Biomass Energy in Nigeria: An Overview

Oil and gas accounts for over 70% of energy consumed in Nigeria, according to the World Bank. Considering this dependency on fossil oil and possibility of it running out in the future, there should be an urgent intervention to look into other ways to generate energy in Nigeria. The world is moving away gradually from fossil oil and aligning towards sustainable energy resources to substitute conventional fuel, Nigeria should not be exempted from this movement. Biomass, a popular form of renewable energy, is considered as a credible and green alternative source of energy which many developed and developing countries have been maximizing to its potential.

biomass-sustainability

Power generation and supply have been inadequate in Nigeria. This inadequacy of power limits human, commercial and industrial productivity and economic growth . What is the use of infrastructure without constant electricity? Even God created light first. Sustainable and constant supply of power should be one of the priority of government in nation development. Investing in biomass will cause an increase in the amount of power generated in Nigeria. Infact, biomass energy has the potential to resolve the energy crisis in the country in the not so distant future.

What is Biomass

The word biomass refers to organic matter (mainly plants) which acts as a source of sustainable and renewable energy. It is a renewable energy source because the plants can be replaced as oppose to the conventional fossil fuel which is not renewable. Biomass energy is a transferred energy from the sun; plants derives energy from the sun through photosynthesis which is further transferred through the food chain to animals’ bodies and their waste.

Biomass has the potential to provide an affordable and sustainable source of energy, while at the same time help in curbing the green house effect. In India the total biomass generation capacity is 8,700 MW according to U.S. of Commerce’s International Trade Administration, whereas the generating capacity in U.S. is 20,156  MW with 178 biomass power plants, according to Biomass Magazine.

Power Sector in Nigeria

Unfortunately, the total installed electricity capacity generated in Nigeria is 12,522 MW, well below the current demand of 98,000MW . The actual output is about 3,800MW, resulting in a demand shortfall of 94,500MW throughout the country. As a result of this wide gap between demand and output, only 45% of Nigeria’s population has access to electricity. Renewable energy contributed 19% of total electricity generated in Nigeria out of which biomass contribution is infinitesimal.

Electricity generation for Nigeria’s grid is largely dominated by two sources; non-renewable thermal (natural gas and coal) and renewable (hydro). Nigeria depends on non-renewable energy despite its vast potential in renewable sources such as solar, wind, biomass and hydro. The total potential of these renewables is estimated at over 68,000MW, which is more than five times the current power output.

Biomass Resources in Nigeria

Biomass can come in different forms like wood and wood waste, agriculture produce and waste, solid waste.

Wood

Electricity can be generated with wood and wood product/waste(like sawdust) in modern day through cogeneration, gasification or pyrolysis.

Agriculture Residues

In Nigeria, agricultural residues are highly important sources of biomass fuels for both the domestic and industrial sectors. Availability of primary residues for energy application is usually low since collection is difficult and they have other uses as fertilizer, animal feed etc.

However secondary residues are usually available in relatively large quantities at the processing site and may be used as captive energy source for the same processing plant involving minimal transportation and handling cost.

Municipal Solid Waste

Back then in secondary school, I learnt that gas could be tapped from septic tank which could further be used for cooking.  Any organic waste (like animal waste, human waste) when decomposed by anaerobic microorganisms releases biogas which can be tapped and stored for either cooking or to generate electricity.

Biomass can be used to provide heat and electricity as well as biofuel and biogas for transport. There are enough biomass capacity to meet our demand for electricity and other purposes. From climatic point of view, there is a warm climate in Nigeria which is a good breeding ground for bacteria to grow and decompose the wastes. There are plant and animal growth all year round which in turn create waste and consequently produce biomass.

In November 2016, The Ebonyi State Government  took over  the United Nations Industrial Development Organization (UNIDO) demonstration biomass gasifier power plant located at the UNIDO Mini -industrial cluster in Ekwashi Ngbo in Ohaukwu Local Government Area of the State. The power plant is to generate 5.5 Megawatt energy using rice husk and other available waste materials available. More of these type of power plants and commitment are needed to utilize the potential of biomass fully.

Why Biomass Energy?

