Compost Production with Biochar to Improve Compost Product Quality and Business Profit

Although compost and biochar production both utilize and recycle organic waste, there are several differences: compost production through aerobic fermentation is a biological process, while biochar production through pyrolysis is a thermal process. Furthermore, regarding raw materials, ideal compost production requires a moisture content of 60–70%, high nutrient content, and low lignin content, such as food waste and animal manure. Conversely, ideal biochar production requires a moisture content of 10–20% and a high lignin content, such as woody biomass.

Recent research suggests that adding biochar to the composting process accelerates composting, reduces greenhouse gas emissions such as methane (CH4) and nitrous oxide (N2O), reduces ammonia (NH3) loss, increases aeration and reduces compost density, and reduces odor. The biochar itself is not damaged or decomposed during the composting process but enriches it with various nutrients.

To achieve optimal results, the biochar dosage must be appropriate to the amount of organic matter used in the compost. Using too much biochar will disrupt the composting biodegradation process, and using too little biochar will diminish the positive effects mentioned above. With the appropriate dosage, biochar can accelerate the composting process. This is because it increases the homogeneity and structure of the mixture and stimulates microbial activity in the composting process.

This increased microbial activity will increase the temperature and speed up the composting process. Several studies have shown that adding 5% to 10% of the biochar volume at the start of composting can speed up the composting process by 20%. While the average compost production time is 2 months (9 weeks), adding biochar at the above dosage can speed up the composting process by 20%, or approximately 1.6 months (7 weeks). With the shorter production time and better compost quality, the added biochar can lead to a higher selling price, potentially equivalent to premium compost. This can offset the cost of adding biochar to the compost production process.

The pores in biochar reduce the bulk density of the compost and aid aeration during composting. For nitrogen-rich compost materials such as livestock manure, adding biochar can reduce N loss during composting, particularly NH3. The unpleasant odor is caused by the release of NH3 during composting, and for this reason, many composting facility developments are rejected by local residents. In a study, adding 20% ​​biochar (mass basis) to poultry litter reduced NH3 concentrations in gas emissions by 64% and N loss by 52% without negatively impacting the composting process.

When used, compost decomposes, with nutrients absorbed by plants, while biochar remains in the soil for centuries. This makes biochar a long-term solution for improving soil quality. Using biochar in compost offers both short-term and long-term benefits. The short-term benefit is as an organic fertilizer, while the long-term benefit is improving or stabilizing soil quality and sequestering carbon. CO2 absorbed through photosynthesis becomes biomass, or organic matter, as the raw material for biochar, and the carbon in biochar remains stable for hundreds of years, and is not released into the atmosphere during this time.

There is no data yet showing the calculated amount of compost production in Indonesia per year. However, the potential for compost production from domestic organic waste is very large, reaching around 60% of the total national waste generation which reaches more than 60 million tons per year or more than 36 million tons of organic waste as raw material for compost. There are a number of parties carrying out compost production in various regions in Indonesia, both government and private parties who contribute to compost production, with varying production capacities. With the very abundant organic raw materials (more than 36 million tons/year), the production of biochar-enriched compost can be carried out so as to maximize the quality of compost and other benefits.

This can be achieved by building a biochar production unit or installing a pyrolysis unit at the organic waste source. Organic waste materials that are less suitable for composting can be used for biochar production. Several companies are already planning to do this. Read the related article here. 

Decarbonization in the Steel Industry

World steel production reached 1.9 billion tons in 2020, with China accounting for around half and followed by European Union countries. Germany, with annual production of around 42 million tonnes, is the largest steel producer in Europe or around a quarter of European steel production, while the other quarter is Italy and France, followed by Belgium, Poland and Spain. The steel industry contributes 8% of CO2 globally, each ton of steel production produces an average of 1.85 tons of CO2 emissions and compared to iron ore mining, iron and steel production contributes much more to CO2 emissions. Efforts to decarbonize the steel industry begin with the use of renewable energy for its smelters. Biomass-based fuel in the form of charcoal which has a high carbon value can replace the use of coke derived from coal. And the use of hydrogen from renewable energy sources is the ultimate target for decarbonization in the steel industry. 

