11-CS-3 Engineering Management · May 2019
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2019 — 11-CS-3 Sustainability, Engineering and the Environment. Closed book; approved Casio or Sharp calculator permitted. Any four questions constitute a complete paper; all questions are of equal value (25 marks each).
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
| Technology | Initial cost | Fuel cost | GHG emissions | Health risks to local populations | Land requirement |
|---|---|---|---|---|---|
| Wind turbines | M–H: turbines are moderately priced per MW of nameplate, but a ~35% capacity factor means roughly 570 MW of turbines (plus transmission and backup) to deliver an average 200 MW | L: the wind is free; only O&M costs | L: no combustion; only embodied emissions of steel, concrete and blade manufacture upstream | L: no air emissions; minor nuisance (noise, shadow flicker) and bird/bat impacts | H: turbines need wide spacing (tens of km²), although farming or grazing continues between towers |
| Nuclear (one plant) | H: reactor, containment and safety systems make it the most capital-intensive option, with long construction times and cost overruns | L: uranium is energy-dense, so fuel is a small share of cost even after mining, enrichment and fabrication | L: no combustion; small upstream emissions from mining, enrichment and construction | L–M: negligible routine exposure, but a low-probability, high-consequence accident risk, spent-fuel storage, and uranium-mine tailings upstream | L: compact site; upstream mining and waste storage add modest land |
| Solar PV farm | H: at a Canadian capacity factor of ~15%, over 1,300 MW of panels, inverters and storage are needed to average 200 MW | L: sunlight is free; only cleaning and O&M | L: no combustion; embodied emissions of silicon refining and panel manufacture upstream | L: no emissions in operation; upstream mining and panel-manufacturing chemicals are the main concern | H: the largest land take of the five (tens of km² of panels, largely excluding other uses) |
| Wood pellets | M: boiler, steam turbine and particulate controls, much like a solid-fuel steam plant | M–H: harvesting, drying, pelletizing and hauling a bulky, lower-energy fuel is costly | M: combustion CO₂ per MWh is high and is only offset over decades of forest regrowth; harvesting, pelletizing and transport add fossil emissions | M: fine particulates, CO and NOₓ from combustion, plus heavy truck traffic | H: sustained supply needs a very large area of managed forest (hundreds of km²) |
| Coal-fired (one plant) | M: large boiler, coal handling and SO₂/PM/NOₓ controls, but a mature, standard technology | M: coal is cheap per GJ, but large tonnages must be mined and hauled by rail | H: the highest CO₂ per MWh (about 1 t/MWh), plus methane from mines | H: PM₂.₅, SO₂, NOₓ and mercury emissions, ash-pond failures, and coal dust from mines and rail | M: plant plus coal storage, ash ponds and upstream strip mines |
Each rating in the table is justified in its own cell and covers both the plant and its upstream fuel or material chain. Wind: no fuel and almost no emissions, but capital-intensive per delivered MW and land-extensive. Nuclear: very high capital, cheap fuel, compact and near-zero carbon; the social concern is accident and waste risk rather than routine exposure. Solar PV: no fuel and clean in operation, but at Canadian latitudes the low capacity factor makes it the most capital- and land-intensive per average MW. Wood pellets: a moderate-capital steam plant whose fuel chain is costly and land-hungry, which is only conditionally low-carbon and emits particulates locally. Coal: moderate capital and fuel cost, but the highest GHG and (through particulates, SOₓ, NOₓ and mercury) the highest health risk to local populations. Considering the environmental, social and economic triad and upstream processes: wind, solar and nuclear are the genuinely low-carbon options (trading land or capital/risk), biomass is only conditionally low-carbon and adds local pollution, and coal is worst on emissions and health.
