Journal of Applied Input-Output Analysis, Vol. 11 & 12, 2006

Energy productivity during the years of Doi Moi

By

Nguyen Thi Anh T\iyet and Keiichi N. Ishihara*

Abstract
Economic reform during the last two decades in Vietnam has required a large energy demand. Using the input-output (10) tables of 1989 and 1996, which are key years of Doi

Moi (Reform), this work reveals the changes in energy intensities in all economic sectors
and identifies sectors that are directly and indirectly responsible for the changes in the energy requirements. Furthermore, the agriculture effects on energy consumption among thevarious sectors are discussed. The valuable contribution of fertilizer production for sustain
ing the agriculture sector is clarified.

Introduction
10 table, which displays the exchanges of goods and services among the economic sec
tors, will be used to analyze the nature of energy consumption in Vietnam. Using thismethod, the total energy required to deliver a product to the final consumer, including
both the energy directly consumed in the production process and the energy indirectly
embodied in that industry's input, can be estimated. In the mid-1970s, the common

method for analyzing the changes in energy utilization using IO tables is structural decomposition analysis (SDA). In some SDA, the direct and indirect effects of changes in

embodied energy intensity can be measured (Rose A. and Casler S., 1996). The directchanges of energy input only explain part of the relationship between energy use andproduct output since indirect effects also contribute to changes in total energy use.

After adopting Doi Moi policy in 1986, Vietnam's chief goal became "Moderniza

tion and Industrialization" and its economy has been gradually shifting from an agri
cultural to an industrial based economy, which has caused a large increase in energy
requirements. The energy flow in Vietnam in 1996 was analyzed by the authors in two
previous works. In one of them (Nguyen T.A.T. and Ishihara K.N., 2003), manufactur
ing sector represented the major energy consumer and energy efficiency of cement pro

duction was mainly discussed. In the other (Nguyen T.A.T. and Ishihara K.N., 2004),
the hidden energy flow from supply and demand sides was analyzed and fertilizer was

Received October 2003, final version received February 2007.
* Graduate School of Energy Science, Kyoto University, Japan

Permanent address of Nguyen Thi Anh Tuyet: Institute for Environmental Science and Technology(INEST), Hanoi University of Technology, Vietnam

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Journal of Applied Input-Output Analysis, Vol. 11 & 12, 2006

presented as a key sector in order to raise the energy productivity in food processing
sectors.

The purpose of this work is to determine the changes in energy intensity for eacheconomic sector using SDA and identify the sectors that are directly or indirectly responsible for the change during the years of Doi Moi. Furthermore, given the importance of agricultural production, there is a particular interest in evaluating the effects ofagriculture on the consumed energy among the economic sectors. The significance of

the agriculture is substantial since this sector generates economic activities in other sec
tors through its demand for intermediate goods and services and by supplying interme
diate inputs to the food processing industries.

Basis for SDA
It is reported that the energy required to deliver a product to final demand can be esti
mated using 10 table (Bullard C. and Herendeen R., 1975, Miller R. and Blair P.,

1985). IO tables are usually in monetary units, but for the energy sectors analyses,

physical units rather than monetary units are preferred. Hence, we, first, modified thetechnical coefficient matrix, A, to hybrid-unit one, A* (hereafter, superscription* denotes hybrid unit), by assuming that the amount of goods transferred is proportional totheir monetary value. Then the matrix of embodied energy intensity, e, can be obtainedby extracting energy rows from the hybrid-unit Leontief inverse.

e = (I-A*y(1)

where e is defined as a product matrix of type mxn and m of n sectors are assumed
energy sectors. This matrix consists of zeroes and ones with the ones denoting energy
sectors.

Embodied energy consumption of any sector j is obtained by multiplying embod
ied energy intensity of that sector £j by the corresponding value of final demand, y/.

xl = er(2)where A denotes a diagonalized matrix.

The SDA can be performed to separately measure the change of embodied energy
intensity caused by direct use of energy (directly related to the energy sectors) and byindirect use (associated with the consumption of energy in the non-energy sectors) be
tween two years (Millan A. J. and Millan S. J., 2002). The direct changes of energy in

put only explain a part of the relationship between energy use and product output since

indirect effects also contribute to changes in embodied energy use. Based on Eq.(l),the relationship between years is:

ex -£,a; = £o-£oAo(3)

where e0 and et represent embodied energy intensity in the based and terminal year, respectively.

