Energy Plantation for Coal Mine Reclamation

Indonesia as one of the largest coal producers in the world, turns out to leave environmental problems in its mining activities. It is estimated that around 8 million hectares or around 3/4 of Indonesia's palm oil plantation are former coal mine holes. The holes become a kind of lake that also often takes casualties. The regulations that apply are reclaiming the hole by returning the soil excavated after the coal deposit being extracted. In practice there are still very few who do this so that holes like lakes are still scattered everywhere. Of the very few, most of them only do it symbolically, meaning that reforestation of reclaimed land is only done in certain areas.

Energy plantations with fast rotation plants and leguminoceae groups such as calliandra and gliricidae are the right solutions to reduce these environmental impacts. After the reclaimed energy plantation can be made in the area of ​​the former coal pit. With an area of ​​thousands to millions of hectares, the woody biomass production from the energy plantation will also be large. The wood is then used as an energy source too. Coal companies are basically energy companies, so it will be in line if it also produces wood as an energy source as well. The difference is that wood from the energy plantation is renewable energy, is a carbon neutral fuel and sustainable. Reclamation with energy plantation also provides a positive image for the company. In order to provide high added value, the wood can be processed into wood chips or wood pellets.

Why are fast-rotating plants from the leguminoceae group such as calliandra or gliricidae chosen as energy plantation tree species? This is because a number of advantages of these plants include pioneer plants and are very easy to grow, easy to care for, can be harvested quickly and with roots that are symbiotic with azetobacter so that they can bind nitrogen from the atmosphere to increase soil fertility. The condition of infertile reclamation land can also be repaired with the energy plantation. Indonesia's position on the equator is also very supportive for the production and use of energy from biomass, especially energy plantations. There is a lot of cloudiness because the island nation makes solar energy use of solar panels less suitable to be applied in Indonesia, for more details can be read here.

The use of renewable energy is gradually starting to replace fossil energy. Renewable energy, especially biomass, is environmentally friendly and sustainable. The coal power plant can also gradually use biomass as its fuel by means of cofiring. Cofiring is the easiest and cheapest way for coal power plants to go to biomass power plants. In this way automatic waste of fly ash will also be reduced. Conversion of up to 100% biomass or full firing is the target for the coal power plant. In addition, power plants also do not have to be centralized with large capacity, for example, hundreds of MW or thousands of MW, but more scattered with small to medium capacity with biomass fuels, especially those that are intensively cultivated with energy plantations that can be made in various corners of the archipelago. Gasification and fluidized bed technology are a number of technologies that can be used for small and medium scale power plants and use wood biomass as fuel. It is not even impossible that the power plant is only the size of a refrigerator.

Higher Power Plant Efficiency Demands Higher Fuel Quality

When we want to refuel our vehicle at a gas station, of course we choose what fuel is most suitable for our vehicle. Our vehicles will be able to run optimally when using the appropriate fuel. Over spec fuel quality or too low (under spec) will only provide less optimal performance. Technically, the vehicle has been designed with a certain pressure ratio on the combustion system, if the quality of the fuel is too high then low compression is difficult to burn perfectly, and vice versa. In the operation of vehicles, even fuel that burns prematurely or after time will produce a performance that is not optimal. High-quality fuels also have higher prices so that they are economically also not profitable, as are low quality fuels, although they are cheaper but performance is also below standard.

The analogy above is also more or less the same for electricity generation. The higher the level of efficiency the higher the quality of the fuel required because the operating conditions are also above the average, for example compression, temperature and so on. If the quality of gasoline is expressed by octane numbers, or on diesel oil the quality is stated by cetan numbers, then in solid fuels such as wood pellets the size of quality is expressed as a caloric value. Other elements that are also considered in fuel are elements that can damage the equipments or machines used. Especially for wood pellets, high potassium and chlorine content can have a bad effect on the power plant. Potassium will be a deposit / fouling on boiler pipes thereby reducing its efficiency, while corrosive chlorine will shorten the life of the power plant.

