energy efficient brick and pottery industry -

30 Tech MoniTor • nov-Dec 2011

IntroductionBrick making is a traditional job in rural areas in many developing countries. Bricks are an indispensable construc-tion material with an ever-increasing demand as economies in the region are growing. it is estimated that over 1,000 billion bricks are produced and consumed in Asia per year. To produce 1,000 billion bricks, it needs 110 million tons of coal per annum emitting roughly 180 million tons of carbon dioxide emis-sions (heierli and Maithel, 2008).

Biomass such as wood and rice husk is also used for kiln firing. From green-house gas standpoint, biomass fuel is considered as carbon-neutral, but even biomass direct fuelled traditional kilns with low energy efficiency have problems emitting dark, polluting smoke causing harmful health effects to people and destroying productivity of neighboring agricultural fields as soot covers plant leaves obstructing photosynthesis. The growing interest on black carbon (com-monly known as soot) as one of the sig-nificant contributors to global warming, after carbon dioxide, has brought interna-tional attention to identify its sources and find ways to curb black carbon emissions (UneP, 2011). The UneP study identified traditional kilns with direct fuel system, regardless of fuel used for firing, as one of the main sources of black carbon.

To mitigate climate change and improve local air quality, how can small brick factories using traditional kilns adopt cleaner technologies and improve

efficiency without causing rural unem-ployment?

The Asia-Pacific Forum for environ-ment and Development (APFeD) show-case Programme in 2008 selected the proposal by the energy conservation research and Development center (enerTeAM) to “Set up a demonstra-tion model for the application of rice husk gasification in brick and pottery industry in Viet nam” with dual goals of introducing cleaner technology — a biomass gas fuelled kiln — to reduce air pollution while utilizing available rice husks as fuel and present a viable business model suitable to small and medium brick factories. The institute for Global environmental Strategies (iGeS) supervised and monitored the project.

Brick and pottery industry in Viet Namin Mekong Delta — especially in Dong Thap, Vinh Long and An Giang prov-inces — there are approximately 4,500 traditional rice husk fuelled kilns for clay burning producing bricks, tiles and pot-tery. it is a major source of local jobs with one kiln owner employing 10 to 100 employees.

The brick and pottery industry in Viet nam, even the small scale enter-prises in rural areas, are well advanced compared to operations in South Asia. The government supported the indus-try providing incentives to improve brick making technologies paving the way for hollow bricks as well as export-quality pottery products. Unfortunately, while

AbstractThe brick industry is considered the industry of the poor employing many low skilled workers in rural areas in the Asia-Pacific region. Traditional kilns emit dark smoke which is harmful to the health of the workers as well as other peo-ple in the community. Upgrading the traditional kiln technology will improve the quality of life in brick producing communities; reduce fuel consumption as well as car-bon emissions. A case study on a 4-chamber continuous burning kiln integrated with rice husk gasifica-tion system in Viet nam implement-ed by enerTeAM and supervised by iGeS is discussed to share how it achieved better quality products, reduced environmental pollution and utilized locally available bio-mass as fuel.

Dr. Jane RomeroPolicy researcher/climate change Specialist institute for Global environmental Strategies (iGeS), 2108-11 Kamiyamaguchi, hayama, Kanagawa, 240-0115, Japan

Tel: +81-46-855-3847; Fax: +81-46-855-3809e-mail: [email protected]; Web: http://www.iges.or.jp

EnErgy EfficiEnt brick and pottEry industrythE casE of ricE husk gasification tEchnology in ViEt nam

Tech MoniTor • nov-Dec 2011 31

Energy efficient brick and pottery industry

the quality of products improved, the production process mostly relying on traditional kilns with direct fuelling sys-tem using rice husks remained polluting. Air pollution from the kilns put a strain on the quality of life in the communities.

in 2001, the government, in response to clamours to improve air quality, issued a regulation to prohibit traditional brick making kilns in 2010 (Decision 115/2001/QD-TTg of the Prime Minister). The ten-year window to clean up the industry introduced some cleaner technologies such as hoffman kiln and tunnel kiln. Those government promoted alterna-tives use fossil fuels either fuel oil or coal as fuel, an additional expense compared to the almost free rice husks. Some tun-nel kilns built in Mekong Delta consumed 20 to 30 tons of fuel oil per month which made production unprofitable.

