in The Netherlands

ENERGY SOURCES

VAN KOPPEN

Mechanical

Engineering

Division,

University

of Technology,

Eindhoven,

The Netherlands

ABSTRACT The solar

light radiation

more than four orders

intercepted

of magnitude

by the earth

represents

larger than the present

On the earth's

surface,

of man, mainly

in the form of light, but also in substantial

energy,

wave-energy,

income

requires

the development

simple

domestic

hot water

solar power economic, sumption

towers

of energy

and construction

thermal

energy

and legal structures will

quantities

converters.

associated

with

demand. supply

as wind-

of this energy-

of installations

and small photovoltaic

energy

flow

for the energy

The utilization

and biomass.

systems

and ocean

financial

global

one third of this flow is available

hydroenergy

an energy

ranging

generators

from

to huge

Additionally,

the social,

the supply and con-

have to be revised.

INTRODUCTION It is impossible

to foretell

the future and consequently,

tion to try to do so in this presentation. about

the potential

developments.

What

in this paper?

of renewable

which

level of certainty

e.g. efficiencies

little

for many centuries

attached

lower,

be stopped. the world

The gradual

population

are develooments

will

of solar

little sense to talk discussing

of any statements to distinguish

to the occurrence

can obviously

radiation

that will be made

between

of coming

well established

various events: events facts;

the limits set by thermo-

can safely

be taken to vary

to come.

which

degree

are already

depletion

to between

of certainty

can further

be

under way and are very unlikely

of oil and gas resources 10 and 15 billions

sometime

0 1981 Elsevier Scientific

Publishing

to

and the growth of in the next century

of this nature.

0166-3097/81/0000~000/$02.75

future

be given to those future

never surpass

but still acceptable

to developments

without

laws and scientifically

of equipment

and the intensity

- A somewhat

it is useful

that can be attached

are based on physical

dynamics

Yet, it makes

sources

then can be the significance

In this connection

levels of certainty - The highest

energy

there is no inten-

Companp

18 - And, finally, happen.

a large group of events

Many cultural

the speed and degree social

attitudes

and political

developments

of the progress

in science

should

calculations

of certainty

figures,

they will

in mind,

Netherlands political

although

to this group,

but also

of new

for the middle

might

degree

required

energy

will

in definite

With this reser-

as a conditional

model-for

the main condition

for its implementation

guesses,

sources

are presented

of uncertainty.

be designated

of the next century,

changes

that calculated

of the renewable

the results

have a corresponding

the results

and cultural

belong

and the breakthrough

and uncertainty

of the potential

have to be made. Accordingly,

vation

which may or may not

be included.

It is with this mixture or guessed

can be identified

the

being that the

are actually

realised.

THE GEOPHYSICAL Almost

POTENTIAL

all renewable

OF RENEWABLE

energy

(one part in two billion) earth.

On the average

(1) and thereby by four orders

sources

this intercepted

surpasses

the current

of magnitude.

and converted

fortuitous).

This leaves

corresponding almost power

exclusively

brings about

land-based

by the way,

light energy

heat

them hardly

of this renewable

energy

the insolation

into sensible

resulting

of these indirect

sources

global

Practically

speaking,

(the

lakes etc.).

differences

or in and natural

lead to new, be it indirect

are two or more orders

commercial

or secondary

This

As borne out by fig. 1, the geo-

sources

the present

is

(RES) down to

by the earth

on rivers,

temperature

of the light radiation

more than a regional

surface,

energy.

heat in the atmosphere

from the conversion

of solar energy.

surpass

problem.

as utilisable

to l/7 of the flow intercepted

order of magnitude. playing

the earth's

is

only the light

phenomena

potentials

in the

of the numbers

to consider

km2 of land surface

converted

than the potential

41.4 PW

it seems appropriate

convection

smaller

re-radiate

41.4 PW are absorbed

(the equality

is lost as a RES. The evaporation,

physical

10 TW (2)

use of mankind

still includes

for the utilization

to 172.5 PW.

use of nearly

and the atmosphere

the oceans

ways,

flow amounts

energy

by the

flux of 176 W mm2. As the energy

potential

Not all the light energy

from the tiny fraction

flow that is intercepted

a light power of 89.7 PW reachinq

26.0 PW, corresponding

potential,

their energy

and an additional

into sensible

the 148 million

the geophysical

derive

commercial

The clouds

with an average

reaching

SOURCES

of the solar radiation

of light power back into space, atmosphere

ENERGY

itself. energy

this excludes

of magnitude

Even the largest of use by more than one

all indirect

role in the solution

RES from

of the energy

19

1

TPACE, 17250

1

4140

i--f

1 ! /

6370

I

4140

*

? *

OCEANS

OTEC

iii&g

Fig.1. Origin and geophysical potential of the various renewable energy sources, related to the present global commercial energy use (10 PW approximately); with use of (1) and reduced to land based utilization.

