Large quantities of agricultural wastes, resulting from crop cultivation activities, are a promising source of energy supply for production, processing and domestic activities in rural areas of the concerned region. The available agricultural residues are either being used inefficiently or burnt in the open to clear the fields for subsequent crop cultivation.
On an average 1.5 tons of crop residue are generated for processing 1 ton of the main product. In addition, substantial quantities of secondary residues are produced in agro-industries processing farm produce such as paddy, sugarcane, coconut, fruits and vegetables.
Agricultural crop residues often have a disposal cost associated with them. Therefore, the “waste-to-energy” conversion processes for heat and power generation, and even in some cases for transport fuel production, can have good economic and market potential. They have value particularly in rural community applications, and are used widely in countries such as Sweden, Denmark, Netherlands, USA, Canada, Austria and Finland.
The energy density and physical properties of agricultural biomass wastes are critical factors for feedstock considerations and need to be understood in order to match a feedstock and processing technology.
There are six generic biomass processing technologies based on direct combustion (for power), anaerobic digestion (for methane-rich biogas), fermentation (of sugars for alcohols), oil exaction (for biodiesel), pyrolysis (for biochar, gas and oils) and gasification (for carbon monoxide and hydrogen-rich syngas). These technologies can then be followed by an array of secondary treatments (stabilization, dewatering, upgrading, refining) depending on specific final products.
It is well-known that power plants based on baled agricultural residues are efficient and cost-effective energy generators. Residues such as Rice Husks, Wheat Straw and Maize Cobs are already concentrated at a point where it is an easily exploitable source of energy, particularly if it can be utilized on-site to provide combined heat and power.
The selection of processing technologies needs to be aligned to the nature and structure of the biomass feedstock and the desired project outputs. It can be seen that direct combustion or gasification of biomass are appropriate when heat and power are required.
Anaerobic digestion, fermentation and oil extraction are suitable when specific biomass wastes are available that have easily extractable oils and sugars or high water contents. On the other hand, only thermal processing of biomass by pyrolysis can provide the platform for all of the above forms of product.
Moisture content is of important interest since it corresponds to one of the main criteria for the selection of energy conversion process technology. Thermal conversion technology requires biomass fuels with low moisture content, while those with high moisture content are more appropriate for biological-based process such as fermentation or anaerobic digestion.
The ash content of biomass influences the expenses related to handling and processing to be included in the overall conversion cost. On the other hand, the chemical composition of ash is a determinant parameter in the consideration of a thermal conversion unit, since it gives rise to problems of slagging, fouling, sintering and corrosion.
Polyvinyl chloride is one of the most widely used plastics worldwide. A major problem in the recycling of polyvinyl chloride is the high chlorine content in raw PVC and high levels of hazardous additives added to the polymer to achieve the desired material quality. As a result, PVC requires separation from other plastics before mechanical recycling. PVC products have an average lifetime of 30 years, with some reaching 50 or more years. This means that more PVC products are reaching the end-of-life and entering the waste stream, and the amount is likely to increase significantly in the near future.
PVC Recycling Methods
Currently, PVC is being recycled by either one of the two ways:
Mechanical recycling – This involves mechanically treating the waste (e.g. grinding) to reduce it into smaller particles. The resulting granules, called recyclate, can be melted and remolded into different products, usually the same product from which it came.
Feedstock recycling – Chemical processes such as pyrolysis, hydrolysis and heating are used to convert the waste into its chemical components. The resulting products – sodium chloride, calcium chloride, hydrocarbon products and heavy metals to name a few – are used to produce new PVC, as feed for other manufacturing processes or as fuel for energy recovery.
In mechanical recycling, because no chemical reaction is involved, the recyclate retains its original composition. This poses a recycling challenge because PVC products, depending on their application, contain different additives. For example, rigid PVC is unplasticized whereas flexible PVC is added plasticizers because this additive increases the plastic’s fluidity and thus, its flexibility. Even products used for the same application may still differ in composition if they have different manufacturers.
When different kinds of PVC waste are fed to a mechanical recycler, the resulting product’s composition is difficult to predict, which is problematic because most PVC products, even recycled ones, require a specific PVC content. In order to produce a high-quality recylate, the feed ideally should not be mixed with other kinds of plastic and should have a uniform material composition.Material recycling is therefore more applicable for post-industrial waste than for post-consumer waste.