When As = e, - £0 and AA* = Ai - Al then:Energy productivity during the years of Doi Moi

139

(4)

^^ = (e, + e0) AA*
When e = —-— and A(5)= —-— then:Ae =£AA*(1 -AV(6)

The A matrix can be separated into 2 matrices: A = Ae + An where matrix Ae consistsof the energy rows and the remaining rows with zeroes and matrix An consists of the
non-energy rows and the energy rows with zeroes. Consequently:

AA* = A A; + A A,;(7)

The changes of direct energy requirements of sector i are accounted for column i inmatrix AA, that has only non-zero entries in the energy rows. Column i of the matrix

AAn measures the change of non-energy inputs, which are goods and services sold tosector i. Since energy is required to produce all non-energy inputs, the changes of nonenergy inputs indirectly affect the embodied energy intensity of sector i.

Substituting Eq. (7) in the expression (6), then:Ae = eAAl (/ - A*)"1 + eAA*n (I - A*)"1(8)

Eq. (7) consists of the change ~eAA*e (I - A*)"1 caused by changing energy inputs andthe change ~eAA*n (/ - A*)"1 caused by changing non-energy inputs.

Results
In this work, the 1989 and 1996 IO tables (General Statistical Office, 1992 and 1999)

are used as the basis for calculations. In order to interpret the results, 46 sectors are ag
gregated for 1989 and 1996 IO tables. These sectors are classified following the Vietnamese Classification of Economic Activities issued by the Government as Decree 75/
CP on 30th October 1993. It is noted that the competitive IO tables are used, wherethe vector of final demand is reduced by the amount of imports.
The following adjustments were made in order to fit our purpose.
• In this study, three sectors, coal, petroleum refineries, and electricity, are consid
ered as energy sectors. Coal is obviously a primary energy source. Refined petro
leum is treated as an energy source because this energy is completely imported.

Electricity is also treated as an energy source, therefore, the electricity sector is
not considered as an energy consumer but energy producer. Crude oil is produced
but completely exported, therefore this energy is not taken into account as an energy source.

• To reflect above conditions, when we convert to energy unit in technical coeffi
cient matrix, the following adjustments are performed. In the case of electricity
sector, the value of heat equivalence is calculated based on the primary energy

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Journal of Applied Input-Output Analysis, Vol. 11 & 12, 2006

Table I. Price and heat equivalence of energy sources(Ministry of Science Technology and Environment, 2001)
1989

1996

Unit

Coal

0.566

0.566

toe/t

Refined petroleum

1.030

1.030

toe/t

Electricity*

0.233

0.159

toe/MWh

Energy typeHeat equivalence of energy sources:

Energy price (at 1994 constant price):
Coal

168

Refined petroleum
Electricity

VND/kg

3,000

VND/kg450

VND/kwh

The heat values are taken from the results of hydroelectricity and electricity produced from fossil
fuel used in reference year.

(fossil fuel and hydro source) using the efficiency of thermal power plants, as
shown in Table I. The coefficient of coal use and petroleum use in electricity pro

duction, AcoaLeiectridty, and Apetrvieum,eiectridty, are put to zero. The coefficient of electricity

use in electricity production, A^crwc/rye/mnci/y counts only the amount of utilities. In
the case of coal sector, the coefficient of coal use in coal production, AL/w, is as
sumed to be zero.

• When domestic energy consumption is calculated, the amount of energy exports,

q*e, is subtracted from the total primary energy consumption, x*e
IO tables are normally based on the current producer prices. To make two tables com
parable, excluding the impact of the price factor, the technical coefficient matrices,gross output and final demand vectors must be adjusted to a constant price. In thisstudy, due to the availability of data, the set of prices in 1989 and 1996 were con
structed for 1994.

A = P'AcP(9)

X = P-!XC(10)

Y = P~1Yc(11)

where P is the diagonal matrix of price indices (1994 = 1) which is the ratio of thecurrent price to the constant price; Ac, Xc, Yc, are the technical coefficient matrix, gross
output vector and final demand vector at current price, respectively.

