Tag Archives: cogeneration

Biomass Energy in Thailand

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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.

Thailand_paddy

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.

Biomass Potential in Thailand

Several studies have projected that biomass wastes can cover up to 15 % of the energy demand in Thailand. 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 in Thailand. 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.

Biomass Resources from Rice Industry

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The cultivation of rice results in two major types of biomass wastes – Straw and Husk –having attractive potential in terms of biomass energy. Although the technology for rice husk utilization is well-proven in industrialized countries of Europe and North America, such technologies are yet to be introduced in the developing world on commercial scale.

Rice-Biomass

The importance of Rice Husk and Rice Straw as an attractive source of energy can be gauged from the following statistics:

Rice Straw

  • 1 ton of Rice paddy produces 290 kg Rice Straw
  • 290 kg Rice Straw can produce 100 kWh of power
  • Calorific value = 2400 kcal/kg

Rice Husk

  • 1 ton of Rice paddy produces 220 kg Rice Husk
  • 1 ton Rice Husk is equivalent to 410- 570 kWh electricity
  • Calorific value = 3000 kcal/kg
  • Moisture content = 5 – 12%

Rice husk is the most prolific agricultural residue in rice producing countries around the world. It is one of the major by-products from the rice milling process and constitutes about 20% of paddy by weight. Rice husk, which consists mainly of lingo-cellulose and silica, is not utilized to any significant extent and has great potential as an energy source.

Rice husk can be used for power generation through either the steam or gasification route. For small scale power generation, the gasification route has attracted more attention as a small steam power plant is very inefficient and is very difficult to maintain due to the presence of a boiler. In addition for rice mills with diesel engines, the gas produced from rice husk can be used in the existing engine in a dual fuel operation.

The benefits of using rice husk conversion technology are numerous. Primarily, it provides electricity and serves as a way to dispose of agricultural waste. In addition, steam, a byproduct of power generation, can be used for paddy drying applications, thereby increasing local incomes and reducing the need to import fossil fuels. Rice husk ash, the byproduct of rice husk power plants, can be used in the cement and steel industries further decreasing the need to import these materials.

Rice straw can either be used alone or mixed with other biomass materials in direct combustion. In this technology, combustion boilers are used in combination with steam turbines to produce electricity and heat. The energy content of rice straw is around 14 MJ per kg at 10 percent moisture content.  The by-products are fly ash and bottom ash, which have an economic value and could be used in cement and/or brick manufacturing, construction of roads and embankments, etc.

Straw fuels have proved to be extremely difficult to burn in most combustion furnaces, especially those designed for power generation. The primary issue concerning the use of rice straw and other herbaceous biomass for power generation is fouling, slagging, and corrosion of the boiler due to alkaline and chlorine components in the ash. Europe, and in particular, Denmark, currently has the greatest experience with straw fired power and CHP plants.

Biomass Energy in Vietnam

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Vietnam is one of the few countries having a low level of energy consumption in the developing world with an estimated amount of 210 kg of oil equivalent per capita/year. A significant portion of the Vietnamese population does not have access to electricity. Vietnam is facing the difficult challenge of maintaining this growth in a sustainable manner, with no or minimal adverse impacts on society and the environment.

Being an agricultural country, Vietnam has very good biomass energy potential. Agricultural wastes are most abundant in the Mekong Delta region with approximately 50% of the amount of the whole country and Red River Delta with 15%. Major biomass resources includes rice husk from paddy milling stations, bagasse from sugar factories, coffee husk from coffee processing plants in the Central Highlands and wood chip from wood processing industries. Vietnam has set a target of having a combined capacity of 500 MW of biomass power by 2020, which is raised to 2,000 MW in 2030.

Rice husk and bagasse are the biomass resources with the greatest economic potential, estimated at 50 MW and 150 MW respectively. Biomass fuels sources that can also be developed include forest wood, rubber wood, logging residues, saw mill residues, sugar cane residues, bagasse, coffee husk and coconut residues.