Since biomass makes use of waste to supply energy, it helps in waste management. It also has the potential to supply more energy (10 times) than the one produced from sun and wind. Biomass will lead to increase in revenue generation and conserves our foreign exchange. Increase in energy generation will yield more productivity for industries and the rate at which they are shutting down due to the fact that they spend more on power will be reduced to minimal.

Many local factories/companies will spring up and foreign investors will be eager to invest in Nigeria with little concern about power. Establishment of biopower plants will surely create more jobs and indirectly reduce the number of people living in poverty which is increasing everyday at an alarming rate.

Africa’s most populous country needs more than 10 times its current electricity output to guarantee supply for its 198 million people – nearly half of whom have no access at all, according to power minister Babatunde Fashola. Biomass energy potential in Nigeria is promising –  with heavy investment, stake holder cooperation and development of indigenous technologies. The deployment of large-scale biomass energy systems will not only significantly increase Nigeria’s electricity capacity but also ease power shortages in the country.

What Determines the Price of a Home Solar Panel Installation?

People are leaning toward installing solar panels to have a “green” source of energy that would eventually cost them nothing. However, the price point is one of the major concerns that worry homeowners. People feel more inclined to check the price tag on solar panels to decide whether they are going to go for them or not. Just like any renewable source of energy, the initial cost may sound very expensive, however, afterwards, the fuel price comes down to zero. The average cost swings between $15k and $25k, this gap in the range of prices depend mainly on the solar panel size.

But other than the size of solar panels, what other factors affect the price of installation?

The Size Of Solar Panels

The cost of solar panels is calculated by dollar per watt depending on how much electricity you need to generate. A bigger system requires more work to install and that’s how the size affects the cost of installing solar panels. 2kW would averagely cost around $4k, while solar panels that would generate 25 kW costs $53k. Crunching the numbers, it does sound that solar panel cost a lot more than average electricity bills paid per month, thanks to low-interest installment plans, buying big solar panels won’t cost you an arm and a leg.

Variation Of Price Between States

Solar panel prices may seem like they’re all the same across all states, however, you can use the same exact solar panels at two different states and you will get different costs. The reason behind these variations depends on the cost of electricity in every state. Let’s take Washington, for example, the cost of 6kw generated from a solar panel will cost around $9k, while the same in New York will cost $12k.

Solar panels are becoming more accessible, for homeowners and businesses

The prices definitely seem costly, however, if one thought about the overall cost of electricity from solar energy and normal sources, solar is definitely cheaper.

The Quality

Prices differ according to the manufacturer brand; prices can range from $13k up to $17k. The local Sandbar Solar not only provides high-quality panels, complex commercial and residential setups, but also cares about the community by sponsoring many events with their eco-friendly Solar Trailer.

Other than the panel brand you are going to choose, other factors must be kept in mind; the experience of the installer, racking equipment, and the location also affects the prices. So, when you are choosing the brand for the installation project, you need to be careful and consider all the factors and aspects.

Clean Energy

Choosing a renewable source of energy is the best thing one can do these days. The greenhouse effect that is caused by coal, petroleum, and gas will put an end to the earth at some point. It’s our responsibility to go “green” to save the Earth for a better world. Other than that, even if you don’t care about the environment, a clean source of energy that depends on wind or the sun, would definitely cost you a big amount at the beginning, but in the long run, they are cheaper sources of electricity.

Tips to Choose the Budget-Friendly System of Energy for Your New Home

Newly arrived at your new home, the first thing is to make sure that you are going to pay the bill for the area that is in your use. That’s why the first day in your new home is advisable to take the meter reading. Good time to introduce yourself to the president of the community … or whoever wants to keep the keys of the accounting room. This advice also applies to gas, water, and other supplies whether it’s new construction or used housing, you should take a meter reading.  Look for iselect energy website! When moving, the first thing is to take note of the different counters (light, water, gas) in order to take responsibility only for what you are going to consume.

Your freedom of choice is sacred

It is very important that you know that you are always entitled to choose your electric company freely. You decide you send.  You have bought a house, or you are renting, this is a right of every consumer to choose the budget-friendly ways for electricity consumption. It is so legitimate that you are interested in changing or continuing with the electric company that you are hired.