Feedstock recycling is seen to be complementary to conventional mechanical recycling as it is able to treat mixed or unsorted PVC waste and recover valuable materials. However, a study showed that feedstock recycling (or at least the two that was considered) incurred higher costs than landfilling, primarily due to the low value of the recovered products. This provides little incentive for recyclers to pursue PVC recycling. This may change in the future as more stringent regulations to protect the environment are enacted. Some countries in Europe have already banned PVCs from landfills and PlasticsEurope is targeting a “zero plastic to landfill” in Europe by 2020.
Post-industrial waste is relatively pure and comes from PVC production and installation, such as cut-offs from laying of cables or scraps from the installation of window frames. These are easily recycled since they can be collected directly from processors or installers or even recycled by producers themselves as raw material to manufacture the same product.
Post-consumer waste contains mixed material and has been used for different applications. These are products that have reached the end-of-life or are replaced due to damage, like pipes from underground, window frames being replaced for renovation and electric cables recovered from demolition. These would require further sorting and cleaning, adding cost to the recycling process. The recyclate produced is usually of lower quality and consequently of decreased economic value.
Europe is leading the way for a more sustainable use of PVC with programs, such as RecoVinyl and VinylPlus, where recycling is advanced as one of the ways to use resources more efficiently and to divert as much waste as possible from landfills. Recovinyl, created in 2003, is an initiative of the European PVC industry to advance the sustainable development of the PVC industry by improving production processes, minimise emissions, develop recycling technology and boost the collection and recycling of waste.
Having been successful in all of its goals, including an increase in recycling of PVC across Europe to over 240,000 tonnes a year, in 2011 the PVC industry redefined the role of Recovinyl as part of the ambitious new ten-year VinylPlus sustainable development programme. VinylPlus works in partnership with consumers, businesses, municipalities, waste management companies, recyclers and converter, as well as the European Commission and national and local governments. The goal is to certify those companies who recycle PVC waste and those accredited converting companies who purchase recyclate to manufacture new products and applications.
Even if some types of PVC recycling are not feasible or economically viable at present, it will likely be reversed in the future as governments, manufacturers, consumers and other stakeholders create programs that innovate and find ways to achieve a sustainable future for the PVC industry.
The major techno-commercial limitations of existing biofuels has catalyzed the development of advanced biofuels such as cellulosic ethanol, biobutanol and mixed alcohols. Biobutanol is generating good deal of interest as a potential green alternative to petroleum fuels. It is increasingly being considered as a superior automobile fuel in comparison to bioethanol as its energy content is higher. The problem of demixing that is encountered with ethanol-petrol blends is considerably less serious with biobutanol-petrol blends. Besides, it reduces the harmful emissions substantially. It is less corrosive and can be blended in any concentration with petrol (gasoline). Several research studies suggest that butanol can be blended into either petrol or diesel to as much as 45 percent without engine modifications or severe performance degradation.
Production of Biobutanol
Biobutanol is produced by microbial fermentation, similar to bioethanol, and can be made from the same range of sugar, starch or cellulosic feedstocks. The most commonly used microorganisms are strains of Clostridium acetobutylicum and Clostridium beijerinckii. In addition to butanol, these organisms also produce acetone and ethanol, so the process is often referred to as the “ABE fermentation”.
The main concern with Clostridium acetobutylicum is that it easily gets poisoned at concentrations above 2% of biobutanol in the fermenting mixture. This hinders the production of bio-butanol in economically viable quantities. In recent years, there has been renewed interest in biobutanol due to increasing petroleum prices and search for clean energy resources. Researchers have made significant advances in designing new microorganisms capable of surviving in high butanol concentrations. The new genetically modified micro-organisms have the capacity to degrade even the cellulosic feedstocks.
Biobutanol production is currently more expensive than bioethanol which has hampered its commercialization. However, biobutanol has several advantages over ethanol and is currently the focus of extensive research and development. There is now increasing interest in use of biobutanol as a transport fuel. As a fuel, it can be transported in existing infrastructure and does not require flex-fuel vehicle pipes and hoses. Fleet testing of biobutanol has begun in the United States and the European Union. A number of companies are now investigating novel alternatives to traditional ABE fermentation, which would enable biobutanol to be produced on an industrial scale.
