Sustainable energy is a great goal, but reliable, sustainable energy is even better. The sun and the wind only work for generating energy when they are present. Global demand for energy and in particular electricity is expected to rise with renewable energy sources playing an increasingly larger role. Input for tidal energy models was hampered in many places until satellite observation made it possible to make accurate recordings of tidal flows. Now energy models for tidal energy analysis need to take into account the availability of suitable technology.
Comparative energy models – Canadian oil sands and tidal energy
The biggest source of tidal energy in the world is in the Bay of Fundy in Nova Scotia, where conditions come together for an energy generating potential that could rival that of Canada’s other untapped natural energy resources, the oil sands. Energy models to compare these two very different reserves need to take account of current markets and energy-consumer habits, government policy, ecological effects and possibly time-scales. While both present their own individual challenges, oil sands resources are theoretically limited, whereas as tidal energy will effectively be available forever.
Although tidal energy is commonly viewed as ecologically friendly, models make also need to take environmental impacts into account as well. Negative impacts contributed to the stalling of the tidal energy program in the United States before: early inlet barrage generating stations, rather like wind turbines, were visible blots on the landscape. In-stream turbines however may allow interested parties to refine their energy models, as this newer version is under water and more out of sight. The problem may however regain importance if waterways become littered with such ‘micro-generating stations’. Putting in many turbines in a restricted area could effectively change the tides themselves and hence the fundamental inputs to the energy model.
Modeling and real-world difficulties
Even if the tidal energy generation equation is reasonably simple, current estimates of potential electricity generation from the Bay of Fundy vary between 300 and 8,000 megawatts. That’s a big spread for anyone trying to estimate both feasibility and economic and environmental impact. As a point of reference, 2,500 megawatts would be enough for the electricity needs of Nova Scotia alone. Another difficulty is that until technology catches up and offers good enough solutions. In initial trials in the Bay of Fundy, the underwater turbines were soon destroyed because the water flows were too powerful.
Modelers may need to adopt approaches that are flexible to allow for changes in tidal energy scenarios and technological lines of attack. New designs based on orthogonal turbine cylinders and hydrofoils may allow tidal energy generators to be installed in a far greater range of locations, including many shallower, coastal waters. In a variant on the tidal theme, osmotic power generating stations may allow models to simplified yet further by generating power from the exchanges between fresh and salt water – no noise, no pollution, and the only waste product being brackish (slightly salty) water.
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