Waste-To-Energy: Killing two birds with one stone

Amaka Analysis, Energy & Environment, Featured, HighlightsEnergy

Waste to Energy: A dumpsite in Lagos
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Opaluwa Enebi

Waste-to-energy (WTE) is the process of generating energy in form of electricity or heat from municipal solid waste (MSW). This is also known as energy recovery. According to Deltaway energy, a California-based company that specializes in the design, operation and maintenance of waste-to-energy and biomass power plants, the WTE process can reduce a community’s landfill volume by up to 90% and prevent the emission of one tonne of carbon dioxide for every tonne of waste burned[i].

Waste to energy plants operate like other traditional steam power plants, the only variation being the primary source of energy- garbage. The process is divided into a series of stages. First the waste is collected into a large pit. Then, using heavy mechanical equipment, the garbage is lifted and transferred to a combustion chamber. The next stage involves burning the waste to release heat which is used to boil water into steam in a boiler. Under high pressure, the steam turns the blades of a turbine which is connected to a generator to produce electricity. An air pollution control system removes pollutants from the combustion gas before it is released through a smoke stack. Finally, ash is collected from the boiler and the air pollution control system[ii].

Waste to energy plant

Source: https://www.eia.gov/energyexplained/index.cfm/data/index.cfm?page=biomass_waste_to_energy

 

Waste-to-energy has been implemented as a sustainable waste management solution in North America, Europe and Asia. The process leaves behind as little as 10% of the total volume of waste consumed as ash which is used as daily land cover in landfills or for road construction as is the case in the E.U[iii]. Data of selected countries from these regions showed that between 13% (United States) and 70% (Japan) of MSW generated in 2013 and 2014 were burned with energy recovery. In the United States, of the 258 million tonnes of MSW generated in 2014, 53% was sent to landfills, 35% was recycled and composted and 13% was burned with energy recovery. In 2015 alone, WTE plants across the US burned a total of 29 million tonnes of MSW and generated about 14 billion kilowatt hours of electricity in the process. WTE is capable of providing waste management and electricity supply solutions, especially in densely populated areas that generate large amounts of garbage.

Source: https://www.eia.gov/energyexplained/images/charts/waste_to_energy_world-large.jpg

In Nigeria, proper waste management is a challenge that government authorities are still trying to solve. It is estimated that the country generates about 32 million tonnes of MSW per annum, however only 20-30% is collected[iv]. The rest are recklessly left to litter the environment or end up in arbitrary dumpsites constituting serious health, environmental and infrastructural hazards. The awful odour from these dumpsites makes the surrounding environment inhospitable and inhabitable. Drainage networks and sewer systems get clogged on occasion while air and ground pollution due to indiscriminate waste disposal is rampant. In addition, water bodies like rivers and waterways, especially in urban areas are visibly littered with solid waste consisting of plastic bags and containers, scrap metal and food items.

Densely populated cities, like Lagos, Abuja, Port Harcourt and Ibadan generate the most MSW, largely because of the population size and the volume of economic activity. For example, at 0.5kg per capita, Lagos generates more than 10,000tons of waste per day[v]. While the state has a fairly organized system for collecting and disposing MSW, waste collection agencies are still yet to provide complete statewide coverage as random unauthorised dumpsites can still be found across the state. Nationwide, the situation is further worsened by poor methods of waste management and treatment. The more common method, usually open air incineration, directly results in more emissions and reduces air quality and visibility. This method of treatment has also been associated with increased risk of contracting respiratory diseases and cardiovascular damage[vi] as well as some reproductive and cancer outcomes[vii].

Waste to Energy: A dumpsite in Lagos

Waste to Energy: A dumpsite in Lagos

Source: http://nigeriaenvironment.blogspot.com.ng/2012/12/municipal-solid-waste-management-in.html

Implementing an efficient and sustainable waste management system through a waste-to-energy facility would be beneficial to Nigeria. Improved air quality, reduced emissions and hospitable, conducive living and business surroundings are some of the added economic or social gains that can be derived from the waste management process.