The price index for each category was estimated based on sectoral data of GDP

and output values in Yearbooks. The energy unit is toe (tons of oil equivalence) and thecurrency unit is VND (Vietnamese Dong). Conversion factors are shown in Table I.
Economic scene and industrial structure

Between 1989 and 1996, the Vietnamese economy has been gradually moving from acentrally-planned to a market economy. The structure of gross output (GO) for the 17
sectors, which was aggregated from a detailed description of the 46 sectors, in 1989

Energy productivity during the years of Doi Moi

141

Table II. Gross output (GO) of 17 sectors in 1989 and 1996
Economic sectors

1989 (at 1994-price)
billion VND

Agriculture, forestry and fishing
Mining (exception of coal)
Manufacturing

78777

%
32.7%

1996 (at 1994-price)
billion VND
115422

%

20.8%

1856

0.8%

16480

3.0%

84355

35.0%

22630040.8%■

Food processing

18137

7.5%

64469

11.6%

■

Textile and leather

10649

4.4%

26289

4.7%

■

Pulp paper and wood products

5181

2.1%

15388

2.8%

■

Chemical products

12501

5.2%

28531

5.1%

■

Petroleum refineries and coal

7045

2.9%

13734

2.5%

■

Glass, clay and stone products

6554

2.7%

17507

3.2%

■

Iron and steel

2842

1.2%

3324

0.6%

■

Non-ferrous metals

2313

1.0%

9585

1.7%

■

Machinery and equipments

16852

7.0%

38056

6.9%

■

Other industries

2282

0.9%

9417

1.7%

12023

5.0%

49628

9.0%

Construction

Electricity, gas and heat supply
Trade and services
Transportation
Others
Total

3184

1.3%

10393

1.9%

23196

9.6%

46068

8.3%

5343

2.2%

18048

3.3%

32504

13.5%

71746

12.9%

241239100%

554084100%

and 1996 are shown in Table II. The share in GO of agriculture dropped from 32.7%
in 1989 to 20.8% in 1996. The following industries drastically increased their shares in

GO, in descending order: food processing (from 7.5% in 1989 to 11.6% in 1996), mining (from 0.8% in 1989 to 3.0% in 1996), and construction (from 5.0% in 1989 to
9.0% in 1996). Service activities (including transportation) have been maintained a ra
tio of 25% for both years.

Parallel to raising final demand, the calculated energy consumption in Vietnam

was approximately 13.2 Mtoe in 1996, which is nearly twice as much as in 1989 (6.7
Mtoe) as shown in Table HI and Fig. I. However, due to the small scale of the economy, the level of energy use is still very low. In 1996, the energy consumption percapita of Vietnam was only 0.452 toe based on author's estimation (or 0.432 toe basedon The World Bank, 2004). As shown in Table IV, with the exception of Myanmar, energy consumption per capita of Vietnam was lowest among the one of East Asia andPacific countries.

In term of sectoral energy consumption, the embodied energy consumption in petroleum refineries and coal is the largest because these sectors are the energy producers
and the huge final demand of coal exists. That in construction is the second largest anddrastically increased because of the large final demand from the operating urban infra
structure in Vietnam. The modernization in living standards also increased the demand

for the sectors which produce end-use products, such as food processing, textile andleather, pulp paper and wood products. Due to the huge contribution to total gross out-

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Journal of Applied Input-Output Analysis, Vol. 11 & 12, 2006

Table ffl. Embodied energy consumption of 17 sectors in 1989 and 1996
Sector1989

Agriculture, forestry and fishing

1996
517

Mining (exception of coal)
Manufacturing

755

151

310

3218

7584

■

Food processing

777

1057

■

Textile and leather

237

549

■

Pulp paper and wood products

60

278

■

Chemical products

68

117

■

Petroleum refineries and coal*

1285

5058

■

Glass, clay and stone products

403

248

■

Iron and steel

50

1

■

Non-ferrous metals

12

8

■

Machinery and equipments

286

149

■

Other industries

46

118

Construction

1252

2203

Electricity, gas and heat supply

159

492

Trade and services

525

588

Transportation

286

302

Others

625

957

6732

13191

Total

*Note: including final demand

Figure I. Embodied energy consumption of 17 sectors in 1989 and 1996
Argiculture, forestry and fishing
Mining (exception of coal)□ Embodied energy in 1989

Food processing

D Embodied energy in 1996

Textile and leather

Pulp paper and wood products
Chemical products
Petroleum refineries and coal

Glass, clay and stone products
Iron and steel

Non-ferrous metals
Machinery and equipments

Other industries
Construction

Electricity, gas and heat supply
Trade and services
Transportation
Others

1—

1000

2000

3000
ktoe

4000

5000

6000

Energy productivity during the years of Doi Moi

143

Table IV. Energy indices of East Asia and Pacific countries(The World Bank, 2004)
Country

Energy use (kgoe per capita)
1989

1996

Australia

5070

5512

Brunei

5160

6563

China

737

915

Hong Kong, China

1947

2113

Indonesia

494

651

Japan

3377

4045

Korea, Dem. Rep.