The palm kernel shells used to be initially dumped in the open thereby impacting the environment negatively without any economic benefit. However, over time, palm oil mills in Southeast Asia and elsewhere realized their brilliant properties as a fuel and that they can easily replace coal as an industrial fuel for generating heat and steam.
Nowadays, the primary use of palm kernel shells (PKS) is as a boiler fuel supplementing the fibre which is used as primary fuel. In recent years kernel shells are extensively sold as alternative fuel around the world. Besides selling shells in bulk, there are companies that produce fuel briquettes from shells which may include partial carbonisation of the material to improve the combustion characteristics.
Palm kernel shells have a high dry matter content (>80% dry matter). Therefore the shells are generally considered a good fuel for the boilers as it generates low ash amounts and the low K and Cl content will lead to less ash agglomeration. These properties are also ideal for production of biomass for export.
As a raw material for fuel briquettes, palm shells are reported to have the same calorific characteristics as coconut shells. The relatively smaller size makes it easier to carbonise for mass production, and its resulting palm shell charcoal can be pressed into a heat efficient biomass briquette.
Although the literature on using oil palm shells (and fibres) is not as extensive as EFB, common research directions of using shells, besides energy, are to use it as raw material for light-weight concrete, fillers, activated carbon, and other materials. However, none of the applications are currently done on a large-scale. Since shells are dry and suitable for thermal conversion, technologies that further improve the combustion characteristics and increase the energy density, such as torrefaction, could be relevant for oil palm shells.
Torrefaction is a pretreatment process which serves to improve the properties of biomass in relation to the thermochemical conversion technologies for more efficient energy generation. High lignin content for shells affects torrefaction characteristics positively (as the material is not easily degraded compared to EFB and fibres).
Furthermore, palm oil shells are studied as feedstock for fast pyrolysis. To what extent shells are a source of fermentable sugars is still not known, however the high lignin content in palm kernel shells indicates that shells are less suitable as raw material for fermentation.
The leading palm oil producers in the world should consider limiting the export of palm-kernel shells (PKS) to ensure supplies of the biomass material for renewable energy projects, in order to decrease dependency on fossil fuels. For example, many developers in Indonesia have expressed an interest in building palm kernel shell-fired power plants. However, they have their concerns over supplies, as many producers prefer to sell their shells overseas currently. Many existing plants are facing problems on account of inconsistent fuel quality and increasing competition from overseas PKS buyers. PKS market is well-established in provinces like Sumatra and export volumes to Europe and North Asia as a primary fuel for biomass power plants is steadily increasing.
The creation of a biomass supply chain in palm oil producing countries may be instrumental in discouraging palm mills to sell their PKS stocks to brokers for export to foreign countries. Establishment of a biomass exchange in leading countries, like Indonesia, Malaysia and Nigeria, will also be a deciding factor in tapping the unharnessed potential of palm kernel shells as biomass resource.
Waste-to-Energy is the use of modern combustion and biochemical technologies to recover energy, usually in the form of electricity and steam, from urban wastes. These new technologies can reduce the volume of the original waste by 90%, depending upon composition and use of outputs. The main categories of waste-to-energy technologies are physical technologies, which process waste to make it more useful as fuel; thermal technologies, which can yield heat, fuel oil, or syngas from both organic and inorganic wastes; and biological technologies, in which bacterial fermentation is used to digest organic wastes to yield fuel.
The global market for waste-to-energy technologies was valued at US$6.2bn in 2012 which is forecasted to increase to US$29.2bn by 2022. While the biological WTE segment is expected to grow more rapidly from US$1.4bn in 2008 to approximately US$2.5bn in 2014, the thermal WTE segment is estimated to constitute the vast bulk of the entire industry’s worth. This segment was valued at US$18.5bn in 2008 and is forecasted to expand to US$23.7bn in 2014.
The global market for waste to energy technologies has shown substantial growth over the last five years, increasing from $4.83 billion in 2006, to $7.08 billion in 2010 with continued market growth through the global economic downturn. Over the coming decade, growth trends are expected to continue, led by expansion in the US, European, Chinese, and Indian markets. By 2021, based on continued growth in Asian markets combined with the maturation of European waste management regulations and European and US climate mitigation strategies, the annual global market for waste to energy technologies will exceed $27 billion, for all technologies combined.