In 2030, Japan will implement the use of power plants with higher efficiency, which is a minimum of 41%, while most of the efficiency of coal power plants currently ranges from 30-35%. To achieve an efficiency level of more than 41% the technology used is ultra supercritical pulverized coal. Ultra supercritical pulverized coal technology is basically a further development of pulverized coal technology that is most widely used by coal power plants or more than 95% in the entire world today. The difference in ultra supercritical pulverized technology with pulverized is the use of higher pressure and temperature so that its efficiency is also higher. Modification of the power plant can also be done to increase the efficiency. The use of biomass fuels such as wood pellets can be done by cofiring or full firing (100% wood pellets). The characteristics of the fuel used will also affect the boiler technology used.

The ash of wood pellet required for industries such as electricity generation can be up to 6% according to the American pellet fuel institute (PFI). But chemical ash is an important consideration in the use of the power plant. South Korea for example currently requires a maximum chlorine level of 500 ppm (500 mg / kg) or Japan requires a maximum potassium level of 1000 ppm (1000 mg / kg). This makes the production of wood pellets follow these specifications if the specifications are not appropriate. A number of special pretreatments need to be done to achieve these specifications. The potential of wood pellets from energy plantations in Indonesia is very large, as are pellet fuels from agricultural or plantation waste such as palm oil empty fruit bunches which are estimated to reach approximately 38 million tons per year. But once again the specifications of the pellets (wood pellets or agro waste pellets) produced need to be adjusted to the needs of power plants in Japan or South Korea - two countries that are highly energy dependent - of course if the pellet producers are export oriented. What are the next pretreatment questions that need to be done on the production of the pellet? InsyaAllah, we discussed on another occasion.

PKS For Coal Powerplant in Europe

Europe with its bio-economic program in the RED (Renewable Energy Directive) has targeted the use of renewable energy to reach a minimum of 20% by 2020 with biomass consumption reaching 70% of all renewable energy and by 2030 to be at least 27%. For biomass energy, Europe is also the largest producer of wood pellets, which is currently estimated at 13.5 million tons / year while its consumption is 18.8 million tons / year. The biggest wood pellet producing countries in Europe are Germany and Sweden. Even though the production of wood pellets of 13.5 million tons / year has not been able to meet the internal needs of the region, so it still needs supply from outside. America and Canada are the main suppliers of wood pellet needs for the country. Most of the use of wood pellets for electricity generation. In addition to wood pellets, PKS has also been imported from Indonesia. Along the size of the target to be achieved, the need for biomass fuel is predicted to increase.

Although most power plants currently use pulverized coal boiler technology which reaches around 50% of the world's electricity generation, the use of grate combustor boiler technology and fluidized bed boilers is also increasing. Pulverized coal boiler is mainly used for very large capacity plants (> 100 MW), while for ordinary medium capacity uses fluidized bed technology (between 20-100 MW) and for smaller capacity with combustor grate (<20 MW). The advantage of boiler boiler combustion and fluidized bed technology is fuel flexibility including tolerance to particle size. Various agricultural waste, municipal waste, used tires and so on can be used as fuel. When the pulverized coal boiler requires a small particle size (1-2 cm) like sawdust so that it can be atomized on the pulverizer nozzle, the combustor grate and fluidized bed the particle size of gravel (max. 8 cm) can be accepted. Based on these conditions agricultural waste, namely PKS has a great opportunity as fuel for these boilers.

49 MW Biomass Powerplant with Fluidized Bed Technology
in Japan that use PKS as fuel, has been operating since 2015 

To be able to fuel the boiler combustor grate and fluidized bed boiler PKS can be used directly, without additional pretreatment. More specifically for fluidized bed boilers, circulating fluized beds (CFB) boilers are more suitable for PKS compared to boiler fluidized bed (BFB) boilers, for more details read here. Then is PKS not suitable for pulverized coal boiler? There are several things that need to be considered for the use of PKS in pulverized coal boilers. The first thing that can be done is to reduce PKS particle size to a maximum of 2 cm so that it can be atomized in a pulverized system. The second thing to note is the percentage of PKS in coal, or the term cofiring. Unlike a grate and a fluidized bed combustor that can be flexible with various types of fuel, pulverized almost all use coal only. Of course it can also be pulverized to be replaced with biomass, especially PKS, but there are specific things that distinguish biomass and coal fuels, namely ash content and ash chemistry. Both of these things greatly influence the combustion characteristics in the pulverized system.

