Decarbonization of Coal Mining with Reclamation for Energy Plantations for Wood Pellet Production

Wood pellets are carbon neutral fuel so they do not add CO2 to the atmosphere, which is different from fossil fuels such as coal which are carbon positive, namely adding CO2 to the atmosphere, which is part of the climate solution. Net zero emissions and decarbonization efforts are also accelerated by the use of carbon neutral fuel such as wood pellets. This is an important and main reason for the production of wood pellets in mining companies, especially coal, so that they can reduce CO2 emissions from burning coal. Post-mining land at coal companies can be reclaimed in another form, namely by creating energy plantations as raw material for wood pellet production. There are millions of hectares of ex-mining land that have potential as energy plantations, for more details read here.

Cofiring coal with biomass is an easy and cheap entry point for coal power plants to gradually use renewable fuels. Over time the biomass to coal cofiring ratio can continue to be increased so that CO2 emissions from carbon positive coal are reduced. Technically, a cofiring ratio of up to 5% does not require equipment modifications at the coal power plants. The amount of CO2 that can be replaced (carbon offset) with carbon neutral fuel such as wood pellets also has the opportunity to get carbon credits or other compensation. The implementation of a carbon tax also increasingly encourages a reduction in the use of coal in power plants and vice versa, namely encouraging an increase in the use of renewable fuels, especially wood pellets in these coal power plants or an increase in the cofiring ratio, even ideally fulfiring can be done, namely 100% using renewable fuel.

The implementation of a carbon tax in Indonesia is planned for 2025, after several postponements. The lowest carbon tax rate is IDR 30 per kilogram of carbon dioxide equivalent (IDR 30,000 or around US$ 2 per ton of CO2 equivalent). This tariff is actually much smaller than the initial proposal of IDR 75. With a tariff of IDR 30, Indonesia is one of the countries with the lowest tariff in the world for carbon tax. By burning 1 ton of coal, it will produce around 3 tons of CO2 emissions, so the carbon tax imposed will reach IDR 90,000 per ton of coal. Meanwhile, the use of renewable or carbon neutral fuels such as wood pellets is not subject to the carbon tax. Apart from that, mining companies are also obliged to reclaim their post-mining land, which if not done will be subject to heavy sanctions.

Energy plantation plants are a type of pioneer plant, easy to grow, efficient at using water, fertilize the soil and have strong roots to resist erosion. Legume types such as calliandra and gliricidia are commonly used as energy plantation plants. Integration of energy plantation product processing must be carried out so that optimal benefits are obtained, namely the main product is wood for wood pellet production, leaves as ruminant animal feed and honey as high quality food. The energy plantation must also be created to be able to produce sustainably, namely by maintaining a balance between wood productivity for wood pellet production, environmental functions in the form of maintaining erosion and groundwater, and the volume of wood harvested must not exceed the growth rate or be at least the same (carbon balance) and using by-products for additional revenue, such as using leaves for animal feed and honey from honey bee farms.

Case Study India: Priority of Biomass Pellet Production Over Biomass Briquette

There are dozens of biomass briquette machine manufacturers in India and almost all of these machine manufacturers use mechanical press technology for the production of these briquettes. With this technology, briquettes will be formed due to mechanical press such as repeated strokes every minute (about 220 strokes per minute). This briquette machine manufacturer industry has also existed for decades in India so that biomass briquette products have also been widely known in India. Technically, there are actually 2 other technologies for the production of biomass briquettes, namely screw press and hydraulic press. Based on the briquette production technology, the briquette product output is also slightly different, for more details, read here.

The Indian government launched a decarbonization program at their coal power plants, recently, namely on October 8, 2021 which ordered the use of 5% to 10% biomass pellets for cofiring at all power plants and took effect in October 2022 or one year is the target time set. For example, in the early stages, the Indian government targeted only 5% for the cofiring ratio in their coal power plants, where the 5% figure when translated into biomass pellet production would reach around 50 million tons of biomass pellets per year. A very large number especially with a very short target time. And with a cofiring ratio of 5%, coal power plants also do not need to modify their equipment even though the biomass pellets used come from agricultural wastes, whose quality is below that of woody biomass.