Asia-Pacific’s waste-to-energy market will post substantial growth by 2015, as more countries view the technology as a sustainable alternative to landfills for disposing waste while generating clean energy. In its new report, Frost & Sullivan said the industry could grow at a compound annual rate of 6.7 percent for thermal waste-to-energy and 9.7 percent for biological waste-to-energy from 2008 to 2015.
The WTE market in Europe is forecasted to expand at an exponential rate and will continue to do so for at least the next 10 years. The continent’s WTE capacity is projected to increase by around 13 million tonnes, with almost 100 new WTE facilities to come online by 2012. In 2008, the WTE market in Europe consisted of approximately 250 players due in large to the use of bulky and expensive centralized WTE facilities, scattered throughout Western Europe.
Many countries around the world have switched to solar power in order to supplement or provide an alternative source of energy that is cheaper, more reliable and efficient, and friendly to the environment. Generally speaking, to convert solar energy to electricity, there are two kinds of technologies used by the solar power plants – the PV (photovoltaic) systems which use solar panels to convert sunlight directly into electricity, and the CSP (Concentrated Solar Power) that indirectly uses the solar thermal energy to produce electricity.
The solar PV systems, which are either placed in ground-mounted solar farms or on rooftops are considered cheaper than CSP and constitutes the majority of solar installations, while CSP and large-scale PV accounts for the majority of the general solar electricity-generation-capacity, across the globe.
Global Trends in Solar Energy
In 2017, photovoltaic capacity increased by 95 GW, with a 34% growth year-on-year of new installations. Cumulative installed capacity exceeded 401 GW by the end of the year, sufficient to supply 2.1 percent of the world’s total electricity consumption. This growth was dramatic, and scientists viewed it as a crucial way to meet the world’s commitments to climate change.
“In most countries around the world there is still huge potential to dramatically increase the amount of energy we’re able to get from solar. The only way to achieve this is through a combination of both governance and individual responsibility.” Alastair Kay, Editor at Green Business Watch
Both CSP and PV systems are undergoing a considerable amount of growth and experts claim that by 2050, solar power will become the greatest source of electricity in the whole world. To achieve this goal, the capacity of PV systems should grow up to 4600 gigawatts, of which 50% or more would come from India or China. To date, the capacity of solar power is about 310 gigawatts, a drastic increase on the 50 gigawatts of power installed in 2010.
The United Kingdom, followed by Germany and France led Europe in the 2016 general statistics for solar power growth with new solar installations of 29%, 21%, and 8.3% respectively. In early 2016, the amount of power across Europe was near 100 gigawatts but now stands at 105 gigawatts. This growth is regarded as slow and experts in the solar industry are calling upon the European Union to give more targets concerning the renewable source of energy. It is said that setting a target that is not less than 35% will revive the solar business in Europe.
Across the United States in places, such as Phoenix and Los Angeles, which are located in a sunny region, a common PV system can generate an average of 7500 kWh – similar to the electrical power in use in a typical US home.
In Africa, many nations especially those around the deserts such as Sahara receive a great deal of sunlight every day, creating an opportunity for the development of solar technology across the region. Distribution of PV systems is almost uniform in Africa with the majority of countries receiving about 2000 kWh/m2 in every year. A certain study shows that generating solar power in a facility covering about 0.3% of the area consisting of North Africa could provide all the energy needed by the European-Union.
Asia alone contributed to 66.66% of the global amount of solar power installed in 2016, with about 50% coming from China.
With these reports, it is clear that the development of solar energy technology is growing in each and every continent with just a few countries with little or no apparent growth.
The growth of solar power technology across every continent in the world is very fast and steady and in the near future, almost every country will have a history to tell about the numerous benefits of going solar. The adoption of solar power will help improve the development of other sectors of the economy, such as the electronics industry, hence creating a lot of employment opportunities.
Biogas that has been upgraded by removing hydrogen sulphide, carbon dioxide and moisture is known as biomethane. Biomethane is less corrosive than biogas, apart from being more valuable as a vehicle fuel. The typical composition of raw biogas does not meet the minimum CNG fuel specifications. In particular, the CO2 and sulfur content in raw biogas is too high for it to be used as vehicle fuel without additional processing.
Biomethane can be liquefied, creating a product known as liquefied biomethane (LBM). Biomethane is stored for future use, usually either as liquefied biomethane or compressed biomethane (CBM) or since its production typically exceeds immediate on-site demand.
