Environmental Impact And Pollution Control In Kenya Environmental Sciences Essay

Currently the Kenyan household sector is completely dependent on kerosene and charcoal and in rare cases on solar power. Use of kerosene and firewood are inefficient use of fuel in Kenya. They are already high in scarcity value and expensive thus a cheaper and cleaner option is necessary. The proposed project activity is a biomass based power project. These categories of projects do require an environmental impact analysis to be performed under the existing NEMA regulations and obtain environment license. The operation of the power plant produces emissions, waste water and solid wastes such as boiler ash. Impact of release of pollutants is planned as follows to minimize the impact.

Turbo Generator and Auxiliaries: The system consists of one multistage steam turbine coupled with an electric generator, air cooled condenser, air ejector system for air cooled condenser, condensate pumps, lubricating oil and governing oil system. Controls and instrumentation are provided as per the needs. The proposed biomass based power plant, will have one no. 10.0 MW turbo generator. The turbine is provided with devices to safeguard against over speed, low steam inlet pressure, high axial movement of the shaft, low lube oil pressure, high condenser vacuum, excessive vibration etc.

Power generation will be 10.0 MW during the operation. The Auxiliary power (Home load) demand will be 0.9 MW. The balance power 9.1 MW will be exported to KPLC grid. Emergency Power System consists of 1 No. DG Set of 250 kVA is provided to make available emergency power supply to the station in case of black out. The total requirement of raw water for this unit will be 256 KLD. The entire raw water requirement for the unit will be met from dug well and bore well inside and outside the factory premises. This will ensure that the natural water catchment areas are preserved and the underground water is used instead. The acidic effluents generated during regeneration of caution and mixed bed exchangers and alkaline effluents generated during regeneration of anions and mixed bed exchangers of dematerialized water plant will be led into a neutralization pit. These effluents are self neutralizing but provisions will be made for final pH adjustment before disposal.

Wastewater Generation

S. No

Particulars

Wastewater Generated m3/hr

Method of Treatment

1

Sewage

2.0

Septic tank with Dispersion trench

2

Softener regeneration & DM Plant

0.3

Neutralization tank

3

Filter back wash/ R.O reject

0.55

Waste Water Storage Tank

4

Boiler blow down

2.46

5

Cooling tower blow down

1.159

Since, the small quantity of wastewater will be generated from domestic usages, the chances of contamination of soil will be nil. Wastewater drained from the treatment plant is pumped to a neutralization pit to maintain PH as prescribed by Pollution Control norms.

The blow down water from boiler will be mixed with cooling tower to bring down the temperature to ambient level.

The sewage from the various power plant buildings will be taken to a common septic tank through trenches for safer disposal.

The water used in the surface condenser will be cooled in a cooling tower. Blow down from the cooling tower will be trenched out and finally conveyed to the effluent pit.

The vacant area in the industry will be used for tree plantation to improve the surrounding environment of the industry.

Ash

The main solid waste from the proposed Power Plant will be ash (Fly ash and Bottom ash) by the combustion of fuel in boiler which will be around 35 tons/day which includes the bottom ash, ash collected in the ESP ash hoppers. The boiler will be sized to produce 45 tph steam under normal conditions. The proposed boiler will be primarily bio-mass fired single-drum, vertical type balanced draft with a furnace having traveling grate type furnace. The boiler will consist of air pre-heater, economizer, evaporators, super-heaters, fuel firing equipment, integral piping, flue gas ducting with expansion joints, supporting structures, platforms and walkways, etc. The firing system consists of a traveling grate, air plenum, regulating dampers and ash discharges valve.

The traveling grate is driven by a hydraulic arrangement and the tie bars of the traveling grates are made of cast iron, to withstand the heat from the burning. The combustion air to the grate is supplied from the bottom plenum hoppers and the air is controlled by the air dampers. The discharge end of the grate discharges the ash into a water impounded hopper. The shifting are collected in the plenum hopper and discharged by an air lock valve. Based on preliminary estimates, the maximum annual generation of ash from boiler operation is 2.5 tons/hr, based on 100 percent Prosopis juliflora firing. Fly ash constitutes the major part, accounting for 75% of total generation, the balance being bottom ash. The fly ash will be utilized for land filling, Brick making or Cement blending, for road building material and for farmers, who can use the ash as manure for the crops, and also through dense phase pneumatic handling system with fly ash silos which have a capacity to store 1 week generation of ash. The ash will be transported through trucks and the roads will be asphalted within the plant area.