Coal ash content is generally greater than biomass, besides that coal ash chemistry is very different from biomass ash chemistry. Biomass ash has lower an inorganic than coal, but the alkali content in biomass can change the properties of coal ash, especially aluminosilicate ash. Practically, if you want to change the pulverized system from coal to biomass, especially PKS, it is necessary to modify the power plant and this is also not cheap, but if you want without modification or just a small modification of the power plant is needed, namely the cofiring method. Biomass cofiring with coal in small portions for example 3-5% does not need to modify the pulverized power plant. For example, Shinci in Japan with a capacity of 2 x 1,000 MW of supercritical pulverized fuel with 3% cofiring requires 16,000 tons / year of biomass and no modification, likewise with Korea Shoutheast Power (KOSEP) 5,000 MW with 5% cofiring requiring 600,000 tons / year of biomass and also without modification. Why is the cofiring in the pulverized system discussed a lot? In addition to this type of generator, the most number with a very large electricity production capacity so as to be an effective means of reducing CO2 levels in the atmosphere which also automatically reduces coal use, also the use of biomass in cofiring has an effect on plant operations and the price of electricity produced. The other main reason is because is the cheapest way to enter renewable sector especially for big coal powerplants.

Denmark 700 MW Studstrup power station conducts cofiring up to 20% with straw

Combustor grate technology, fluidized bed and pulverized are basically combustion technologies. Combustion technology is one of the 3 thermal biomass processes that are widely applied, with the other two are gasification and pyrolysis. Gasification as well as pyrolysis can also be used for electricity production, but its use is not as much as combustion technology and its electricity production capacity is generally also small. Almost the same as a combustor grate and fluidized bed, fuel for gasification and pyrolysis is also flexible, including coal and PKS. In gasification technology mainly to maximize gas products (syngas) while in pyrolysis to maximize its solid products. PKS can be pyrolyzed to produce charcoal while coal will produce coke if it is pyrolyzed. Charcoal from PKS can be used for fuel, briquette production and activated charcoal while coke for steel smelting. Syngas is a pyrolysis by-product that can be used for electricity production while in gasification, syngas is the main product that can also be used for electricity production.

Why use PKS for the powerplant fuel? This is because PKS has almost the same characteristics as wood pellets, many are available and are cheap. Indonesia and Malaysia are the two main producers of PKS. PKS is produced from palm oil processing and considered as waste. With an area of ​​Indonesian oil palm plantations reaching 12 million hectares in Indonesia and 5 million hectares in Malaysia, the number of PKS produced from both countries reached 15 million tons / year. The number of PKS in both countries exceeds the production of wood pellets from the United States and Canada, or the two largest producers of wood pellets today. And of course the United States and Canada cannot produce PKS, because they do not have oil palm plantations, but Indonesia and Malaysia can also produce wood pellets because they have large forests. The production of wood pellets in Indonesia and Malaysia is still small today, which is less than 1 million tons / year, but the production of PKS is quite large which can act as an initial driver of bioeconomy in the countries and supply the PKS biomass to Europe.

Dive Cofiring Market

Cofiring becomes an easy entry point for substitution of coal into wood pellet at pulverized power plant system. The cofiring process can also start from small to large percentage, even can change it to 100% using wood pellet later. All pellets fuel of either wood pellet or agro-waste pellet can be used in this cofiring. Agro-waste pellets can be used in smaller portions than wood pellets, because the content of ash is higher than wood pellets. In addition, the agro-waste pellet or pellet ash content made from agricultural wastes is also high in potassium and silica content which has low melting point. In addition, some agricultural wastes also contain high chlorine which is corrosive to boiler pipes.