Currently, the steel industry mostly uses coal as fuel using blast furnaces. To reduce carbon intensity, natural gas is used as fuel. The use of gas fuel in the form of natural gas is also a transition medium and basically because it comes from fossil fuels it is also a carbon positive fuel. Apart from that, the use of CNG in the form of natural gas is also a transition fuel before switching to hydrogen from renewable energy. The use of biomass-based carbon fuel in the form of charcoal has a better effect on the climate because it is a carbon neutral fuel. Apart from that, technically, because it is a solid fuel, the same as coal, practically there is not much or even no need for changes or modifications to the smelting furnace. The availability of high quality charcoal, large volumes and continuous supply are still the main obstacles.

The use of charcoal for metallurgy or steel making has actually become commonplace for some time. In the early 1900s, world charcoal production experienced its heyday with production of more than 500 thousand tons. In the 1940s, charcoal production decreased to almost half of what it was in the early 1900s, due to other carbon materials, namely coke from coal, replacing charcoal in the manufacture of metals.

With the current conditions of using coal as the main fuel in smelting furnaces or blast furnaces, slag will be produced. Slag or GGBFS (Grounded Granulated Blast Furnace Slag) from the steel plant is used in cement plants as a cement additive or SCM (supplementary cementious material) thereby reducing the portion of clinker in cement production. In the cement plant itself, the more slag or SCM used, the more clinker use is reduced, thereby also reducing CO2 emissions. In cement production, the clinker production section contributes the most to the CO2 emissions produced, so the use of slag or SCM is part of decarbonization in cement plants. It is estimated that around 70% of world steel production uses the blast furnace or BF-BOF process which produces quite a lot of GGBFS, even in China more than 90% of steel production uses the BF-BOF process. It is worth noting that the decarbonization of the steel sector is resulting in a shift away from blast furnaces, which will impact the availability of GGBFS worldwide in the coming decade. However, this change will occur slowly and gradually and, in the meantime, there are a number of GGBFS that will be available for use as SCM to reduce the carbon footprint of cement and concrete.

To be able to produce charcoal in large quantities, raw materials are also needed in large quantities. Raw materials in the form of biomass, especially wood, can be produced from energy plantations. Energy plantations from fast growing species and short rotation crops will be suitable to meet the need for raw materials because apart from the fast harvest period they also have high productivity. Apart from that, there is no need to replant every time it is harvested and it is easy to grow and easy to maintain. To produce steel per ton, an average of 6,000 MJ of energy is required (equivalent to 50 kg of hydrogen) or the equivalent of 200 kg of charcoal and requires around 600-800 kg of wood biomass as raw material. Apart from raw materials from energy plantation wood, raw materials from agricultural and plantation wastes can also be used.

The future palm oil industry could produce hydrogen from biogas. Each ton of steel will require 50 kg of hydrogen, while each palm oil mill with a capacity of 30 ffb/hour can produce 1 MWh of electricity, while the production of 1 kg of hydrogen requires 50 KWh, so that with the capacity of the palm oil mill it can produce 20 kg of hydrogen. Areas with a high concentration of palm oil mills such as Riau province could create a hydrogen pipeline network for environmentally friendly steel mills.

With higher prices for steel produced with renewable energy (green steel), market share is also limited. Currently, only certain uses, such as automotive, buy such premium or green steel. Decarbonization efforts in steel industries can also be carried out in stages, along with the development of renewable energy. With the increasing supply of renewable energy, the price will decrease so that environmentally friendly steel (green steel) will also become more competitive in price. New steel industries can be built close to these cheap renewable energy sources so that green steel production can become competitive.