As illustrated in Figure 1, while the use of fossil fuels could reduce local air pollution, it would contribute to the rising global carbon emissions, which is the main driver of climate change.

The fossil-fuelled kilns were deemed inadequate to both mitigate the pollution problem and be an effective business model appropriate to small and medium brick factories. Traditional kiln owners had limited options — close their polluting fac-tory and create unemployment or switch to fossil-fuelled kilns with higher produc-tion costs risking eventual bankruptcy. eventually, the social repercussion is so high that the government withheld the full implementation of the law continuing the search for better alternatives.

How does the new system work?The technology is not new — con-tinuous kilns and biomass gasification system are proven technologies but the integration of both systems applied to

clay burning has not been tried before. The dome shaped traditional kiln com-monly used in Viet nam has uneven dispersion of heat so it was replaced by a 4- chamber continuous burning kiln with better energy efficiency (Figure 2). it was developed by Songkla University in Thailand for wood and saw dust fir-ing. it was modified for rice husk firing by enerTeAM engineers as rice husks are abundant in the Mekong Delta, esti-mated at over 3.6 million tons per year from paddy production. The gasifier was supplied by AnKUr, a pioneering in-dian gasification systems manufacturer, while the burners were locally fabri-cated by enerTeAM to reduce costs. enerTeAM collaborated with SMe

renewable energy Ltd. (cambodia) which has considerable experience on rice husk gasification for small scale power generation on how to integrate the gasification system into the kiln.

The 4-chamber continuous burning kilnBasically, the main principle to operate the 4-chamber burning kiln is to recover the heat from the previous processes for use in the subsequent processes as illustrated in the following diagram and described as follows:

• Fresh outdoor air flow into the cooling chamber D to cool the fired bricks while the air is heated up before go-ing into the firing chamber.

200,000

150,000

100,000

50,000

0

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

With Non Fossil BAU (ton of CO2) Year

Tons

of c

arbo

n em

issi

ons

Fig. 1. Trend of carbon emissions if traditional kilns shift to fossil-fuelled kilns

Fig. 2. The 4-chamber continuous burning kiln

Fresh air

Drying

Chimney/fan

Firing

Hot air control valves

Fresh air

A

PreheatingB

C

CoolingD

Rice husk



• The exhaust gas from the firing chamber A is channeled to pre-heat raw products in the preheating chamber B.

• At the preheating chamber, the gas from firing chamber release a part of the heat to the raw products as well as continuously being vented to the drying chamber c to dry the raw products before the gas is dis-charged through the chimney. The exhaust gas temperature is about 80° c to 100° c.

• The firing flame is then shifted to the next chamber after finishing a batch. continuously, the firing flame is sequentially shifted to all four kiln chambers as the activity in other chambers also move to the next step of the firing process.

The rice husk gasification systemin the gasifier, rice husk is put through an anaerobic pyrolysis to generate com-bustible gas mixture from solid biomass (Figure 3). The combustible gas mixture is then conveyed through one of the

many filter systems to remove dust, tar and other by-products to get a cleaner combustible gas. The number of filters required is based on the product quality, could be up to six filters for glazed pottery.

After the pyrolysis process, the ash and non-flammable remaining rice husks are removed by water. The water used for ash removal is recycled so no wastewater is discharged. The ash is col-lected and sold to sugar cane farmers or gardeners to be used as fertilizer. The combustible gas is vented to the dif-fuser to remove dust and be cooled. The wastewater is also collected for reuse.