Currently biomass is generally treated as a non-commercial energy source, and collected and used locally. Nearly 40 bagasse-based biomass power plants have been developed with a total designed capacity of 150 MW but they are still unable to connect with the national grid due to current low power prices. Five cogeneration systems selling extra electricity to national grid at average price of 4 US cents/kWh.

Biogas potential is approximately 10 billion m3/year, which can be collected from landfills, animal excrements, agricultural residues, industrial wastewater etc. The biogas potential in the country is large due to livestock population of more than 30 million, mostly pigs, cattle, and water buffalo. Although most livestock dung already is used in feeding fish and fertilizing fields and gardens, there is potential for higher-value utilization through biogas production.

It is estimated that more than 25,000 household biogas digesters with 1 to 50 m3, have been installed in rural areas. The Dutch-funded Biogas Program operated by SNV Vietnam constructed some 18,000 biogas facilities in 12 provinces between 2003 and 2005, with a second phase (2007-2010) target of 150,000 biogas tanks in both rural and semi-urban settings.

Municipal solid waste is also a good biomass resource as the amount of solid waste generated in Vietnam has been increasing steadily over the last few decades. In 1996, the average amount of waste produced per year was 5.9 million tons per annum which rose to 28 million tons per in 2008 and expected to reach 44 million tons per year by 2015.

Biomass Cogeneration Systems

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Biomass fuels are typically used most efficiently and beneficially when generating both power and heat through biomass cogeneration systems (also known as combined heat and power or CHP system). Biomass conversion technologies transform a variety of wastes into heat, electricity and biofuels by employing a host of strategies. Conversion routes are generally thermochemical or biochemical, but may also include chemical and physical.

The simplest way is to burn the biomass in a furnace, exploiting the heat generated to produce steam in a boiler, which is then used to drive a steam turbine. Advanced biomass conversion technologies include biomass integrated gasification combined cycle (BIGCC) systems, cofiring (with coal or gas), pyrolysis and second generation biofuels.

Biomass Cogeneration Systems

A typical biomass cogeneration (or biomass cogen) system provides:

  • Distributed generation of electrical and/or mechanical power.
  • Waste-heat recovery for heating, cooling, or process applications.
  • Seamless system integration for a variety of technologies, thermal applications, and fuel types into existing building infrastructure.

Biomass cogeneration systems consist of a number of individual components—prime mover (heat engine), generator, heat recovery, and electrical interconnection—configured into an integrated whole. The type of equipment that drives the overall system (i.e., the prime mover) typically identifies the CHP unit.

Prime Movers

Prime movers for biomass cogeneration units include reciprocating engines, combustion or gas turbines, steam turbines, microturbines, and fuel cells. These prime movers are capable of burning a variety of fuels, including natural gas, coal, oil, and alternative fuels to produce shaft power or mechanical energy.

Key Components

A biomass-fueled cogeneration facility is an integrated power system comprised of three major components:

  • Biomass receiving and feedstock preparation.
  • Energy conversion – Conversion of the biomass into steam for direct combustion systems or into biogas for the gasification systems.
  • Power and heat production – Conversion of the steam or syngas or biogas into electric power and process steam or hot water

Feedstock for Biomass Cogeneration Plants

The lowest cost forms of biomass for cogeneration plants are residues. Residues are the organic byproducts of food, fiber, and forest production, such as sawdust, rice husks, wheat straw, corn stalks, and sugarcane bagasse. Forest residues and wood wastes represent a large potential resource for energy production and include forest residues, forest thinnings, and primary mill residues.

combined-heat-and-power

Energy crops are perennial grasses and trees grown through traditional agricultural practices that are produced primarily to be used as feedstocks for energy generation, e.g. hybrid poplars, hybrid willows, and switchgrass. Animal manure can be digested anaerobically to produce biogas in large agricultural farms and dairies.

To turn a biomass resource into productive heat and/or electricity requires a number of steps and considerations, most notably evaluating the availability of suitable biomass resources; determining the economics of collection, storage, and transportation; and evaluating available technology options for converting biomass into useful heat or electricity.