Environmental pollution and control

Noise

Noise Level Survey: The foremost objective of noise monitoring in the study area is to evaluate the baseline noise and assess the impact of the total noise expected to be generated by proposed project. The details of the expected noise monitoring locations as per studies on other similar projects are that noise levels during day time were found to be in the range 52.6 – 48.3 dB. The maximum noise level was observed to be 52.6 dB at the Nalli, India and a minimum of 48.3 dB was observed at Alavattam, India. Noise levels observed to fall in the range 48.6- 46.5 dB during the night time. A maximum of 48.6 dB was observed at the Nalli, India and a minimum of 46.5 dB at Alavattam, India. Equipment will conform to noise levels prescribed by regulatory authorities.

Adequate noise control measures will be provided to satisfy the ambient noise level standards prescribed by NEMA. Noise absorbing materials will be used in the construction of roofs, walls, floors and in the generators. Provision of acoustic enclosures to noise generating equipments like pumps will be installed; major noise-producing equipments such as turbo generator compressors are to be provided with suitable noise abatements. Provision of thick greenbelt to attenuate the noise levels will be made.

Safety equipment for noise like ear muffs and other protective devises will be provided to the staff working near noise generation source. The pollution control measures planned for the plant will ensure that it has the least adverse impact on the environment.

Air

The project is techno economically viable, based on the various technical and financial analyses for generating power using bio-mass. During the growth of plants, CO2 in the air is absorbed through photosynthesis. The same quantity of CO2 will be released on burning, and will be again absorbed while growing (juliflora plants). Branches of juliflora will be cut, leaving the stem for the future growth. Although there will be some emissions from the burning process itself, the project will earn substantial carbon credits as the complete carbon cycle is calculated from the oxygen generated by the Prosopis while it is growing until it is finally burned. In this way the process is neutral and qualifies for carbon credit from the developed countries. Incidentally this is revenue for the biomass power generation plant. The quantity of CO2 for a 10 MW power plant is around 51,500tonnes/year. Please advice on the highlighted part.

Biomass energy generation, if done in a sustainable fashion, would greatly reduce emissions of greenhouses gases. The amount of carbon dioxide released when biomass is burned is very nearly the same as the amount required to replenish the plants grown to produce the biomass. Thus, in a sustainable fuel cycle, there will be no net emissions of carbon dioxide, although some fossil-fuel inputs will be required for planting, harvesting, transporting, and processing biomass. Efficient cultivation and conversion processes will used and the resulting emissions will be small (around 20% of the emissions created by fossil fuels alone). Also if the energy needed to produce and process biomass comes from renewable sources in the first place, then the net contribution to global warming will be zero.

Draft System and Electro-Static Precipitator: The boiler will be equipped with one number of forced draft fan, secondary air (SA) fan and induced draft fan. The FD & SA fans will supply the required combustion air to the boiler. The flue gases generated in the boiler will be evacuated by the ID fan and the capacity and head of FD fan will be selected considering maximum air that would be required for the fuel firing modes. In the same way, ID fan will also be selected based on the maximum flue gas generated in any of the fuel firing modes under consideration. The boiler is connected to an electro-static precipitator, which will remove the dust and ash particles from the flue gas, before the ID fan could handle it. The efficiency of the precipitator will be 99.9% and the dust concentration at the outlet of the ESP will be less than 100.0 mg/Nm3. Control of ground level concentration of SO2 emitted will be achieved by providing a stack at sufficient height of 65 m for dispersion.

The unit will install an electrostatic precipitator at the exit of boilers so as to limit the suspended particulate matter and achieve the standards prescribed by NEMA. Electrostatic precipitator of 99.9% efficiency will be installed to limit the SPM concentrations below100 mg/Nm3. A stack of 55-m height will be provided for wider dispersion of gaseous emissions.