Actually

two groups of indirect

are biomass,

hydropower

such a role is conceivable, geothermal should

energy,

be pointed

RES can be distinguished:

and windenergy

which

(and maybe

and the group of the small

the upper and still

theoretical

potentials

such as uneven

in the tropical

at heights

above 200 m), and low efficiencies

and subtropical

than 3% for OTEC)

invariably

that can actually

be realised.

of magnitude

is a better

It needs no comment in solar

radiation.

heat from underground Rotterdam, years,

mOSt

However, bodies

occurring

conversions

(windenergy (less

in the power output

the reduction

other cases,

a reduction

and geothermal

it may be useful of hot water,

is not a RES because

energy

reduction

from

(60% of the bio-

bad accessibility

in subsequent

only

amounts within

to only one two orders

first estimate.

that tidal-

and is only very slowly

geothermal

For hydropower

and

It

given so far represent

distribution

forests),

cause a substantial

(1) but in

of magnitude

tidal-,

limits of the power that can be derived

RES. Factors

mass grows

order

are wave-,

for which

are bound to remain of only local significance.

out that the geophysical

each of the different

the three larger

in the future OTEC),

energy

to note that the utilization

as was considered

the heat is depleted replenished

as a RES only refers

in areas of high volcanic

do not have their origin

in a short period,

from the interior

to hot springs

activity.

in Spijkenisse

near

say 25

of the earth.

and similar

of the

phenomena

The

20

THE CONVERSION

OF THE PRIMARY

All renewable order

to obtain

version

primary energy

route should

of supply

in renewable in which

In the framework

technology.

component

conversion energy

and the Potentialities

of Wind-

in this volume,

and on alcohol

in the conversion

role

based systems,

that may be required.

in two other papers

these options.

in

sources

important

fossil-fuel

known in the current

Energy Conversion

of waste

energy

little sense to discuss well

steps

such a con-

for adjustment

the renewable

plays a much more

all storage

it makes

covered

here just to mention

they are listed

of energy

that are already

on the bioconversion

pleteness

level of most of

provide

As Ocean Thermal

it suffices

one or more conversion

for final use. Preferably

than in the conventional,

of this paper

methods

energy will be adequately formation

require

(at least) one storage

the storage

systems

the fuels virtually

steps and storage

sources

As the power

by nature, energy

energy

ENERGY

in a form suitable

encompass

and demand.

is fluctuating

RENEWABLE

and in-

fuels are also included,

However,

and storage

for the sake of comsurveys

in Figs. 2a and

2b.

SOURCE

CON”ERSION

PRIMARY

DEVICE

MAX.

PRODUCT

EFF

STORAGE

DEVICE(S) FLAT PLATE COLLECTORS EVACUATED COLLECTORS

HEAT

40-150°C

70%

WATER, SALTS

ROCK

CONCENTRATING COLLECTORS FOCUSSING COLLECTORS

HEAT

150~500%

60%

SALTS,

SODIUM

PHOTOVOLTAIC

ELECTRICITY (LOW VOLTAGE)

12%

BATTERIES HYDROGEN

FUELS AND/OR ELECTRICITY (LOW VOLTAGE)

5 - 10%

LIGHT CELLS

PHOTOCHEMICAL-, PHOTOELECTROCHEMICAL-, PHOTOBIOCHEMICAL CELLS

AND

Fig.Za. Ways for the direct conversion form; with use of (1) and (5).

As shown

in Fig. 2a, there

can be converted ciencies

into a

into heat.

often

plate and evacuated heat by means

system

collectors,

of black metal

are thermally

however,

shielded

plates

effi-

the quality

in practice.

is absorbed

exposed

from the environment

of the energy

and do not include

losses occurring

the light energy

light energy

conversion

that the listed efficiencies

peak efficiencies

or plastic

along which

energy

high for the well developed

and do not take into account

and operational

into a utilisable

form. The maximum

are fairly

be noted,

they are the instantaneous

considerable

The plates

energy

be attained

It should

are first law efficiencies Moreover,

is a large number of ways

utilisable

that can presently

conversion

of light energy

FUEL AS SUCH BATTERIES HYDROGEN

the

In flat

and transformed

into

to the light radiation. by some envelope

with

a

transparant usually

front cover.

For the so-called

is a glass tube which

heat losses. the greater

The radiative

fluid,

passing

through

The energy

density

1 kW m-* in bright

radiation

by means

shifting

with

in which

the generation

mirror

array

tower, which

(20). In moist

trating

devices

Consequently,

2 to 4, are applicable Within version

of 12% are common

installation a factor

of 5, is expected for the years

law efficiencies in the laboratory

may be, it should hundred

before

methods,

storage

thereafter.

laboratory

high pressure

steam for

as "power towers", point of the

like the Dutch, where

most of concen-

light can not be focussed. with a concentrating

phase.

has been made

ratio of

(3). A further

cells.

reach

In laboratory

experiments

studies

(4). However,

much

cells with such performances

mentioned

efficiencies

research

and development

can actually

be marketed

and photobio-

Fig. 2a. The theoretical

the direct

production

be kept in mind that usually

accomplishments

in cost, by

improvements

have shown that an

photoelectrochemical

last in

including

reach up to 40% (1) but all methods

How attractive

con-

Conversion

reduction

1985 and large additional

and how vast the number of candidate

always

in the direct

of photovoltaic

and theoretical

for these methods

may appear,

the costs of the mirror

by now and the costs have been reduced

even more for the photochemical,

conversion

to

have been and are being

3000 US $ per m* of solar panel,

by the year

of 60% is not beyond

sunlight

by means

battery

efficiency

This counts

mirrors

practice

30% have been attained

chemical

scattered

for

the operating

(up to 70% (I)), such highly

much progress

of almost

work will be required

climates,

the light method

has been proposed

the higher

in the focussing

to about

and a 24-hour

are projected

Concentrating

carries

the boiler

low, only temperatures

designated

of light into electricity

by more than a tenfold

is rather

of schemes

is used to produce

because

and

and rocks

here.

the past few decades

efficiencies

water

They are generally

concentrating

coating by some

plate. Water

is the obvious

installations

and cloudy

are unsuitable

only weakly

or lenses

the focussing,

in the atmosphere

for

of the heat.

on the earth

but also the higher

realistic

solar energy

the light is scattered

to the absorber

and a wide variety

of electricity.

the central

selective

plate is removed

flat plate collectors.

that can be attained,

constructed

after

simple

fairly

spectral

This sets a limit to the operational

and more accurate

Nevertheless,

can be eliminated

media and, correspondingly,

used for the storing

this limit upward,

temperature

the convective

ducts attached

of an array of mirrors

this end. The better

array.

to eliminate

of the light incident

sunshine.

that can be reached

in order

in the absorber

used cooling

are the media most widely

this envelope

of a so-called

The heat developed

air are the most widely

collectors,

heat losses from the absorber

part by the application

on the absorber. cooling

is evacuated

evacuated

first

are still

of fuels from

photochemical

reactions

only one out of every

turns out to be feasible

in practice.