The pilot project While APFeD, iGeS and enerTeAM provided technical assistance, a willing traditional kiln owner has to bear the cost of setting up the new system. TAn MAi ceramics co. Ltd. in Sa Dec, Dong Thap, Viet nam agreed to be build the dem-onstration project. it is a medium sized enterprise with 59 employees engaged in manufacturing and trading of bricks, pottery and other ceramic products.

To acquire the gasification system, TAn MAi had to secure a bank loan which was guaranteed by the Project on Pro-moting energy conservation in Small and Medium enterprises (PecSMes) hosted by the Ministry of Science and Technol-ogy co-financed by United nations for Development Program (UnDP) and the Government of Viet nam managed by VietinBank. The process took longer than initially planned as parties were not aware of the necessary procedures. it was the first gasification technology project in Viet nam with no defined standards yet. A dialogue among parties was convened to facilitate the transaction. The results of the dialogue became the benchmark for parties to aid future projects.

The 22.6 m3 x 4 chambers was con-structed behind the traditional kiln as shown in the photo. it was constructed by TAn MAi using local materials. The imported gasifier was assembled by enerTeAM in collaboration with the cambodian partners who also assisted in calibrating various parameters appro-priate for clay burning.

During construction of new kiln Commissioning of gasifier Layout of integrated system

Cold water in from scrubber pump

Drain tubwith spout

PVC duct hose

PVC flexible hose pipe Flare valve

Combustion air inlet

Separation tank

Venture scrubber(Cools & removes particulates from gas)

Biomass in

GL

Reactor

Gasifier(Converts biomass

to hot gas)

SS sieve(For char — water

separation)

Coarse filter(Removes tar, particulates

and moisture)

Gas blower(Delivers gas

to burner)

Flare(For testing gas quality)

Hopper

Water in from char removal pump

Air Hot

gas line

Drain box Gas

control valvedrain tub

Shut-offvalve

Producergas burner

Air Air

Fig. 3. Illustration of the biomass gasification system

Tech MoniTor • nov-Dec 2011 33


The chamber can hold up to 12,000 bricks (1 kg – 1.2 kg each) and the fir-ing period is 36 hours. The kiln can also produce other products like terracotta with variation in the duration of firing time. The quality of the finished product is better than that of the traditional kiln with only less than three per cent rejects so most customers preferred products fired by the new gasifier-kiln complex.

The average annual production capacity is estimated to be about 200,000 equivalent standard terracotta products and 450,000 flooring tiles per year. Like-wise, it was estimated that the payback period could be less than four years to the US$176,000 total investment cost. The equipment lifetime is 20 years.

Environmental impacts and energy performance To ensure that the new kiln complies with the government pollution standards, the exhaust emission was measured by a third party authorized by the Ministry of environment and natural resources in Dong Thap province (Table 1).

Dust, ash, tar and other impurities are filtered during the gasification proc-ess so there is no black smoke emitting from the exhaust vent.

The energy performance of the 4-chamber continuous burning kiln with rice husk gasifier compared to tra-ditional kiln with direct fuelling system is presented in Tables 2 and 3.

Summary and way forward The pilot project showed the superior-ity of the new kiln integrated with rice

husk gasifier in terms of producing quality products, better energy perform-ance, and in eliminating the black smoke identified with traditional kilns and other pollutants as shown in the comparison in Table 4. With little ingenuity, the project showed the possibility to come up with a low-carbon alternative from existing technologies.

Seminars coupled with visits to the actual pilot project location were conducted to promote its replication1.Through the pilot project, other kiln

owners could learn and seek assist-ance on how to shift to energy efficient and environment-friendly technology to sustain their operations. The project also demonstrated the possibility for small and medium enterprises to access funding support from organizations pro-moting measures to improve the envi-ronment and mitigate climate change. it is feasible to replicate and diffuse this technology in other countries though it may need modifications if other types of biomass are used as fuel.

