Palm kernel shells are widely used in fluidized bed combustion-based power plants in Japan and South Korea. The key advantages of fluidized bed combustion (FBC) technology are higher fuel flexibility, high efficiency and relatively low combustion temperature. FBC technology, which can either be bubbling fluidized bed (BFB) or circulating fluidized bed (CFB), is suitable for plant capacities above 20 MW. Palm kernel shells (PKS) is more suitable for CFB-based power plant because its size is less than 4 cm.
Palm kernel shells is an abundant biomass resource in Southeast Asia
With relatively low operating temperature of around 650 – 900 oC, the ash problem can be minimized. Certain biomass fuels have high ash levels and ash-forming materials that can potentially damage these generating units.
In addition, the fuel cleanliness factor is also important as certain impurities, such as metals, can block the air pores on the perforated plate of FBC unit. It is to be noted that air, especially oxygen, is essential for the biomass combustion process and for keeping the fuel bed in fluidized condition.
The requirements for clean fuel must be met by the provider or seller of the biomass fuel. Usually the purchasers require an acceptable amount of impurities (contaminants) of less than 1%. Cleaning of PKS is done by sifting (screening) which may either be manual or mechanical.
In addition to PKS, biomass pellets from agricultural wastes or agro-industrial wastes, such as EFB pellets which have a high ash content and low melting point, can also be used in CFB-based power plants. More specifically, CFBs are more efficient and emit less flue gas than BFBs.
The disadvantages of CFB power plant is the high concentration of the flue gas which demands high degree of efficiency of the dust precipitator and the boiler cleaning system. In addition, the bed material is lost alongwith ash and has to be replenished regularly.
A large-scale biomass power plant in Japan
The commonly used bed materials are silica sand and dolomite. To reduce operating costs, bed material is usually reused after separation of ash. The technique is that the ash mixture is separated from a large size material with fine particles and silica sand in a water classifier. Next the fine material is returned to the bed.
Currently power plants in Japan that have an efficiency of more than 41% are only based on ultra supercritical pulverized coal. Modification of power plants can also be done to improve the efficiency, which require more investments. The existing CFB power plants are driving up the need to use more and more PKS in Japan for biomass power generation without significant plant modifications.
Cofiring of biomass involves utilizing existing power generating plants that are fired with fossil fuel (generally coal), and displacing a small proportion of the fossil fuel with renewable biomass fuels. Cofiring of biomass with coal and other fossil fuels can provide a short-term, low-risk, low-cost option for producing renewable energy while simultaneously reducing the use of fossil fuels.
Biomass can typically provide between 3 and 15 percent of the input energy into the power plant. Cofiring of biomass has the major advantage of avoiding the construction of new, dedicated, biomass power plant. An existing power station is modified to accept the biomass resource and utilize it to produce a minor proportion of its electricity.
Cofiring of biomass may be implemented using different types and percentages of biomass in a range of combustion and gasification technologies. Most forms of biomass are suitable for cofiring. These include dedicated energy crops, urban wood waste and agricultural residues such as rice straw and rice husk.
The fuel preparation requirements, issues associated with combustion such as corrosion and fouling of boiler tubes, and characteristics of residual ash dictate the cofiring configuration appropriate for a particular plant and biomass resource. These configurations may be categorized into direct, indirect and parallel firing.
1. Direct Cofiring
This is the most common form of biomass cofiring involving direct cofiring of the biomass fuel and the primary fuel (generally coal) in the combustion chamber of the boiler. The cheapest and simplest form of direct cofiring for a pulverized coal power plant is through mixing prepared biomass and coal in the coal yard or on the coal conveyor belt, before the combined fuel is fed into the power station boiler.
2. Indirect Cofiring
If the biomass fuel has different attributes to the normal fossil fuel, then it may be prudent to partially segregate the biomass fuel rather than risk damage to the complete station.
For indirect cofiring, the ash of the biomass resource and the main fuel are kept separate from one another as the thermal conversion is partially carried out in separate processing plants. As indirect co-firing requires a separate biomass energy conversion plant, it has a relatively high investment cost compared with direct cofiring.