22

SOURCE

CON”ERSION

DEVICE(S)

PRPlARY

PRODUCT

HYDROPOWER

WATERTURBINE

YECH.

ENERGY

WINDENERGY

WINDMILL

YECH.

ENERGY

MAX.

EFF.

STORAGE FLYWHEEL, ELEVATED

WATER

FLYWHEEL, i ELEVATED

WATER

90%

I

50%

DEVICE(S)

Fig.Zb. Ways for the conversion of the indirectly renewable energy sources into a utilisable energy form. Storage of mechanical energy as such is not envisaged for wave- and tidal-energy; with use of (1).

In actual

use for centuries

for the indirectly thermal

energy

some earlier

conversion

- on the countrary

sources,

care and the energy

of all these conversion

crises

alised

In this connection,

countries.

is an appreciable

extension There

of enterprise

REGIONAL

Up to now, mainly

and upgrading

biomass

features

in various

the

high

industri-

not be overlooked

production

of an existing

are some opportunities

that

(2). Here also

technology,

here for industries

has not yet been pensioned

the potential

To complete

taken into account, are favorable

more than in which

the

off.

some of which

for the utilization

in the coastal

for the foundation

differences

important

several

of biomass,

point of view has been

differences

For example, which

have to be

tropical

explains

Brasil's

climates leading

In a similar way the high average wind speed

and the Netherlands

offers

an excellent

oppor-

of an internationally

leading windmill

industry.

RES, light radiation,

the consequences

of the regional

are rather more difficult

goes with a high energy

the accommodation

regional

are obvious.

fuels.

areas of Denmark

For the most

of RES from a global

this picture

role in the field of alcohol

usually

it should energy

Generally,

the economical

DIFFERENCE

considered.

tunity

improved

In particular,

however,

are new and even here

of science.

that have been put forward

for about 8% of the global

a new technology. spirit

of wave energy

have greatly

methods.

and scenarios

still accounts

- are most of the conversions in Fig. 2b. Only the ocean

can be found in the history

in the RES models

wood

summarised

and the utilization

experiments

environmental viability

renewable

to assess.

use density,

of large solar collector

A high population

density

but also with a lack of space for

arrays.

Moreover,

in the centers

of

23 larger

cities

the energy

solar radiation, A similar

use density

implying

argument

often

that the demand

surpasses

the average

density

of the

can not be met with the local radiation.

holds for the concentrated

energy

use in

heavy

industries.

In order to obtain some insight in these matters, Fig. 3 has been prepared showing

the

solar

radiation

and the

energy

use in

W/m* of land for various

countries.

COUNTRY

POP’N D,TY

AREA

ABUNDANCE

RADIATION

ENERGY

USE (1978; JUNE

DEC

AVER

RATIOS

I

I

NETHERL’S

0.041

328

2.10

212

21

108

101

10

51

U.K.

0.245

229

1.12

225

25

110

200

22

98

I 0.248

I 249

1.46

I 225 I

25

F.R.G.

148

GLOBAL UNITS

27

lo6 KM2

Fig.3. Seasonal and density for various (countries) or 1980 are included in the

The three figures

in the fourth

uniform

over the year.

highest

than the climate average

-

-

2600

-

countries,

populated

The population

hardly

countries

at high latitudes

abundance

ratio.

use, varies

ones,

like Japan

exceeds

obviously

position

and (yearly)

i.e. the ratio be-

over almost U.S.A.

two orders

and Brasil,

and the Western is a more

of the country;

to winter

European

important

factor

the spread

variation

that such high latitude

of

feature

in the

a factor of 2. As was to be expected,

show a large summer

It is not surprising

mid-winter

to be approximately

ratio,

such as Sweden,

density

and the geographical

solar radiation

use is assumed

that the abundance

and the energy

populated

lowest.

176

refer to mid-summer,

the energy

It appears

radiation

Thinly

-

(HORIZONTAL)

column

repectively;

and the densely

countries,

WM-*

-

1551 17

average solar radiation density in comparison to energy use countries, with use of (5-7). Demographical data for 1977 (global). The figures are approximate; lakes, rivers etc. area.

radiation,

tween the light

0.068

KM-*

average

magnitude.

I

the

of the

countries

show a

24

particular

interest

Netherlands, figure

in the season

the midwinter

lands rank as the most sharing

countries,

unfavorable

this position

For many

ENERGY

reasons

sufficiently objectives

The degree

requires

present

new energy

dwellings

Fairly

following

1. The world billion

and should

shop system figure

will

and information

on this basis,

of world

sources

somewhere

complete inter-

roads and

lifetime

of the

(11). As a

can only be estimated

to sketch,

at least in

in the middle

from the present

by about a factor

of the population

of the next

one in the

of 3, to say, 13

of the Third World,

as will

efficiency

the political

will

be required

considerably,

nation

in meeting

life all

in many areas

countries

to

power; most probably

in the world.

