I’ve talked about the costs of energy before, but money is just money and they are always making more of it. But what about the costs in terms of something that is actually finite? Land usage. I’ve touched on it before, but never really explored what those numbers actually look like.
First we need to determine how much space we are working with.
Alberta has 661,848 square kilometers of territory. Of that area, 19,531 sq km are lakes. Then there are 5 national parks, 76 provincial parks, 31 Wildland provincial parks, 208 Provincial Recreation Areas, 3 Wilderness Areas, 15 Ecological Reserves, 139 Natural Areas, and 2 Heritage Rangelands totaling 90,747 sq. km of protected land. There are also 140 Native Reserves across all of the Treaty 6, Treaty 7, and Treaty 8 lands totaling 6566.7 sq. km. Add in the three military reserve areas (CFB Suffield, CFB Wainright, and CFB Cold Lake/ Cold Lake Air Weapons Range) at 2250 sq km, 609 sq km and 11,700 sq km respectively and our total available area for development has shrunk to 530,444.3 sq. km. And of that, 183,060 sq km are private land. so that leaves 350, 384 sq km.
In Alberta there are two main types of land, White and Green land. and the main difference is that Green land is naturally forested while White land is natural pastoral. And as you can see in the image, it looks to be about a 50-50 split green to white. But lets put all this land area math aside for now, and move on to exciting new math!
How much land does it take to make energy? I’ve made some comparisons between nuclear and wind and solar previously but relative values like that lack impact I’ve found. So now I’m doing some napkin math for renewables and nuclear to show just how much land we need to use them. And in a twist from my usual focus on solar, today I’m going to start with wind.
So converting wind energy runs up against what is called the Betz Limit. Basically according to the math, the absolute maximum amount of energy that can be extracted from a moving volume of air by windmills is 59.3%, and current cutting edge windmill designs can reach about 80% of that maximum limit. So to figure out how much energy a windmill can extract, we need data for how much energy is in the wind across Alberta. Environment Canada to the rescue!
Looking around the cells of the model they have built of Alberta area, about half of Alberta has 200 W/m^2 of wind energy or less. And that’s in terms of turbine area, not ground area. Getting some assumptions out of the way: 80% Betz limit conversion efficiency, 80 m turbine, 45 m blades (just like the Halkirk wind farm outside of Stettler), minimum spacing between turbines (6x blade diameter tower to tower space), maximum packing on flat ground, uniform direction and always aligned prevailing winds, and a max Power requirement of 11.7 GW to cover all of Alberta’s energy requirements. This is the absolute best case scenario I can reasonably give wind power in Alberta. With those assumptions we can determine that the energy density in terms of ground area ranges from 1.32 W/m^2 to 13.18 W/m^2
This means that the smallest amount of space required would be 2787 km^2 and would require over 11,000 wind turbines. And that is only if we can place them in the Alberta Rocky Mountains. For comparison, that’s about half the size of Banff National Park logged to grass and filled with wind turbines, because trees mess up the air flow characteristics and lower the energy output of wind turbines.
Now I doubt the federal government is going to allow the effective paving over of a chunk of a national park that large so we need to look for less optimal locations to place those turbines. the south east of Alberta is where most people think about wind as a viable resource but in fact it has only half the energy that the mountains do, meaning that 2800 km^2 balloons to 5600 km^2 filled with 22000 turbines. Going farther north it gets larger at an exponential rate as the wind intensity dies down.
So what gets displaced to make these farms? The options are National park, ranch and farmland, Oil sands land, or Boreal forest. Now of course most of the land under the windmills can still be used for things like agriculture or possibly resource extraction, but you shouldn’t build anything tall enough to really upset the wind flow otherwise you are reducing the efficiency of the turbines, meaning you need more of them and more land. Also you wouldn’t have one monolithic wind farm, you would scatter them around here and there but the numbers don’t lie, these options are the least total amount of space that would be required for given average wind energy levels. If you want my data I will gladly send you my spreadsheets.
So what about solar? It’s got to be more reasonable right? Solar panels take up way less space than wind turbines. Technically yes, but also you require a few orders of magnitude more of them than you do windmills. Here’s some data about solar energy yields across Alberta. Using this, and information from other solar projects around Canada like the Sarnia Photovoltaic Plant in Ontario, we can get a feel for the amount of space that would have to be used to cover Alberta’s energy demands.
Luckily since we were given the average for the whole province it’s very easy to determine the land area required for solar. It’s just a touch over 4000 sq. km. Noticeably larger than the smallest wind farm, but not quite as big as the one covering Medicine Hat.
Now I’ve mentioned before that I like solar, when it Isn’t being used as an array in a grid scale farm. This is because it can be placed literally anywhere. And this benefit really shows itself here. When you don’t need to worry about the panels interfering with eachothers sun, or space them so that maintenance vehicles can get in between rows to service them (ie. when they are placed on the roofs of already existing buildings), the amount of real estate required drops from 4000 sq. km to 2300 sq. km. Still a huge amount of space, but much closer to reasonable.
Fun fact, that much solar power would have a peak output of 72 GW if made from the same panels that the Sarnia plant was. That’s right, in order for the yearly energy requirements of Alberta to be met, we need to overbuild our power requirements by almost 7 times. And then we would also need the batteries or other storage to hold the excess from the summer for use in the winter. If you have a really good memory you might be about to mention that this is hugely more than the 38 GW of generation capacity I said in a previous post would be needed, but the distinction being that that post was only concerned with the power generation and storage requirements for a single spring day, not an entire year.
Now for the final comparison I’ll be very quick. I’ve mentioned it before but the Bruce Power Generating Station in Ontario produces 6.29 GW of electricity, has a total land usage of 9.32 sq. km, and runs at ~87.4% capacity. This means that to provide all 11.7 GW of possible power requirements for the Alberta grid we would require 17.34 sq. km of land to site the nuclear reactors. Even if you put a 20 km radius evacuation zone around it and mandated that nothing was allowed within it for some strange reason that is still only 1569.2 sq. km. Remember the purple circle on the map? That’s what that is, and the tiny dot at its center is as close to scale as I can make it for the plant itself using MS Paint. Also, unlike wind and solar, you can actually build anything you want in that area, or leave it completely untouched, wild nature.
Land is the only think we aren’t making more, and it isn’t only for our benefit. We have to share it with everything else that lives in our province, so we have to use it wisely. We could build tens of thousands of windmills, or thousands of square kilometers of solar panels, and then pave over ranch lands or knock down the boreal forest for them. Or, we could build once facility in a tiny section of the province that keeps all denizens of Alberta warm and cozy in their homes, no matter if they are humans, elk, bison, foxes, mice, or birds.
Good to see someone looking into this big picture aspect of renewable energy in Alberta. Might be interesting to consider the effect of extracting global energy needs from wind on atmospheric circulation and planet cooling heat transfer to outer space.
Perhaps you should have a discussion with Mark Jacobson!
Click to access NuclearVsWWS.pdf
Seems he has missed some important facts!