Green Economy in the Cement Industry Part 6: Clinker Substitution in Cement Plants

Substituting clinker with additives or SCM (Supplementary Cementious Material) plays a major role in efforts to reduce CO2 emissions in cement plants. This clinker substitution is ranked second after carbon capture or CCS (Carbon Capture and Storage) in efforts to reduce CO2 emissions or decarbonization in the cement industry. This is because the largest CO2 emissions in cement plants are not from combustion or related to fuel but in the calcination process. CCS technology is still expensive so its implementation still faces many obstacles, but clinker substitution is easier to do, so many cement plants are already doing it. 

In the cement industry, all fuel use and around 60% of electricity use is used for clinker production starting from grinding raw materials, fuel preparation and cement kilns. The higher the clinker to cement ratio, the higher the electricity and fuel used for each ton of cement produced. The clinker to cement ratio can be reduced if less clinker is used in cement production or more additional materials or SCM are added to the clinker. This also means that substituting clinker with SCM can significantly reduce energy use (electricity and fuel) for each ton of cement produced. 

China currently has the lowest clinker to cement ratio in the world, namely 0.58, while a number of areas in other countries have the highest ratio, up to 0.9. It can also be understood that China uses the highest portion of SCM compared to countries in the world. The most commonly used SCMs today are fly ash, ground granulated blast-furnace slag (GGBFS) and ground limestone. Meanwhile, other SCMs such as pozzolan and calcined clay have the potential to be used in the future.

Fly ash comes from by-products or waste from coal-fired power plants. Decarbonization of coal power plants is also continuing to be carried out, namely by cofiring coal with biomass, but this is being done in stages so that fly ash production will still be large for a while. Fly ash from coal-fired power plant waste is very useful in cement production because it reduces the clinker to cement ratio, thereby reducing energy requirements for cement production or in other words reducing the carbon footprint of cement products. Meanwhile, GGBFS comes from iron and steel plant waste. Not all iron and steel plants produce GGBFS waste, this is because it depends on the type of furnace used. Only plants that use blast furnaces - basic oxygen furnaces (BF - BOF) can produce GGBFS, while those that use electric arc furnaces (EAF) cannot. Around 70% of iron and steel plants in the world currently use the BF – BOF process so as to produce quite a lot of GGBFS, even in China more than 90% use this BF – BOF process. Decarbonization in the iron and steel industry is marked by the switch from BF – BOF to EAF which results in the availability of GGBFS. However, the process is running slowly and gradually, so that for a while the amount of GGBFS will be available and can reduce the carbon footprint of cement production.

The use of fly ash in cement production is usually limited to 25-35% for technical performance reasons. Meanwhile, GGBFS can be used in larger portions than fly ash or other SCM. Even European standards allow the use of GGBFS up to 95% but in practice it is lower. Other SCMs commonly used are pozzolan and calcined clay. Pozzolan comes from mining, namely from deposits in nature. Pozzolan requires drying and grinding before being used in cement production. The electricity used for crushing (grinding) pozzolan is also almost the same as crushing clinker. Calcined clay can also be used as a substitute for clinker. The initial use of calcined clay with a higher portion causes a decrease in the compressive strength of the cement product produced. However, further developments using a combination or mixture of calcined clay with limestone powder have the potential to substitute up to 50% clinker without affecting the quality of the cement. Calcined clay is produced from the clay calcination process which requires energy, but the energy required is much less than the energy for clinker production. It is predicted that in 2050 by the IEA (International Energy Agency) / WBCSD (World Business Council for Sustainable Development) cement production with the above combination of materials will reach more than 25% worldwide.

It turns out that the use of SCM is not only a substitute for clinker in cement production but also in concrete production. The use of SCM in concrete production is also no less than a substitute for clinker, even in the United States SCM is mostly added during concrete production and not during cement production. A study in the United States estimated that only 5% of SCM was added to cement production and around 13% to concrete production. But basically the addition of SCM to both cement production and concrete production has reduced the carbon footprint or is in line with decarbonization. The problem is that the lack of education regarding the benefits of SCM, especially in concrete production, is a barrier to increasing the use of SCM. Other factors such as the availability of SCM, price and its relation to cement and building quality are also similar barriers. The creation of new standards and codes related to increasing the use of blended cement with SCM and concrete production needs to be developed to transform the current market.