Consequently

2.2 kW). As yet,

contribute

from the western

and economic

to present

for both environmental

say about

into daily

may have been overcome

be high compared

grade ores and for recycling.

presently

will have penetrated

trade will have shifted

be the most powerful

capita,

energy

starvation

China will

energy will

is that the mean

it necessary

have increased

by an increase

Asia,

increased

it implies

is no less than 83 years

of renewable

south-east

energy will

society

to prove this point.

this world will differ

mainly

science

4. The energy

The building

the multiple

of industry,

not

in south and east Asia.

over the world; 3. The center

among the

that will

not be pursued.

because

Only a

(among others):

population

2. Technology,

but also, and to a

Considering

in this context

makes

not only on

for an industrialised

simply,

suffices

so far can

depends

to discriminate

better

system

of the future world,

certain

people,

in particular

it possible

supply

in the Netherlands

respects

London.

is used in the assessment.

car and the structure

the real potential

lines, a picture

century.

restrictions

which

makes

on such a long term. This condition broad

in other

of the RES discussed

infrastructure.

the private

interesting

consequence,

the Nether-

of solar energy,

areas

this is possible

of the order of a century,

and the retail

An other

inhabited

in the long run and the solutions

of the societal

actions betweene.g. streets,

potential

than a few decades

a period

ratio,

and the region around

and economical

time horizon

up of a fundamentally

reconstruction

abundance

for the application

to which

on the time horizon

that are realistic

last for longer

country

Ruhr district

of technical

distant

In the

ratio even goes down to only 10, the lowest

with some densely

the geophysical

larger extent,

of solar energy.

SOURCES?

not fully be utilized. a large variety

storage

But also for the average

e.g. the German

WHY RENEWABLE

much

abundance

in the last column.

probably

to season

fivefold

standards,

the global

energy

(corresponding

it is uncertain this demand.

but much

care and preparation

of low

use will

to roughly

to which

extent

have 4 kW per

nuclear

5. The oil, gas and many (7). This applies and Africa.

high grade mineral

in particular

Because

resources

to the indigenous

of the high global demand

will be all but depleted resources

the prices

of Western

Europe

of raw materials

will

be very high, also for coal. The conclusion is gradually

to be drawn from this sketch

moving

into a highly

energy

but also that in the next century number,

is going

to draw on its finite

main reason why a fundamental necessary

to the fullest

possible

It is, by the way,

resources

in an unacceptably

not the first time in history

his food supply

system

to the steadily

societies

and the ancient

population

has increased

RES MODELS

FOR VARIOUS

increasing

civilisations

character

of the energy

countries

are still of a rather

primitive

of possibilities

is an essential

proposition. low level,

The energy

of living.

known

nature,

way,

been indicated

report

"Limits

depicting

because

activities,

of that

(8, 9, 13, 14). Most of only a single

area. The economic

for. For obvious

factors

are

many data are still realistic, transport, reasons

in the sense communications

energy

efficiency

energy

in Sweden

(8) is interesting

between

and Norway,

Norway,

Sweden

in combination

in the latter and of biomass

turn energy

use per capita

efficiency

two of them are schematically

for Scandinavia

of renewable

density

country,

all energy

then, the world

in the RES models

or regions

of these models,

of hydroelectricity

mentioned

in a similar

the sedentary

in all the models.

the exchange

large potential

standard

accounted

the character

The low population

to adaot

in the many publications

may be called

needs for industrial

are well

in Fig. 4. The RES model

incorporates

earlier

hand, most models

element

To illustrate depicted

for a delimited

in only an approximate

that the basic energy

density

has earlier

in the well

it is expressed

for various

and space heating,

Since

faces a challenge

was forced

from which

situation

detectable

(e.g. 12). Most concretely

haven been constructed

On the other

is

COUNTRIES

It is implicitely

into account

system

of magnitude.

to the Club of Rome and very outspoken

lacking.

This is the

and exploited

that mankind

have emerged.

by two orders

to Growth"

taken

supply

population

revolution

ways.

these models

strong and

problem.

hunter and collector

in various

combination

situation,

extent.

way. This led man into the agricultural

Lovins

waste

in the global energy

Long ago, the Neolithian

Amory

dependent

Europe

by the shear impact of its

of RES will have to be explored

of this nature.

The revolutionary

as a whole,

a most difficult

change

and why the potential

and raw materials

mankind

fast way, at the same time creating

is not only that Western

export

to Denmark

is assumed

serving

a modest

because

it

and Denmark.

with the (forests)

in the

into a good commercial

to remain increase

constant

at a fairly

of the material

26

1 Scandinavia

1975

0

Solar

DIII

Bio

m

Wind and hydro

a

Non-renewable sources

2030

1975

2050

Fig. 4. Renewable

The U.S.A.

energy

RES model,

source models

on the contrary,

essential

element

important

(9). Also,

role than in the Scandinavian

view on the possibilities are related

for Scandinavia

the direct

of storage.

to th nly populated

includes

energy

conversion model.

(8) and the U.S.A.

conservation

of solar energy

This implies

It should be noted

areas with an average

(9).

as an

plays a more

a rather optimistic

that both RES models

abundance

ratio beyond

500 (see Fig. 3). A report recently

on the short

for the year Federal economic

2000 are shown

policies

restrictions,

an increase

estimates

of renewable

it is concluded

solar

from 6% in 1977 to nearly

period

in the U.S.A.

(10). The main

has results

that the State and

use, but also taking

into account

that the share of RES in the U.S.A. energy

of 25% in the total energy

for the initial

energy

of Energy

in Fig. 5. Under the assumption

are used to accelerate

supply may increase ing

term prospects

been pub 1 ished by the U.S. Department

20% in the year

demand.

in the RES model

2000, notwithstand-

This fully agrees with the

for this country.