1739

891

Korea, Rep.

1892

3581

Malaysia

1153

1873

Myanmar274

263

New Zealand

3910

4409

Philippines

456

514

Singapore

3358

6010

Thailand

695

1167

Vietnam366

431

put, the agriculture sector also consumed a considerable amount of energy, 5.5% and3.5% of the total in 1989, 1996, respectively.
Since, in this study, energy price in each economic sector in 1989 and 1996 is notavailable, the calculations were done under the assumption that the amount of goods
transferred is proportional to their monetary value in every sector. We are able to makea comparison between the estimated coal, petroleum, electricity consumption by all
sectors using IO table and corresponding data in the yearly energy balance tables (Ministry of Science Technology and Environment, 2001). The estimated energy consump

tion by sectoral groups, such as manufacturing, construction, transportation is also
compared with the corresponding statistics (Institute of Energy, 2002). As the results, it
is confirmed that all the values which we used in this work are reasonable.
Changes in energy intensities
In this section, the inter-linkage changes in the embodied energy intensity are exam
ined using SDA. Tables V and VI illustrate the changes in energy inputs and thechanges in non-energy inputs, respectively, in each sector affected the embodied inten
sities of coal, petroleum and electricity use in the productive system in the period 1989

-1996. Embodied coal intensity has been decreased in almost all economic sectors, andthis change mainly caused by reducing energy inputs, indicated by negative values incolumn "coal" of Table V. On the contrary, embodied petroleum and electricity inten
sity have been increased in almost all economic sectors, but this change mainly causedby changing non-energy inputs, indicated by positive values in columns "petroleum"and "electricity" of Table VI. Embodied energy intensity dominantly has been reduced

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Journal of Applied Input-Output Analysis, Vol. 11 & 12, 2006

Table V. Changes in energy intensities (toe/106 VND) caused by direct effects(changes of energy inputs) eAAl(I-A*)"1
Changes inin period 1989 - 1996

Coal

Petroleum

Electricity

0.004-0.001-0.001

0.002

Forestry-0.002-0.007-0.001-0.010Fishing-0.012-0.0350.000-0.047

Coal-0.007-0.003-0.003-0.013Mineral mining-0.009-0.0430.008-0.044

Other mining-0.019-0.045-0.005-0.069Other food stuff-0.056-0.004-0.001-0.061Vegetable, fruit canning-0.046-0.001-0.006-0.054

Alcoholic, other beverages-0.049-0.0020.002-0.049Sugar-0.022-0.0070.003-0.025

0.039

0.000

0.002

0.041

Tobacco, cigarettes-0.003-0.001

0.002-0.002-0.043

Agriculture

Tea, coffee processing

Total

Aquatic products-0.021-0.0250.003

Milling and grain products-0.045-0.007-0.007-0.059Ceramics, glass, porcelain-0.080-0.0130.003-0.090Paper, paper products-0.013

