Under the cost estimates we have in the article, it would be substantially cheaper to fill it in - cost of doing so is only 9% of the total cost, compared to 12% from merely having the pumps active for 100 days - of which half is the cost of the backflow during that length of time. We now think our backflow estimates were probably too hi…
Under the cost estimates we have in the article, it would be substantially cheaper to fill it in - cost of doing so is only 9% of the total cost, compared to 12% from merely having the pumps active for 100 days - of which half is the cost of the backflow during that length of time. We now think our backflow estimates were probably too high (especially as rain seems to be a substantial portion of the water ingress in similar projects), but it remains the case that it seems that managing to avoid pumping altogether after filling has begun would probably be cheaper on net.
If backflow is lower that's great news for wanting fewer pumps that you'd never need to use again (unless maybe for a next project) after the intial drainage phase. Don't quite see though how the optimization works out to want to do it so quick: My logic says as long as you pump faster than backflow it'll eventually empty out. So the minimum number of pumps to maintain a narrow surplus should be optimal? Understood its *desirable* to not let it take too long.
We include electricity costs in the cost of pumping at current UK market prices (due to proximity to wind we might be able to do this slightly cheaper), so it does minimise total expenses to do it at the calculated rate (and these do end up as a substantial portion of the total at the optimal choice). Optimal rate will necessarily be slightly faster than this due to including the delay on benefits from longer construction times etc.
Yup, gotcha. Also thought if the planned Dogger Bank wind farm was fully operational at construction start proximity might facilitate deals to use excess capacity the grid can't handle when there is a lot of wind across the region to lower power cost even more. Anyway, again, great piece. I really do wonder why it feels fantastical when it checks out as a financial proposal in terms of ROI and represents a credible nuts & bolts plan to alleviate population pressure & massively stimulate growth across the board, not just particular industries.
Pumping while getting paid is nice of course—but then the question arises whether to keep pumping at a higher price or wait for the next oversupply window to then compensate with negative cost for back seepage that happened while pumps were stalled? Wind prediction enters the picture!
Under the cost estimates we have in the article, it would be substantially cheaper to fill it in - cost of doing so is only 9% of the total cost, compared to 12% from merely having the pumps active for 100 days - of which half is the cost of the backflow during that length of time. We now think our backflow estimates were probably too high (especially as rain seems to be a substantial portion of the water ingress in similar projects), but it remains the case that it seems that managing to avoid pumping altogether after filling has begun would probably be cheaper on net.
Thanks, great explanation!
If backflow is lower that's great news for wanting fewer pumps that you'd never need to use again (unless maybe for a next project) after the intial drainage phase. Don't quite see though how the optimization works out to want to do it so quick: My logic says as long as you pump faster than backflow it'll eventually empty out. So the minimum number of pumps to maintain a narrow surplus should be optimal? Understood its *desirable* to not let it take too long.
We include electricity costs in the cost of pumping at current UK market prices (due to proximity to wind we might be able to do this slightly cheaper), so it does minimise total expenses to do it at the calculated rate (and these do end up as a substantial portion of the total at the optimal choice). Optimal rate will necessarily be slightly faster than this due to including the delay on benefits from longer construction times etc.
Yup, gotcha. Also thought if the planned Dogger Bank wind farm was fully operational at construction start proximity might facilitate deals to use excess capacity the grid can't handle when there is a lot of wind across the region to lower power cost even more. Anyway, again, great piece. I really do wonder why it feels fantastical when it checks out as a financial proposal in terms of ROI and represents a credible nuts & bolts plan to alleviate population pressure & massively stimulate growth across the board, not just particular industries.
Actually negative power prices makes the optimization problem even more fun: https://www.theguardian.com/environment/2023/may/29/weather-tracker-power-prices-dip-to-negative-in-europe-amid-clean-energy-boost
Pumping while getting paid is nice of course—but then the question arises whether to keep pumping at a higher price or wait for the next oversupply window to then compensate with negative cost for back seepage that happened while pumps were stalled? Wind prediction enters the picture!