Biomass

INTRODUCTION OF BIOMASS AS ENERGY RESOURCE

Biomass energy is an indirect solar energy and it is the oldest known renewable energy that humans have been using since the discovery of fire. The term biomass refers to vegetative and organic materials coming from agricultural, forestry, urban, and other rural activities, mainly via photosynthetic process capturing some of the solar energy.

Biomass energy is also known as the energy that contained in the plants and organic matter. Historically, biomass has supplied food, feed, fiber, and structural materials needs for humans through metabolism of biological organisms and, over millions of years of geologic time, to form fossil fuels like oil, natural gas, and coal. By category, biomass includes agricultural residues, forest slash and thinning, urban wood wastes, yard wastes, food processing wastes, livestock manure, chaparral, lumber mill waste, municipal solid wastes, and other residues derived there from.

The potential of biomass resources to supply much larger amounts of useful energy with reduced environmental impacts compared to fossil fuels has stimulated substantial research and development of systems to grow, harvest, handle, process, store and convert biomass to electricity, heat, liquid and gaseous fuels, and other chemicals and products. However, the key to accessing the energy content in biomass is converting the raw biomass materials (feedstock) into a usable form, which can be accomplished through three principal routes:


1) Thermo-chemical (combustion and gasification),
2) Biochemical (via anaerobic digestion and fermentation), and
3) Physicochemical (mechanical and chemical extractions).

The first two energy conversion routes are commonly used, and in practice, combinations of two or more of these routes may be used in the generation of final product or products. Electricity from biomass is significant and contributes to the long term targets for electricity generation from renewable sources due to the availability of biomass and also attributed as economic ways to increase renewable energy.


THE OBJECTIVE

The aim of the Renewable Energy Study is to ensure that the state of Sarawak’s biomass resources are properly supported and utilized, and that it delivers additional economical benefits whilst making a contribution to the emissions reduction.

This plan, for the first time, sets out the directions for the coordinated development of the biomass sources in the State. The plan will establish the status of current and future indigenous biomass feedstock and utilization of biomass power generation to meet the renewable energy target in the State of Sarawak.


BIOMASS FOR ELECTRICITY

Electricity can be generated from all types of biomass by several available technologies including the “co-firing” technique that mixes it with coal or natural gas in a combustion chamber.

Large centralized power plants offer the best economic performance, especially if they were also used for heat as in combined heat and power (CHP). Co-firing biomass with coal is a good centralized option in the large power plants. It is more efficient, when electricity is generated from biomass, to make use of the heat that is produced as well particularly for industries consumption.

Smaller decentralized plants burning solid biomass or biogas tend to cost more, but often have advantages for the environment and for rural development. These shall be considered as rural development program in Corporate Social Responsibilities (CSR) scopes. The main concern will be in relation to biomass availability, transport infrastructure and grid connection possible.
In long terms, SEB believes that it is more pragmatic to harness the potential of all cost-effective forms of biomass electricity generation rather than focusing on certain forms alone. Hence, we need to look into variety of options especially when taking into account the future expansion of agriculture and biological sources.


BIOMASS IN SARAWAK

With the abundant of eco-agricultural industries residues, biomass is widely considered as the most viable mean for SEB to achieve the 100 MW renewable energy target by 2015. In line with the Malaysia Plan’s target and the incentives provided, Sarawak Energy envisages grasping the significant potential of biomass power generation to contribute to the renewable energy shares in the state.

The main biomass sources are palm oil biomass and paddy waste. With current production rate of oil palm fresh fruit bunch and paddy at about 9,300,000 tons and 208,000 tons per annum respectively, Sarawak has the theoretical potential of drawing.

Having said that, not all of these potential can be brought to fruition due to the logistic constrains. Hence, strategic approaches are vital to ensure the biomass sources could be efficiently utilized and supported. Power generation from palm oil biomass will be on grid generation whereas the others sources including rice husk and rice straw will be non-grid power generation. The latter shall be planned for community-based rural electrification to partly displace diesel generation at this stage.
Furthermore, the efficiency of the energy-harnessing or conversion technology is becoming an important factor in utilizing most of the biomass available. The conversion technologies include combustion, co-firing, gasification, anaerobic digestion and fermentation where the end-products are used for generating electricity is fairly common nowadays. The electricity efficiency through boiler and gas engine is generally 32% and 38% respectively.

The upgrading and centralization of landfill and sewerage system in Sarawak also possess an opportunity for power generation in future. The waste produced in the process of waste treatment is considered biomass as it involves microorganisms that degrade carbon-based materials.

There are more biomass source options in Sarawak including cocoa husk and sago wastewater but the extent of production is not yet promising for power generation. The algae cultivation for biofuel is seen as a solution to mitigate the CO2 emission as algae are utilizing the CO2 from power plants. Nonetheless, the high production cost associated with the biological engineering is the hindrance to deploy the algae cultivation at this moment.

Definitely, the policies and regulations that directs to the efficient utilization of biomass and the environment conservation as well as appealing incentives for the plants and more attractive electricity price are more importance to spur the development of biomass utilization.
 

BIOMASS UTILIZATION IN THE STATE

In 2002, the government of Malaysia initiated a project, Biomass Power Generation and Cogeneration in Palm Oil Industry (BIOGEN) to help promote the use of renewable energy, with support from the United Nations Development Program (UNDP), the Global Environment Facility (GEF) and the private sectors. It aims to reduce Greenhouse Gas (GHG) emissions from fossil fuel use and to accredit these reductions for sale through the Clean Development Mechanism (CDM).

