23-CS-3 Sustainability, Engineering and the Environment · May 2016
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2016 — 11-CS-3 Sustainability, Engineering and the Environment. Closed book; approved 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 | Land | Fuel requirement | GHG emissions | Local health risk | Initial cost | Operating cost (excl. fuel) |
|---|---|---|---|---|---|---|
| Wind | H (spacing) | L (none) | L | L | M | L |
| Nuclear | L | M (uranium) | L | M–H (accident/waste) | H | M |
| Solar PV farm | H | L (none) | L | L | M–H | L |
| Natural-gas turbine | L | H (gas) | M | L–M (air pollutants) | L | L–M |
Wind: to reach 200 MW, turbines are spread over a wide area (high land, though the ground between remains usable); no fuel; negligible GHG and low local health risk; medium capital and low non-fuel operating cost. Nuclear: compact site; requires uranium fuel; near-zero GHG; the highest local health concern (radioactive-waste handling and low-probability accident); very high capital and moderate operating/maintenance cost. Solar PV farm: needs a large panel area (high land); no fuel; negligible GHG and low health risk; medium–high capital and low operating cost. Natural-gas turbine: compact; consumes natural gas (high fuel requirement); emits CO₂ (medium GHG) and some air pollutants (low–medium local health risk); low capital and low–medium non-fuel operating cost. Two notes on the ratings. Wind land is H by footprint, but the turbine pads and roads occupy only a few percent of it and farming continues between them, whereas a PV farm covers its ground almost completely. Nuclear fuel is M rather than H because of uranium's energy density: a 200 MW reactor needs only a few tonnes of enriched fuel a year, against roughly 0.3 million tonnes of natural gas a year for a gas turbine at the same full output. The pattern: renewables trade higher land use and capital for zero fuel and emissions; gas trades low capital for fuel dependence and CO₂; nuclear offers compact, low-carbon, reliable power at high capital cost and a distinctive risk profile.
