Revisiting Wind Turbine Numbers

Paul Driessen
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Posted: Sep 02, 2017 12:01 AM
Revisiting Wind Turbine Numbers

It’s amazing, though hardly surprising, how quickly some used Hurricane Harvey’s devastation to claim that fossil fuel emissions are driving catastrophic climate change and weather. Their proffered solution, of course, is to replace those fuels with “clean, sustainable, renewable” energy.

I’ve criticized this supposed solution many times, on multiple grounds. Unfortunately, a hasty numerical calculation for a recent column was way off base, and readers properly chastised me for the error. I just blew it, using megawatts instead of megawatt-hours to derive the number of wind turbines … and amount of land … it would take to replace the world’s 2016 electricity entirely with wind energy.

My conclusion that it would require 830 million turbines and twice the land area of North America was thus off by embarrassing amounts. However, my reviewers offered many “correct” numbers.

Their turbine totals ranged from 2 million to 4, 10 and 12 million; their acreage figures from 0.5 to 40, 60 and even 247 per turbine. Total acreage for all the turbines ranged from the size of France or Texas – to half of North America. Energy scholar Cork Hayden graciously provided analytical aid.

Bottom line: Assumptions are key – about turbine size; number, location and extent of good wind sites; ability to actually erect turbines on those sites; wind turbine capacity factor, in average hours per day of electricity generation; duration and quality of wind power per year, especially as turbines proliferate into increasingly poor wind areas; and power generation needed to charge huge battery arrays to ensure reliable electricity during multiple windless days (2, 7, 14 or more) when turbines provide no power.

Another variable, of course, is the amount of electricity that is to be replaced by wind. In 2016, the world used 25 billion megawatt-hours (MWh) of electrical energy, generated by fossil fuel, hydroelectric and nuclear power stations, with minor contributions from wood (biomass) and trivial amounts of wind and solar. Year-round average power generation was 2.85 million megawatts (MW) or 2.85 terawatts (TW) – compared to zero generation in 1881.

Electricity makes our industries, jobs, travel, communication, living standards, health and safety possible, and demand will certainly grow as more nations electrify, and more vehicles are battery-powered.

Here are my fundamental assumptions: Wind turbines replace 100% of today’s 2.85 TW global electricity generation, by some future date – as many activists and politicians insist we must (and can) do. Turbines are all 1.8-MW nameplate power. Average turbine capacity factor gradually falls from 33% to 16.5% as the best wind sites are utilized, and much poorer sites must be developed.

(In the USA many of the best wind sites are off the Washington-to-California and Maine-to-Georgia coastlines, and in the Great Lakes, where water depths and powerful local opposition would make it impossible to install many turbines. Onshore turbine size is limited by the size of blades that can be hauled by trucks on winding roads. The same situation would likely apply around most of the globe.)

Further assumptions: One-third of turbine output powers society; two-thirds charge batteries that provide power for 48 of every 72 hours that wind is not blowing. And winds always cooperate with that scheme – always arriving just in the nick of time, as batteries are depleted, and never disappearing for more than two days, even during sweltering summers or frigid winters when demand soars but winds disappear.

Of course, most of these assumptions exist only in the realm of fairies, pixie dust, green energy utopia and easy number crunching. They are meant to initiate important analyses and debates that climate alarmists, renewable energy proponents, legislators and policy makers have never conducted.

Using these assumptions, generating 25 billion megawatt-hours would require 1.6 million 1.8-MW turbines functioning at full 1.8-MW capacity in strong winds, all day, every day, with no worries about storage. If they operate only eight hours a day (33% engineered capacity), we just use electricity when it’s available, instead of when we need it. But that’s terribly inconvenient and disruptive.

So we employ the Dr. Hayden system, instead. We erect 4.8 million turbines that operate steadily for eight hours, sending one-third of their electricity to the grid and two-thirds to batteries. That would yield 8 hours of direct power while the wind is blowing (33% capacity factor) – and let us draw power from the batteries for the next 16 hours, until the wind regularly picks up again. “I love magic,” he says.

That clearly won’t work. We really need at least 48 hours of storage – and thus three times as many turbines, under a similar arrangement, but providing more flexibility, to recognize unpredictable wind patterns and the likelihood of two windless days in a row. We’re up to 14.4 million 1.8-GW turbines.

Want a bigger safety net? To assure against seven windless days? 50 million turbines should do it.

But then we’re really into the mediocre wind sites. Capacity plummets to 16.5% or so. Perhaps 100 million turbines will do the trick. Pray that lulls last no more than a week. Or send the army to those intransigent, unpatriotic coastal communities, and forcibly install turbines in their super windy areas.

That would also ensure that electricity generation is close to our big urban centers – hence shorter transmission lines, and less cement, steel, copper, et cetera to build the power lines. It’s a win-win situation, except for those who have to look at or live next to turbines and transmission lines, of course.

How much land are we talking about, to generate 25 billion megawatt-hours of global annual electricity? Assuming top quality wind sites, at 5 kilowatts per acre (average output per land area for any turbine at the windiest locations), onshore turbines operating 24/7/365 would require some 570 million acres.

That’s 25% of the United States – or 30% of the Lower 48 US states. It’s almost all the land in Washington, Oregon, California, Idaho, Nevada, Montana, Wyoming, Utah and Arizona combined!

Change the assumptions – change the numbers. To store electricity for windless days, total power generation (and thus turbine numbers and land acreage) begins to skyrocket. For 48 hours of backup, triple the power generation; that’s the entire Lower 48. For a full week of backup, add in Canada.

Let’s not forget the transmission lines and batteries. They also need land (and raw materials).

How many batteries? Storing 1 gigawatt-hour (GWh) of electricity – to provide power for 48 windless hours for a US city of 700,000 people – would require 480,000 of Tesla’s new 100-kWh lithium-ion battery packs. Backing up 2.85 TW for just two windless days would require 1.4 trillion Tesla units! And this assumes the batteries are charged and discharged with 100% efficiency.

Just imagine the land, raw materials, mining, manufacturing and energy that would be needed to make all those batteries (and replace them every few years). As energy and technology analyst Mark Mills has noted, all the world’s existing lithium battery factories combined manufacture only a tiny fraction of that.

I’m sure the world’s battery makers would be more than happy to take our hard-earned taxpayer and consumer cash to build more factories and make all those batteries – to save us from dangerous climate change that is no longer governed by the sun and other powerful natural forces.

Let’s get real. It’s time to stop playing with pixie dust and renewable energy utopia schemes. Time to open our schools and legislatures to actual thinking about energy, sustainability, climate change and what makes our jobs, health and living standards possible. Time for full-bore studies and legislative hearings on all these issues – in the USA, UK, EU and everywhere else.

Sustainability and renewable energy claims are too grounded in ideology, magic and politics. Wind and solar energy forecasts ignore the need to find and mine vast new metal and mineral deposits – and open US lands that are now off limits, unless we want to import all our wind turbines, solar panels and batteries. They assume land use impacts don’t really exist if they are in other people’s backyards.

Worse, too often anyone trying to raise these inconvenient truths is shouted down, silenced, ignored. That has to stop. The stakes are too high for ideology and pixie dust to drive fundamental public policies.

Paul Driessen is senior policy analyst for the Committee For A Constructive Tomorrow (www.CFACT.org), and author of Eco-Imperialism: Green power - Black death and other books on the environment.