What can you choose?

 The company that will send your electricity bill, that is, the electric energy trader.

What can you not choose?

The company that is responsible for providing the energy to your home, that is, the distributor. You do not choose it because you have to choose the one that corresponds to your place of residence.

When you arrive at a new house, it may happen that:

  1. The light is discharged, and both the power and the rate seem appropriate:

If so, and if you want to continue being a client of the same marketer, all you have to do is change the owner of the contract. This procedure is simple, fast and free.

  1. The light is discharged, but the power seems excessive or insufficient

You will have to make a change of power. This procedure costs money, although lowering the power can save a lot on your bill.

  1. The electricity connection is registered, but you want to change the tariff

When you arrive, you can “inherit” a contract with a certain company and a certain rate. If what you find does not convince you, you are free to change your electric energy provider. It is your choice, which service you want to choose for your home.

  1. The light has no connection to the electricity network

If your supply point has not been used for more than 3 years, this procedure costs money. The contract of registration is processed with the distributor, but it is the distributor that installs the meter and activates the supply. For this reason, the payment of this procedure will be made to the distributor in the first invoice.

The payment procedure for the efficient electricity providers is very simple and easy for the consumers. You can pay your bills and others online via credit and debit card.

Finding the Most Affordable Electricity Supplier

Have you recently checked out your energy tariffs? If not, then you need to be paying more attention to it now. Keep in mind that your energy bill doesn’t merely indicate or show how much energy you consume.

Take note that your postcode plays an essential role in tracking down how much you pay. According to your region, energy providers charge different rates, although they’re offering the same service. Even if there’s hardly anything you can do about price variations, you can look for the most affordable electricity provider in your region and ensure you are on the optimal tariff.

To save on your energy bill, it might be time to switch to a new supplier. For a little help, here’s how you can find one.

Compare Energy Prices

To analyze all the tariffs for every region as well as the payment method to discover the most inexpensive electricity supplier near you, you can leverage many online services such as the Compare Texas Electricity Rates, Prices & Plans at Eligo Energy.

To start, you need to register online your postcode or zipcode and information about your usage, tariff, and energy supplier. Once you’re done, you can compare deals throughout the market and get the best offer possible.

Keep in mind that aside from ensuring you are on the best available energy deal, you can keep electricity and gas bills to a minimum by making sure that your home is energy efficient. There are short-term measures to save energy that includes;

  • Using low-consumption bulbs.
  • Lowering down your thermostat by one degree.
  • When using an electric kettle, it is wise only to heat as much water.
  • Choose draught-proof doors and windows to cut down heat loss.
  • Turn off standby electrical items.

What’s more, there are long-term measures to save energy that includes;

  • Installing a condensing boiler.
  • Proper insulation.
  • Installing cavity wall insulation.
  • Purchasing energy-efficient electrical items.

Switching Incentives and Refer-A-Friend

A lot of energy providers are now presenting or providing financial rewards for shifting to them. And it includes refer-a-friend deals. So, if you are invited to switch energy providers through a refer-a-friend scheme, ensure you check and examine the following:

  • Customer service
  • Exit fees
  • Attached conditions to the switching incentive
  • Price compared to other deals
  • Price of the tariff

Variable Vs. Fixed Energy Tariffs

More often than not, energy deals arrive in two types: variable and fixed. The question now is, which is best for you? Variable tariffs can alter in price every time your energy provider changes its rates. The default tariff of your supplier will typically be a variable deal.

That said, if you are committed to an energy provider for a couple of years, or did not change after your fixed tariff ended, it is likely that you are on its default tariff. Take note that default tariffs are liable to a price cap, which is a cap on the price for every energy unit, not on your total bill.

Even so, a few small energy suppliers provide variable tariffs that are more affordable compared to large suppliers. Although they can alter their rates too, these suppliers are surely worth considering, especially if you want to pay less without a fixed contract.

On the other hand, fixed tariffs settle the amount you pay for every energy unit you consume for the particular period. Meaning, you know the price beforehand, and it will not increase throughout the contract period. Therefore, if the energy provider increases its prices, yours won’t. However, you will not benefit if the prices decrease, either.

