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.

 

Wood Pellet Production: With a Rotary Dryer or Belt Dryer?

Air quality is an important factor in environmental health. The better the air quality, the better the environmental quality. Maintaining clean air quality is sometimes not something that is easy and cheap, especially for industry players. The higher the air quality standard used, the greater the effort and cost incurred.

In the wood pellet industry as an example, especially in the use of dryer. Almost all wood pellet industries in Asia use rotary dryer and almost none use belt dryer. Meanwhile, in Europe belt dryers are widely used because of lower emission than rotary dryers. In addition, belt dryers also have higher efficiency and can work at lower temperatures than rotary dryers. With a number of these advantages, however, belt dryer are also more expensive compared with rotary dryer.

Basically, rotary dryer can also have good performance, especially in terms of emissions if they are designed and operated properly. The use of high-efficiency dust collectors such as cyclones and bag filters can achieve high emission quality standards. However, the higher the efficiency of the dust collector, the higher the power required.

So the choice used actually depends on the expected air emission target. Europe and US/Canada generally have higher air quality standards than countries in Asia. This makes the emission aspect an important concern for them. Meanwhile, in terms of wood pellet production, the priority aspect is efficiency, so that with good performance the dryer can produce dry wood powder product that are suitable for feeding into pelletiser. The quality of the wood pellets as the final result is also very dependent on the quality of the dry powder product from the dryer. Meanwhile, in terms of safety, the high concentration of dust particles so that they can accumulate in a number of places in the wood pellet factory also has a greater potential for fires to occur.

Wood Pellet Export Opportunities
The lack of supply of wood pellets in Europe due to the Russia-Ukraine war caused wood pellet producers from Southeast Asia and North America to try to seize this opportunity. Production of wood pellets from Russia is estimated at around 3 million tonnes/year which previously filled the European market is now banned, so as a result of this ban the stocks of wood pellets in Europe have decreased drastically. The large demand and lack of supply will naturally push up prices, especially when coupled with increases in other energy commodities, so that the price of wood pellets continues to increase. In fact, because of the high price of wood pellets in Europe, wood pellets from Vietnam, which previously planned to be exported to Japan, were diverted to Europe.

It is also predicted that this uncertain condition will not recover in a short time. In 2021 Europe leads the production of wood pellets with production reaching nearly 20 million tons or around 48% of global production, while consumption of wood pellets reaches 24.5 million tons. Meanwhile, according to Hawkin Wright's data for 2020-2021, the growth in global demand for wood pellets has reached 18.4%, while supply or production growth is only 8.4%. Indonesia should have a great opportunity to become a major wood pellet player with its potential. The wood pellet production can be exported to Europe to cover the shortage of supply and in general to meet global demand.

Green Economy in the Cement Industry

The trend of decarbonization, including the low carbon economy, has penetrated various sectors, including the cement industry. Cement is the most common human-made product in the world, consuming about 0.5 tons per person per year. The cement industry is also a significant contributor to greenhouse gases, reaching 21% (IPCC 2014), with these conditions making it one of the biggest contributors to climate change. And because the cement industry has a history as a major contributor to these greenhouse gas emissions, there are opportunities today to reduce emissions significantly through increasing efficiency and innovation in the industry.

Increasing energy efficiency in cement production will reduce the resulting carbon emissions. Even in the cement industry, the use of energy is also slowly starting to be used as renewable energy or alternative energy, including the use of RDF from municipal waste or household waste, which more or less reduces environmental pollution. While in the production aspect the use of additional materials originating from other industrial waste (circular economy) such as slag and fly ash or SCM (supplementary cementious materials) has also been widely used. The addition of these materials depends on the type of cement to be made and aims to reduce the use of clinker because clinker production requires high costs and produces CO2 gas as a result of calcination. For example, the manufacture of slag cement produces 38% less CO2 emissions than the process for the production of portland cement because less limestone is burned for the production of slag cement than is required for Portland cement. In addition, a number of countries also support the production and use of slag cement in order to support environmentally friendly products. The things above also indicate concern for the environment and sustainability is increasing.

In the cement industry, about 50% of emissions come from the calcination process itself, 40% from fuel for heating the kiln, and the remaining 10% from grinding and transport. Inside the calciner, a calcination process occurs, namely the decomposition of CaCO3 into CaO and CO2 and a little MgCO3 into MgO and CO2. Because the calcination reaction is endothermic, high heat is required, so it is equipped with a burner for burning coal utilizing tertiary air from the cooler and hot gas from the kiln. The release of CO2 due to the reaction in the calciner is a crucial environmental issue in the cement industry, the volume of CO2 gas from calcination is much greater than CO2 from burning fuel (coal) or 50% to 40%.

Various types of cement with different qualities often require specific SCM qualities as well. Under these conditions the review is not only general specifications but down to the chemistry of the material. For example slag from a steel plant or Granulated Blast Furnace Slag (GBFS) with a certain chemical content or fly ash but with a low alkaline content or slag from a nickel smelter not suitable for certain types of cement and so on. To obtain specific SCM such as slag and fly ash is closely related to the particular source of slag and fly ash, although in some cases it is possible to add certain materials to obtain the desired chemical composition.

And in the cement industry, emissions are not easily reduced. Emissions from processes cannot be reduced by optimizing or using only renewable energy or alternative energy. In the cement industry, when following the scenarios developed by the International Energy Agency (IEA) or the Intergovernmental Panel on Climate Change (IPCC), it is clear that to reach the limit of 2 C or even 1.5 C, cabon capture and storage / carbon capture and utilization (CCS / CCU) is needed. However, more is needed if the industry is to meet the ambitious goals set by the Paris agreement. The cement industry is particularly challenged by this target because carbon is generated by the energy used in the process and the calcination process itself. Even if energy-based emissions could be eliminated by switching to carbon-neutral fuels, those calcination process emissions would still be present and would require a carbon capture unit (CCS/CCU).

Europe has become a research center for carbon capture and storage (CCS) and carbon capture and utilization (CCU). From a number of carbon capture technologies, amine-based absorption (organic compounds and functional groups whose contents consist of lone-paired nitrogen atoms) is the most advanced carbon capture technology and has been implemented on a commercial scale. Carbon capture technology seems to play an important role in fighting climate change, especially in the cement industry.