Waste-to-Energy Initiative in Vietnam

Vietnam Environment

Tu Ngoc An, board chairman of Kien Giang Composite Co. (KGC), has paid a visit to Australia to finalize the whole plan of building a plant generating power from garbage in HCMC with Australian partner Trisun International Development Co.

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Food Waste in Singapore

222 million tons

According to the UN study quoted in the first entry on this blog, consumers in sub-Saharan Africa, South Asia and Southeast Asia throw away an average of 13 to 24 pounds of food a year – which, compared to the 210 to 250 pounds of food the average North American or European consumer throws away each year, is amazing.

As I was in Singapore in March, I decided to take advantage of the opportunity to do a little research into food waste there. The first thing I wanted to figure out was if Singapore, with the (by far) highest GDP per capita in Southeast Asia, was typical for the region when it comes to food waste. I wasn’t able to find any rigorous studies on household food waste per capita. What I did find was a two-week study of 150 families that found that the average household food waste…

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Thailand’s Biomass Energy Scenario

© Guerito 2005

Thailand’s annual energy consumption has risen sharply during the past decade and will continue its upward trend in the years to come. While energy demand has risen sharply, domestic sources of supply are limited, thus forcing a significant reliance on imports. To face this increasing demand, Thailand needs to produce more energy from its own renewable resources, particularly biomass wastes derived from agro-industry, such as bagasse, rice husk, wood chips, livestock and municipal wastes.

In 2005, total installed power capacity in Thailand was 26,430 MW. Renewable energy accounted for about 2 percent of the total installed capacity. In 2007, Thailand had about 777 MW of electricity from renewable energy that was sold to the grid. Several studies have projected that biomass wastes can cover up to 15 % of the energy demand in Thailand (Thailand-Danish Country Programme for Environmental Assistance 1998-2001, Ministry of Environment and Energy, 2000). These estimations are primarily made from biomass waste from the extraction part of agricultural activities, and for large scale agricultural processing of crops etc. – as for instance saw and palm oil mills – and do not include biomass wastes from SMEs in Thailand. Thus, the energy potential of biomass waste can be much larger if these resources are included. The major biomass resources in Thailand include the following:

  • Woody biomass residues from forest plantations
  • Agricultural residues (rice husk, bagasse, corn cobs, etc.)
  • Wood residues from wood and furniture industries    (bark, sawdust, etc.)
  • Biomass for ethanol production (cassava, sugar cane, etc.)
  • Biomass for biodiesel production (palm oil, jatropha oil, etc.)
  • Industrial wastewater from agro-industry
  • Livestock manure
  • Municipal solid wastes and sewage

Thailand’s vast biomass potential has been partially exploited through the use of traditional as well as more advanced conversion technologies for biogas, power generation, and biofuels. Rice, sugar, palm oil, and wood-related industries are the major potential biomass energy sources. The country has a fairly large biomass resource base of about 60 million tons generated each year that could be utilized for energy purposes, such as rice, sugarcane, rubber sheets, palm oil and cassava. Biomass has been a primary source of energy for many years, used for domestic heating and industrial cogeneration. For example, paddy husks are burned to produce steam for turbine operation in rice mills; bagasse and palm residues are used to produce steam and electricity for on-site manufacturing process; and rubber wood chips are burned to produce hot air for rubber wood seasoning.

In addition to biomass residues, wastewater containing organic matters from livestock farms and industries has increasingly been used as a potential source of biomass energy. Thailand’s primary biogas sources are pig farms and residues from food processing. The production potential of biogas from industrial wastewater from palm oil industries, tapioca starch industries, food processing industries, and slaughter industries is also significant. The energy-recovery and environmental benefits that the KWTE waste to energy project has already delivered is attracting keen interest from a wide range of food processing industries around the world.

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Introduction to POME

Pure palm oil - production from rural Jukwa vi...
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Palm Oil processing gives rise to highly polluting waste-water, known as Palm Oil Mill Effluent (POME), which is often discarded in disposal ponds, resulting in the leaching of contaminants that pollute the groundwater and soil, and in the release of methane gas into the atmosphere. POME is an oily wastewater generated by palm oil processing mills and consists of various suspended components. This liquid waste combined with the wastes from steriliser condensate and cooling water is called palm oil mill effluent (POME). On average, for each ton of FFB (fresh fruit bunches) processed, a standard palm oil mill generate about 1 tonne of liquid waste with biochemical oxygen demand (BOD) 27 kg, chemical oxygen demand (COD) 62 kg, suspended solids (SS) 35 kg and oil and grease 6 kg

POME has a very high Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD), which is 100 times more than the municipal sewage. POME is a non-toxic waste, as no chemical is added during the oil extraction process, but will pose environmental issues due to large oxygen depleting capability in aquatic system due to organic and nutrient contents. The high organic matter is due to the presence of different sugars such as arabinose, xylose, glucose, galactose and manose. The suspended solids in the POME are mainly oil-bearing cellulosic materials from the fruits. Since the POME is non-toxic as no chemical is added in the oil extraction process, it is a good source of nutrients for microorganisms.