Which is more affordable between the two? Well, the most inexpensive deals out there tend to be a combination of variable and fixed. As such, it is not easy to choose between the two.

Avoiding Exit Fees

Before you even decide to change the energy provider, be sure to check the agreements or terms of your deal. If you choose to withdraw a fixed tariff before your contract ends, you might have to pay an exit fee.

However, do not let this dismay you because not all fixed-term deals include exit fees. So, if you switch, better choose one without exit fees. Also, your energy provider cannot charge an exit fee if you shift provider in the last forty-nine days of your term. Moreover, if you are moving home, you don’t need to pay exit fees.

Takeaway

If you have switched energy providers, there are a few things you can do to ensure that your bills are accurate. You can send your meter readings to your provider to ensure you are being billed only for what you consume. Aside from this, you can ask for a refund if you are unduly in credit. Also, be sure to determine the end date of your fixed-term tariff before you switch to a new deal so that you won’t be moved to a default tariff.

Moving Grate Incineration: Preferred WTE Technology

Incineration is the most popular waste treatment method that transforms waste materials into useful energy. The incineration process converts waste into ash, flue gas, and heat. The type of thermal WTE technology most commonly used worldwide for municipal solid waste is the moving grate incineration. These moving grate incinerators are even sometimes referred to as as the Municipal Solid Waste Incinerators (MSWIs).

As of August 2013, of more than 1000 of 1200 Waste-to-Energy plants (among 40 different countries) there is no pre-treatment of the MSW before it is combusted using a moving grate. The hot combustion gases are commonly used in boilers to create steam that can be utilized for electricity production. The excess energy that can’t be used for electricity can possibly be used for industrial purposes, such as desalination or district heating/cooling.

moving-grate_incinerator

Benefits of Moving Grate Incineration

The moving grate incineration technology is lenient in that it doesn’t need prior MSW sorting or shredding and can accommodate large quantities and variations of MSW composition and calorific value. With over 100 years of operation experience, the moving grate incineration system has a long track record of operation for mixed MSW treatment. Between 2003 and 2011, it was reported that at least 106 moving grate incineration plants were built worldwide for MSW treatment. Currently, it is the main thermal treatment used for mixed MSW.

Compared to other thermal treatment technologies, the unit capacity and plant capacity of the moving grate incineration system is the highest, ranging from 10 to 920 tpd and 20 to 4,300 tpd. This system is able to operate 8,000 hours per year with one scheduled stop for inspection and maintenance of a duration of roughly one month. Today, the moving grate incineration system is the only treatment type which has been proven to be capable of treating over 3,000 tpd of mixed MSW without requiring any pretreatment steps. Being composed of six lines of furnace, one of the world’s largest moving grate incineration plants has a capacity of 4,300 tpd and was installed in Singapore by Mitsubishi in 2000

Working Principle

Moving-grate incineration requires that the grate be able to move the waste from the combustion chamber to allow for an effective and complete combustion. A single incineration plant is able to process thirty-five metric tons of waste per hour of treatment.

The MSW for a moving grate incinerator does not require pretreatment. For this reason, it is easier to process large variations and quantities. Most of these incineration plants have hydraulic feeders to feed as-received MSW to the combustion chamber (a moving grate that burns the material), a boiler to recover heat, an air pollution control system to clean toxins in the flus gas, and discharge units for the fly ash. The air or water-cooled moving grate is the central piece of the process and is made of special alloys that resist the high temperature and avoid erosion and corrosion.

Working principle of a grate incinerator

The waste is first dried on the grate and then burnt at a high temperature (850 to 950 degrees C) accompanied with a supply of air. With a crane, the waste itself is emptied into an opening in the grate. The waste then moves towards the ash pit and it is then treated with water, cleaning the ash out. Air then flows through the waste, cooling the grate. Sometimes grates can also be cooled with water instead. Air gets blown through the boiler once more (but faster this time) to complete the burning of the flue gases to improve the mixing and excess of oxygen.

