OVERKILL
$100 Site Donor 2021
If you ever do the tour of Bruce Nuclear like @Rand has now done, and I've done a couple of times, one of the things that is pointed out by the guide is that the differential between inlet/outlet temperature on their OTC is only ~3C and it has no impact on lake temperature, as the sun is by far the biggest contributor to lake temperature change.
This is a good picture of Bruce B, where you can clearly see the outlet channel in the foreground, with the 4 units of Bruce A in the background. This is the largest power plant in North America and the largest operating nuclear power plant in the world, which uses Lake Huron as its cooling source. When at full nameplate after the refurbs, it should be at ~7,040MWe.
The inlet draws water in from the bottom of the lake about a kilometre out.
But, how "insignificant" is it really?
Well, I've had a few folks bring this up on twitter lately so I figured it might make sense to share what I wrote there, here:
For those following along who might actually benefit from this information, the earth receives 8,160Wh per square meter in a 24hr period (340W per square meter averaged over a 24hr period). The surface area of Lake Huron is 59.6 billion m2, so it receives 20.26TW per hour.
So, again, because we are using a 24hr average (solar peak is over 1,000W/m2) that is 486.25TWh/day. Bruce, at 100% nameplate with all 8 units at full thermal capacity produces 22,656MWth, ~7,000MW of which is converted into electricity with 15,656MW rejected into the lake.
This means, in a 24hr period, the plant sinks 375,744MWh of thermal output into the lake; 0.376TWh, compared to 486.25TWh from the sun. Now, on smaller bodies of water of course, this is going to be more significant, as this relates to surface area and Huron is a big lake.
This is why OTC isn't used on smaller bodies of water typically and cooling towers are employed, to reduce water volume cycled from the body and thermal impact.
I did the same math for Pickering, which is 2 the output of Bruce (but Lake Ontario is smaller) and the numbers aren't really any different because of the scale factor:
If we want to look at the specifics of this, for fun, like I did for Bruce, it's pretty straight-forward. Pickering has 6 active units, each with a thermal capacity of 1,744MWth, so a total of 10,464MWth. 3,114MW of that gets turned into electricity, leaving 7,350MWth to sink.
Lake Ontario receives, roughly, averaged over the year, 8,160Wh per square meter from the sun in a 24hr period (340W per square meter per hour). It is the smallest of the Great Lakes with a surface area of 18,960 square kilometres; 18.96 billion square meters.
This means it sinks (averaged to be per hour) 6.45TW per hour (Huron sinks 20.26TW in comparison); 154.7TWh/day from the sun, compared to 0.176TWh from Pickering.
A comment also mentioned the fact that the Great Lakes have water inflows of 10-16,000 cubic meters of water per second. Ergo, the impact is even lower than just based on surface area.
This is a good picture of Bruce B, where you can clearly see the outlet channel in the foreground, with the 4 units of Bruce A in the background. This is the largest power plant in North America and the largest operating nuclear power plant in the world, which uses Lake Huron as its cooling source. When at full nameplate after the refurbs, it should be at ~7,040MWe.
The inlet draws water in from the bottom of the lake about a kilometre out.
But, how "insignificant" is it really?
Well, I've had a few folks bring this up on twitter lately so I figured it might make sense to share what I wrote there, here:
For those following along who might actually benefit from this information, the earth receives 8,160Wh per square meter in a 24hr period (340W per square meter averaged over a 24hr period). The surface area of Lake Huron is 59.6 billion m2, so it receives 20.26TW per hour.
So, again, because we are using a 24hr average (solar peak is over 1,000W/m2) that is 486.25TWh/day. Bruce, at 100% nameplate with all 8 units at full thermal capacity produces 22,656MWth, ~7,000MW of which is converted into electricity with 15,656MW rejected into the lake.
This means, in a 24hr period, the plant sinks 375,744MWh of thermal output into the lake; 0.376TWh, compared to 486.25TWh from the sun. Now, on smaller bodies of water of course, this is going to be more significant, as this relates to surface area and Huron is a big lake.
This is why OTC isn't used on smaller bodies of water typically and cooling towers are employed, to reduce water volume cycled from the body and thermal impact.
I did the same math for Pickering, which is 2 the output of Bruce (but Lake Ontario is smaller) and the numbers aren't really any different because of the scale factor:
If we want to look at the specifics of this, for fun, like I did for Bruce, it's pretty straight-forward. Pickering has 6 active units, each with a thermal capacity of 1,744MWth, so a total of 10,464MWth. 3,114MW of that gets turned into electricity, leaving 7,350MWth to sink.
Lake Ontario receives, roughly, averaged over the year, 8,160Wh per square meter from the sun in a 24hr period (340W per square meter per hour). It is the smallest of the Great Lakes with a surface area of 18,960 square kilometres; 18.96 billion square meters.
This means it sinks (averaged to be per hour) 6.45TW per hour (Huron sinks 20.26TW in comparison); 154.7TWh/day from the sun, compared to 0.176TWh from Pickering.
A comment also mentioned the fact that the Great Lakes have water inflows of 10-16,000 cubic meters of water per second. Ergo, the impact is even lower than just based on surface area.