37

CONTRIBUTION

SOLAR TECHNOLOGY

ACTIVE HEATING AND COOLING

2.0

PASSIVE HEATING AND COOLING

1.0

INDTJSTRIAL AND AGRICULTURAL

2.6

BIO'
5.4

PHOTOVOLTAIC

1.0

SYSTEMS

WIND SYSTEMS

1.7

SOLAR THERtAL POWER

0.4

OCEAN THERYAL

0.1 3.5

HYIjXO POWER: HIGH HEAD

0.9

: LOW HEAD

TOTAL

18.5

(QUADS) IN THE YEAR 2000

19 1 QUAD = 1Ol5 BTU = 1.055.10 J. TOTAL U.S.A. ENERGY "SE ESTIMATED TO INCREASE FRO?? THE PRESEEJT 78 QUADS TO 95 QUADS IN THE YEAR 2000.

Fig.5. D.O.E. estimate of solar contributions by the end of this century, under the assumption that State and Federal Policies are used to accelerate solar use 110).

ASSUMPTION

FOR A CONSERVATION

As illustrated for renewable in which

before,

energy

sources

the RES situation

(see Fig. 3). The latter possibilities in first

an essential because

element

the construction

various

circumstance

energy

related

solar energy

FOR THE NETHERLANDS

it is surrounded

better,

except maybe

it significant

without

countries,

is subdivided

by countries in France

exchange, valuable

Energy efficiency

plan for an industrialised As a consequence,

countries

to investigate

any regional

country,

the starting

the

at least indications has to te if only

points

for

in two groups:

to the future developments

conversion

MODEL

a Dutch RES model may procure

prices.

of the model

points

SOURCE

Moreover,

makes

for the surroundinq in any energy

of increased

- starting

in the world.

Additionally,

the options

ENERGY

is one of the most unfavorable

is not substantially

of RES for the Netherlands

instance.

regarding

AND RENEWABLE

the Netherlands

and improvements

of the

methods,

and - starting

points

related

In order to express be called energy

a conditional

conversion,

to the long term effects

these two aspects or CRES model.

the following

of energy

conservation.

in the name of the model

As regards

the efficiencies

it will

further

of solar

six long term

(75 years)

assumptions

are

solar energy

conversion

Imethods with an

conservative. 1. Because

of the required

efficiency significant materials

below

space,

108, such as energy

degree

in densely

can be excluded

plantations,

populated

areas

from this general

are not applicable

like the Netherlands.

rule.

to a Only waste

28 2. The efficiency raised

of low temperature

to 45%, as an annual

average.

storage

methods

present

50% to 75%, regardless

mand.

Further,

the dwellings 3. The research

the coverage

and buildings

can actually

demand

fluctuations

4. Some photochemical been developed

conversion

demand

and the real practical

supplies

any increase waste will implies

philosophy

considerably

recent

use will

publications

for electricity

of daily or

of 15% will

fuels can be stored

turbines

have

so easily

demand

zero.

is well developed

on energy

into a decrease

by higher

conservation

and

in energy

use. This philosophy

efficiencies

these changes

energy

of living and any economic

the structure

in energy

use, longer

of industry

will change

are so unpredictable

For similar

are not considered,

reasons,

because

Based on this philosophy, the following

conservation,

is that

and that all present

standard

use has to be omitted.

on energy

to 2500 MW

(15).

in the material

for the future.

amounts

is virtually

and other waste

have to be avoided

of the Netherlands

is expected

have resulted

methods

for the Netherlands

goods, etc. Certainly

on energy

in the Population

in the deonly 80% of

with solar heating.

cells will

an efficiency

the assumptions

in the long run. However,

their influence

increase

energy

behind

have to be accompanied

of capital

with

photochemical

materials

have to be converted

growth will

be provided

etc.,

for 50%, regardless

land use of wind

of bio-waste

in energy

fluctuations

from the

can be met for 100%.

that any improvement

lifetimes

methods

of windenergy

5% of the present

The general

heat

in the demand.

5. The long term potential

6. The utilization

can be

of improved

of 25% and in such storage can be covered

devices

can be raised

town planning

work on photovoltaic

and the produced

that any specific

demand

of daily or seasonal

of orientation,

that any specific seasonal

As a consequence

for reasons

efficiencies

conversion

of any specific

and development

in conversion

photothermal

that

any changes

no substantial

and on various

six assumptions

appear

to be justifiable: I. By means

of thermal

insulation,

air-tight

the heat demand

appliances

etc.,

be reduced

to l/3 of its present

2. Implementation zation

heat, etc., will

temperature

heat

3. The industrial

(below

one, a modest

because

of a higher

4. The industrial

for the manufacture 5. The efficiency

can

coproduction

reduce

of power and heat, utili-

the net industrial

demand

for low

15O'C) by 50% (15).

increase

industrial

demand

and services

(15, 16).

power plus high temperature

present

high performance

for the built environment value

of heat regeneration,

of waste

construction,

will be equal

activity

energy

(15).

for fuels

of plastics)

of central

heat demand

of the industrial efficiency

for non-energy will

remain

power stations

remaining

to the possible

use (e.g. as a raw material

constant.

will,

sometime

in the next century,

29 reach 50%, as compared of the power Further,

stations

to 40% at present. will be utilized,

the end use of electricity

efficiency

of electrical

be compensated information

equipment

Moreover,

preferably

half of the waste for district

will have increased and appliances

for by a large increase

in efficiency

in the capacity

which

from waste So the problem

photochemical

lised society,

installations.