0.001

0.010

-0.002

Wood processing, wood products-0.015

0.000

0.003

-0.012

Cement-0.101-0.013-0.002-0.116

Bricks, tiles-0.035-0.0180.010-0.043

Other construction materials-0.272-0.0140.005-0.280Chemical products

0.009-0.001-0.006

0.002

Fertilizer, insecticide

0.031-0.001

0.000

0.030

Pharmaceuticals-0.003

0.000

0.000

-0.003

Rubber, rubber products-0.040-0.005-0.011-0.056

Soap and cleaning materials-0.014-0.004-0.002-0.020

Plastic, plastic products-0.001

0.000

0.003

0.002

Other chemical products-0.001

0.000

0.010

0.009

Equipment, machinery, other metallic products-0.017-0.001-0.002-0.021-0.003

Electrical and electronic products-0.0020.000-0.001

Manufacture of non-ferrous metals-0.006

0.000

0.006

0.001

Manufacture of ferrous metals-0.058-0.003-0.005-0.065

Manufacture of textiles-0.021

0.002

0.008

-0.011

Carpets and rugs

-0.009

0.014

0.004

0.009

Leather, foot wear, bleaching, dyeing of fabrics-0.012

0.000

0.002

-0.010

Other industry-0.012-0.003-0.006-0.021Other materials-0.005

0.005

0.005

0.006

0.000

0.001

0.000

0.001

Electricity-0.005-0.0010.000-0.006

Water-0.0040.003-0.024-0.026

Construction-0.059-0.0060.001-0.064Trade-0.007

0.000

0.001

-0.006

Personal repairs-0.019

0.006

0.000

-0.013

Restaurants-0.025

0.002

0.012

-0.011

Transportation-0.010-0.029-0.001-0.039Communication-0.002-0.0050.000-0.008Others-0.010

0.002

0.002

-0.006

Petroleum, natural gas

Energy productivity during the years of Doi Moi

145

Table VI. Changes in energy intensities (toe/10^VND) caused by indirect effects(changes of non-energy inputs) eAA^I-A*)1 in period 1989-1996
Changes in

Coal

Petroleum

Electricity

0.001

0.000

0.000

0.001

Forestry-0.001

0.001

0.000

0.000

Fishing-0.0020.004-0.001

0.001

Coal

-0.004

0.002

0.000

-0.002Mineral mining-0.010

0.011

0.000

0.001

Other mining

0.001

0.002

0.001

0.004

Other food stuff-0.003

0.000

0.000

-0.003

Vegetable, fruit canning-0.004

0.002

0.000

-0.002

Alcoholic, other beverages-0.004

0.000

0.000

-0.004

Sugar

0.003

0.003

0.002

0.008

Tea, coffee processing

0.002

0.001

0.000

0.003

Tobacco, cigarettes-0.0050.000-0.001-0.007Aquatic products-0.003-0.0040.000-0.006

Milling and grain products-0.012-0.001-0.002-0.015

Ceramics, glass, porcelain-0.0100.000-0.001-0.012Paper, paper products

0.008

0.003

0.002

0.013

Wood processing, wood products

0.000

0.004

0.001

0.005

Agriculture

Total

Cement-0.014

0.003

0.000

-0.011

Bricks, tiles-0.031

0.002-0.002-0.031Other construction materials-0.012

0.001

0.002

-0.009Chemical products-0.001

0.001

0.000

0.001

Fertilizer, insecticide

0.001

0.000

0.000

0.002

Pharmaceuticals

0.000

0.000

0.000

0.000

-0.003-0.001-0.002-0.006

Rubber, rubber products

Soap and cleaning materials

0.000

0.000

-0.001-0.001

Plastic, plastic products

0.001

0.001

0.001

0.004

Other chemical products

0.004

0.003

0.003

0.010

-0.002

0.000

0.000

-0.002

Electrical and electronic products

0.002

0.001

0.000

0.003

Manufacture of non-ferrous metals

0.001

0.001

0.000

0.002

-0.001

0.002

0.001

0.002

0.003

0.003

0.003

0.009

-0.001

0.000

0.000

-0.001Equipment, machinery, other metallic products

Manufacture of ferrous metals
Manufacture of textiles
Carpets and rugs

Leather, foot wear, bleaching, dyeing of fabrics

0.001

0.001

-0.001

0.002

Other industry-0.001

0.000

0.000

-0.001Other materials

0.004

0.003

0.003

0.011

Petroleum, natural gas

0.000

0.000

0.000

0.000

Electricity

0.000

0.000

0.000

0.001

Water

0.004

0.003

0.004

0.011

Construction-0.008

0.002

0.001

-0.004Trade-0.002

0.003

0.000

0.001

0.000

0.001

0.000

0.000

Restaurants-0.003

0.001

0.001

-0.001

Transportation-0.0010.001-0.001

0.000

Communication

0.000

0.001

0.000

0.002

-0.002

0.000

0.000

-0.001

Personal repairs

Others

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Journal of Applied Input-Output Analysis, Vol. 11 & 12, 2006

Figure II. Electricity production in Vietnam during 1989-1996

14• Fossil-electricity

12• Hydro-electricity

10

8
6
4
2

0

1989

1990

1991

1992

1993

1994

1995

1996

for food processing; glass, clay and stone product. Leading to those changes, the direct

effects, WAAl (I - A*)~\ of coal use played an important role.
It was indicated in Fig.II about electricity production that due to the inaugurationof the two biggest hydroelectric power stations, Tri An and Hoa Binh, the ratio of hy

droelectricity production dramatically increased during the period 1989-1996. This
caused the decrease in energy consumption because using hydroelectricity more effi
cient in conversion than thermal electricity.