Avoidance of methane emissions due to decay and de-gradation of the biomass waste is also necessary. The company intends to lay out an approach of CO2 neutrality in production and utilization of bio- mass for heat and power generation as well as avoiding CO2 emissions from the fossil fuels for the corresponding requirement. A combustion technology route is selected for the power plant, where bio-mass is burnt as fuel in a steam generator to produce high pressure steam which is then expanded in a steam turbine to generate power. This will in effect neutralize the CO2 emissions.

The design of fuel handling system, involving biomass fuels is based on the estimated quantities of annual fuel requirements. Fuels will be received at the site by road. Adequate road facilities will be provided to handle the road-bound vehicles on a daily peak basis. The fuels arriving at site by different types of vehicles such as trucks, tractor trailers etc. will be weighed on a pit less type electronic road weighbridge provided in the plant premises. The CO2 emissions from these transport vehicles will be subsequently absorbed by the juliflora plants.

Conveyor belt will be closed to prevent dust generation and water sprinkling system will be provided at the material handling and storage yard so as to satisfy the Ambient Air Quality/emission standards prescribed by NEMA. Well maintained greenbelt covering 25 %of the land area will be provided to arrest the fugitive emissions.

Soil

It has been observed that the pH of the soil ranged from 6.6 -6.7 indicating that the soils are acidic to slightly alkaline. Soils are mainly clay loams with alluvial deposits derived from tertiary / quaternary volcanic and pyroclastic rock sediments that have been weathered and eroded from the uplands. They contain high levels of P, K, Ca and Mg and low levels of N and C. The soil from the study area shows moderate to good fertility. By carrying out a replantation of the Prosopis on the cleared land then the soil fertility will be improved and maintained.

Although energy crops will be grown without pesticide and fertilizer, large-scale energy farming could nevertheless lead to increases in chemical use simply because more land would be under cultivation. Soils could be depleted of organic content and nutrients unless care is taken to leave enough wastes behind. These concerns point up the need for regulation and monitoring of energy crop development and waste use.

Ecology

The major environmental impact of biomass energy may be that of loss of biodiversity. Transforming natural ecosystems into energy plantations with a very small number of crops, as few as one, can drastically reduce the biodiversity of a region. There are no wild life sanctuaries/parks within 20 km radius of the project site. Also because of the denuded land, wildlife is quite scarce with the most common animals being the ostrich and dik dik. However snakes are in abundance. The records of Forest Department of Kenya did not indicate presence of any high endemic or vulnerable species in this area. The natural plants which are mainly shrubs and acacia trees will not be affected by the projects routine. The out growers will be trained on how to identify and avoid these natural plant species. Please advice if this part is adequately addressed.

This will lead to increasing the amount of forest wood harvested for energy and could provide an incentive for the forest-products industry to manage its resources more efficiently, and thus improve forest health. But it could also provide an excuse to exploit forests in an unsustainable fashion. Biomass energy production involves annual harvests or periodic removals of trees from the land. These harvests and removals will be at levels that are sustainable, i.e., surety that current use does not deplete the land’s ability to meet future needs, and also be done in ways that don’t degrade other important indicators of sustainability. Because biomass markets may involve new or additional removals of trees, we will be careful to minimize impacts from whatever additional demands biomass growth or harvesting makes on the land.

Unfortunately, commercial forests have not always been soundly managed, and many people view with alarm the prospect of increased wood cutting. Their concerns can be met by tighter government controls on forestry practices and by following the principles of “excellent” forestry. If such principles are applied, it should be possible to extract energy from forests indefinitely.

Greenbelt Development

Greenbelt will be developed inside the factory premises covering a total area of about 10.5 acres. The unit will also develop the nearby area around the industry for greenbelt. The inter-spaces will be laid with shrubs. The inter-space between trees planted will be about 5m. It is proposed to double the tree density in future in accordance to the factory requirements.

Socio – Economic

One other side effect of growing trees for energy is that it will benefit soil quality and farm economies. Energy crops will provide a steady supplemental income for farmers in off-seasons and allow them to work unused land without requiring much additional equipment. Moreover, energy crops will be used to stabilize cropland or rangeland prone to erosion and flooding. Trees will be grown for several years before being harvested, and their roots and leaf litter will help stabilize the soil. The planting of coppicing, or self-regenerating, varieties will minimize the need for disruptive tilling and planting.