Suitability for Developing Nations

For lower income and developing countries with overflowing landfills, the moving grate incinerator seems suitable and efficient. Moving grate incineration is the most efficient technology for a large-scale mixed MSW treatment because it is the only thermal technology that has been able to treat over 3,000 tons of mixed MSW per day. It also seems to be considerably cheaper than conventional technologies.

Compared to other types of Waste-to-Energy technologies, this type of system also shows the highest ability to handle variation of MSW characteristics. As for the other incineration technologies like gasification and pyrolysis technologies, these are either limited in small-scale, limited in material for industrial/hazardous waste treatment, requiring preprocessing of mixed MSW before feeding, which make them not suitable for large-scale mixed MSW treatment.

Conclusion

For the reduction of significant waste volume, treatment using a moving grate incinerator with energy recovery is the most commonly used form of waste-to-energy (WTE) technology. The moving grate’s ability to treat significant volumes of waste efficiently, while not requiring pre-treatment or sorting is a major advantage that makes this suitable for developing countries. This technology could provide many other benefits to such nations. Implementing moving grate incinerators is most suitable for developing nations because not only will it reduce waste volume, but it would also reduce the demand for landfills, and could recover energy for electricity.

References

 “A Rapidly Emerging WTE Technology: Circulating Fluid Bed Combustion”. Huang, Qunxing, Yong Chi1, and Nickolas J. Themelis. Proceedings of International Thermal Treatment Technologies (IT3), San Antonio, TX, October 2013. Columbia University. Available: http://www.seas.columbia.edu/earth/wtert/sofos/Rapid_Emerging_Tech_CFB.pdf accessed on 29 March 2016.
“Incineration.” Waste Management Resources. Waste Management Resources. Available: http://www.wrfound.org.uk/articles/incineration.html accessed on 29 March 2016.
Kamuk, Bettina, and Jørgen Haukohl. ISWA Guidelines: Waste to Energy in Low and Middle Income Countries. Rep. International Solid Waste Association, 2013. Print.
“Municipal Solid Waste Management and Waste-to-Energy in the United States, China and Japan.” Themelis, Nickolas J., and Charles Mussche. 2nd International Academic Symposium on Enhanced Landfill Mining, Houthalen and Helchteren, Belgium, 4-16 October 2013.  Enhanced Landfill Mining. Columbia University.
“Review of MSW Thermal Treatment Tecnologies.” Lai, K.C.K., I.M.C. Lo, and T.T.Z. Liu. Proceedings of the International Conference on Solid Waste 2011- Moving Towards Sustainable Resource Management, Hong Kong SAR, P.R. China, 2 – 6 May 2011. Hong Kong SAR, P.R. China. 2011. 317-321. Available: http://www.iswa.org/uploads/tx_iswaknowledgebase/10_Thermal_Technology.pdf. accessed on 14 April 2016.
UN-HABITAT, 2010. Collection of Municipal Solid Waste in Developing Countries. United Nations Human Settlements Programme (UN-HABITAT), Nairobi. Available:
http://www.eawag.ch/fileadmin/Domain1/Abteilungen/sandec/E-Learning/Moocs/Solid_Waste/W1/Collection_MSW_2010.pdf.
World Bank, 2012. What a Waste: A Global Review of Solid Waste Management. Urban Development Series Knowledge Papers. Available: http://documents.worldbank.org/curated/en/2012/03/16537275/waste-global-review-solid-wastemanagement. accessed on 14 April 2016.

Pay Your Electricity Bill Effortlessly

Utilities like water and power can end up costing nearly as much as your rent or house payment in a bad month. Unfortunately, you can’t cut off your water service to save money the way you could cut the cable. Here are a few tips to tame your utility bills and make it easier to pay your electric bill with ease.

Clean Up

Cleaning the coils on your refrigerator helps it work more efficiently. Cleaning the coils on your air conditioner can do the same, but your AC uses far more power than your fridge. Remove any debris from the air intakes, whether it is leaving piles up by the AC or the air vent to your furnace. Rinse the air filters for your room air filters, the air conditioner, and your dehumidifier.

Turn It Off

While the appliances that are sleeping may use less energy than when on, the reality is that they use almost as much power in standby as they do when active. The solution is to turn things off. Unless your game station is downloading updates, unplug it to save power. Turn off the TV instead of letting it sit in standby, or worse, use it as background noise.

