It should be glaringly obvious that, if we are shortly going to try to convert to a “net zero” carbon emissions energy system based entirely on wind, sun and batteries, then there needs to be serious focus on the feasibility and costs of such a system. The particular part of such a prospective system that needs the most focus is the method of energy storage, its cost and, indeed, feasibility. That part needs focus because, as wind and solar increase their share of generation over 50% of the total, storage becomes far and away the dominant driver of the total costs. Moreover, there is no clear way to identify some fixed amount of storage that will be sufficient to make such a system reliable enough to power a modern economy without full backup from dispatchable sources. This also should be glaringly obvious to anyone who thinks about the problem for any amount of time.
And yet, as recently as a couple of weeks ago, it seemed like the entire Western world was racing forward to “net zero” based on wind and sun without anyone anywhere giving real thought to the problem of the amount of storage needed, let alone its cost, and let alone whether any fixed amount of storage could ever fully assure complete reliability. A retired, independent guy named Roger Andrews had done some calculations back in 2018 for test cases of California and Germany, which had showed that at least 30 days’ of storage would be needed to back up a fully wind/solar system. Andrews’s work showed that storage costs just to be sufficient to match actual wind/solar intermittency patterns for 2017 would likely cause a multiplication of the cost of electricity by something in the range of a factor of 14 to 22. But Andrews did not even get to the point of considering how much storage might be needed in worst case scenarios of lengthy winter wind or sun droughts.
And then Andrews died suddenly in early 2019, and nobody immediately took up where he left off.
But then a few weeks ago I discovered at Watts Up With That some new work from someone named Ken Gregory (again, a retired, independent guy — funny, isn’t it?), who produced a spreadsheet for the entire United States again showing that about 30 days’ storage would be needed to back up a fully wind/solar system. (Cost for the storage, assuming all energy use gets electrified: about $400 trillion.)
And now, some others are getting into the act. And none too soon. A guy named Roger Caiazza has a blog called Pragmatic Environmentalist of New York. Caiazza, as you might by now have guessed, is another independent retired guy. In the past few months, he has turned his attention principally to the energy transition supposedly getting underway here in New York State, as a result of something called the Climate Leadership and Community Protection Act of 2019 (the Climate Act). The Climate Act created a gaggle of bureaucracies, and the end of 2021 saw those bureaucracies utter something they call the “Scoping Plan,” laying out how New York is going to go from its current energy system to the nirvana of electrification of everything together with “net zero” emissions by no later than 2050.
The Scoping Plan is a massive document (some 330 pages plus another 500+ pages of appendices) of breathtaking incompetence. The basic approach, summarized by me in this post of December 29, 2021, is that designated “expert” bureaucrats working for the State, themselves having no actual idea how to achieve “net zero” from an engineering perspective, will get around that problem by simply ordering the people to achieve the “net zero” goal by a date certain. Then, presumably some engineers will magically emerge to work out the details. The thousands of people who put this thing together apparently do not regard proof of cost or feasibility as any part of their job. As to the key problem of energy storage to achieve “net zero” goals, the Scoping Plan, in nearly 1000 pages of heft, never even gets to the point of recognizing that the MWH (as opposed to MW) is the key unit that must be considered to assess issues of cost and feasibility.
For the past many weeks, Caiazza has been putting out one post after another ripping the Climate Act and the “Scoping Plan” apart, piece by piece. But for today, I want to focus on one post from January 24 titled “Scoping Plan Reliability Feasibility – Renewable Variability.” This post considers the implications of dependence only on wind and solar power, particularly as to how much storage would be needed with such a system, and without remaining fossil fuel backup, to achieve necessary system reliability.
Rather than creating a spreadsheet for annual wind and solar generation, in the manner of Andrews or Gregory, Caiazza takes a different approach, which is simply to consider a worst-case scenario. (For this purpose Caiazza draws on a January 20 piece from a guy named David Wojick at PA Pundits International.). The beauty of considering the worst-case scenario is that the math becomes so simple you can do it in your head.
So here is the scenario considered by Caiazza. Your mission as the State is to deliver 1000 MW of power continuously with complete reliability, but with only the wind and sun to provide the generation. How much generation capacity do you need, and how much storage do you need? And how much will it cost? (New York’s average current usage is about 18,000 MW, and by the time everything is electrified that will be at least 60,000 MW, so we can multiply everything by 60 at the end to see what the cost implications are for the State of New York.)