Two of the main advantages of LBM are that it can be transported relatively easily and it can be dispensed to either LNG vehicles or CNG vehicles. Liquid biomethane is transported in the same manner as LNG, that is, via insulated tanker trucks designed for transportation of cryogenic liquids.
Biomethane can be stored as CBM to save space. The gas is stored in steel cylinders such as those typically used for storage of other commercial gases. Storage facilities must be adequately fitted with safety devices such as rupture disks and pressure relief valves.
The cost of compressing gas to high pressures between 2,000 and 5,000 psi is much greater than the cost of compressing gas for medium-pressure storage. Because of these high costs, the biogas is typically upgraded to biomethane prior to compression.
Applications of Biomethane
The utilization of biomethane as a source of energy is a crucial step toward a sustainable energy supply. Biomethane is more flexible in its application than other renewable sources of energy. Its ability to be injected directly into the existing natural gas grid allows for energy-efficient and cost-effective transport. This allows gas grid operators to enable consumers to make an easy transition to a renewable source of gas. The diverse, flexible spectrum of applications in the areas of electricity generation, heat provision, and mobility creates a broad base of potential customers.
Biomethane can be used to generate electricity and heating from within smaller decentralized, or large centrally-located combined heat and power plants. It can be used by heating systems with a highly efficient fuel value, and employed as a regenerative power source in gas-powered vehicles.
Biomethane to Grid
Biogas can be upgraded to biomethane and injected into the natural gas grid to substitute natural gas or can be compressed and fuelled via a pumping station at the place of production. Biomethane can be injected and distributed through the natural gas grid, after it has been compressed to the pipeline pressure. In many EU countries, the access to the gas grid is guaranteed for all biogas suppliers.
One important advantage of using gas grid for biomethane distribution is that the grid connects the production site of biomethane, which is usually in rural areas, with more densely populated areas. This enables the gas to reach new customers. Injected biomethane can be used at any ratio with natural gas as vehicle fuel.
Biomethane is more flexible in its application than other renewable sources of energy.
The main barriers for biomethane injection are the high costs of upgrading and grid connection. Grid injection is also limited by location of suitable biomethane production and upgrading sites, which have to be close to the natural gas grid.
Several European nations have introduced standards (certification systems) for injecting biogas into the natural gas grid. The standards, prescribing the limits for components like sulphur, oxygen, particles and water dew point, have the aim of avoiding contamination of the gas grid or the end users. In Europe, biogas feed plants are in operation in Sweden, Germany, Austria, the Netherlands, Switzerland and France.
There has been a flurry of activity in the biomass energy and waste-to-energy sector in recent year, with many new projects and initiatives being given the green light across the globe. This movement has been on both a regional and local level; thanks to the increased efficiency of green energy generators and a slight lowering in implementation costs, more businesses and even some homeowners are converting waste-to-energy systems or by installing biomass energy units.
Latest from the United Kingdom
Our first notable example of this comes from Cornwall in the UK. As of this week, a small hotel has entirely replaced its previous oil-based heating system with biomass boilers. Fuelled from wood wastes brought in from a neighboring forest, the BudockVean hotel has so far been successful in keeping the entire establishment warm on two small boilers despite it being the height of British winter – and when warmer weather arrives, plans to install solar panels on the building’s roof is to follow.
Similar projects have been undertaken across small businesses in Britain, including the south-coast city of Plymouth that has just been announced to house a 10MW biomass power plant (alongside a 20MW plant already in construction). These developments arein part thanks to the UK government’s Renewable Heat Incentive which was launched back in 2011. The scheme only provides funding to non-domestic properties currently, but a domestic scheme is in the works this year to help homeowners also move away from fossil fuels.
Initiatives (and Setbacks) in the US
Back across the pond, and the state of New York is also launching a similar scheme. The short-term plan is to increase public education on low-emission heating and persuade a number of large business to make the switch; in the longer term, $800m will be used to install advanced biomass systems in large, state-owned buildings.
A further $40m will be used as part of a competition to help create a series of standalone energy grids in small towns and rural areas, which is a scheme that could hopefully see adopted beyond New York if all goes well.
Unfortunately, the move away from fossil fuels hasn’t been totally plain sailing across the US. Georgia suffered a blow this week as plans to convert a 155MW coal plant to biomass have been abandoned, citing large overheads and low projected returns. The company behind the project have met similar difficulties at other sites, but as of this week are moving ahead with further plans to convert over 2000MW of oil and coal energy generation in the coming years.