When gadgets are fully charged, disconnect them from the charging station and turn off the charging station. If you can’t stand to turn off your computer, turn off the monitor instead. Turn off lights when they aren’t in use, and consider when you can utilize natural light instead. Don’t let appliances idly run while you’re busy. Get the clothes out of the dryer instead of letting it run every five minutes to prevent clothes from wrinkling.

Turn off the oven when you’re done with it. The same might be said for your pool pump or air filters. Does it need to be running? If not, consider turning it off for a while.

Track Energy Usage

You can get apps that report energy usage in your home. These apps can tap into your smart meter and tell you which appliances are consuming the most energy. If you can’t cut back on energy usage, you could get advice on how to shift energy usage in order to reduce your electric bill.

For example, running the clothes dryer at night may allow you to get utility discounts. One of the advantages of hydroelectric energy is that despite facing daily and seasonal variations, utility companies will still provide discounts when the demand for power is lower.

Set up the dishwasher to run a heavy load when you go to bed, and the cost per kilowatt maybe a third of what you’d pay if it ran during the day. You may also find that the AC is running heavily during the hottest part of the day.

Could you alter the thermal profile of your home so that it uses less energy while keeping you comfortable, such as not trying to keep the house at 65 when you’re at work? If you cannot get the house comfortable without the AC running full blast all the time, you may need to have the air conditioner repaired or replaced with a more powerful unit.

Check for Leaks

If you’ve ever heard the joke that you’re not heating the neighborhood, recognize that there is an element of truth to that joke. When you leave the door open while you’re bringing in groceries or getting the mail, you’re wasting the energy used to heat or cool that air. Gaps in your window frame and window stripping cost you the same way.

Leaks in your hot water heater waste both water and the energy used to heat it. Look for water leaks when you suspect them, too. Not only does this damage the structure of your home and wastewater, but damp insulation has a fraction of the thermal value of dry insulation. This is how a water leak could be contributing to your higher energy bills.

There are a number of things you can do to reduce your energy and water bills without radically changing your lifestyle. Then you’ll be able to save the Earth’s resources and money at the same time. It is truly a win-win for everyone.

Description of a Biogas Power Plant

A biogas plant is a decentralized energy system, which can lead to self-sufficiency in heat and power needs, and at the same time reduces environmental pollution. The key components of a modern biogas power (or anaerobic digestion) plant include: manure collection, anaerobic digester, effluent treatment, biogas storage, and biogas use/electricity generating equipment.

anaerobic_digestion_plant

Working of a Biogas Plant

The fresh animal manure is stored in a collection tank before its processing to the homogenization tank which is equipped with a mixer to facilitate homogenization of the waste stream. The uniformly mixed waste is passed through a macerator to obtain uniform particle size of 5-10 mm and pumped into suitable-capacity anaerobic digesters where stabilization of organic waste takes place.

In anaerobic digestion, organic material is converted to biogas by a series of bacteria groups into methane and carbon dioxide. The majority of commercially operating digesters are plug flow and complete-mix reactors operating at mesophilic temperatures. The type of digester used varies with the consistency and solids content of the feedstock, with capital investment factors and with the primary purpose of digestion.

Biogas Cleanup

Biogas contain significant amount of hydrogen sulfide (H2S) gas which needs to be stripped off due to its highly corrosive nature. The removal of H2S takes place in a biological desulphurization unit in which a limited quantity of air is added to biogas in the presence of specialized aerobic bacteria which oxidizes H2S into elemental sulfur.

Utilization of Biogas

Biogas is dried and vented into a CHP unit to a generator to produce electricity and heat. The size of the CHP system depends on the amount of biogas produced daily.

Treatment of Digestate

The digested substrate is passed through screw presses for dewatering and then subjected to solar drying and conditioning to give high-quality organic fertilizer.  The press water is treated in an effluent treatment plant based on activated sludge process which consists of an aeration tank and a secondary clarifier. The treated wastewater is recycled to meet in-house plant requirements.

