Renewables Are Expensive Because You Can’t Stick ‘Em Where the Sun Don’t Shine (or the Wind Don’t Blow)

I’m sure you’ve read articles claiming that the cost of renewables electricity generation is approaching that (or even lower than) the cost of traditional thermal generation. I am deeply skeptical of these claims even when evaluated on their own terms (which focus on generation costs alone), but find them particularly misleading because they ignore other costs attributable to the facts that renewables are intermittent and diffuse, and that the siting of renewables generation is sharply constrained because they are energy limited resources; the distribution of energy is dictated by nature; and typically is not closely related to the distribution of load.

In other words, renewables are costly because you can’t stick them where the sun don’t shine (or the wind don’t blow).

Case in point: Australia. As even Bloomberg (a tiresome renewables fanzine) reports:

Australia’s financing of cleaner power is slowing because the country’s aging grid isn’t being upgraded quick enough to accept new, intermittent generation and transport it efficiently to demand centers.

Although Bloomberg attempts to blame an old, creaky transmission system, this is misleading in the extreme. It would be far cheaper to upgrade Australia’s transmission system to accommodate thermal generation than it will be to build transmission to increase the fraction of generation coming from renewables.

This is true for at least a couple of reasons.

First, the energy-limited nature of renewables means that you have to site them where the energy is available–sunny or windy places. This imposes a constraint on the location of generation resources that is not relevant for thermal generation. With traditional fossil-fueled generation, you have more flexibility in trading off transmission costs with generation costs (including the cost of brining fuel to plants) than is the case with wind. This flexibility means that all else (notably the spatial distribution of load) equal, transmission costs are lower with thermal generation than renewable power.

Second, the intermittent and inherently more volatile nature of renewables generation increases the variance in the spatial distribution of generation. This variability in the spatial distribution of generation necessarily requires more transmission capacity per unit of load. This, in turn implies a lower average rate of utilization of transmission resources.

The basic idea here can be illustrated relatively simply. Consider a system with two generation resources. One is highly volatile (e.g., a renewable resource). The other is controllable. There is one load location. The transmission capacity from the volatile location to load must be high enough to carry the power when output is high (because the energy input is high due to the vicissitudes of sun or wind). The transmission capacity from the location with controllable generation must also be high enough to transmit enough power to fill the gap left when the renewable output is low.

Note that when renewable output is high, controllable output will be low and the transmission lines from the latter will operate at low capacity. When renewable output is low, the lines serving it will be operating at low capacity.

It’s possible to expand the example to include multiple variable, energy limited, but imperfectly correlated renewables resources, but the outcome is the same. You need more transmission capacity to deal with the spatial volatility in generation, and given load, higher capacity translates into lower average capacity utilization.

Thus, the problem that Australia is confronting isn’t a function of an old grid: it arises from the fact that increased reliance on renewables requires investment in new transmission capacity even in a system where transmission is optimized relative to (thermal) generation and load.

The need to maintain relatively underutilized transmission capacity to deal with the inherent volatility of renewables generation is mirrored by the need to maintain underutilized thermal generation capacity:

While new clean energy projects struggle to gain access to a congested grid, aging coal and gas-fired generators are being kept running for longer to maintain system stability. AGL Energy Ltd. said Friday it would delay the planned closure of its Liddell and Torrens A plants, both around 50 years old, to help the national energy market cope with peak summer demand, which has seen blackouts in parts of southeastern Australia in recent years.

Who knew?

Yet the renewables industry/lobby continues to flog the dogma that they will inevitably be more efficient:

Despite the challenges facing the industry, it’s not all doom and gloom. A number of coal-fired plants will be retired over the next decade and they will only be replaced by the cheapest cost of energy, which is renewables, Clean Energy Finance Corp. Chief Executive Ian Learmonth said in an interview.
“I’m hoping once some of these issues around the grid and regulations are settled that we’ll see another significant uptick in the renewable energy pipeline,” he said.

What costs is Mr. Learmonth including in his assertion that renewables are the “cheapest” source of energy? His statement that settling “issues around the grid” will lead to increased renewables investment suggests that he is ignoring crucial costs, because settling these issues doesn’t come for free.

It’s not as if the transmission issue is unique to Australia. It is present in every locale that has force-fed renewables. Germany is a prominent example. Wind energy is abundant in the North Sea, but believe it or not, there aren’t a lot of electricity consumers there. Major sources of load are in central and southern Germany, so bringing North Sea wind power to load requires massive transmission investments, which inevitably are not just costly, but politically difficult (Der NIMBY, anyone?). These difficulties inflate the cost.

Renewables boosterism operates in an atmosphere of serious unreality because it consistently glosses over–or ignores altogether–the costs arising from intermittency, diffusiveness, the energy-limited nature of wind and solar, and the caprices of nature that cause a mismatch between where the energy exists and where it is needed. When these facts are considered, sticking renewables where the sun don’t shine makes perfect sense.