For parallel firing, totally separate combustion plants and boilers are used for the biomass resource and the coal-fired power plants. The steam produced is fed into the main power plant where it is upgraded to higher temperatures and pressures, to give resulting higher energy conversion efficiencies. This allows the use of problematic fuels with high alkali and chlorine contents (such as wheat straw) and the separation of the ashes.
South Africa is experiencing a mammoth energy crisis with its debt-laden national power utility, Eskom, being unable to meet the electricity needs of the nation. After extensive periods of load shedding in 2018 and again earlier this year, it is becoming increasingly important to find an alternative source of energy. According to Marko Nokkala, senior sales manager at VTT Technical Research Centre of Finland, South Africa is in the perfect position to utilize biomass as an alternative source of energy.
Things to Consider
Should South Africa choose to delve deeper into biomass energy production, there are a few things that need to be considered. At present, a lot of biomass (such as fruit and vegetables) is utilized as food. It will, therefore, be necessary to identify alternative biomass sources that are not typically used as food, so that a food shortage is never created in the process.
One alternative would be to use municipal solid waste from landfills and dumpsites as well as the wood waste from the very large and lucrative forestry industry in the country. It is also essential to keep in mind that an enormous amount of biomass will be needed to replace even a portion of the 90 million tons of coal that Eskom utilizes every year at its various power stations.
Potential Biomass Conversion Routes
There are a number of processing technologies that South Africans can utilize to turn their biomass into a sustainable energy source. Biochemical conversion involving technology such as anaerobic digestion and fermentation makes use of enzymes, microorganisms, and bacteria to breakdown the biomass into a variety of liquid or vaporous fuels.
Fermentation is especially suitable when the biomass waste boasts a high sugar or water content, as is the case with a variety of agricultural wastes. By placing some focus on microbial fermentation process development, a system can effectively be created that will allow for large-scale biofuel production. Other technologies to consider include thermal methods like co-firing, pyrolysis, and gasification.
Future of biomass energy in South Africa
Despite the various obstacles that may slow down the introduction of large-scale biomass energy production in the country, it still promises to be a viable solution to the pressing energy concern. Biomass energy production does not require any of the major infrastructures that Eskom is currently relying on.
Although the initial setup will require a substantial amount of electricity, running a biomass conversion plant will cost significantly less than a coal-powered power plant in the long run. With the unemployment rate hovering around 27.1% in South Africa at present, any jobs created through the implementation of biomass energy conversion will be of great benefit to the nation.
Without speedy intervention, South Africa may very soon be left in the dark. Although there are already a number of wind farms in operation in the country, the addition of biomass conversion facilities will undoubtedly be of great benefit to Africa’s southernmost country.
In recent years, the world has seen significant economic progress, which greatly relied on energy fueled by coal and petroleum among others. With the continuously growing demand for energy, it is a fact that these energy sources may be depleted in the near future. Apart from this, there are several other reasons why humankind already needs to find alternative energy sources.
It is a known fact that different manufacturing processes and human activities, such as using vehicles, cause pollution in the atmosphere by releasing carbon dioxide. Carbon dioxide traps heat in the earth, and this phenomenon is known as global warming. Global warming has several harmful impacts such as stronger and more frequent storms, as well as drought and heat waves. Renewable energy sources such as wind, solar, geothermal, hydroelectric, and biomass to name a few, all generate minimal global warming emissions.
Wind power, for instance, has the capability to supply energy with a significantly lower emission compared to burning coal for fuel. This is the reason why wind energyis more beneficial compared to carbon-intensive energy sources. Still, the emissions generated by wind power are even lower compared to other renewable energy sources such as solar, geothermal, and hydroelectric power sources. This makes a huge potential for wind power to sustain the world’s energy demands, while preserving the environment.
It goes without saying that the pollution caused by burning coal and fuel not only has an environmental impact, but it also has a significant effect on public health. Various diseases and ailments can be attributed to pollution, which usually affects the respiratory tract. Contaminated water also causes various bacterial infections. Wind power, solar energy, and hydroelectric systems have the capability to generate electricity without emitting air pollutants.
Additionally, wind and solar energy sources do not need water to operate, thereby, eliminating the probability of polluting water resources. Clean air and water that is free from pollutants, will have a significant positive impact on public health.