Revenue accrued from the sale of electricity generated is a major benefit. 1 tonne of MSW can generate a net of 500-600kWh of electricity[viii]. Assuming this was supplied to residential consumers with a three phase supply (R2T[1] category of consumer), at N28.39 per kWh, Eko electricity distribution company could potentially generate from 141.95 to 170.34 million naira from Lagos’s 10,000 tonnes of MSW per day. However, WTE facilities, like other power plants are expensive to construct. Based on estimates by the Waste-to-Energy Research and Technology Council (WTERT); WTE facilities in the US process from 500 to 3000 tonnes of waste per day. Expectedly, larger plants have lower capital and operating costs per ton of MSW processed. At an average of $650 per annual tonne, a 3000 tonne per day WTE plant would cost $643.5 million to build[2] and would supply 594GWh of electricity a year. Using the aforementioned Eko disco rate, 594GWh of electricity would generate the equivalent of $55.11 million[3] per annum in revenue. Lagos State would require four of such plants to sufficiently process its MSW. By comparison, in 2010, a 640,000 tonnes per year WTE plant in Montevideo, Uruguay was estimated at $420 million in capital investment and $22 million in operating cost[ix].

Benefits that could be derived from a Waste-to-Energy plant in Lagos

While WTE plants require huge capital investments, the added advantages are numerous. In addition to the revenue accrued from the supply of electricity generated, a gate fee per ton of waste could also be charged. In 2010, the average gate fee for the WTE plant in Uruguay was $16 per tonne. Assuming maximum operational capacity, a 3000 tonne facility would generate $43,000 per day and $14.4 million per annum in gate fees alone. Other benefits include acquiring carbon credits and keeping international climate agreements. WTE facilities could also incorporate recycling and composting facilities which could reduce overall capital cost while providing more avenues for revenue generation.

The establishment of a WTE facility is nonetheless a momentous project and requires far-reaching preliminary conditions that should be met to ensure its success. First, waste disposal culture in Nigeria needs to be revisited. Households and communities can no longer convert their backyards or the closest, unused expanse of land to a dumpsite. Furthermore, waste should be properly collected and sorted out into bio degradable, non-biodegradable and hazardous waste and disposed accordingly. This would reduce the total number of man hours needed for processing; especially when the generation of bio gas is included in the energy recovery process. It would also improve the total time allocated for sorting out garbage at recycling facilities.

Second, adequate information is crucial before any project can be successfully implemented. Waste disposal data in the country is still largely unavailable or not easily accessible. Government energy and environmental agencies and ministries at both Federal and State levels are yet to publish waste disposal data through available channels. This could be due to the fact that many states still lack proper municipal waste disposal programmes, while those that do have, operate with limited efficiency. Proper waste management requires adequate collection and dissemination of information to facilitate effective planning and execution. Such data would include the total volume of MSW collected as well as characterization in terms of composition, heating content, moisture, etc.

Third, efficient transport infrastructure is necessary to keep the cost of transportation within manageable limits. If transportation costs are too high, overall cost of operation would equally increase which would result in higher electricity tariffs. Other factors that need to be addressed in order to make a WTE facility economically viable include availability and accessibility of a site, waste supply commitments, ash disposal (landfill) capacity as well as availability and cost of disposal alternatives.

Lastly, political will and commitment is very vital for the establishment of a WTE facility in Nigeria. Government actors must recognize the long term tangible, intangible, social and economic benefits and throw their support behind such initiatives for projects to be successfully implemented. Relevant legislation should be updated or created and enforced. For instance, while the National Environmental Standards and Regulations Enforcement Agency (NESREA) at federal level is responsible for enforcing environment and waste management laws and almost all states have at least one agency that caters to issues relating to the environment; regulation focuses on toxic and hazardous materials such as industrial waste or oil spills[x]. Little is mentioned of MSW management. Very few states, particularly Lagos, seem to display some level awareness of the challenge with proposed alternatives to address it.

In as much as it is clear that waste disposal is an irritating problem in Nigeria, state actors must evolve from just identifying problems towards developing and implementing practical steps to tackle them. WTE facilities are a sustainable method of waste management and treatment, with added local and international benefits. In a country like Nigeria which experiences an acute shortage of electricity supply, waste-to-energy as a method of waste management should be considered and included in government policies with practical steps to facilitate and ensure its implementation. It would not only provide electricity for the country but also help to address the problem of solid waste management, especially in urban clusters around the country.

[1] R2T is one of four classifications of residential consumers by NERC. It represents residential consumers with a 3-phase meter and with demand below 45kV. This category of consumer presently pays N28.39 in electricity tariff.

