Can solar or floating offshore windmills supply our energy?
Humboldt’s denial of Terra-Gen’s wind plant leaves us without enough carbonfree electricity to meet Redwood Coast Energy Authority’s commitment to clean power. And RCEA’s goal is what we need, because the climate crisis most agree we face demands massive reductions in CO2 emissions.
Reports by Schatz Lab show how fossil fuels dominate Humboldt’s energy consumption. To reduce CO2 emissions and provide a tolerable future for our grandchildren, we’ll have to electrify heating and transportation with renewable sources. But if not from Terra-Gen, where will we find that electricity?
Solar PV can provide some, but California already has so much that its peak loads have shifted from mid-day to evening. Electric loads in Humboldt, unlike the rest of the state, peak in the morning and evening. Only if combined with unprecedented investment in battery storage can mid-day solar be shifted to evening and night-time and morning hours.
Humboldt’s two thermal power plants burn wood waste 24/7, but don’t provide enough for an electrified future.
Limited imports on two transmission lines can’t provide enough. Loss of either or both, as during PG&E’s shutdowns, condemns us at best to rolling blackouts.
Some say we can provide the shortfall with floating offshore wind (FOW). What is that? Offshore wind turbines can either be fixed to the sea bed, as are all installations but one in Europe and the East Coast, or mounted on floating structures where it’s too deep for fixed structures. Ocean depth increases close to Humboldt’s shore, so advocates say offshore FOW is the only wind power option.
Winds are stronger offshore, which means a turbine further out will normally produce more energy than one onshore. How much more?
The energy production measure commonly used is capacity factor, the ratio of energy actually produced to what could be if the generator runs at rated capacity all the time. The wind doesn’t blow at rated speed all the time, and capacity factors vary by location. The highest I know of is at La Ventosa in Mexico, where capacity factors average about 60%. A typical figure for land-based wind is 40%. The only operating FOW plant (Hywind in Scotland) recorded a capacity factor of 56%.
There’s no evidence that higher FOW energy production is high enough to justify the higher installation costs. To the contrary.
For one thing, FOW has been tested for only a few years at a few sites, and isn’t commercially ready. It might not ever be, and cost predictions are only educated guesses. Optimistic supporters like BVG Energy note that FOW costs are four times more than onshore wind costs now, and predict that by 2030 they might decline to twice onshore costs.
An improvement from 40 to 56 percent doesn’t justify such higher investment costs, and RCEA’s partner Principle Power has not released its projections.
Ignoring these details, a local assertion is that Humboldt Bay might provide the industrial support FOW requires: docking facilities, assembly for material manufactured elsewhere, and maintenance services. So a reasonable question is whether FOW could be assembled on the peninsula and floated out 30 miles to their permanent locations.
That raises the question whether huge FOW structures can traverse our harbor entrance. Blades are 100 meters long, and towers supporting them will exceed 150 meters. Principle Power’s design implies an underwater portion of each turbine structure 40 meters deep. They say 10.
Silt accumulation reduces entrance depth to 5 meters sometimes, so moving FOW structures in and out of the harbor would require constant dredging.
Installation and maintenance will require a marine crane in the bay, perhaps full-time. It’s not clear that one large enough can even be maneuvered in and out of the entrance.
Thus in my view it is imprudent for Humboldt to count on FOW, now or ten years from now.
After years in renewable energy, I’ve observed as new technology comes on line— or not—that the first key to success is to avoid failure. I would like to be wrong about this, but FOW in Humboldt County is a likely failure. Wishful thinking can’t change that.