Constant Energy Source
While coal and fossil fuels are on the threshold of depletion, renewable energy sources are inexhaustible. Wind can be a constant energy source and no matter how high the demand for energy will be, the wind will not be depleted. In the same manner, as long as the sun shines bright on earth, there will always be an abundant solar energy source.
Fast-moving water that can be translated into hydroelectric energy, the earth’s heat that can be converted into a geothermal power source, as well as abundant plant matter that can be used as biomass, can all be constantly replenished. These can never be fully exhausted no matter how great the energy demand will be. The utilization of a combination of each of these energy sources will prove to be even more beneficial. Additionally, with its continued use, there will no longer be a need for combustible energy sources.
Lower Energy Costs
The cost of electricity continues to be a burden on the earth’s greater population. The use of renewable energy sources to light up the earth is considerably cheaper and inexpensive compared to the cost of burning fossil fuels for electricity and other energy needs. Apart from a cheaper cost, renewable energy sources can help stabilize to cost of energy in the long run, with an unlimited supply being able to cater to greater demand.
While it cannot be denied that setting up clean energy technologies comes with a cost, it can be noted that the cost of its operation is significantly lower. Conversely, the cost of coal and fossil fuels for energy consumption fluctuates over a wide range and is greatly affected by the economic and political conditions of its country of origin.
Fossil fuel technologies, often, revolve around the capitalistic market. Hence, the use of combustible fuels is often linked to unfavorable labor conditions, and even child labor and slavery. On the other hand, the use of renewable energy sources provides decent jobs, contributing to several economic benefits and aids in decarbonizing the future.
For instance, workers are needed to install and maintain solar panels. In the same manner, wind farms employ technicians for maintenance. Thus, jobs are created directly in parallel with the unit of energy produced. This means that more jobs will be produced if more renewable energy sources are utilized.
Clean energy sources, specifically wind and solar power, are less susceptible to large-scale failures. The reason behind this is that both wind and solar power both employ distributed and modular systems. This means that electricity will not be totally cut off in instances of extreme weather conditions because the energy sources powering up the electricity is spread out over a wider geographical area. In the same manner, there will still be a continuous supply of energy even if certain equipment in the entire system is damaged because clean fuel technologies are made up of modules such as a number of individual wind turbines or solar panels.
With all the reasons to check out alternative energy sources, it still holds true that there remain several barriers that hinder the full implementation of renewable energy technologies. Some of these challenges are capital costs because of reliability misconceptions, as well as a difficult market entry due to an unequal playing field.
Because renewable energy sources are cheap to operate, the bulk of the expenses in its implementation is building the technology. Thereby, the rate of return for capitalists and investors in the market entails a longer waiting period. Adding to this barrier is the hidden political agenda that most governments need to overcome.
Economic progress and advancement in technology are not at all bad. On the contrary, it has brought forth a lot of benefits such as cures for ailments and diseases, resources for deep-sea or space explorations, as well as meaningful collaboration and communication. However, this progress came with a price, and unfortunately, it’s the world’s energy resources that are on the brink of exhaustion. Hence, mitigation has been already necessary and finding alternative energy sources is just one of the probable solutions.
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 and Africa has emerged as 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.
Homeowners have a variety of energy sources to choose from to power their homes. Each kind offers its own set of benefits and disadvantages. When you are wanting to be more eco-friendly with your energy consumption, there are many benefits of considering natural gas as your go-to energy source.
Uses Of Natural Gas
Natural gas is non-toxic, colorless, odorless and the lowest-carbon hydrocarbon. It can be used for heating and cooking purposes in both residential and commercial settings. It can also be used to fuel power stations to create electricity for use in businesses and homes.
Natural gas can also be found in many industrial processes to create goods and materials from clothing to glass. Plastics and paints are some important products that have natural gas as a crucial ingredient. The uses of natural gas are many and diverse.
In most areas, natural gas is much more affordable than electricity for heating your house and your water. For the same heating tasks, natural gas can cost almost half as much as oil or coal when used as the energy source. Natural gas is a deregulated utility. This means that consumers have fewer restrictions and are able to have control over how much they pay for the gas. Affordable natural gas prices mean a lot of savings throughout the year for homeowners.