Green Economy in the Cement Industry Part 5 : Increasing Production and Reducing Emissions

Increasing production capacity but simultaneously reducing CO2 emissions (carbon dioxide, the dominant greenhouse gas) sounds contradictory / paradoxical. It is indeed like that in passing. However, with a decarbonization or CO2 removal (CDR) program, efforts to reduce emissions can be done while increasing cement production. How big the target of reducing emissions and increasing cement production will depend on how much decarbonization efforts are made. The greater the reduction in emissions, the more expensive it will usually be. This is why efforts to reduce emissions while increasing production must also be carried out in stages with certain strategies.

Cement plant is an industry that contributes to an increase in CO2 of more than 6% globally. However, there is something unique about this cement industry, namely that most of the CO2 emissions produced do not come from fuel use, but from the calcination process. The percentage of CO2 produced from the calcination process reaches around 60%, while from fuel use it is only around 40%. The fossil fuels commonly used in cement industries are coal and petcoke, both of which are the two fossil fuels that pollute the air the most. In fact, in a number of areas cement plants are the largest coal users. Cement plants close to oil refineries will use more petcoke.

Decarbonization programs or efforts to reduce CO2 emissions that can be carried out in cement plants include increasing energy efficiency, using clinker substitute materials, using alternative/renewable energy, and using CCUS (Carbon Capture Utilization and Storage). With these characteristics, total decarbonization in the cement industry cannot be carried out by using only the best efficiency technology or by simply replacing the fuel. Meanwhile, the use of clinker substitutes and CCUS is very important among other technologies to achieve near-zero emissions in cement production.

The best scenario for increasing production and reducing emissions can be done by using much higher energy efficiency improvements using commercially available technology, using more aggressive fuels to low carbon or even carbon neutral fuels, using higher rates of clinker substitute materials. and adopting a higher portion of commercially available CCUS technologies.

And it's worth noting that all suggested improvements in these best-case scenarios can be achieved by implementing technologies that are already commercially available and most of them should also be cost-effective. As for CCUS, while the technology is commercially available, implementation requires large investments that demand higher financial incentives or carbon prices. However, on the other hand, CCUS has the largest contribution to CO2 reduction, followed by the use of clinker substitutes and the switch to low-carbon or even carbon-neutral fuels. And the use of efficiency-enhancing technology has the smallest contribution to reducing CO2 emissions. This is mainly because process-related emissions from calcination account for around 60% of total CO2 emissions and are not related to energy use.

Green Economy in the Cement Industry Part 3

Fly ash is a byproduct or waste of coal power plants. Like slag, fly ash is also an additive or supplement (SCM/supplementary cementious material) in cement production. The difference is that fly ash is very fine so it doesn't need to be refined anymore and can be mixed directly with clinker and gypsum. Every ton of fly ash used prevents about 1 ton of carbon dioxide (CO2) from escaping into the atmosphere. This is in line with the green economy or decarbonization as a climate solution effort for the industry.

Unloading fly ash

As the same with slag, the chemical content of fly ash also influences the quality of the cement produced, for example certain regions or countries have requirements for grade 120 alumina in the slag. Cement with a certain quality can be designed with the use of these additives. In the current era, apart from technical factors such as mechanical strength or cement adhesion, microstructure, durability and so on, and economic factors, environmental friendly product factors are also a concern or have their own positive image. Circular economy in the form of utilizing waste from other industries to become raw materials for this industry, also occurs in the cement industry. And basically the cement industry besides being able to process waste is also a waste destroyer.

Production of Cow Dung Briquettes / Pellets as Fuel and Bioeconomy

The use of renewable energy is increasing along with global awareness of environmental and climate issues. Materials that used to be considered waste and polluted the environment, now with the concept of zero waste and circular economy, many have been converted into alternative energy or renewable energy. Large industries such as power plants, cement industry and so on have started to use this renewable energy in the framework of CO2 emission reduction or decarbonization programs. This decarbonization program is increasingly popular and is applied to various lines of life. 