With the number of power plants reaching about 900 units with an average consumption of 50 thousand tons of biomass pellets per year or a total of almost 50 million tons per year, so that a biomass pellet factory with a capacity of around 5 thousand tons / month seems to be suitable, and even if each factory supplying one power plant, the need for a biomass pellet plant will also be the same as the number of power plants, which is 900 units. A huge amount.

Production of biomass briquettes or biomass pellets?
In India, biomass briquette is indeed more popular than biomass pellets, but for the world level pellets are much more popular than briquette, even in 2021 alone, the need for pellets for global power generation alone is estimated to have reached 23 million tons. In addition, the production or pellet factory in general is also larger than the briquette factory. There are many pellet factories with a capacity of 5 thousand tons or even 10 thousand tons per month, while for briquettes it is very rare for a biomass briquette factory to have a capacity like the pellets above. Pelletisers for pellet production for commercial capacity have a capacity of 3 tons/hour or more, while briquette machines are generally less than 2.5 tons per hour, even for the screw press type the average machine capacity is only 300 kg/hour. Technically, even though they are both products of biomass densification technology with the difference that the size of the briquettes is larger than pellets, the production of briquettes is easier than pellets. 

The driving force from the business side makes biomass pellet production more attractive, especially because of its need as cofiring fuel in coal power plants as part of the decarbonization program. The need for biomass pellets can be a driving force for the production of biomass pellets or in general, namely the economy in various regions. The program should also be able to provide three benefits at once, namely environmental, social and economic. In addition, because briquette products are mainly used for boilers in industry, while pellets are for power generation, both of them also have their own market segments so that there is no market competition.

What about the Briquette Machine Manufacturing Industry?
Dozens of industries producing biomass briquette machines should now see this as an opportunity so that they can respond to it. These industries can adapt by creating a new line of business, namely helping the manufacture of a biomass pellet factory. Technically, the biomass briquette production line with biomass pellets also has many similarities (both use biomass densification technology) with the main difference being the pelletiser and briquetter. A number of equipment that can be made themself will reduce imported machines. Pelletisers are almost certain to be imported, so the selection of pelletisers as the heart of the pellet production process must be of high quality so that the pellet production target can be achieved. In the production of large capacity pellets, a number of equipments come from a number of providers, as is common in wood pellet factories with a more detailed explanation here.

In the long term, the goal is to minimize import spending, and even 100% can be made or fabricated by themself. This effort will usually take longer because the complexity of the pelletiser is higher than that of the briquetter. These briquette machine-producing industries can also cooperate with machine manufacturers in Europe who are more experienced and proven with pellet production as an effort to accelerate the transfer of the technology. Within one year as the target was set, it is very difficult to do this, so the practical effort is to buy a 100% complete line from a proven vendor, or sort out a number of equipment that can be produced yourself as above and gradually substitute the imported equipment. This is because achieving the production target for the decarbonization effort is a priority.

In conclusion, at this time India has to maximize efforts to accelerate the construction of biomass pellet factories to achieve this target. However, 1 year to achieve this target is very difficult. With these conditions in the future, it is possible that power plants in India will import biomass fuels such as wood pellets and PKS (palm kernel shell) to meet their needs. With the planned cofiring ratio, which is the lowest target of 5%, the need for biomass pellets reaches around 50 million tons, if only 2% of the biomass fuel needs are imported, both PKS and / or wood pellets, it will reach 1 million tons, a fixed amount still quite big.