This project does not involve any displacement of local people. Employment opportunities will be improved in the nearby villages because of this proposed unit and this will provide indirect employment opportunities for more than 1000 families.

Safety PPE’s -Operation and Maintenance

The following measures will be provided to ensure safety of the workers;

• Industrial safety helmets

• Crash helmets

• Face shield

• Welders equipment for eye and face protection

• Cylindrical type earplug

• Ear muffs

• Canister gas mask

• Self contained breathing apparatus

• Leather apron

• Boiler suit

• Safety belt /line mans safety belt

• Leather hand gloves

• Canvas cum leather hand gloves with leather palm

• Lead hand glove

• Electrically tested electrical resistance hand gloves and

• Industrial safety shoes with steel toe.

Environment, Safety and Health Monitoring Programme

The Environment, Safety and Health-Monitoring Programme in the factory will be as follows:

• Monthly Monitoring of Stack Emissions – SPM, RSPM, SO2, NOX

• Daily Monitoring of Water and Treated Water – pH, TDS, TSS, COD

• Monitoring of Ambient Air – SPM, RSPM, SO2, NOX & CO, Noise and Work Place Air

• Occupational Safety

• Occupational Health

Budgetary allocation for Environmental Management

Category

Capital Investment

Annual Operating Costs

(KES in 000′)

Air Pollution Management

125

1

Water and Wastewater Management

50

2

Solid Waste Management

50

5

Greenbelt

5

1

Environmental Monitoring and Training

5

1

Total

235

10

Please advice on this table. Is it necessary and are the figures almost correct.

Other impact of growing Prosopis Juliflora and using it to generate energy include;

Fossil fuel cogeneration and carbon mitigation will be encouraged.

The furnace and boiler will have to be especially modified to be able to generate steam at the high temperatures necessary for making the plant more energy efficient.

Sustainability of a biomass power plant will generally depend on the participation of the beneficiaries in terms of increased environmental awareness by distinguishing biomass power and conventional grid power. During the field survey it was found out that very little environmental concerns exist among the villagers. This is not to mean that they are ignorant of the negative impacts of deforestation, soil erosion, and loss of biodiversity but that they are aware and are willing to address these impacts accordingly. They are also willing to share the responsibility to plant more trees in their land to counter effect the negative impact that the power plant may generate and to maintain the sustainability.

The key to successful biomass power development is to use the resources efficiently in modern conversion systems that maximize the energy produced and minimize the byproducts of the conversion processes. In modern times, the combination of improved technological efficiencies, scientific advances, increased environmental-awareness and environmental protection regulations have turned biomass conversion into a cleaner, more efficient process.

In view of the above,the following activities along the biomass value chain will require consideration in an EIA:

􀂃 any activity or structure out of character with its surrounding;

􀂃 major changes in land use;

􀂃 all roads in scenic, wooded or mountainous areas and wetlands;

􀂃 railway lines;

􀂃 oil and gas pipelines;

􀂃 water transport;

􀂃 river diversions and water transfer between catchments;

􀂃 drilling for the purpose of utilizing ground water resources;

􀂃 timber harvesting;

􀂃 clearance of forest areas;

􀂃 reforestation and afforestation;

􀂃 large-scale agriculture;

􀂃 use of pesticides, including aerial spraying;

􀂃 introduction of new crops;

􀂃 use of fertilizers;

􀂃 irrigation;

􀂃 fertilizer manufacture or processing;

􀂃 oil refineries and petro-chemical works;

􀂃 chemical works and process plants;

􀂃 bulk grain processing plants;

􀂃 management of hydrocarbons including the storage of natural gas and combustible or explosive fuels;

􀂃 waste disposal, including: sites for solid waste disposal; sites for hazardous waste disposal; sewage disposal works; works involving major atmospheric emissions; works emitting offensive odors.

As required for implementation of the project activity, project participants have studied the possibility of environmental impacts and conclude that no negative impacts are possible due to the project activity. In fact, the project activity contributes to minimize the environmental pollution due to fossil fuel based electricity generation.