Natural gas is not as eco-friendly as renewable energy sources like wind and solar. However, it is the cleanest form of fossil fuel available. When compared to coal, natural gas releases almost a third less carbon dioxide and half as less than oil when it is burned. Compared to other fuels, it also lets off little to no sulfur.
Using natural gas as your energy source is more reliable and dependable for your energy needs. When a big storm hits your area and the power goes out, you will not be able to depend on any appliance that runs off of electricity. For some homeowners, this means no lights, air conditioning, heating or hot water until the power is restored. When you run your appliances using natural gas, you can still operate them when your power is out.
When you have water heaters and other important home appliances operating using natural gas, the gas is often fed to your home in underground pipelines. This allows your energy source to be safe and well-protected from extreme weather conditions such as heavy storms. If you lose electricity, you will not lose all of your comforts while waiting for the power company to fix the issues.
4. Domestic Energy Source
Much emphasis is put on finding energy sources locally instead of having to depend on foreign oils. In addition to being more abundant and economical, relying more on local energy sources is great for the economy and creates more jobs and revenue.
Learn More About Using Natural Gas In Your Area
If you are looking to turn your home into an eco-friendly environment, turning to natural gas can be a great place to start. Natural gas providers offer plans and pricing options that can be suitable for all homeowners and budgets. Allowing most or all of your appliances to receive energy derived from natural gas can bring you many rewards as a homeowner and someone who cares about their impact on the environment.
This alternative energy source over oil and coal will be good for the global community for generations to come. The use of natural gas is on the rise and will become more competitive as consumers and energy providers look to reduce the impact on air pollution and the environment.
The share of energy received from the Sun is steadily increasing every year. Last year, the global solar market increased by 26%. According to forecasts, in 2018 for the first time, the mark of 100 gigawatts of new installed capacity per year will be passed all over the world. Writing a research paper on solar energy is not an easy assignment, as you will have to deal with lot’s of statistics, results of experiments, and, surprisingly, sociology — the usage of alternative sources of energy are strongly connected with the social issues and moods. In this article, you’ll receive some tips on how to write a research paper on solar energy and impress your professor.
We are sure you know how to structure a research paper, and you won’t forget about an engaging thesis (problem) statement. Our tips will cover the latest trends you should mention and the discussions related to the usage of solar energy, pros, cons and exciting facts.
An increasing number of countries are developing solar energy projects at the national level. In 2016, there were 32 such countries, at the end of last year already 53. Tenders for the development of solar energy are planned in 23 countries.
In the United States in the next 4 years, the number of states installing more than 1 gigawatt will reach 18. They will account for 80% of all US photovoltaic plants.
Reducing the cost of solar energy can be achieved through the use of more powerful modules, which will reduce the proportion of equipment and maintenance costs.
The role of electronics operating at the level of a single photovoltaic panel will grow. Now micro-inventors and current converters for one module are not used very widely.
Prices for stationary solar systems in the world are falling, but in the USA they remain at the same level (the cost of watts of power for US home systems is the highest in the world). The price for a “sunny” watt from state to state can vary by 68 cents, and companies will have to look for ways to reduce production costs.
Talk about the Future
Naturally, interest in renewable energy sources will continue to grow. The year 2050 will be the point of no return – it is by this time that most countries will completely switch to clean energy. And in 2018 serious steps will be made in this direction.
The first to be hit will be coal power plants in Europe. To date, 54% of them are not profitable, and there are only for the sake of peak load. In 2018, Finland will ban the use of coal to generate electricity and increase the tax on carbon dioxide emissions. By 2030, the country plans to abandon this fuel completely.
The Indian coal mining company Coal India also plans to close 37 coal mines in March 2018 – their development has become uneconomical due to the growth of renewable energy. The company will save about $ 124 million on this, after which it will switch to solar power and install at least 1 GW of new solar capacity in India.
Don’t Focus Solely on Content
It is a no-brainer that the content of your research paper is the most essential part of your work. However, if you forget about formatting, citations, plagiarism, using valid academic sources, etc., your research paper can fail despite having an amazing thesis statement or the project idea. https://plagiarismdetector.net/ can help in detecting plagiarized content.