[2] According to WTERT, WTE plants have an overall availability of 330 24-hr days per year. On a daily basis, annual volume of MSW processed would be 3000*330= 990,000 tonnes per annum. At $650 per annual ton, construction cost= $650*990,000= $643.5 million.

[3] 594GWh would generate N16.86 billion. At N306 to $1, this is equivalent to $55.11 million.

END NOTES

 

[i] http://www.deltawayenergy.com/wte-tools/wte-anatomy/

[ii] Waste-to-energy (Municipal Solid Waste), available at https://www.eia.gov/energyexplained/index.cfm/data/index.cfm?page=biomass_waste_to_energy

[iii] The ABC of sustainable waste management (SWM), available at  http://www.seas.columbia.edu/earth/wtert/faq.html

[iv] Bakare W. (2016), “Solid Waste management in Nigeria”, Bio energy consult, available at   http://www.bioenergyconsult.com/solid-waste-nigeria/

[v] Bakare W. (2016), “Solid Waste management in Nigeria”, Bio energy consult, available at http://www.bioenergyconsult.com/solid-waste-nigeria/

[vi] Franchini M, Rial M, Buiatti E and Bianchi F., “Health effects of exposure to waste incinerator emissions:

a review of epidemiological studies”, Ann Ist Super Sanità 2004, 40(1), pgs 101-115, available at http://www.hia21.eu/dwnld/20131216_Health%20effects%20of%20exposure%20to%20waste%20incinerator%20emissions.pdf

[vii] Porta D, Milani S, Lazzarino A.I, Perucci C.A, and Forastiere F (2009), “Systematic review of epidemiological studies on health effects associated with management of solid waste”, Open access, available at  https://ehjournal.biomedcentral.com/articles/10.1186/1476-069X-8-60

[viii] http://www.seas.columbia.edu/earth/wtert/faq.html

[ix] Rodriguez M. E. (2011), “Cost-benefit analysis of a waste to energy Plant for Montevideo; and waste to Energy in small islands”, department of earth and environmental engineering, University of Columbia, pg 2, available at http://www.seas.columbia.edu/earth/wtert/sofos/Rodriguez_thesis.pdf

[x] Amachree M. (2013), “Update on e-waste management in Nigeria”, proceedings at the 3rd annual meeting of the global e-waste management network, San Francisco, USA; available at   https://www.epa.gov/sites/production/files/2014-05/documents/nigeria.pdf

 

 

 

 

 

 

 

 

 

 

 

 

 

END NOTES

[1] http://www.deltawayenergy.com/wte-tools/wte-anatomy/

[1] Waste-to-energy (Municipal Solid Waste), available at https://www.eia.gov/energyexplained/index.cfm/data/index.cfm?page=biomass_waste_to_energy

[1] The ABC of sustainable waste management (SWM), available at  http://www.seas.columbia.edu/earth/wtert/faq.html

[1] Bakare W. (2016), “Solid Waste management in Nigeria”, Bio energy consult, available at   http://www.bioenergyconsult.com/solid-waste-nigeria/

[1] Bakare W. (2016), “Solid Waste management in Nigeria”, Bio energy consult, available at http://www.bioenergyconsult.com/solid-waste-nigeria/

[1] Franchini M, Rial M, Buiatti E and Bianchi F., “Health effects of exposure to waste incinerator emissions:

a review of epidemiological studies”, Ann Ist Super Sanità 2004, 40(1), pgs 101-115, available at http://www.hia21.eu/dwnld/20131216_Health%20effects%20of%20exposure%20to%20waste%20incinerator%20emissions.pdf

[1] Porta D, Milani S, Lazzarino A.I, Perucci C.A, and Forastiere F (2009), “Systematic review of epidemiological studies on health effects associated with management of solid waste”, Open access, available at  https://ehjournal.biomedcentral.com/articles/10.1186/1476-069X-8-60

[1] http://www.seas.columbia.edu/earth/wtert/faq.html

[1] Rodriguez M. E. (2011), “Cost-benefit analysis of a waste to energy Plant for Montevideo; and waste to Energy in small islands”, department of earth and environmental engineering, University of Columbia, pg 2, available at http://www.seas.columbia.edu/earth/wtert/sofos/Rodriguez_thesis.pdf

[1] Amachree M. (2013), “Update on e-waste management in Nigeria”, proceedings at the 3rd annual meeting of the global e-waste management network, San Francisco, USA; available at   https://www.epa.gov/sites/production/files/2014-05/documents/nigeria.pdf

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