To satisfy energy demand in Missouri would require a wind farm the size of Iron County, or a solar photovoltaic farm 7% the size of the state, or a combination of both.

In the past 3 posts I have constructed “back-of-the-envelope” estimates of how much land would be required in order to meet the USA’s energy needs from wind power and solar photovoltaic power. In this post I bring it back to Missouri: how big a wind farm, how big a solar photovoltaic farm, would you need to meet Missouri’s energy consumption?

I won’t go through all the calculations like I did in the previous posts. I’ll simply say that total energy consumption in Missouri was 557,946,666 MWh in 2014.

http://www.eia.gov/state/seds/data.cfm?incfile=/state/seds/sep_sum/html/rank_use.html&sid=US.

To satisfy this demand using wind farms would occupy 556 square miles. That’s a square less than 24 miles on each side. It is roughly the size of Iron County or St. Charles County. The largest county in Missouri, Texas County, is twice as large.

To satisfy the demand using solar photovoltaics would require solar farms occupying 4,819 square miles. That is a square 69 miles on each side. It is larger than any Missouri county, but only about 7% of the state.

As in previous posts, I must here caution that the examples I drew upon to construct my analyses, the Alta Wind Farm and the Topaz Solar Farm, are located in locations with strong wind and solar resources. Wind and solar farms elsewhere would be trying to reap lesser resources, and thus, would require more land to generate the same amount of power. Thus, my estimates represent the lower limit of the land that would be required. Still, they give some estimate of the size of the task involved.

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So what does all this rumination mean? First, let me reiterate that these are very rough “back-of-the-envelope” estimates. But they may be useful in demonstrating the size of the task required to convert to renewable energy.

Second, given current technology, it isn’t possible to cover the nation’s entire energy consumption using either wind power or solar photovoltaics. These technologies generate electricity, and a significant portion of the nations energy requires petroleum and natural gas. There are also engineering issues regarding the stability of the electrical grid that need to be solved

Third, it isn’t necessary to cover the nation’s entire energy consumption to have a significant effect. If we could derive 30%, 40%, 50% of the nations energy from renewables, it would make a significant impact on GHG emissions.

Fourth, converting to renewable energy would reduce air pollution, acid rain, and mercury poisoning, because all three come primarily from burning fossil fuel to create energy.

Fifth, it would also reduce our balance of payments deficit by reducing the amount of petroleum we have to buy from other nations. And it would enhance our energy security by making us less dependent on on foreign nations for our energy.

And sixth, it would take the money we currently send overseas to purchase oil and reinvest it here, in this country, possibly stimulating our own economy.

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My analysis suggests, that from a land coverage viewpoint, converting to renewable energy would require a lot of land, but not a prohibitive amount. Very large wind farms and solar farms have already been installed and are generating electricity. We would have to continue installing them, but the land exists.

We would have to have a national consensus that this is an appropriate way to use our land, however. And then the technological and economic issues would have to be resolved. Many of them already have been, but some remain, and those would be the issues that would make or break the project.

To generate enough energy with rooftop solar panels to cover total energy consumption in the USA would require more than 6 times as much rooftop space as exists in the whole country.

In the previous two posts I have constructed “back-of-the-envelop” estimates of how much land you would have to use to satisfy the USA’s energy consumption with wind and solar power. I discovered that to do it with wind power would require at minimum wind farms occupying land the size of South Carolina. To do it with solar would require at minimum a solar farm at almost as big as the state of Texas.

What if solar was distributed around the country, on every building in the country? Obviously, not every building is suitable for solar power – they are shaded by trees or other buildings, they are oriented the wrong direction, or the slope of their roofs isn’t good for solar panels. Still, this is an interesting exercise to demonstrate the size of the requirement.

There are an estimated 113 million residential structures in the USA, totaling an estimated 180 billion square feet. There are an estimated 4.7 million commercial buildings totaling 68.5 billion square feet. Combined, they total 248.5 billion sq. ft.

https://www.aps.org/energyefficiencyreport/report/energy-bldgs.pdf.

The average new residence in the USA has 1.6 stories, and I will use that as my estimate for all housing. Thus, the average size of the roofs would be 180 billion / 1.6 = 112.5 billion = 112,500,000,000 sq.ft. This is probably an overestimate, because it does not account for multifamily buildings, but it will have to do.

https://www.census.gov/construction/chars/highlights.html.