When you start doing research, note down every link you use or want to use, every quote you like, every piece of statistical information. At first, it seems very dull and unnecessary — you think you can find this information at any moment. However, days pass, and you fail to make proper references, which can be a reason of being accused of plagiarism. Proofread your research paper several times, use online sources to check grammar and spelling, don’t forget about plagiarism checkers to stay on the safe side.
If you find out that writing a proper research paper on solar energy is too complicated for you now, or you don’t have enough time energy to deal with it, it is a wise choice to get affordable research paper writing by experts who can help you immediately with your assignment. When writing a research paper on solar energy don’t forget to check on the latest numbers and analytical data worldwide. Good luck!
To improve the quality of biomass, especially for cofiring purposes, biomass waste can be processed with torrefaction (also known as mild pyrolysis). With the torrefaction process, it becomes easier to make powder (high grindability) so that the desired particle size for cofiring of biomass is easier to obtain. Another advantage of the torrefaction process is that the caloric value of biomass increases by about 20%. Torrified biomass is essentially hydropobic which means ease in storage including outdoor storage. This condition also makes it easier to handle and use, in addition to reduction in transportation costs.
What is Torrefaction?
Torrefaction, which is currently being considered for effective biomass utilization, is also a form of pyrolysis. In this process (named for the French word for roasting), the biomass is heated to 230 to 300 °C without contact with oxygen. For comparison, pyrolysis of biomass is typically carried out in a relatively low temperature range of 300 to 650 °C compared to 800 to 1000 °C for gasification. Torrefaction is a relatively new process that heats the biomass in the absence of air to improve its usefulness as a fuel.
Torrefaction, a process different from carbonization, is a mild pyrolysis process carried out in a temperature range of 230 to 300 °C in the absence of oxygen. During this process the biomass dries and partially devolatilizes, decreasing its mass while largely preserving its energy content. The torrefaction process removes H2O and CO2 from the biomass. As a result, both the O/C and the H/C ratios of the biomass decrease.
Benefits of Biomass Torrefaction
Torrefaction of biomass improves its energy density, reduces its oxygen-to-carbon (O/C) ratio, and reduces its hygroscopic nature. Torrefaction also increases the relative carbon content of the biomass. The properties of a torrefied biomass depends on torrefaction temperature, time, and on the type of biomass feed.
Torrefaction also modifies the structure of the biomass, making it more friable or brittle. This is caused by the depolymerization of hemicellulose. As a result, the process of size reduction becomes easier, lowering its energy consumption and the cost of handling. This makes it easier to cofire biomass in a pulverized coal-fired boiler or gasify it in an entrained-flow reactor.
Another special feature of torrefaction is that it reduces the hygroscopic property of biomass; therefore, when torrefied biomass is stored, it absorbs less moisture than that absorbed by fresh biomass. For example, while raw bagasse absorbed 186% moisture when immersed in water for two hours, it absorbed only 7.6% moisture under this condition after torrefying the bagasse for 60 minutes at 250 °C (Pimchua et al., 2009). The reduced hygroscopic (or enhanced hydrophobic) nature of torrefied biomass mitigates one of the major shortcomings for energy use of biomass.
In biomass, hemicellulose is like the cement in reinforced concrete, and cellulose is like the steel rods. The strands of microfibrils (cellulose) are supported by the hemicellulose. Decomposition of hemicellulose during torrefaction is like the melting away of the cement from the reinforced concrete. Thus, the size reduction of biomass consumes less energy after torrefaction. During torrefaction the weight loss of biomass comes primarily from the decomposition of its hemicellulose constituents. Hemicellulose decomposes mostly within the temperature range 150 to 280 °C, which is the temperature window of torrefaction.
As we can see from figure above, the hemicellulose component undergoes the greatest amount of degradation within the 200 to 300 °C temperature window. Thus, hemicellulose decomposition is the primary mechanism of torrefaction. At lower temperatures (< 160 °C), as biomass dries it releases H2O and CO2. Water and carbon dioxide, which make no contribution to the energy in the product gas, constitute a dominant portion of the weight loss during torrefaction.
Above 180 °C, the reaction becomes exothermic, releasing gas with small heating values. The initial stage (< 250 °C) involves hemicellulose depolymerization, leading to an altered and rearranged polysugar structures. At higher temperatures (250–300 °C) these form chars, CO, CO2, and H2O. The hygroscopic property of biomass is partly lost in torrefaction because of the destruction of OH groups through dehydration, which prevents the formation of hydrogen bonds.