Finished products after firingFlame from burner Raw bricks before firing

Indicator Unit National standard Testing results

Dust µg/m3 300 200

NOxµg/m3 200 2.79

SO2µg/m3 350 155.2

Noise dB 75 66.4

CO µg/m3 30,000 3,400

HF µg/m3 20 11.6

Table 1. Exhaust gas emission testing results

Type of kilnThermal energy

consumption standard (MJ/kg)

Note

Traditional kiln 3.54Fuelled directly by

rice husk

4-chamber continuous burning kiln with rice husk gasifier

2.48Using rice husk to provide fuel gas

Table 2. Comparison of specific thermal energy consumption

Type of kilnFuel quantity (in kg of

rice husk per 1,000 equivalent product)

Traditional kiln 2,654

4-chamber continuous burning kiln with rice husk gasifier

1,858

Table 3. Rice husk consumption for 1,000 products

1 For more information, contact Mr. Le hoang Viet, Director — enerTeAM at [email protected] and TAi MAi at [email protected].



The project was recognized in the 2010 enerGY GLoBe Awards as national Winner for Viet nam. The award-ing was held in rwanda during Un’s cel-ebration of World environment Day 2010.

ReferencesenerTeAM (2009). “Feasibility study of setting up a demonstration of technical

and financial model for the application of rice husk gasification in Viet nam,” unpublished (submitted to iGeS).

enerTeAM (2010). “Final report on set-ting up a demonstration model for the ap-plication of rice husk gasification in Viet nam,” unpublished (submitted to iGeS).

heierli, Urs and Sameer Maithel (2008). Brick by brick: the Herculean task of

cleaning the Asian brick industry (Berne, Switzerland, Swiss Agency for Develop-ment and cooperation SDc).

UneP and WMo (2011). integrated Assessment of Black carbon and Tropospheric ozone: Summary for Decision Makers. Accessed at http://www.unep.org/dewa/Portals/67/pdf/Black_carbon.pdf.

Evaluation parameters Traditional kiln 4-chamber kiln with rice husk gasification Coal fuelled kiln

Product variety Various products (bricks, terracotta ceramics, tiles, etc.)

Various products (bricks, terracotta ceramics, tiles, etc.)

Bricks only

Burning process completely interrupted intermittent with the pilot flame

continuous with fixed fire area

Batch duration Long (several weeks) Short (daily) Short (daily)

Investment required Multiple investment levels Multiple choices with flexible kiln size and configuration

high investment

Fuel type Biomass Biomass Fossil fuel (coal)

Fuel sources Available locally Available locally not available locally

Technology features no heat recovery heat recovered by recovery chambers

heat recovered by recovery zones

GHG emission carbon-neutral carbon-neutral high

Overall local pollution risks

high Very low Low

Air pollution affecting cash crops

high none none

Air pollution affecting human health and safety

high Very low Low

Table 4. Analysis of alternatives

UNEP Climate Finance Innovation FacilityThe climate Finance innovation Facility (cFiF) supports finance-industry engagement in the new climate sectors renewable energy (re) and energy efficiency (ee). The Facility provides developing country financial institutions with technical assistance and funding for the development of climate focused financial products and services. The support covers up to 50% of true costs, dispersed in milestone based tranches, with the remaining out of pockets expenses covered by the requesting financial institution.A broad range of activities are eligible for support, ranging from feasibility studies, to market assessments and legal reviews. The overall aim of cFiF is to help mobilise a scaling up of financial flows into climate change solutions. More broadly, by encouraging early action within the finance community, the facility helps cultivate on-the-ground leadership amongst financial actors that can have replication effects across markets and geographies.initiators of the facility are the United nations environment Programme and the Frankfurt School of Finance & Manage-ment. investment committee members come from ADB, BMU, KfW and UneP.

For more information, contact:

Frankfurt School – The UNEP Collaborating Centre for Climate & Sustainable Energy Finance Sonnemannstraße 9-11

60314 Frankfurt am Main, Germany Tel: +49-0-69-154008-0; E-mail: [email protected]

Web: http://www.climate-finance.org

energy efficient brick and pottery industry -

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