Can wind compete with solar?

It’s lucky I like solar power because it’s impossible for me to open the X app without seeing insanely great news about solar deployment progress.

This progress is driven by consistent declines in solar cost, summarized in the graph below. Solar is on a fast track to “rounds to zero” cost for land-based energy generation.

Wind was initially cheaper than solar, but its learning rate is not as steep and solar, with no moving parts and no cranes required for deployment, has passed it in most places. Still, it’s a long road from here to energy market saturation with solar and batteries, so wind is not entirely out of the fight.

What will it take for wind to compete with solar? In other words, can wind get to $10/MWh? How?

Wind has clear economies of scale, expressed in the size of the turbine. This allows the dilution of engineering costs in the hub to be spread over more blade, as well as greater and more consistent winds higher above the ground. This trend has mostly topped out with the standard 1 MW wind turbine on land, now a common sight through much of the American West.

For offshore wind, however, there are fewer size constraints on part transportation and turbines can get truly monstrous. Take, for example, the latest behemoth: 16 MW out of China. Each blade weighs 54 T and is 123 m long. In principle, one of these can produce as much energy as ~100 acres of solar PV.

If the wind industry survives current cost growth challenges, the next frontier is the scale up off floating off-shore deployment in the deep ocean. Such turbines could be assembled on shore in ports and floated into position, taking advantage of unobstructed open ocean to reach impossibly enormous sizes and hopefully low enough costs to compete with solar.

What could this look like?

First, to solve the energy transport problem, I think it makes sense for floating offshore turbines to convert their cheap power into cheap energy-rich products, including synthetic fuel or light metals extracted from sea water. Instead of having to engineer some marine-compatible high voltage DC power transmission line, send a ship every few months to offload the product.

Second, floating offshore turbines may see the resurrection of the vertical axis wind turbine. While not impossible, achieving consistent orientation of a floating horizontal axis turbine into the wind presents substantial challenges and, more importantly, added cost. Vertical axis turbines work regardless of wind direction, potentially making up for their lower efficiency.

Third, what materials are cheapest? A post-stressed floating concrete structure could be 10x as cheap as a steel one, as concrete is significantly cheaper than steel.

Fourth, stability can be ensured by building a spar buoy-style structure. A floating structure is moved by waves in proportion to the change in wetted volume. A cork is thrown around, while a very long vertically oriented tower barely moves. The FLIP ship moved just a few inches in the heaviest seas. (I just learned it was scrapped last year – outrageous!)

Combine these ideas and we get a long cylindrical cement tower structure built horizontally on shore, floated into position, then uprighted by shifting water ballast internally. A lightweight steel vertical axis turbine is deployed from the top of the structure, driving a generator and any internal industrial hardware for synthetic fuels or metals.

A 1200 m long turbine, modeled below, would generate in excess of 100 MW per turbine. A fleet of 10,000 could supply the entire oil and gas energy needs of South Korea, Japan, or the UK. The idea could be proven at much smaller scale, or potentially scaled up to the limits of the abyssal depths.

The fin features inhibit vertical and rotational motion, but small thrusters or differential torque would allow the turbine to maintain its station in an ocean current.

I am not quite convinced that even a tech road map this bold could beat solar on cost, but for markets constrained in land area, this could be the next best thing.