The Earth is facing a climate crisis, as the burning of fossil fuels to generate electricity and power our cars overloads the atmosphere with carbon dioxide, causing a dangerous atmospheric imbalance that’s raising global temperatures.
A report from the UN’s Intergovernmental Panel on Climate Change (IPCC) released earlier this month cautioned that the planet has just 12 years to dramatically curb greenhouse gas emissions, by overhauling our energy systems and economies and likely, our societies and political systems. Even a half degree rise beyond that would cause catastrophic sea level rises, droughts, heat, hunger, and poverty, spelling disaster for our species.
UK’s Commitment to Climate Change Mitigation
The UK government has committed to reducing carbon emissions by 80% of 1990 levels by 2050, a process that will involve overhauling our energy supply, which is responsible for 25% of greenhouse emissions in the country, just behind transport (26% of all emissions). But it may be too little too late. The government has already said it is reviewing these targets in light of the IPCC report and in the spring began consulting on a net-zero carbon emissions target for 2050.
But despite these dire prognoses and the enormity of the task facing us as a species, there’s reason to be optimistic. The UK has already managed to cut greenhouse gas emissions by 43% on 1990 levels, with much of the reduction coming from a 57% decline in emissions from energy generation. This is in part thanks to several providers offering you the chance to have a 100% renewable domestic energy supply.
Reduction in Coal Usage
The use of coal has plunged nearly overnight in the UK. In 2012, 42% of the UK’s electricity demand was met by coal. Just six years later, in the second quarter of 2018, that figure had fallen to just 1.6%. Emissions from coal-fired power stations fell from 129 million tonnes of CO2 to just 19 million tonnes over the same period.
A coal-free Britain is already on the horizon. In April 2017, the UK logged its first coal-free day since the Industrial Revolution; this past April we extended the run to 76 consecutive hours. In fact, in the second quarter of 2018, all the UK’s coal power stations were offline for a total of 812 hours, or 37% of the time. That’s more coal free hours than were recorded in 2016 and 2017 combined and in just three months.
When the UK does rely on coal power, it’s primarily to balance supplies and to meet demand overnight and during cold snaps, such as during the Beast from the East storm in March. The UK is so certain that coal is a technology of the past, that the government has plans to mothball all seven remaining coal-fired power stations by 2025.
Share of Renewables in Energy Supply
The decline in coal has been matched by an explosion in renewable energy, particularly in wind power. In the second quarter of 2018, renewables generated 31.7% of the UK’s electricity, up from under 9% in 2011. Of those, wind power produced 13.3% of all electricity (7.1% from onshore turbines farms and 6.2% from offshore wind farms), biomass energy contributed another 11% of the UK’s electricity, solar generated 6% and hydro power made up the rest of renewables’ pie share.
The UK’s total installed renewables capacity has exploded, hitting 42.2GW in the second quarter of 2018, up from under 10GW in 2010. That includes 13.7GW of onshore wind capacity and 7.8GW of offshore wind capacity—a figure which will get a boost with the opening in September of the world’s largest wind farm, the Walney Extension, off the coast of Cumbria, itself with a capacity of nearly 0.7GW. Solar panels contributed another 13GW of renewable capacity, and installed plant biomass infrastructure reaching 3.3GW.
However, while renewables are transforming electricity generation in the UK, our energy system consists of more than simply electricity. We also have to account for natural gas and the use of fuel in transport, and renewables have made fewer in roads in those sectors.
The UK is meeting just 9.3% of its total energy needs from renewable sources, short of the 15% it has earmarked for 2020 and far behind its peers in the EU, where Sweden is already running on 53.8% renewable energy.
Emissions are dropping overall in the UK, largely due to an ongoing revolution in electricity generation and a decisive move away from coal. But these reductions have concealed stagnant and even increasing levels of greenhouse gas emissions from other sectors, including transport and agriculture.
Our transition to a sustainable economy has begun but will require more than wind farms and the shuttering of coal-fired power stations. It must encompass electric vehicles, transformed industries, and ultimately changing attitudes toward energy and the environment and our responsibility toward it.