Currently, recovery of renewable organic-based product is a new approach in managing POME. The technology is aimed to recover by-products such as volatile fatty acid, biogas and poly-hydroxyalkanoates to promote sustainability of the palm oil industry. In addition, it is envisaged that POME can be sustainably reused as a fermentation substrate in production of various metabolites through biotechnological advances. In addition, POME consists of high organic acids and is suitable to be used as a carbon source

Anaerobic digestion is widely adopted in the industry as a primary treatment for POME. Biogas is produced in the process in the amount of 20 m3per ton FFB. This effluent could be used for biogas production through anaerobic digestion. At many Palm-oil mills this process is already in place to meet water quality standards for industrial effluent. The gas, however, is flared off. Liquid effluents from Palm Oil mills in Southeast Asia can be used to generate power through gas turbines or gas-fired engines.

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Biomass Resources from Sugar Industry

Venezuelan sugar cane (Saccharum) harvested fo...
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Sugarcane is one of the most promising agricultural sources of biomass energy in the world. It is the most appropriate agricultural energy crop in most Cane producing countries due to its resistance to cyclonic winds, drought, pests and diseases, and its geographically widespread cultivation. Due to its high energy-to-volume ratio, it is considered one of nature’s most effective storage devices for solar energy and the most economically significant energy crop. The climatic and physiological factors that limit its cultivation to tropical and sub-tropical regions have resulted in its concentration in developing countries, and this, in turn, gives these countries a particular role in the world’s transition to sustainable use of natural resources.

 According to the International Sugar Organization (ISO), Sugarcane is a highly efficient converter of solar energy, and has the highest energy-to-volume ratio among energy crops. Indeed, it gives the highest annual yield of biomass of all species. Roughly, 1 ton of Sugarcane biomass-based on Bagasse, foliage and ethanol output – has an energy content equivalent to one barrel of crude oil.   Sugarcane produces mainly two types of biomass, Cane Trash and Bagasse. Cane Trash is the field residue remaining after harvesting the Cane stalk and Bagasse is the milling by-product which remains after extracting the Sugar from the stalk. The potential energy value of these residues has traditionally been ignored by policy-makers and masses in developing countries. However, with rising fossil fuel prices and dwindling firewood supplies, this material is increasingly viewed as a valuable Renewable Energy resource.

Sugar mills have been using Bagasse to generate steam and electricity for internal plant requirements while Cane Trash remains underutilized to a great extent. Cane Trash and Bagasse are produced during the harvesting and milling process of Sugar Cane which normally lasts 6 to 7 months.

Around the world, a portion of the Cane Trash is collected for sale to feed mills, while freshly cut green tops are sometimes collected for farm animals. In most cases, however, the residues are burned or left in the fields to decompose. Cane Trash, consisting of Sugarcane tops and leaves can potentially be converted into around 1kWh/kg, but is mostly burned in the field due to its bulkiness and its related high cost for collection/transportation.

 On the other hand, Bagasse has been traditionally used as a fuel in the Sugar mill itself, to produce steam for the process and electricity for its own use. In general, for every ton of Sugarcane processed in the mill, around 190 kg Bagasse is produced. Low pressure boilers and low efficiency steam turbines are commonly used in developing countries. It would be a good business proposition to upgrade the present cogeneration systems to highly efficient, high pressure systems with higher capacities to ensure utilization of surplus Bagasse.

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Biomass Energy in Southeast Asia

The rapid economic growth and industrialization in Southeast Asia is characterized by a significant gap between energy supply and demand. The energy demand in the region is expected to grow rapidly in the coming years which will have a profound impact on the global energy market. In addition, the region has many locations with high population density, which makes public health vulnerable to the pollution caused by fossil fuels. Another important rationale for transition from fossil-fuel-based energy systems to renewable ones arises out of observed and projected impacts of climate change. Due to the rising share of greenhouse gas emissions from Asia, it is imperative on all Asian countries to promote sustainable energy to significantly reduce GHGs emissions and foster sustainable energy trends. Rising proportion of greenhouse gas emissions is causing large-scale ecological degradation, particularly in coastal and forest ecosystems, which may further deteriorate environmental sustainability in the region.

The reliance on conventional energy sources can be substantially reduced as the region is one of the leading producers of biomass resources in the world. The energy generating capacity of biomass-based CHP plants is comparatively much higher than other alternative energy technologies like solar, wind and geothermal energy. In addition, solar and wind projects are confined to remote rural electrification and community centres, where the required installed capacity is low. On the other hand, biomass-based cogeneration plants can generate higher capacities of electrical and heat energy that could benefit an entire township and industries in the immediate area.