Elsewhere in the US, a company has conducted a similar study as to whether biomass plant building will be feasible in both Florida and Louisiana. Surveying has only just been completed, but if things go better than the recent developments in Georgia, the plants will go a long way to converting biomass to fertilizer for widespread use in agriculture in both states.
Far East Leading the Way
One country that is performing particularly well in biomass energy investment market is Japan. Biomass is being increasingly used in power plants in Japan as a source of fuel, particularly after the tragic accident at Fukushima nuclear power plant in 2011. Palm kernel shell (PKS) has emerged as a favorite choice of biomass-based power plants in the country. Most of these biomass power plants use PKS as their energy source, and only a few operate with wood pellets. Interestingly, most of the biomass power plants in Japan have been built after 2015..
On the contrary, the US and Europe saw a fairly big fall in financing during this period; it should be noted, however, that this relates to the green energy investment market as a whole as opposed to biomass-specific funding. The increase seen in Japan has been attributed to an uptake in solar paneling, and if we look specifically to things such as the global demand for biomass pellets, we see that the most recent figures paint the overall market in a much more favorable light for the rest of the world.
Brighter Times Ahead
All in all, it’s an exciting time for the biomass industry despite the set backs which are being experienced in some regions. On the whole, legislators and businesses are working remarkably well together in order to pave the way forward – being a fairly new market (from a commercially viable sense at least), it has taken a little while to get the ball rolling, but expect to see it blossom quickly now that the idea of biomass is starting to take hold.
Europe is targeting an ambitious renewable energy program aimed at 20% renewable energy in the energy mix by 2020 with biomass energy being key renewable energy resource across the continent. However, the lack of locally-available biomass resources has hampered the progress of biomass energy industry in Europe as compared with solar and wind energy industries. The European biomass industry is largely dependent on wood pellets and crop residues.
Europe is the largest producer of wood pellets, which is currently estimated at 13.5 million tons per year while its consumption is 18.8 million tons per year. The biggest wood pellet producing countries in Europe are Germany and Sweden. Europe relies on America and Canada to meet its wood pellet requirements and there is an urgent need to explore alternative biomass resources. In recent years, palm kernel shells (popularly known as PKS) from Southeast Asia has emerged has an attractive biomass resources which can replace wood pellets in biomass power plants across Europe.
What are Palm Kernel Shells
Palm kernel shells are the shell fractions left after the nut has been removed after crushing in the Palm Oil mill. Kernel shells are a fibrous material and can be easily handled in bulk directly from the product line to the end use. Large and small shell fractions are mixed with dust-like fractions and small fibres.
Moisture content in kernel shells is low compared to other biomass residues with different sources suggesting values between 11% and 13%. Palm kernel shells contain residues of Palm Oil, which accounts for its slightly higher heating value than average lignocellulosic biomass. Compared to other residues from the industry, it is a good quality biomass fuel with uniform size distribution, easy handling, easy crushing, and limited biological activity due to low moisture content.
Press fibre and shell generated by the palm oil mills are traditionally used as solid fuels for steam boilers. The steam generated is used to run turbines for electricity production. These two solid fuels alone are able to generate more than enough energy to meet the energy demands of a palm oil mill.
Advantages of Palm Kernel Shells
PKS has almost the same combustion characteristics as wood pellets, abundantly available are and are cheap. Indonesia and Malaysia are the two main producers of PKS. Indonesian oil palm plantations cover 12 million hectares in Indonesia and 5 million hectares in Malaysia, the number of PKS produced from both countries has exceeded 15 million tons per year. Infact, the quantity of PKS generated in both countries exceeds the production of wood pellets from the United States and Canada, or the two largest producers of wood pellets today.
Interestingly, 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 per year, but the production of PKS is much higher which can power biomass power plants across Europe and protect forests which are being cut down to produce wood pellets in North America and other parts of the world.
PKS as a Boiler Fuel
Although most power plants currently use pulverized coal boiler technology which reaches around 50% of the world’s electricity generation, the use of grate combustion 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 combustion and fluidized bed technology is fuel flexibility including tolerance to particle size.
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, palm kernel shells has a great opportunity to be used as a boiler fuel in large-scale power plants.