First what is the hypothesized worst case? To make the math simple, Caiazza hypothesizes a solar/storage only system, and a five day winter period of overcast, followed by two sunny days to recharge before the next such worst-case 5-day sun drought.
The required battery capacity is simple. Five days at 24 hours a day is 120 hours. To supply a steady 1,000 MW that is a whopping 120,000 MWh of storage. We already have the overnight storage capacity for 16 hours so we now need an additional 104 hours, which means 104,000 MWh of additional storage.
But the 120,000 MWH of storage assumes that you charge the batteries up to 100% and discharge them down to 0%. Real world batteries are supposed to only range between about 20% and 80% charge for best performance.
The standard practice is to operate between 80% and 20%. In that case the available storage is just 60% of the nameplate capacity. This turns the dark days 120,000 MWh into a requirement for 200,000 MWh.
I might throw in that solar panels don’t produce at full capacity for anything close to 8 hours on even the sunniest winter day, but who’s quibbling?
Now suppose that in this worst-case scenario we only had two days to charge up since the last 5 day drought:
Two days gives us 16 hours of charging time for the needed 120,000 MWh, which requires a large 7,500 MW of generating capacity. We already have 3,000 MW of generating capacity but that is in use providing round the clock sunny day power. It is not available to help recharge the dark days batteries. Turns out we need a whopping 10,500 MW of solar generating capacity.
That’s right, it’s not just that you need 200,000 MWH of storage, but you also need more than ten times the “capacity” of solar panels as the mere 1000 MW that you are trying to deliver on a firm basis, just to deal with this worst case scenario to deliver 1000 MW firm through one bad month in the winter.
For cost of storage, Caiazza takes what he calls a standard EIA figure of $250/MWH for the batteries. At this price, 200,000 MWH would cost $50 billion. Then there is the cost of the solar panels. Here, Caiazza has a standard EIA figure of $1.3 million per MW. For the 10,500 MW capacity case, that would mean $13.7 billion. Add the $50 billion plus the $13.7 billion and you get $63.7 billion.
And that’s for the 1000 MW firm power case. Remember, fully-electrified New York State is going to need 60,000 MW firm. So multiply the $63.7 billion by 60, and you get $3.822 trillion. For comparison, the annual GDP of New York State is approximately $1.75 trillion.
Caiazza points out that the state’s Scoping Plan gives necessary storage costs for the new wind/solar/battery system in the range of $288.6 to $310.5 billion. These figures are about 10 times lower than we just calculated. But Caiazza attempts to find in the Scoping Plan the assumptions on which these numbers were calculated, and he can’t find it. Neither can I. Maybe some reader can take a crack.
The reader may find that Caiazza’s $3.8 trillion figure for New York State seems remarkably small relative to the number calculated by Gregory. Gregory got about $400 trillion for the U.S. as a whole. New York representing about 7% of the U.S. economy, that would mean that the cost of the storage piece for New York would be closer to $30 trillion than $4 trillion. The difference is that Caiazza is calculating the cost of just getting through one “worst case” week in the winter, while Gregory considers the cost of trying to get through a whole year where energy needs to be stored up from the summer to get through the whole winter.
One final point. Suppose that, based on even a few decades of meteorological data, you determine that this five day winter sun drought is the true worst case scenario, and you put together a system on that basis. OK, what now happens when one year you get a six day drought? By hypothesis your fossil fuel backup has been dismantled and is no longer available. Does all power then just go out on that sixth day? Remember, this is the dead of winter. People are going to freeze to death. So are you going to keep the fossil fuel backup around just for this one day that might occur only once every few decades? If so, how much of the fossil fuel backup capacity do you need to keep? Think about that for a second. The answer is, all of it. In the 60,000 MW firm power requirement scenario for New York State, you will need 60,000 MW of available fossil fuel capacity to cover that one day when the batteries run out. Dozens of major power plants, fully maintained, and with fuel at the ready, capable of being turned on for this one emergency day perhaps once every twenty years.
Or you can try to avoid that by building yet more solar panels and more batteries so that you can get through a six day sun drought. But what happens when you get a drought of seven days?