Netherlands,

supply

rivers

is summarised

the fuel use for the various the corresponding measures

primary

mentioned

above,

In the third column The corresponding

term roughly sources,

large fraction

"between

after

for the accommudation

resulting

On

of these

from the fore-

in the table gives

in 1979 and the second implementation

In short,

In the bottom

it appears

supply may be derived

one third and two thirds".

part of

from renewable

energy

of land area. As this is a surprisingly

energy.

character;

parts.

that over the long

to point out that this fraction

radiation

nuclear).

into "fuel" and "renewable"

in the last column.

large engagement

column

of the conservation

based on fuel (fossil and/or

supply is split

are given.

are of an illustrative

facilities.

land area of present

lakes.

sectors

supply

but completely

it may be useful

less than 1:; of the solar figures

societal

the energy

an unduly

for an industria-

, or 2.3% of the land surface of the

for the Netherlands

half the Dutch energy

without

and the

in the industry.

importance

in Fig. 6. The first column

energy

results

the energy

of its high production

of the photovoltaic

to the present

to 750 km*

land use is given

the table the final

land area. Also,

FOR THE NETHERLANDS

or CRES model

going assumptions

Solar collectors

than e.g., good transport

and the larger

OR CRES MODEL

The conditional

by an increase

the space that

installations

is of fundamental

be made available

This amounts

because

need not be taken into

land, because

to the accommodation

that a land area equal

excluding

THE CONDITIONAL

separate

and the photothermal

energy

roads can and will eventually solar

require

and not less important

assume

on roofs,

does not require much reduces

regarding

of solar installations.

can be mounted

installations

No doubt an adequate

this ground,

has to be made

for the accommodation

purposes,

constant

will be annihilated

system.

assumption

here as they do not really

production density.

and organisation

of the transport

a very crucial

will be available

account

for

purposes).

improvements

for heating

greater part

(in particular

6. The fuel needs for transport will remain substantially

Finally,

by 25% as the higher

will to the

in their number

heat

heating.

It is also useful

e.g.,

"roughly

still represents

to repeat

that the

half" is equivalent

to

30

PRESENT FUEL USE (1979)

SECTOR

1 EFFICIENT 1 FUEL "SE ) (2050)

R.E.s. (TYPE) AND/OR FUEL (2050)

2500 2500 5000

WIND PHVC FUEL

41250) 5400 2350

WSTE PHTL FUEL

ELECTRICITY

BUILT ENVIRONMENT + SERVICES

27000

9000 I

/

INDUSTRY LOW TEMP. HEAT INDUSTRY POWER + HIGH TEMP. HEAT

INDUSTRY NON-ENERGY

LAND USE (KM21

(100) 100 ~ 1 ' (120)

lRO0 1200 ,(3000)

PHTL FUEL WSTE

'

40

\ 12000

FUEL

1

-

14000

FUEL

1

-

I

-

e-j--

TRANSPORT

10000

10000

TOTAL

FUEL

63000

yi-q-r

ACTUAL GROSS FUEL USE OF WHICH: ENERGY FROM (BIO)WASTE PHOTOCHEMICAL FUEL NET USE OF IMPORTED FUEL ") FUEL DISPLACED By R.E.S."')

31400

') REAL + DISPLACED FUEL ") FOSSIL, NUCLEAR OR PHOTOCHEIJICAL "'1INCLUDING (BIO) WASTE

Fig.6. Conservation and Renewable Energy Source Model for the Netherlands sometime in the next century. All energy flows in MW. The RES displace roughly half of the fossile and/or nuclear fuel. Numbers between brackets do not enter in additions. For premises see text.

It might

be argued

that the model

of the still very hypothetical renewable

energy

be sustained

because

of "renewable voltaic

fuel"

compensate

It deserves

power stations

photovoltaic

action with

electricity

(e.g. hydrogen).

However,

conversion

attention

efficiencies

capacity

the renewable

that the average

by a factor

because

in the future about half the

this objection

cannot

may also be used for the production

The difference

for the losses associated

is reduced

in the installed

an undue confidence conversion,

from that source.

and the photochemical

can easily process.

is expected

reflects

photochemical

with

between

the assumed

photo-

(25% and 15X respectively) the additional

production

conversion

of the conventional

of 2.4 in the CRES model.

The reduction

will have to be less, however,

because

power supply

load fluctuations.

and the resulting

of the inter-

31 SOME ECONOMIC

ASPECTS

The potential model might saying

of renewable

be designated

that economical

the real potential. preliminary

itself

in a recent

report

area

(V.A.T.

mass

productions

Dfl. 300/m'

With some optimism

and technological

(accounting

are expected

for inflation).

1500/m2

photochemical

have to be comparable

the most optimistic

future.

investment area

devices).

This brings

area, mentioned

well provide

solar systems.

Three points

which

should

the investment

system

by the solar systems

for the

are not included

corresponds

has to be excluded).

breeder

power stations

installed,

such a park would

be kept in mind,

to a

From a

might

- in

of 50%

require

is not much below the investment

costs are quoted

- the "fuel" of the solar system

for solar

(which may e.g.,

for this power. With a load factor

of Dfl. 5000/kWe

of Dfl. 220 billion,

(18). As

in Fig. 6, to about Dfl. 260

Note that the costs for a windenergy

- both lower and higher

study

of collecting

point of view, a number of nuclear

investment

is slightly

in a recent

cells plus the costs of electricity

power of 22.2 GW (2x 2500 MW for the wind energy

and a unit investment

is still

at all.