Pulverised combustion at power plant

South Korea's Southeast Power Co (KOSEP) power plant Yeongheung 5000 MW power station with 6% cofiring with wood pellets does not require any modification at all and requires about 10 million tons of coal with 600,000 tons / year of wood pellets. At a coefficient ratio of 3-10% on proven success in various electric power plants worldwide and also not needed modification of power plants. While cofiring with agro-waste namely straw  has done Studstrup in Danish, reaching the ratio of 10% also with no modifications. The highest ratio for agro-waste or agricultural waste is 20% can still run well without modification of the power plant. The corrosion rate on 10% cofiring straw matches the routine use of coal, whereas in cofiring 20% ​​the straw corrosion velocity is higher. Even after 2 years of operation, 10% straw cofiring gives good performance and is acceptable in daily operation of the plant. Straw is a very large agricultural waste in Denmark and also as a major biomass fuel. Conversion of up to 100% (full firing) wood pellets has also been carried out by a number of power plants and with only minor modifications to the plant, Ontario Power Generation (OPG) Atikokan 240 MW.

Shinchi Power Station Japan 2 x 1000 MW with 3% cofiring requiring wood pellet 130.000 ton / year

Drax Power Station UK running 2x650 MW with 100% wood pellet requires about 6.3 million tons / year

Studstrup power station Denmark 700 MW cofiring up to 20% with straw

Currently there is a tendency for large coal-fired power stations with pulverized systems to begin cofiring with various percentages and different types of pellets  fuel. In addition, a number of power plants that use 100% wood pellets are also widely built, such as in Japan. The driving force is because the state or government concerned also has a policy in that direction. There are a number of countries that have large forests so that wood pellets can be easily produced eg the United States and Canada, on the contrary there are limited forest areas but abundant agricultural waste, such as China and Denmark. It is predicted that world wood pellet consumption will reach 50million tons in 2024 (minus China only), with South Korea and Japan alone reaching 20 million tons by 2020. A projection for cofiring in China if 16% of power plants there cofiring with a ratio of 5 %, then the wood pellet requirement for that country alone reaches nearly 40 million tonnes. Even with very large agricultural waste but with limited forest area, China will import for the wood pellets according to the projection.

Based on the growing wood pellet market for cofiring is certainly a great opportunity for Indonesia as a tropical country, with a vast, fertile land to become the main player of wood pellets to provide the cofiring market. Of course this is an exciting business opportunity and we should not just be spectators in this era of bioeconomy or biomass. With a tropical climate, energy plantations in Indonesia only need 1 year to produce a woody biomass equivalent to 4 years of energy plantations in Europe. The use of wood from trees (syajara) for energy sources also according to the instructions of the Qur'an for more detail can be read here. The vast lands go green and produce woody biomass for pellets, as well as with sheep grazing as the best treasure and meat production primarily to increase our consumption of the new 1/4 world average or 10 kg / year / capita. Stage of wood pellet production from energy plantation can be read here. Once the oar 2-3 is exceeded, become a producer of wood pellets, meat producers as well as fertilizing the soil. Finally fellow Muslims should bersyirkah (Islamic economic cooperation) to realize the opportunity. 

Ash Problem Up to Modification of Power Plant in the Framework of Coal Substitution to Wood Pellet on Pulverized System

The ash of various biomass in combustion causes a number of problems in the pulverized system. That's because the pulverized system is designed to burn coal. Does not the coal also produce ash after burning even more quantity? Yeah right, but the chemical content of coal ash is different from that of biomass. The difference is that coal ash contains a lot of heavy metals such as arsenic, cadmium, mercury, selenium, lead, and nickel which have high melting point so it does not cause problems to the pulverized, whereas biomass ash mainly contains alkali metals such as potassium and alkaline earths are calcium, which has a low melting point so it creates a problem on the pulverized. The content of coal ash is also much larger compare with biomass ash content.