Use of PKS in 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 combustion that can be flexible with various types of fuel, pulverized coal boilers use coal only. There are specific things that distinguish biomass and coal fuels, namely ash content and ash chemistry, both of which greatly influence the combustion characteristics in the pulverized system.
PKS has emerged as an attractive biomass commodity in Japan
Coal ash content is generally greater than biomass, and coal ash chemistry is very different from biomass ash chemistry. Biomass ash has lower inorganic content than coal, but the alkali content in biomass can change the properties of coal ash, especially aluminosilicate ash.
Biomass cofiring with coal in small portions for example 3-5% does not require modification of the pulverized coal 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 per year of biomass and no modification. Similarly, Korea Southeast Power (KOSEP) 5,000 MW with 5% cofiring requires 600,000 tons per year of biomass without modification.
PKS cofiring in coal-based power plants
Pulverized coal-based power plants are the predominant method of large-scale electricity production worldwide including Europe. If pulverised fuel power plants make a switch to co-firing of biomass fuels, it will make a huge impact on reducing coal usage, reducing carbon emissions and making a transition to renewable energy. Additionally, the cheapest and most effective way for big coal-based power plants to enter renewable energy sector is biomass cofiring. Palm kernel shells can be pyrolyzed to produce charcoal while coal will produce coke if it is pyrolyzed. Charcoal can be used for fuel, briquette production and activated charcoal.
For a society accustomed to the achievements of a linear economy, the transition to a circular economic system is a hard task even to contemplate. Although the changes needed may seem daunting, it is important to remember that we have already come a long way. However, the history of the waste hierarchy has taught that political perseverance and unity of approach are essential to achieving long term visions in supply chain management.
Looking back, it is helpful to view the significance of the Lansink’s Ladder in the light of the sustainability gains it has already instigated. From the outset, the Ladder encountered criticism, in part because the intuitive preference order it expresses is not (and has never been put forward as) scientifically rigorous. Opposition came from those who feared the hierarchy would impede economic growth and clash with an increasingly consumerist society. The business community expressed concerns about regulatory burdens and the cost of implementing change.
However, such criticism was not able to shake political support, either in Holland where the Ladder was adopted in the Dutch Environmental Protection Act of 1979, or subsequently across Europe, as the Waste Hierarchy was transposed into national legislation as a result of the revised Waste Framework Directive.
Prevention, reuse and recycling have become widely used words as awareness has increased that our industrial societies will eventually suffer a shortage of raw materials and energy. So, should we see the waste hierarchy as laying the first slabs of the long road to a circular economy? Or is the circular economy a radical new departure?
Positive and negative thinking
There have been two major transitionary periods in waste management: public health was the primary driver for the first, from roughly 1900 to 1960, in which waste removal was formalised as a means to avoid disease. The second gained momentum in the 1980s, when prevention, reuse and recovery came on the agenda. However, consolidation of the second transition has in turn revealed new drivers for a third. Although analysing drivers is always tricky – requiring a thorough study of causes and effects – a general indication is helpful for further discussion. Positive (+) and negative (-) drivers for a third transition may be:
(+) The development of material supply chain management through the combination of waste hierarchy thinking with cradle to cradle eco design;
(+) The need for sustainable energy solutions;
(+) Scarcity of raw materials necessary for technological innovation; and
(+) Progressive development of circular economy models, with increasing awareness of social, financial and economic barriers.
(-) Growth of the global economy, especially in China and India, and later in Africa;
(-) Continued growth in global travel;
(-) Rising energy demand, exceeding what can be produced from renewable energy sources and threatening further global warming;
(-) Biodiversity loss, causing a further ecological impoverishment; and
(-) Conservation of the principle of ownership, which hinders the development of the so-called ‘lease society’.
A clear steer
As the direction, scale and weight of these drivers are difficult to assess, it’s necessary to steer developments at all levels to a sustainable solution. The second transition taught that governmental control appears indispensable, and that regulation stimulates innovation so long as adequate space is left for industry and producers to develop their own means of satisfying their legislated responsibilities.
The European Waste Framework Directive has been one such stimulatory piece of legislation. Unfortunately, the EC has decided to withdraw its Circular Economy package, which would otherwise now be on track to deliver the additional innovation needed to achieve its goals – including higher recycling targets. Messrs. Juncker and Timmermans must now either bring forward the more ambitious legislation they have hinted at, or explain why they have abandoned the serious proposals of their predecessors.