The fuel flow displaced

the long term - equally

technology

on the future

area in concentrating

technical

a

improve-

price of Dfl. 300/m2 of

This estimate

assumed

of

installations,

estimate

be the mirror

as a minimum.

photovoltaic

is Dfl. 300/m2

that can be made

in this estimate.

that the effects

, it can be argued that either its price will

installations

billion

mentioned collector

this price to, say

(3). Photovoltaic

to that of photovoltaic

870 km2 of collecting

reduce

that a similar

price implicitly

conversion

installations

(17) is Dfl. 400/m'

might

thereafter

into a fuel, or it will not be utilized

complete

on the

pays for

for 1985 and large additional

in the distant

installation

Consequently,

hot water

Regarding

is projected

for the years

cell area can be approached

regards

all calculations conservation

it may be argued

progress

so it is not impossible

below the total

determine

here, but a few

prices.

from the Energy Study Center

price of about Dfl.

are lacking

as energy

CRES

It goes without

will also strongly

Fortunately,

can be skipped

to the conditional

potential.

considerations

price for solar domestic

excluded).

in its infancy

according

firm conclusions

can be developed.

energy

future

sources

and political

conservation

at todays

The lowest

energy

CRES MODEL

as to their technical

Data permitting

viewpoints

costs of energy

ments

OF THE CONDITIONAL

an

in the

however:

for nuclear

breeder

is free and indigenous,

power stations;

contrary

to the nuclear

fuel; and - the estimate timistic

for the solar systems

one that can be made.

from the nuclear voltaic

power stations

and photochemical

is - as mentioned

(Remark:

before

low temperature

waste

but, at least in principle,

conversion

units).

- the most opheat can be gained

also from photo-

32

An other

interesting

the capital

investment

(at US $ 36/barrel) of Slochteren

on an energy

natural

This result

corresponds

as the energy

as it were,

system

as a national

i.e. approximately

present

world

the viewpoint

Europe

market

Europe,

and should

and intermediate

to some demand.

energy dependence connection - Which

higher

of energy

and transport,

- To which

of solar

can be transported

economic

be imported Taken

heat at low

and waste-biomass,

as

to about 25% of the future

have to be imported whether

important

from southern

to Fig. 6 this potential

corresponding

question

In

over large

to its extreme,

forms of energy,

with windenergy

The most

electricity

point of view it is clear,

preferably

of a RES. According

75% would

sense,

in southern

lower than in the Netherlands.

should

fuel),

higher

in one or other form. such a high degree

considerations

of

in this

are:

amount

available

the

nor sound from

the productivity

in the Netherlands.

an energy-political is acceptable.

optimal,

and the costs of photovoltaic

electricity

together

potential

The missing

is of such a vital

for medical

from indigenous degree will

it up,

l/3 of the value from

is appreciably

leave only the non-conveyable

16 GW (displaced

It is obviously

this

equal to the

of Fig. 3, but also common

Correspondingly,

From a strictly

temperatures,

the real, economical

energy

Inspection

not be produced

would

system

and 1% maintenance,

be almost

gas (and about

be appreciably

costs.

to come. Regarding

40 years)

gas would

of solar radiation

fuels will

the windfall

up of a RES supply

only the costs for keeping

not be economically

that these forms of energy

this approach

amounts

would

be appreciably

at moderate

therefore,

counting

(lifetime

fuels and, to a lesser extent,

distances

So directing

the building

This

the same order

OF THE CRES MODEL

than in the Netherlands. will

amply

(19)).

point of view.

that the intensity

and photochemical general

towards

value of our natural

ASPECTS

price of

is being planned.

is roughly

this field for many years

growth

reserves

For the turn of the century

flow from the RES systems.

such an approach

installations

comparison:

of 1 m3 of natural

of economic

world market

For the proved

with

parity with oil

value of about Dfl. 500 billion,

asset and consequently

SOME ENERGY-POLITICAL However,

the present

flow of 30 GW, which

2.5% depreciation

an energy-political

basis,

is a comparison

Assuming

of about 30 Gm3/year

gasfields

perpetuate

price of the equivalent

teaches

energy

of the Slochteren

might,

in this context

gas fields.

for the RES systems.

another

gas consumption

to an average

of magnitude profits

estimated

again suggests

natural

content

to a capital

the investments

a domestic

natural

gas is about Dfl. 0.37/m3.

1400 Gm3, this corresponds exceeding

comparison

value of the Slochteren

importance,

care, for communication sources

the European

e.g. for food processing

etc.,

that is has to be

in all circumstances? COmmUnitY

grow to such a real unity that the

33 exchange

of energy

between

its members

will be reliable,

even in adverse

conditions? - To which

extent

participate

are the members

in the development

of the European of a common,

system

that can meet all sensible

energy

independence?

Only history depends

will

The first question largely

determine

remains

requires

which

account

energy

resource

seriously

quality

European

the manufacture

energy

potential

sources

of Europe.

demand,

it

of the RES

on the just mentioned

Taking

conversion should

in-

also into

that the individual

consider

this energy

implementation

in the context

source much

this means

that

of low and intermediate conversion.

and fundamental

be promoted

Further and applied

in co-operation

solar

of photovoltaic

for remote will

is of only marginal

In the meantime character

of windenergy,

conversion should

significance

everybody

should

equipment

expanding

with

biomass

devices

conversion

first,

Finally,

for the industry for the sorting

supply

offers

situation.

For

interest.

and low and

looks promising.

be pursued

with

and processes.

home market

context, Here specific

as more widespread photochemical at present,

con-

as many

out of the options.

be aware of the instability

energy

lie primarily

but only in a European

five to ten years.

work are required

of the world

to come.

efficient

heat. Further,

locations

take an other

of laboratory

of energy

of the CRES model

a small but rapidly

in the fields

temperature

for many years

studies

and of waste-biomass

conversion

and application

energy

the development

tionary

future

now. For the Netherlands

in the photochemical

the actions

ing opportunities

version

this basic or emergency

countries.