Ash Slagging: Melt ash deposits on boilers or generally on radiant exposed surfaces in a furnace at temperatures above
1,000 C

High-temperature fouling (around 1000 ° C) while low-temperature fouling (300-600 ° C) usually occurs in boiler pipes

What is the problem with the biomass ash chemistry? There are several problems caused by the ash chemistry on the pulverized system, namely slagging and fouling. How to avoid it? There are several ways to avoid it, namely first, determine the exact percentage of biomass fuel in the pulverized system or co-firing. At the appropriate percentage of biomass fuel can be used simultaneously (co-firing) with coal. The type of biomass fuel also determines its percentage, eg wood pellets will have a larger portion than agro-waste pellets. Secondly, by modifying the coal-fired power plant so that it can even be 100% with biomass fuel such as wood pellets.

Burning biomass fuel in addition to environmentally friendly or carbon neutral, fewer CO2 emissions, SO2 emissions are also very small, very little fly ash even does not occur, and the ash is rich in potassium, and phospur so it becomes a good fertilizer for plants. While coal ash is otherwise and even categorized as dangerous waste due to the heavy metal content. Based on these things, it is natural that the use of biomass fuel continues to be improved even has become government policy in some countries.

The entry point for massive biomass fuel usage is co-firing with coal. The modification of the coal-fired power plant has become an opportunity, so a number of companies have emerged to capture such opportunities as Ramboll and Doosan Babcock. While in Indonesia it seems still long enough to make biomass fuel has a large portion as a source of energy, especially in power plants, because there is no policy that supports it.

Global pellet market to reach $9 billion by 2020

The global market for pellets is expected to double in the next seven years, growing from a $4 billion market to $9 billion, Michele Rebiere with Viridis Energy Inc. told attendees at the Pellet Supply Chain Summit, March 24. The summit preceded the International Biomass Conference being held March 24-27 in Orlando, Fla.

Speaking in the closing panel of the day, Rebiere said the largest market, by far, is the European, with 20 million metrics tons (mmt) used in 2013 for both industrial power and residential heat. That is forecast to grow to 28 mmt by 2015 and 42 mmt by 2020. The North American market, is now at 4 mmt and forecast to be 5 mmt in 2015, but she added, are understated going out further. “I think the forecast in North American will increase substantially,” she said added, as the interest in cofiring with coal is likely to increase which the forecasts won’t include until projects are announced. The Asian market is expect to grow as well, from 1 mmt in 2013, to 3 mmt in 2015 and potentially 7 mmt by 2020. While the power market is the largest market contributor, the heating market is growing rapidly. Italy, in particular, garnered attention with the doubling of its demand in one year.

Seth Ginther, executive director of the U.S. Industrial Pellet Association, was a bit more conservative on his growth projections, pointing out that 2020 estimates range between 25 mmt and 70 mmt. “I think that 2013 was the year we’re beginning to see where the market is going to shake out. It’s going to be more like the 25 mmt level, but that still is going to be significant.”

In his discussion on the changes in the United Kingdom’s incentives, Ginther said it is important to note that the incentives for biomass conversions are aimed at helping  develop infrastructure. And, as the carrot is phased out, the stick – the price of carbon – is being increased, making it very expensive to burn coal. As a result, UK power producers are expected to continue to move towards biomass.

As a large UK buyer of North American pellets, Richard Peberdy, vice president of sustainability for Drax Biomass International, outlined his company’s commitment to biomass power and its interest in sustainability. The UK power producer has experimented with a number of biomass sources to supplement coal since 2008, making a commitment to pellets to provide a large portion of its biomass needs. It has two pellet facilities under construction in Mississippi and Louisiana and is building a port facility in Baton Rouge, La.
The first of three boiler conversions has been completed at Drax, with the second to be brought into service later this year and the third planned for 2015. Peberdy reported that Drax was pleased with the performance of its first biomass boiler conversion at the end of the first year of operations. “It’s outperformed our expectations in the first year at 39 to 40 percent efficiency on 100 percent biomass.” That is significant, he added, because UK sustainability reports projected biomass power would only reach 25 percent efficiencies, much lower than coal power’s average 35 percent efficiency.

 

Peberdy described Drax’s commitment to sustainability, pointing out that the company established its own sustainability goals even prior to the development of UK standards. The pressure for sustainability brings benefits, he said, by increasing investments in forests, in outreach to forest owners and in safer and better systems for making, handling and moving pellets.