Monitoring of Environmental Parameters

A chemical laboratory is necessary to continuously monitor important environmental parameters such as BOD, COD, VFA, pH, ammonia, C:N ratio at different locations for efficient and proper functioning of the process.

Control System

The continuous monitoring of the biogas plant is achieved by using a remote control system such as Supervisory Control and Data Acquisition (SCADA) system. This remote system facilitates immediate feedback and adjustment, which can result in energy savings.

Generating Electricity from Municipal Solid Waste

We live in a throwaway society that accumulates vast quantities of waste every day. While this comes with pressing challenges, there are also opportunities for professionals including electrical engineers to process at least some of the waste to produce much-needed renewable energy.

According to the U.S. Energy Information Administration (EIA), in 2018 a total of 68 U.S. power plants generated around 14 billion kilowatt-hours of electricity from 29.5 million tons of combustible municipal solid waste (MSW). Biomass, which comes from plants and animals and is a source of renewable energy, was responsible for more than half (about 51%) of the electricity generated from waste. It also accounted for about 64% of the weight of the MSW used. The rest of the waste used was from other combustible materials including synthetic materials made from petroleum and plastics. Glass and metal are generally not noncombustible.

WTE_Plant_Belgium

Waste-to-Energy is now widely accepted as a part of sustainable waste management strategy.

Municipal Solid Waste in the U.S.

Burning MSW is not only a sustainable way to produce electricity, it also reduces the volume of waste that would inevitably end up in landfills. Instead, the EIA estimates that burning MSW effectively reduces waste volumes by about 87%.

But, while more than 268 million tons of MSW are generated in the United States every year, in 2017, only 12.7% of it was burned to recover energy. More than half (52.1%) went to landfill, about a quarter (25.1%) was recycled, and the rest (10.1%) was used to generate compost.

According to a U.S. Environmental Protection Agency (EPA) fact sheet on sustainable materials management published in November 2019, the total MSW generated in 2017 by material, comprised:

  • Paper and paperboard, primarily containers and packaging 25%
  • Food 15.2% (see below)
  • Plastics 13.2% (19.2% of the total materials that ended up in landfill were plastics)
  • Yard trimmings 13.1% (most of this type of waste is composted)
  • Rubber, leather and textiles 9.7%
  • Metals 9.4%
  • Wood 6.7%
  • Glass 4.2%
  • Other 3.5%

Indicating tremendous human waste in its worst form, 22% of the material that ended up in landfill was classified as food. Trashed food was also the product category with the highest landfill rate, at an alarming 75.3%. Nearly a quarter (22%) of materials that were combusted with energy recovery were food, and overall, food was also the highest product category to recover energy, with a rate of 18.4%.

The total MSW combusted to generate energy was made up of the following materials:

  • Food 22%
  • Plastics 16.4%
  • Rubber, leather, and textiles 16.1%
  • Paper and paperboard 13.2%
  • Wood 8.4%
  • Metals 8.6%
  • Yard trimmings 6.2%
  • Glass 4.3%
  • Other 4.3%

Generating Electricity from MSW

There are a variety of MSW-to-energy technologies, but in the U.S. the most common system involves mass burning of unprocessed MSW in a large incinerator that has a boiler that produces steam, and a generator that produces electricity. Another entails processing MSW into fuel pellets for use in smaller power plants.

Waste materials destined to be processed to generate electricity

Generating electricity in mass-burn WTE plants is remarkably straightforward and follows seven basic steps:

  1. The MSW is dumped out of garbage trucks into a large pit.
  2. A crane with a giant claw attachment is used to grab the waste and dump it into a combustion chamber.
  3. The waste, which now becomes the fuel, starts to burn, releasing heat.
  4. The heat that is released turns water in the boiler into high-pressure steam.
  5. The steam turns the turbine generator’s blades and produces electricity.
  6. The mass-burn plant incorporates an control system to prevent air pollution by removing pollutants from the combustion gas before it is released through a smoke-stack.
  7. Ash is inevitably produced in the boiler and the air pollution control system, and this has to be removed before another load of waste can be burned.

While the volumes burned as fuel in different plants vary, for every 100 pounds of MSW produced in the U.S., potentially, more than 85 pounds could be burned to generate electricity.