Opportunity to Export Wood Pellet to Germany

At the end of 2022 or this year, all nuclear power plants in Germany will be discontinued, then in 2030 or at the latest in 2038 all coal fired power plants will also be discontinued. Germany in the context of decarbonization has planned to reduce fossil fuels, especially coal in its power plant. The percentage of nuclear power plants in Germany is 3.6% or about 8 GW and this requires immediate efforts to replace the electricity supply. Meanwhile, coal-fired power plants reach about 28% or more than 40 GW, and currently electricity production with coal is very expensive, due to the price of coal itself and carbon tax. Coal prices are around $150 but recently there has been a spike to $435 and a carbon tax of over $100 for every ton CO2 emitted. With these cost components, the price of electricity production for each MWh reaches around $220 (not including labor costs, maintenance, and so on), whereas if it is replaced with wood pellets the production price is only around $90 per MWh or approximately one third. Very cheap. Moreover, with the use of wood pellets, the sulfur scrubbing process (FGD = flue gas desulphurisation) can be reduced or even eliminated.

Biomass fuels such as wood pellets are carbon neutral so they do not increase the concentration of CO2 in the atmosphere, so that when using wood pellets for power generation and subsequent CO2 gas emissions, which are greenhouse gases, are captured and stored (CCS = Carbon Capture and Storage) so that they do not escape into the atmosphere, then this becomes carbon negative or reduces the concentration of CO2 in the atmosphere. The amount of CO2 gas that can be captured and soraged can also get carbon credit compensation, so that the coal power plants will get additional income. But without even having to use CCS, the use of wood pellets has reduced the cost of electricity production very significantly and is environmentally friendly. Meanwhile, if the power plant uses coal which is carbon positive and then CO2 emissions are captured and stored with CCS technology, this becomes carbon neutral. Of course, carbon negative efforts are better than carbon neutral.

On the other hand, Germany is famous for its technological products, especially industrial machines. A number of machine manufacturers for the production of wood pellets also come from Germany, such as Muench, Salmatec and Kahl. These machines are widely used for the production of wood pellets around the world and are reliable. It is possible that later the machines for the production of wood pellets will be imported from Germany and wood pellet products from Indonesia will be exported to Germany. This is in accordance with the potential advantages of each country. Indonesia with a land area of 1.91 million km2 with a lot of available land and being in the tropics has great potential as the world's main producer of wood pellets.

Currently about 55% of the fuel for power generation in Germany uses natural gas originating from Russia, and currently war is breaking out between Russia and Ukraine. The issue of Germany's alignment may affect the supply of natural gas from Russia to the country due to the war. Conversion from coal power plant to wood pellet power plant is not difficult and does not require a large investment, so this conversion is the most realistic solution. With the number of coal-fired power plants in Germany more than 100 units or about 1/3 of the electricity supply, so the need for wood pellets will also be very large if the power plants switch to wood pellets.

Mining Sector and Post-Mining Reclamation

The photo is taken from here

Among the mining sector, coal is the largest mining product in Indonesia and even ranks third at the world level. In 2021 coal production was recorded at 576 million tons and it is projected that there will be only a slight decline in 2024, which is to 570 million tons. This coal is also the largest source of state income after Indonesia's oil can no longer be exported because production runs out for domestic consumption and even less so that it has to become an oil importer. But in the long term the future of coal is bleak as its use is increasingly restricted due to climate concerns. Countries that have ratified the Paris agreement have committed to reducing fossil fuels, especially coal with concrete steps, namely not building new coal power plants, cofiring with renewable energy at coal power plants, converting coal power plants into 100% biomass power plants (fulfiring) and closing a number of coal power plants and replace it with other renewable energy sources.

On the other hand, the post-mining activity also caused a lot of environmental damage, especially the land. Land damage will trigger natural disasters that endanger human life. Do not let the mining activities exploit its natural resources to the fullest but also leave natural damage that is no less severe. Of course this condition is very bad. The obligation of reclamation has also not been carried out properly, many even do not do it or just do it symbolically, imaging and mere formality while the purpose of reclamation itself is not achieved. The threat of a fine of 100 billion rupiah is also imposed for companies that ignore the reclamation to further encourage the reclamation activities.