Biomass Energy Scenario in Southeast Asia

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There is immense potential of biomass energy in Southeast Asia due to plentiful supply of diverse forms of biomass wastes including agricultural residues, agro-industrial wastes, woody biomass, animal wastes, municipal solid waste, etc. Southeast Asia is a big producer of wood and agricultural products which, when processed in industries, produces large amounts of biomass residues.

The rapid economic growth and industrialization in Southeast Asian region 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.

biomass_resources

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 Southeast Asian region is one of the leading producers of biomass resources in the world. Southeast Asia, with its abundant biomass resources, holds a strategic position in the global biomass energy atlas.

palm-kernel-shell-uses

Palm kernel shells is an abundant biomass resource in Southeast Asia

According to conservative estimates, the amount of biomass residues generated from sugar, rice and palm oil mills is more than 200-230 million tons per year which corresponds to cogeneration potential of 16-19 GW. Woody biomass is a good energy resource due to presence of large number of forests and wood processing industries in the region.

The prospects of biogas power generation are also high in the region due to the presence of well-established food processing, agricultural and dairy industries. Another important biomass resource is contributed by municipal solid wastes in heavily populated urban areas.

In addition, there are increasing efforts from the public and private sectors to develop biomass energy systems for efficient biofuel production, e.g. biodiesel and bioethanol. The rapid economic growth and industrialization in Southeast Asia has accelerated the drive to implement the latest biomass energy technologies in order to tap the unharnessed potential of biomass resources, thereby making a significant contribution to the regional energy mix.

Bioenergy in Southeast Asia: Perspectives

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Southeast Asia, with its abundant bioenergy resources, holds a strategic position in the global biomass energy atlas. There is immense biomass energy potential in Southeast Asian countries due to plentiful supply of diverse forms of biomass wastes, such as agricultural residues, woody biomass, animal wastes, municipal solid waste, etc. The rapid economic growth and industrialization in the region has accelerated the drive to implement the latest waste-to-energy technologies to tap the unharnessed potential of biomass resources.

Southeast_asia

Southeast Asia is a big producer of agricultural and wood products which, when processed in industries, produces large amounts of biomass residues. According to conservative estimates, the amount of biomass residues generated from sugar, rice and palm oil mills is more than 200-230 million tons per year which corresponds to cogeneration potential of 16-19 GW.

Rice mills in the region produce 38 million tonnes of rice husk as solid residue which is a good fuel for producing heat and power. Sugar industry is an integral part of the industrial scenario in Southeast Asia accounting for 7% of sugar production worldwide. Sugar mills in Thailand, Indonesia, Philippines and Vietnam generate 34 million tonnes of bagasse every year.  Malaysia, Indonesia and Thailand account for 90% of global palm oil production leading to the generation of 27 million tonnes of waste per annum in the form of empty fruit bunches (EFBs), fibers and shells, as well as liquid effluent.

Woody biomass is a good energy resource due to presence of large number of forests in Southeast Asia. Apart from natural forests, non-industrial plantations of different types (e.g. coconut, rubber and oil palm plantations, fruit orchards, and trees in homesteads and gardens) have gained recognition as important sources of biomass. In addition, the presence of a large number of wood processing industries also generates significant quantity of wood wastes. The annual production of wood wastes in the region is estimated to be more than 30 million m3.

The prospects of biogas power generation are also high in the region, thanks to presence of well-established food-processing and dairy industries. Another important biomass resource is contributed by municipal solid wastes in heavily populated urban areas.  In addition, there are increasing efforts both commercially and promoted by governments to develop biomass energy systems for efficient biofuel production, e.g. bio-diesel from palm oil.

Biomass resources, particularly residues from forests, wood processing, agricultural crops and agro-processing, are under-utilised in Southeast Asian countries. There is an urgent need to utilize biomass wastes for commercial electricity and heat production to cater to the needs of the industries as well as urban and rural communities.

Southeast Asian countries are yet to make optimum use of the additional power generation potential from biomass waste resources which could help them to partially overcome the long-term problem of energy supply. Technologies for biomass utilization which are at present widely used in Southeast counties need to be improved towards best practice by making use of the latest trends in the biomass energy sector.