As a real example is the cement industry in the UAE, namely Gulf Cement Co., which uses renewable energy from camel dung. From the results of operational trials it was found that every 2 tons of camel dung can replace 1 ton of coal. The use of animal dung as fuel is actually not a new thing for them, from ancestral stories cow dung has been used as heating or fuel, but many have not thought of camel dung. Gulf Cement Co currently uses 50 tons/day of camel dung as fuel. The UAE has a population of around 9000 camels for milk production, racing and beauty contests. Each camel produces 8 kg of manure per day, more or more than the farmer needs. Through a government program, camel breeders collect the camel dung at collection points. 

Cow dung has also been used as an energy source from the United States, Zimbabwe to China. In Indonesia this should also be done. With each cow producing an average of 15 kg of dung per day (about 2 times that of a camel), this is the same as the conditions in the UAE above, the volume of dung is more or more than what farmers need. The excess of this waste becomes an environmental problem and even has to be thrown into rivers and so on. Hundreds of tons of cow dung every day are not utilized in a number of areas in Indonesia, even though the dung can be used as fuel, especially when processed into briquettes or pellets (dried first). Compaction of cow dung into briquettes or pellets aims to obtain uniform size and shape, compactness, ease of storage and use, as well as saving on transportation costs. And to meet the needs of cement factory materials, such as briquettes / cow dung pellets are needed in large quantities, so large capacity production equipment is needed that works continuously. It is estimated that the need for pellets or briquettes is thousands to tens of thousands of tons every month.

In a cement plant there are 2 places that need heat energy: 1. calciner (where the calcination process occurs), 2. Rotary kiln (the heart of the cement factory, where the clinker is made). Renewable energy, such as briquettes or cow dung pellets, will usually be used in calciners with separate feeding points. Meanwhile, in rotary kilns that require higher heat, cement plants generally still use fossil fuels. The gradual use of renewable energy will reduce environmental pollution and accelerate the global decarbonization program. The cement plant itself can be said to be an industry that processes and destroys waste. This is because the cement plant can process waste such as slag and fly ash as an additive to the cement it produces - more details can be read here and also destroys waste, such as using cow dung as the fuel.

 

Utilization of Land Clearing Wood Waste For Charcoal And Briquette Production

Land clearing is mostly done, especially for the establishment of new plantations, both plantations for food crops and plantations or forests for wood products. The establishment of palm oil plantations and acacia forests are examples. Prior to planting palm oil or acacia, the location which is usually natural forest was cleared of vegetation or trees beforehand. Natural forests, of course, have various types of trees, both in terms of their types and ages. Some trees have a large diameter while others are smaller. After clearing the old trees, then the land is conditioned for the allocation of the plantation.

Indeed, the establishment of the plantation or forest must be in accordance with the land designation. Of course, land that is protected forest or conservation forest cannot be used for production forest or industrial plantation forest. This of course concerns environmental factors in the form of environmental preservation, such as forests as a source of water, preventing the danger of landslides, as a carbon sink and so on. The economic activities of production forests must also pay attention to environmental aspects so that the business being carried out can also be sustainable. Wood, for example, as a source of biomass for various industrial raw materials, can be said to be a renewable source only if it is managed properly and sustainably.

During the land clearing, a lot of wood just becomes waste. Timber with large diameters can be sold to sawmills. However, small diameter woods such as branches and twigs are mostly not utilized, even though there are many. The solution to this problem can be processed into charcoal and briquettes. Non-salable logs for sale in sawmills can be used for charcoal production. With good technology, high quality charcoal production can be done, namely with a fixed carbon of more than 82%. Production quantity up to 3000 tonnes / year of charcoal are also possible. Meanwhile, waste wood in the form of smaller twigs or pieces of wood can be used for briquette production. The production of briquettes is easier and also cheaper than wood pellets. Another thing that distinguishes briquettes from pellets, especially the market segment, can be read here for more details.