According to Rizal Kasli, the general chairman of Perhapi (Indonesian Mining Experts Association), currently there are infrastructure and resource constraints (costs) in the implementation of the reclamation, namely for medium and small mining companies, for more details read here. This means that for large companies with large volumes of mining production there should be no obstacles, but stricter law enforcement is needed, according to Rizal Kasli. If large mining companies carry out reclamation properly, of course this is good and becomes an example for small and medium mining companies, but if the opposite happens, it will exacerbate environmental damage. Compensation or profit from the mining business should be in line and proportional to the improvement of the land or post-mining land (reclamation and rehabilitation).

The photo is taken from here

Why do a lot of mining companies generally ignore or neglect reclamation and post-mining land rehabilitation? In addition to the rules that are not strictly enforced, of course the problem is the cost. Mining companies have to spend a lot of money for the reclamation and rehabilitation of post-mining land, the costs depend on the conditions and the area of ​​the land. This of course burdens and reduces the profits of the mining company itself, causing reluctance. So even if reclamation and land rehabilitation are carried out, they are only symbolic, imaging and formality. This can be said to have no impact or achieve the goals of post-mining land reclamation and rehabilitation itself. 

Whereas the purpose of land reclamation and rehabilitation is one of the efforts to prepare fertile land for the future. So what if the reclamation turns out to be a profitable activity? This is certainly very interesting and motivating the mining companies. Bio-economy based reclamation and rehabilitation projects will be able to provide benefits for mining companies that do so. With these benefits, the land reclamation and rehabilitation program will be able to run well and sustainably, so that the entire post-mining area can be touched. We are currently developing a bioeconomic program for the post-mining land reclamation and rehabilitation, for more detailed information please contact us at cakbentra@gmail.com

Wood Chip, Wood Pellet, and Wood Briquette from Energy Plantations for Local Market Part 2

The PLN (Indonesia State Owned Electricity Company) cofiring program, which is mixing biomass fuel with coal in coal power plants, will clearly encourage the use of biomass as an energy source. Cofiring is the easiest and cheapest way for coal power plants to start entering or gradually using environmentally friendly renewable energy. Emissions are also getting better as the use of biomass fuels increases, such as because the sulfur content is very low, there is little ash instead of hazardous waste, and fly ash is very small. The amount of added biomass, for example, starts from 1% which is then gradually increased and even finally it can be 100% biomass or renewable energy. In 2020 the cofiring program has been initiated with a target of 37 coal power plants and by the end of 2020 it is reported that it has been implemented for 20 coal powerplants. While in total there are 114 coal power plants units owned by PLN that have the potential for cofiring, spread across 52 locations with a total capacity of 18,154 megawatts (MW) with a target of completion in 2024. Consisting of 13 coal power plant locations in Sumatra, 16 coal power plant locations in Java, Kalimantan (10 locations), Bali and Nusa Tenggara (4 coal power plant units), Sulawesi (6 locations) and Maluku and Papua (3 coal power plant locations). Meanwhile, the cofiring ratio ranges from 1-5% biomass with an estimated biomass requirement of 9-12 million tons per year. Technically, with the 1-5% cofiring ratio, the PLTU also does not need to modify its equipment, so that it can be used immediately after the biomass fuel meets the required specifications.

When detailed about the type of technology used by coal power plants in Indonesia today, there are three types of coal power plant, namely, 43 types of PC (Pulverized Coal) with a total capacity of 15,620 MW requiring a mixture of 5% biomass or the equivalent of 10,207.20 tons per day, 38 types of CFB ( Circulating Fluidized Bed) a total capacity of 2,435 MW requires 5% biomass or the equivalent of 2,175.60 tons per day. Meanwhile, 23 types of stoker with a capacity of 220 MW use 100% biomass or the equivalent of 5.088 tons per day. In the short term, the type of biomass used is waste based, while in the long term it is from energy plantations. The Ministry of Environment and Forestry has also allocated a land area of ​​around 12.7 million hectares for the provision of forest land to jointly support the coal power plants biomass supply program. Ex-mining lands covering an area of ​​about 8 million hectares should also be reclaimed using this energy plantation. Even PLN has also signed a memorandum of understanding or a Memorandum of Understanding (MoU) with PTPN III Holding (Persero) and Perum Perhutani. In this case, PLN is the owner of the PLTU, while Perhutani has the resources of industrial forest areas both in Java and outside Java that can be developed as energy plantations. Likewise with PTPN III which has land for the development of energy plantations, read here for more details.