Generally, the changes in embodied energy intensity have resulted by variations in
the direct energy requirements. However, parallel with the diversification of interlinkages in the current development of the Vietnamese economy, the indirect effects,n (I - A*)"1, are getting important.

Discussion
In the previous section, the main structure of Vietnamese energy in the years of Doi
Moi has been described. It shows that the agriculture sector plays a significant role due

to its' dominant contribution in the total gross output. In this section, the main factors,
which affected this, are clarified in the 10 structure of the Vietnamese agriculture.
It is noted that in the Table V, only the sectors, agriculture; tea, coffee processing;chemical products; and fertilizer, insecticide have the plus values in the changes in coalcaused by energy inputs. While the energy intensity in fertilizer sector increases 4.5

times in this time period, since the fully production process started. As a result, thechanging energy inputs caused 0.03 toe/million VND increase in embodied energy intensity of fertilizer production between 1989 and 1996. This change caused an increaseEnergy productivity during the years of Doi Moi

147

Figure III. Comparison of specific fertilizer consumption among countries(The World Bank, 2004)

Pakistan

Bangladesh

Philippines

Indinesia

Vietnumin the embodied energy intensity in agriculture and then caused a chain reaction in theother sectors.
Within the agricultural components, cultivated crops and paddy rice comprised

about 80% of both GDP and production value in the agricultural sector in 1996. These
sub-sectors use fertilizer, pesticides, machinery, energy, and various services as inputs
for their own production processes. From 10 tables, fertilizer's contribution is clearly
important with 24.38% and 38.37% of agriculture's inputs in 1989 and 1996, respec
tively. This increase is from the increase in specific fertilizer consumption during thistime period.

Generally, fertilizer yields high productivity and is inexpensive. However, many
farmers applied more fertilizer to their crops than the plants could absorb. As shown in

Fig. Ill, the specific fertilizer consumption1 (SFC) in Vietnam far exceeds that of theother countries, which have similar agricultural agropedology and climatic conditions.
In 1989, SFC in Vietnam was about 100 kg/ha farmland, which is similar to the Philippines, Indonesia, Bangladesh and Pakistan. But in 1996, the reported SFC in Vietnam
was 273 kg fertilizer/ha farmland, a 2.7 times increase between the two years. This
brings about the serious consequence that the cultivation structure has improved, but

1

Fertilizer consumption (100 grams per hectare of arable land) measures the quantity of plant nutri
ents used per unit of arable land. Fertilizer products cover nitrogenous, potash, and phosphate fertil
izers (including ground rock phosphate). The time reference for fertilizer consumption is the crop
year (July through June). Arable land includes land defined by the FAO as land under temporary
crops (double-cropped areas are counted once), temporary meadows for mowing or for pasture, land
under market or kitchen gardens, and land temporarily fallow. Land abandoned as a result of shifting
cultivation is excluded.

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Journal of Applied Input-Output Analysis, Vol. 11 & 12, 2006

Table VII. Linkage indicators of economic sectors in 1989 and 1996
Economic sectors

Backward linkages
1989

1996

Forward linkages
1989

1996

Agriculture, forestry and fishing

1.640

1.638

0.827

0.714

Mining (exception of coal)

0.480

0.664

0.651

0.578

Food processing

1.981

1.435

3.094

2.880

Textile and leather

1.049

0.808

1.181

1.273

Pulp paper and wood products

0.789

0.800

0.748

0.897

Chemical products

2.663

2.887

3.059

3.127

Petroleum refineries and coal

1.132

0.806

0.910

0.555

Glass, clay and stone products

1.022

0.786

1.524

1.477

Iron and steel

0.724

0.532

0.460

0.397

Non-ferrous metals

0.616

1.126

0.436

0.428

Machinery and equipments

1.574

1.969

1.329

1.808

Other industries

0.244

0.197

0.385

0.397

Construction

0.934

0.898

0.704

0.774

Electricity, gas and heat supply

0.202

0.734

0.230

0.234

Trade and services

0.330

0.501

0.363

0.308

Transportation

0.563

0.639

0.852

0.898

Others

1.057

0.580

0.248

0.256

improper fertilizing is affecting Vietnamese agriculture. Since there is a growing ten
dency of soil degradation, fertilizer is steadily used to increase the annual agricultural
output to the point of abuse. This increase of fertilizer use indirectly caused the increase of coal intensity in agriculture sector as shown in Table VI.
The lack of knowledge of the Vietnamese farmers in cultivation techniques has
contaminated farming land and increased the embodied energy use in their agricultural
products due to very high direct energy intensity for producing fertilizer. According to