Perhaps the major differences between Member States and other countries may require a preliminary two-speed policy, but any differences in timetable between Western Europe and other countries should not stand in the way of innovation, and differences of opinion between the European Parliament and the Commission must be removed for Europe to remain credible.
Governmental control requires clear rules and definitions, and for legislative terminology to be commensurate with policy objectives. One failing in this area is the use of the generic term ‘recovery’ to cover product reuse, recycling and incineration with energy recovery, which confuses the hierarchy’s preference order. The granting of R1 status to waste incineration plants, although understandable in terms of energy diversification, turns waste processors into energy producers benefiting from full ovens. Feeding these plants reduces the scope for recycling (e.g. plastics) and increases CO2 emissions. When relatively inefficient incinerators still appear to qualify for R1 status, it offers confusing policy signals for governments, investors and waste services providers alike.
The key role for government also is to set clear targets and create the space for producers and consumers to generate workable solutions. The waste hierarchy’s preference order is best served by transparent minimum standards, grouped around product reuse, material recycling or disposal by combustion. For designated product or material categories, multiple minimum standards are possible following preparation of the initial waste streams, which can be tightened as technological developments allow.
Where the rubber meets the road
As waste markets increase in scale, are liberalised, and come under international regulation, individual governmental control is diminished. These factors are currently playing out in the erratic prices of secondary commodities and the development of excess incinerator capacity in some nations that has brought about a rise in RDF exports from the UK and Italy. Governments, however, may make a virtue of the necessity of avoiding the minutiae: ecological policy is by definition long-term and requires a stable line; day to day control is an impossible and undesirable task.
The road to the third transition – towards a circular economy – requires a new mind-set from government that acknowledges and empowers individuals. Not only must we approach the issue from the bottom-up, but also from the side and above. Consumer behaviour must be steered by both ‘soft’ and ‘hard’ controls: through information and communication, because of the importance of psychological factors; but also through financial instruments, because both consumers and industry are clearly responsive to such stimuli.
Where we see opposition to deposit return schemes, it comes not from consumers but from industry, which fears the administrative and logistical burden. The business community must be convinced of the economic opportunities of innovation. Material supply chain management is a challenge for designers and producers, who nevertheless appreciate the benefits of product lifetime extensions and reuse. When attention to environmental risks seems to lapse – for example due to financial pressures or market failures – then politics must intervene.
Government and industry should therefore get a better grip on the under-developed positive drivers of the third transition, such as eco design, secondary materials policy, sustainable energy policy, and research and development in the areas of bio, info, and nanotechnologies.
Third time’s the charm
Good supply chain management stands or falls with the way in which producers and consumers contribute to the policies supported by government and society. In order that producers and consumers make good on this responsibility, government must first support their environmental awareness.
The interpretation of municipal duty of care determines options for waste collection, disposal and processing. Also essential is the way in which producer responsibility takes shape, and the government must provide a clear separation of private and public duties. Businesses may be liable for the negative aspects of unbridled growth and irresponsible actions. It is also important for optimal interaction with the European legislators: a worthy entry in Brussels is valuable because of the international aspects of the third transition. Finally, supply chain management involves the use of various policy tools, including:
Rewarding good behaviour
Sharpening minimum standards
Development and certification of CO2 tools
Formulation and implementation of end-of-waste criteria
Remediation of waste incineration with low energy efficiency
Restoration or maintenance of a fair landfill tax
Application of the combustion load set at zero
‘Seeing is believing’ is the motto of followers of the Apostle Thomas, who is chiefly remembered for his propensity for doubt. The call for visible examples is heard ever louder as more questions are raised around the feasibility of product renewal and the possibilities of a circular economy.
Ultimately, the third transition is inevitable as we face a future of scarcity of raw materials and energy. However, while the direction is clear, the tools to be employed and the speed of change remain uncertain. Disasters are unnecessary to allow the realisation of vital changes; huge leaps forward are possible so long as government – both national and international – and society rigorously follow the preference order of the waste hierarchy. Climbing Lansink’s Ladder remains vital to attaining a perspective from which we might judge the ways in which to make a circle of our linear economy.
Note: The article is being republished with the permission of our collaborative partner Isonomia. The original article can be found at this link.
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