To fulfill the need for biomass as an energy source, energy plantations must be increasingly encouraged. The production of biomass fuels from energy plantations takes longer than processing forestry and agricultural wastes such as felled wood waste, sawdust, wood waste from the wood processing industry, palm oil empty fruit bunches, coconut husks, rice husks, and so on. . The route or option with energy plantations was chosen because in addition to ensuring the quality and quantity of biomass fuel it also optimizes land use, including being integrated with livestock and can be harvested multiple times (coppice) without having to replant for the next harvest. In fact, because energy plantation plants use legumes such as gliricidia and calliandra, which the roots can fix nitrogen from the atmosphere, soil fertility also increases. However, more and more efforts are needed for the energy plantation route because it takes at least 2 years for these crops to be harvested and before that it also needs to prepare the soil and plant the trees.

As previously stated, the choice of production for the type of fuel from energy plantations is influenced by several factors, such as the distance between energy plantations and industrial users, production capacity, industrial needs according to combustion technology and investment cost. If the industrial location or power plant is close to each other, even in the energy plantation area, it is sufficient only to make wood chips from the energy plantation. This is because transportation costs are cheap. Meanwhile, if the location is far enough, the wood should be processed into wood pellets or wood briquette. Wood pellets are indeed much more popular than wood briquettes, although technically wood briquette production is easier and production costs are cheaper. In addition, technically, the density of wood briquette can also be higher than wood pellets. This becomes interesting if a producer is interested in wood briquette production as a product diversification and biomass densification technology.

 

For sustainability, energy plantations will also be better than the use of agricultural and forestry wastes or the timber industry as mentioned above. This is because the plantation is designed and made specifically for the purpose of wood as an energy source. This also makes the volume of wood production more certain than relying on the volume of waste, whose availability depends on the main product. Energy plantations and the following livestock businesses are likely to become an exciting new trend and hopefully the momentum will not be anymore.

Activated Carbon For Flue Gas Desulphurisation (FGD) Process

Exhaust gas emissions, especially from coal power plants, must be made environmentally friendly. About 60% of the world's electricity currently depends on coal, this is because coal power plants can provide electricity at low prices. The exhaust gases that pollute and endanger the environment need to be treated in such a way that they no longer endanger the environment. Coal is a fuel that contains a high enough sulfur content, namely 0.5% (5 kg / ton of coal) so that when it is burned, it will cause SO2 and SO3 gas emissions or the SOx gas group. If these gases are emitted in the atmosphere, they will cause acid rain. The acid rain will damage agricultural land, forests due to imperfect photosynthesis, the death of marine life and corrosion of metal objects such as vehicles, buildings and so on, even human health in the form of respiratory problems such as asthma, chronic bronchitis to permanent lung damage. 

For example, China says more than half of the country's cities experience acid rain and only a few have fresh air. One sixth of the major rivers are so polluted that their water is deemed unsuitable for agriculture. Pollution watchdogs say 16.4% of China's major rivers do not even meet agricultural irrigation standards. Water from big cities such as Shanghai, Tianjin and Guangzhou is said to be highly polluted. Only the tourist island area of Hainan and parts of the northern coast are considered truly healthy. Only 3.6% of the 471 cities monitored received the top ranking in terms of air cleanliness.