the previous work (Nguyen T.A.T. and Ishihara K.N., 2003), the fertilizer sector is the
5th largest direct energy consumer in the manufacturing (next to cement, pulp and pa

per, brick and tiles, and textiles), with 332 ktoe consumed in 1996, occupied 8.3% of
the total energy use in manufacturing and 4.2% of the total energy use in the produc
tive system. General economic indicators (The World Bank, 2004) also reported the ra
tio of commercial energy use for agriculture to that for all sectors in 1995 (including
indirect energy input from fertilizers) was about 15% for Vietnam, the highest com
pared to other Asian countries in the same year, for instance: 13.33% for China, 4.30%

for India, 1.91% for Bangladesh. Next to agriculture, food processing was most influ
enced. This sector has increased the dependence on the supply by domestic agricultural
products with 38.9% and 70.2% of intermediate inputs in 1989 and 1996, respectively.

In term of linkage indicators, it is also identified in Table VII that the food processing
has been deeply involved other sectors by the very high backward linkages (1.98 in
1989 and 1.44 in 1996). Therefore, saving energy in fertilizer production indirectly decreases the embodied energy intensity in other economic sectors by means of inter-

Energy productivity during the years of Doi Moi

149

linkages.

One of the ways to enhance agricultural productivity is to apply fertilizers at a

rate that equals plant uptake and improving ammonia production for all nitrogen-based

fertilizers. Based on the macro-production figures (Nguyen V.B., 2001), we roughly es
timate that the amount of energy required to produce the nitrogen portion of the fertil
izers in Vietnam is 26,855 kcal/kg nitrogen, approximately 1.5 times higher than theworld average (18,000 kcal/kg nitrogen) (Kongshaug G., 1998). To reach the world's
average energy use, it is assumed that the 33.3% of coal used to produce fertilizer in

Vietnam can be decreased. It means that 31.5% of the energy used in fertilizer production can be saved. The analysis of IO table indicates that this saving leads to a decrease of 3.7% of the energy cost in its own sector's intermediate expenditures, butalso will cause a decrease of 10.2% and 6.4% in embodied energy intensity in agricul
ture and milling - grain products (food processing sector), respectively. According to
the final report of the Scientific Technological project KHCN 09~08 by Ministry of

Science, Technology and Environment, the fertilizer industry is one of five possible
candidates that possess large energy saving potential.

It is concluded through this analysis that the improvement of energy productivity
in fertilizer production and the effective use of fertilizer products in cultivation activi
ties would play an important role in terms of raising the total energy productivity infood industries.

Conclusion
This paper analyzes the IO tables extended to account for inter-industry energy flows.
During the years of Doi Moi, it is suggested that SDA is useful for analyzing thechanges in energy intensity in economic sectors. The following conclusions are drawn:

O

Embodied energy intensity and consumption were calculated for all economic sec
tors in 1989 and 1996. During the years of reform, coal intensity decreased, whileelectricity intensity increased for almost all sectors. The changes caused by using
direct energy inputs are large and affect the changes caused by using non-energy
inputs.

O>

Saving energy in fertilizer production is crucial for decreasing the embodied energy intensity in economic sectors, especially in agriculture. Based on the enlarged
contribution of food processing inputs, the agriculture sector still constitutes the

backbone of the Vietnamese economy. Further developing food processing will
boost the effect of agriculture on the rest of the economy.

Acknowledgments
The authors wish to thank Mr. Hoang Trung Dong, Department of National Accounts,

the General Statistical Office of Vietnam for providing recent data. One of the authors(Nguyen Thi Anh Tuyet) gratefully acknowledges a scholarship from the Ministry of
Education, Culture, Sports, Science and Technology (MEXT), Japan. This research waspartially supported by MEXT, 21st century COE program "Establishment of COE on

150

Journal of Applied Input-Output Analysis, Vol. 11 & 12, 2006

Sustainable Energy System".

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