For industry,

more years

should

for the gradual

research

applications

whether

of RES, it is clear

than they are doing

be developed

on the photovoltaic

application

for the answer will

ACTIONS

Commission

fundamental

intermediate

but the answer

that, in the long term, RES are the only proved

solar heat, of windenergy

renewable

supply

care and

supply system which will

and more detailed

temperature

other

analysis, energy

for the free countries

and the European

plans should

research

further

part of the 50% technical

of further

the environmental

governments more

careful

AND INDUSTRIAL

the results

issues may be, it is clear digenous

to

have to be exploited.

GOVERNMENTAL

Whatever

energy

to the last two questions,

As long as it is unknown

an open question

REQUIRED

renewable

of both environmental

have to cover more than 25% of the normal

will actually

really prepared

taken.

the size of the independent

have to be created. system will

integrated

requirements

give the final answer

on the actions

Community

and the revolu-

Surprises

will

be normal

34

CONCLUSIONS From the analyses

presented

in this paper,

the following

conclusions

can be

drawn: Provided

that energy

efficiency

technical

potential

of renewable

is pursued energy

amounts

to roughly

related

costs are high but not prohibitive.

Provided

half the future

that a real European

the domestic

production

demand

offers

mainly

directed

toward

energy

energy

better

to roughly

of the should

of windenergy

of the Dutch government

and of waste-biomass,

in European

conversion

of the required

to the government

European

and industries

be

temperatures.

and industry

and photochemical

for the establishment

applies

restricting

The said production

Real participation

condition

The

one quarter

of heat at low and intermediate

equally

the

in the Netherlands.

and the production

in the fields of photovoltaic

limits,

in the next century

can be established,

solution.

the utilization

sometime

demand

co-operation

of renewable

an economically

to its sensible

sources

efforts

is a necessary

co-operation.

of other northern

This

European

countries. Renewable

energy

sources

for the free countries

constitute

of Europe

the only proven

by the middle

indigenous

energy

source

of the next century.

REFERENCES 1.B. Sdrensen, Renewable Energy, Academic Press, London, 1979. 2.J.S. Foster, Prospective Energy Production in Survey of Energy Resources, 11th World Energy Conference, 1980. perspectieven en mogelijk3.L. Vermey and A.H.M. Kipperman, Zonnecelsystemen, heden (Prospects of photovoltaics), De Ingenieur, 92, No. 43 (23 Oct., 1980), pp. 6-11. 4.5.3. Lofersky, Photovoltaics I: Solar Cell Arrays, Advanced Technology, IEEE Spectrum, Febr. 1980, pp. 26-36. 5.J.A. Duffie and W.A. Beckman, Solar Engineering of Thermal Processes, Wiley Interscience, New York, 1980. 6.Commission of the European Community, Toetsing van de doelstellingen inzake het energiebeleid voor 1990 en de investeringsprogramma's van de lidstaten (The objectives of the energy policy of the member states), Commission of the E.C., Rep. COM (81) 64, 25 Febr. 1981. 7.G.0. Barney (study director), The Global 2000, Report to the President of the U.S., Vol 1, Pergamon Press, New York, 1980. 8.B. Qrensen, A renewable energy system for Scandinavia. Proc. Int. Conference on Transitional Program towards a Soft Energy System on European Scale, May 1979, Rome. To be published by Friends of the Earth, Rome. 9.H. Kendall and S. Nadis (Eds.), Energy Strategies: Towards a Solar Future, Ballinger, Cambridge, Mass., 1980. lO.Solar Energy, U.S. Department of Energy, Program Summary Document FY 1981, DOE/CS-0050, U.S. Government Printing Office, 1980. ll.P.C.F. Bekker, Lifetime Theory on Dwellinqs, Rep. A-1980-3, Technisch Centrum Waalsteen, Nijmegen. 12.A.B. Lovins, Soft Energy Paths: Towards a Durable Peace, Ballinger, Cambridge, Mass., 1977. 13.P. Craig e.a., Distributed Technologies in California's Energy Future, U.S., D.O.E., Interim Report, HCP/P 7405-01/02, 1978.

3!j

Renewable Energy Planning for Denmark and Other Countries, ;1982), pp. 293-303. 15.Toekomstige Energiesituatie in Nederland (Future Energy Situation in the Netherlands ), VDN, Arnhem, 1980, pp. 83-85. 16.W. van Lier ,op, De energievoorziening van een toekomstige woonwijk, (The energy supp lly for a future residential district), Rapport WPS3-80.04.R308, Eindhoven, University of Technology, Department of Mechanical Engineering. 17.P.H. van Dijkum and T. Kram, Introductie scenario zonneboilers (Introduction of DHW installations) Report ESC-3, Netherlands Energy Research Foundation, Petten, The Netherlands, Dec. 1980. lB.Solar Engineering Digest, Febr. 1981, see also Technical Survey, Vol. 37, No. 8, 28 Febr. 1981. 19.H. Walz (Reporter), Verslag namens de Commissie voor energie en onderzoek over mogelijkheden en grenzen van decentralisatie van de energieproduktie (Report on potential and limits of soft technologies), European Parliament, Dec. l-696/ 80, 7 Jan., 1981. 20.W. HBfele, Energy in a Finite World, Vol I, IIASA Report, Ballinger, Cambridfge, Mass., 1980. 14.8. SBrensen

Energy,

6,