Of course, the U.S. isn’t the only country that uses waste-to-energy plants to generate electricity from MSW. And in fact, when compared to a lot of other countries, the percentage of MSW burned with energy recovery in the U.S. is minimal. At least nine countries are named by the EIA as bigger producers of electricity from municipal waste. In Japan and some European countries, for instance, there are fewer energy resources and not much open space available for landfills. So generating electricity from MSW is an obvious opportunity.

The four leading nations identified by the EIA as burning the most MSW with energy recovery are:

  • Japan 68%
  • Norway 54%
  • Switzerland 48%
  • France 35%
  • The United Kingdom 34%

One thing’s for certain, the percentages are all set to continue increases globally as the move towards sustainability gains momentum. And U.S. percentages are going to increase too.

Use of Palm Kernel Shells in Circulating Fluidized Bed Power Plants

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-shell-uses

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.

Combined Heat and Power Systems in Biomass Industry

Combined heat and power systems in the biomass industry means the simultaneous generation of multiple forms of useful energy (usually mechanical and thermal) from biomass resources in a single, integrated system. In a conventional electricity generation systems, about 35% of the energy potential contained in the fuel is converted on average into electricity, whilst the rest is lost as waste heat. CHP systems use both electricity and heat and therefore can achieve an efficiency of up to 90%.

CHP technologies are well suited for sustainable development projects because they are socio-economically attractive and technologically mature and reliable. In developing countries, cogeneration can easily be integrated in many industries, especially agriculture and food processing, taking advantage of the biomass residues of the production process. This has the dual benefits of lowering fuel costs and solving waste disposal issues.

CHP systems consist of a number of individual components—prime mover (heat engine), generator, heat recovery, and electrical interconnection—configured into an integrated whole. Prime movers for CHP units include reciprocating engines, combustion or gas turbines, steam turbines, microturbines, and fuel cells. A typical CHP system provides:

  • Distributed generation of electrical and/or mechanical power.
  • Waste-heat recovery for heating, cooling, or process applications.
  • Seamless system integration for a variety of technologies, thermal applications, and fuel types.

The success of any biomass-fuelled CHP project is heavily dependent on the availability of a suitable biomass feedstock freely available in urban and rural areas.

Rural Resources Urban Resources
Forest residues Urban wood waste
Wood wastes Municipal solid wastes
Crop residues Agro-industrial wastes
Energy crops Food processing residues
Animal manure Sewage

Technology Options

Reciprocating or internal combustion engines (ICEs) are among the most widely used prime movers to power small electricity generators. Advantages include large variations in the size range available, fast start-up, good efficiencies under partial load efficiency, reliability, and long life.

Steam turbines are the most commonly employed prime movers for large power outputs. Steam at lower pressure is extracted from the steam turbine and used directly or is converted to other forms of thermal energy. System efficiencies can vary between 15 and 35% depending on the steam parameters.

Co-firing 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. Most forms of biomass are suitable for co-firing.

Steam engines are also proven technology but suited mainly for constant speed operation in industrial environments. Steam engines are available in different sizes ranging from a few kW to more than 1 MWe.

A gas turbine system requires landfill gas, biogas, or a biomass gasifier to produce the gas for the turbine. This biogas must be carefully filtered of particulate matter to avoid damaging the blades of the gas turbine.

Stirling engines utilize any source of heat provided that it is of sufficiently high temperature. A wide variety of heat sources can be used but the Stirling engine is particularly well-suited to biomass fuels. Stirling engines are available in the 0.5 to 150 kWe range and a number of companies are working on its further development.

A micro-turbine recovers part of the exhaust heat for preheating the combustion air and hence increases overall efficiency to around 20-30%. Several competing manufacturers are developing units in the 25-250kWe range. Advantages of micro-turbines include compact and light weight design, a fairly wide size range due to modularity, and low noise levels.

Fuel cells are electrochemical devices in which hydrogen-rich fuel produces heat and power. Hydrogen can be produced from a wide range of renewable and non-renewable sources. A future high temperature fuel cell burning biomass might be able to achieve greater than 50% efficiency.