Biomass power plants in India are based mostly on agricultural wastes. Gasifier-based power plants are providing a great solution for off-grid decentralized power and are lighting homes in several Indian states. While for providing grid-based power 8-15 MW thermal biomass power plants are suitable for Indian conditions, they stand nowhere when compared to power plants being set up in Europe which are at least 20 times larger.
Energy from biomass is reliable as it is free of fluctuation unlike wind power and does not need storage to be used in times of non-availability as is the case with solar. Still it is not the preferred renewable energy source till now, the primary reason that may be cited is the biomass supply chain.
Biomass availability is not certain for whole year. Biomass from agriculture is available only after harvesting period which can stretch only for 2-3 months in a year. So there is a need to procure and then store required quantity of biomass within this stipulated time.
Some of the Indian states leading the pack in establishing biomass-based power projects are Karnataka, Andhra Pradesh, and Maharashtra. Ironically, states having agricultural-based economy have not properly been able to utilize the opportunity and figure low on biomass energy utilization. Only Uttar Pradesh has utilized large part of the biomass potential in north Indian States and that is mainly due to the sugarcane industry and the co-generation power plants.
Interestingly Punjab and Haryana don’t have much installed capacity in comparison to potential even though tariff rates are more than Rs. 5 per unit, which are better than most of the states. This can be attributed to the fact that these tariffs were implemented very recently and it will take time to reflect the capacity utilization.
Table: Biomass Potential and Installed Capacity in Key Indian States
Power Potential (MWe)
Installed Capacity (by 2011)
@ Rs 5.25 per unit, (2010-11)
@ Rs 4.70
@Rs 5.24 per unit
@ Rs 4.72/unit water cooled (2010-11)
@ Rs 4.98 (2010-11)
@ Rs 3.33 to 5.14/unit paise for 20 years with escalation of 3-8 paise
@ Rs 3.66 per unit (PPA signing date)
Rs 4.13 (10th year)
@ Rs 4.28 per unit (2010-11)
@ Rs 4.40 per unit (with accelerated depreciation)
@Rs 3.93 per unit (2010-11)
@ Rs 2.80 per unit escalated at 5% for
five years (2000-01
Source: Biomass Atlas by IISc, Bangalore and MNRE website
The electricity generation could be cheaper than coal if biomass could be sourced economically but ssome established biomass power plants tend to misuse the limit of coal use provided to them (generally 10-15% of biomass use) to keep it operational in lean period of biomass supply. They are not able to run power plants solely on biomass economically which can be attributed to :
Biomass price increases very fast after commissioning of power project and therefore government tariff policy needs an annual revision
Lack of mechanization in Indian Agriculture Sector
Defragmented land holdings
Most of the farmers are small or marginal
Government policy is the biggest factor behind lack of investment in biopower sector in states with high biomass potential. Defragmented nature of agricultural lands do not allow high mechanization which results in reduction of efficiency and increase in procurement cost.
Transportation cost constitutes a significant portion of the costs associated with the establishment and running of biomass power plants. There is need of processing in form of shredding the biomass onsite before transportation to increase its density when procurement is done from more than a particular distance. While transportation in any kind or form from more than 50 Km becomes unviable for a power plant of size 10-15MW. European power plants are importing their biomass in form of pellets from other countries to meet the requirement of the huge biopower plants.
Not all the biomass which is regarded as agri-waste is usually a waste; part of it is used as fuel for cooking while some part is necessary to go back to soil to retain the soil nutrients. According to conservative estimates, only two-third of agricultural residues could be procured for power production.
And as human mentality goes waste is nothing but a heap of ash for the farmer till someone finds a way to make profit out of it, and from there on the demand of waste increases and so its price. Though there is nothing wrong in transferring benefits to the farmers and providing them a competitive cost of the agri-waste but operations becomes increasingly unviable with time.
A robust business model is necessary to motivate local entrepreneurs to take up the responsibility of supplying biomass to processing facilities. Collection centres covering 2-3 villages can be set up to facilitate decentralization of biomass supply mechanism. Biomass power plant operators may explore the possibility of using energy crops as a substitute for crop wastes, in case of crop failure. Bamboo and napier grass can be grown on marginal and degraded lands.
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