 

Efforts to minimize SOx gas emissions (including sulfur dioxide (SO2), sulfur monoxide (SO), and sulfur trioxide (SO3)) are carried out by treating flue gas desulphurisation or the term FGD (Flue Gas Desulphurisation). As of June 1973, there were 42 FGD units operating, 36 in Japan and 6 in the United States, with capacities ranging from 5 MW to 250 MW. Between 1999 and 2000, FGD units were in use in 27 countries, and there were 678 FGD units operating at a total power generation capacity of about 229 gigawatts. About 45% of the FGD capacity is in the US, 24% in Germany, 11% in Japan, and 20% in various other countries. Approximately 79% of the units, representing about 199 gigawatts of capacity, use wet limestone. About 18% (or 25 gigawatts) use spray-dry scrubbers or sorbent injection systems. The use of these FGDs has now been introduced to various places that use fossil fuels such as coal incinerators and waste incinerators.

Basically there are several types of FGD techniques but in general they can be divided into 2, namely the wet method, for example by absorption of wet lime or sea water solutions, dry methods such as activated carbon and semi-dry methods. The wet method is the method most widely used. The "gypsum lime method", which is one of the wet methods, has become a mainstream in the world as a large capacity exhaust gas treatment process especially for thermal power plants. The considerations for selecting the FGD technique include scale, cost, types of by-products, and their application. The lime-gypsum method complicates the gypsum recovery process and the wastewater treatment process, so it is not suitable for application in small boilers. Therefore, in small-scale plants, the "magnesium hydroxide method" which uses magnesium hydroxide, which is a cheap alkaline in addition to lime, is often used. The soda method was a wet method commonly used in pulp mills and small-scale equipment in the second half of the 1960s, but because caustic soda as an absorber is expensive and operating costs are high, a method using magnesium hydroxide, which is a cheaper absorber, has been adopted. 

In the 1960s, Japan developed a lot of dry FGD techniques and since the 1980s wet FGD techniques have been widely used until now. Currently, Japan has all installed the FGD equipment, but it is certain that the need in China and Southeast Asia will increase in the future. Therefore, in recent years, most FGD equipment manufacturers have realized the technological developments being applied to overseas markets, and the development of simple desulphurisation devices suitable for developing countries that are easy to operate and low cost is underway. There is also a by-product from the FGD which has economic value, namely the gypsum FGD. In Indonesia, there is only one coal power plant that uses FGD with wet limestone and produces a gypsum FGD, namely at PLTU Tanjung Jati, Jepara, Central Java. Meanwhile, other coal power plants still use wet technique with sea water absorbtion.

The desulphurisation method with activated carbon is also simultaneous with denitration and functions to remove other components such as removing dioxins and removing heavy metal elements. The activated carbon adsorption method consists of an adsorption tower, a desorption tower, and an activated carbon circulation transfer device. When other components such as NOx are also adsorbed, a module consisting of a number of activated carbon cells forms an adsorption tower, and each component in the exhaust gas is removed as it passes through each module.

Activated carbon which has adsorbed SOx, etc. In the adsorption tower it is sent to the desorption tower, heated to 350 ° C or higher, and regenerated. The regenerated activated carbon is cooled to 150 ° C or lower in the cooling section, then the dust is removed by filtration and reused in the adsorption tower. Instead, the concentrated SO2 gas obtained is washed and purified, then oxidized or reduced, and finally recovered as sulfuric acid, elemental sulfur, or the like.

 Activated carbon has a large surface area because of the many pores on its surface. These pores are intentionally made to increase the efficiency of adsorption. The more pores are formed, the wider the activated carbon surface area. Based on the size of the pores, they are divided into macropore, mesopore and micropore. Activated carbon from coconut shells has many micropores, while activated carbon from wood is dominated by mesopore and macropore (micropore only has a small portion) because the wood structure is also more open. For activated carbon from coal, the distribution of micropore, mesopore and macropore is almost evenly distributed. Based on the above characteristics, coconut shell activated carbon is widely used to absorb small molecules from gas and liquid. Activated carbon from coconut shells and palm kernel shells (PKS) is thought to be the most suitable for the FGD (flue gas desulphurisation) process.