Ben Conte, renewable energy sales manager for Bridgewell Renewables, filled out the panel at the summit on market energies by describing the work his company has done in marketing pellets in the EU. Much of the Bridgewell’s focus has been on meeting the high quality heating market, working to help its customers with their branding efforts. While Bridgewell is developing a brand to be able to meet spot markets, much of the work it’s done has been in seasonal 3-6 month contracts as well as long term contracts for one or two years. “The market is evolving,” he said. “The industrial and residential markets are linked in Europe and Asia,” he added, and are getting more sophisticated.

Other panels during the day included industry speakers addressing forestry ownership implications, sustainable forest management, pellet mill design considerations and infrastructure.

By Sue Retka Schill | March 24, 2014
Source : http://biomassmagazine.com/articles/10194/global-pellet-market-to-reach-9-billion-by-2020

Optimization of Biomass-Coal Cofiring in Coal Fired Powerplant

Biomass-coal cofiring has been commonly performed by a number of coal power plants in Europe and America with a primary motivation for reducing the environmental impact of emissions. Currently the percentage of cofiring biomass with coal is still small on average below 10%. It can also occur due to a limited supply of wood pellets. But in terms of operational cofiring biomass-coal fly ash will reduce significantly. On the other hand, if the percentage of biomass-coal cofiring is added will cause deposits on boiler pipes that will disrupt the process of heat transfer in the furnace causing inefficient use of fuel with one indicated by the high temperature of the fluegas.

There are three techniques commonly used in biomass-coal cofiring:

1.       Mixing of biomass and coal in the fuel handling system (then fed to the boiler).

2.       Setting up a separate biomass with coal, and then inject into the boiler.

3.       Gasification of biomass to produce a gas which is then burned in the boiler directly or using the integrated gasification combined cycle (IGCC) system.Worldwide reported more than 200 coal power plant that has been tested with biomass (IEA 2010).

Several cofiring  options are available on in coal powerplant, among others:

-Cofire with a low percentage of biomass, with a slight modification of the equipment.

-Cofire with a high percentage of biomass, by upgrading equipment.

- Convert/repower individual coal burners to be fired with biomass

- Convert/repower entire coal plants to be fired with biomass

- Cofire with torrefiedwood

Ash content in coal and biomass are generally differ quite large and moreover  ash chemistry are also a lot of different. This is factor that causes a lot or at least a deposit in the boiler pipes. Percentage of cofiring biomass-coal up to 10% is generally acceptable. Optimal percentage that causes minimal boiler tube deposits and significant reduction in fly ash can be searched based on the variable characteristics of coal and biomass are used.

Torrefied Wood: Biomass Fuel of Substituting Coal in The Future

Compared to conventional biomass fuels such as wood pellets are only capable of a maximum of 10% in co-firing with coal because of the nature of chemistry and physic  are much different whereas if the percentage of co-firing with coal increased to 20% required the addition of a large investment for the handling and processingnya, then torrefied wood even capable of co-firing with coal to 40%. Another advantage is on the side of the powerplant also just needed a little extra investment for handling and processingnya for torrefied wood, due to the physico-chemical properties are not much different.

Densification or compaction into pellets or torrefied wood briquettes will also give a more significant savings than wood pellets, ie 15.0-18.7 MJ/m3 on torrified pellets and  7.5-10.4 MJ/m3 at wood pellets. Because the torrefied wood brittle, so it can be burned with coal dipulverize and more advisable, instead of using the material handling, processing to a separate injection system. This will result in significant savings on equipment modification when cofiring at a greater percentage. A number of agro-industry waste biomass such as empty fruit bunches and palm thatch can torrefaksi as well as woody biomass, to enhance combustion conditions in the coal system.

Torrefied wood cofiring has been successfully carried out one of them in the coal power plant in Borselle, Netherlands. Research also shows that the smoothing torrefied wood into powder with a specific particle size distribution and allows for the smooth fluidization regimes on the feeding entrained flow process (gasifier and pulverized coal boilers).