The primary objective is to develop and implement activities that will build stakeholders’ capacity and facilitate the greater adoption of renewable energy system. It focuses on palm oil industries and the use of waste material in generating electricity in the mills and selling it to the grid where possible. The importance of Renewable Energy with emphasis towards Energy Efficiency is further reinforced in the 9th Malaysian Plan (9MP) (2006 - 2010) on the production and utilization whilst meeting the environmental objectives. By 2010, Renewable Energy is expected to contribute 350 MW to total energy supply in Malaysia, which is projected to reach 3,128 PJ. Biomass such as rice husks, palm oil and biological waste will be used on a wider basis mainly for power generation.

Under the Small Renewable Energy Power Program (SREP), small power plants utilizing renewable energy are eligible to apply for selling electricity to the utility companies through distribution systems in which applies to all types of renewable energy, including biomass, biogas, municipal waste as well as solar, mini-hydro and wind. This program particularly focuses on biomass wastes as the key renewable energy resources, especially biomass residues from oil palm industries.
The SREP allows renewable projects with up to 10 MW of capacity to sell their electricity output to the utilities. As of July 2009, a total of 43.5 MW has been generated and connected to the grid from projects under SREP program. For off grid power generation, as to 2007, a total capacity of 421 MW of electricity has been generated using biomass waste. For Sarawak, there are possibilities to instigate biomass power plants with capacity more than 10 MW due to the consistent growth of oil palm plantation in the state.

Sarawak is a state with tremendous biomass and bio waste resources available for immediate exploitation. Much of this is readily available waste from the agricultural sector, mainly from oil palm mass plantation. The State of Sarawak is committed in seeking to intensify the development of renewable energy, particularly biomass, as the ‘fifth fuel’ resource under the country’s Fuel Diversification Policy. The policy, which was set out in 2001, had a target of renewable energy providing 5 % of electricity generation by 2005, equal to 100 MW of installed capacity for the state.

Biomass can be the source of hydrogen for new energy conversion techniques such as fuel cells. Therefore, preliminary investigation with a local partner (potentially the Curtin Institute of Technology) shall be carried out to study the gasification of biomass materials/residues.

Technically, the State of Sarawak possesses the potential of generating a total of 425 MW of electricity from the indigenous biomass sources. Palm oil biomass is the main viable source that could contribute about 375 MW of renewable energy electricity based on current biomass yields in the palm oil plantation. Another emerging potential source is paddy residues from the paddy plantation in which could produce substantial amount of electricity in next couple of years with a relatively small capacity of 50 MW presently that does not has the economy of scale at the moment. The estimation of this potential is shown in Table below.

Biomass

Production Rate (ton/year)

Moisture Content (%)

Lower Heating Value (kJ/kg)

Energy Available (MJ)

Potential Electricity, 32% efficiency (MW)

Oil Palm
Empty Fruit Bunch
Mesocarp Fiber
Shell
POME

 

2,043,360
1,207,440
510,840
6,037,200

 

60
50
10
95

 

6,028
9,134
18,836
22

 

1,406,093
1,258,991
1,098,423
379,048

 

125
112
98
40

TOTAL

375

Paddy
Rice Husk
Rice Straw

 

51,893
259,468

 

13
14

 

13,395
16,350

 

79,351
484,281

 

7
43

TOTAL

50

OVERALL

425

Table: Overall view of electricity potential from biomass in Sarawak

 

BIOMASS CONVERSION TECHNOLOGIES

As been stated earlier, the conversion technologies can be categorized into thermo, bio and physicochemical routes. The useful end product of the route can be gaseous or liquid that is used in gas engine or turbine to generate electricity. The routes from biomass to electricity are simplified in Figure 1.4.

COMBUSTION

Energy production from biomass through combustion is the most common technology, but is usually economical only when the raw material is available at little or no cost and is burnt near the source. Transportation costs for unprocessed biomass are far greater than for fossil fuels as they contain less energy per unit volume than fossil fuels. Therefore, before being transported, biomass must first be converted into a fuel with higher energy density. This is done by compressing the material. Wood and its residues, for example, can be converted into dense pellets, cubes or briquettes.

ANAEROBIC DIGESTION

Simple biogas producing devices create anaerobic digestion by decomposing organic matter like crop residues or domestic wastes in an oxygen deprived environment. The resulting biogas (mixture of gases) can be burnt to provide energy for cooking and space heating, or create electricity to power other equipment. Since many of the parasites and disease producing organisms in the waste are killed by the relatively high temperature in the digester tanks, the digested material can also be used as fertilizer or fish feed.

GASIFICATION, PYROLYSIS AND PLASMA ARC

These technologies are the other version of combustion where heat is used to degrade biomass into gaseous or liquid form. In gasification, biomass is heated in the presence of oxygen to produce primarily gaseous fuels while pyrolysis involves the heating of biomass in the absence of oxygen to produce a mixture of oils, gases and solid charcoal. Plasma arc on the other hand uses high voltage of electricity to break the feed into its elemental components in gaseous form.

FERMENTATION

Some conventional food crops that are high in starches and sugars, like sugarcane, corn, sorghum, etc. can be fermented to produce ethanol, a relatively clean burning, high-energy fuel. The commercial production of ethanol, however, requires a major surplus of crops or the production of crops specifically energy purposes. Other less expensive biomass feedstocks such as wood or plant wastes can also be used for ethanol production but present conversion techniques in this field are not very efficient, hence overall cost of ethanol produced from these sources is relatively greater.

 

Figure: Routes of energy conversion from biomass besides combustion