I could find no data regarding the average number of stories for commercial buildings. However, there is data that buildings over 50,000 sq. ft. constitute half of the entire square footage, even though they represent only about 6% of all buildings. Obviously, some very large skyscrapers are going to account for a lot of internal square footage, but have comparatively small roofs. It’s just a guestimate, but I’m going to say that the square footage of commercial building roofs is only 1/4 that of their total square footage.

68.5 billion / 4 = 17.1 billion sq. ft. = 17,100,000,000 sq. ft.

https://www.eia.gov/consumption/commercial/reports/2012/buildstock/.

Thus, I estimate the total amount of roof space in the United States to be 112,500,000,000 + 17,125,000,000 = 129,625,000,000 sq.ft.

In 2014, total energy consumption in the United States was 98,385.2 trillion Btu. = 28,833,750,564 MWh.

http://www.eia.gov/state/seds/data.cfm?incfile=/state/seds/sep_sum/html/rank_use.html&sid=US.

The Desert Southwest has the strongest solar resource in the country, while northerly latitudes with lots of cloudy days have the weakest. The Wikipedia article on solar efficiency says that in Colorado, one could expect a solar panel to generate 440 kWh/sq.m./year, while in Michigan, one could expect 280 kWh/sq.m./year.

https://en.wikipedia.org/wiki/Solar_cell_efficiency.

The National Renewable Energy Laboratory provides a map of the solar resource across the country in kWh/sq.meter/day, but I could find no resource that gave a nationwide average. Since I am assuming solar panels installed on every building across the country, I must use a national average.

http://www.nrel.gov/gis/images/map_pv_national_lo-res.jpg.

“Eyeballing” the map, it is clear that Colorado does not represent the strongest solar resource in the country. On the other hand, the area that does have the strongest solar resource is relatively sparsely settled, meaning there are fewer buildings there than in, say, the Northeast. I will assume that these factors balance out, and that one may estimate the annual yield from solar panels by averaging the figures from Colorado and Michigan.

Thus, I estimate the average annual yield from a solar installations to be (440 + 280) / 2 = 360 kWh per square meter per year = 33.4 kWh per square foot per year.

Therefore, the total potential energy production that could be achieved by completely covering every roof in the country with solar panels would be 129,625,000,000 * 33.4 = 4,335,324,557,000 kWh, = 4,335,000,000 MWh.

The fraction of national consumption that could be met would be 28,833,750,564 / 4,335,324,557 = 15%. Put another way, we would need more than six times as much roof space as exists in the USA to meet our energy consumption using rooftop solar photovoltaic.

Some thoughts on where Missouri fits in all this and what it all means in the next post.

To generate enough electricity with solar photovoltaics to cover total energy consumption in the USA, you would need land almost equal to the size of Texas.

My brother asked me how much land you would have to cover to satisfy the demand for energy in the USA using renewables. In the previous post I constructed a “back-of-the-envelope” estimate for wind power, finding that it would require a wind farms covering land roughly equal to the size of South Carolina. In this post, I construct a similar analysis for solar power.

The largest U.S. solar farm listed in Wikipedia is Solar Star, but it has not been operational long enough to have good generating statistics posted. I will use the Topaz Solar Farm, which Wikipedia lists as the second largest in the USA.

https://en.wikipedia.org/wiki/List_of_photovoltaic_power_stations#World.27s_largest_photovoltaic_power_stations.

Topaz is located in San Luis Obispo County, in California’s Central Valley. It is sited on 9.5 square miles, and its average annual generation is 1,100,000 MWh.

https://en.wikipedia.org/wiki/Topaz_Solar_Farm.

The amount of power generated per square mile is 1,100,000 / 9.5 = 115,789 MWh per square mile per year.

In 2014, total energy consumption in the United States was 98,385.2 trillion Btu. = 28,833,750,564 MWh.

http://www.eia.gov/state/seds/data.cfm?incfile=/state/seds/sep_sum/html/rank_use.html&sid=US.

To provide that much power would require 28,833,750,564 / 115,789 = 249,019 square miles.

How to put that in context? It is a square 499 miles on each side. It is just under the size of the state of Texas, it would occupy more than 90% of the state.

https://en.wikipedia.org/wiki/Texas.

Of course, Topaz is located in California’s Central Valley, which has a strong solar resource. The Desert Southwest has an even stronger one, however, and there is a great deal of land there. Still, some of the solar farms would be likely to be spread around the country. That would put some of them in areas with weaker solar resources. In addition, this analysis does not consider the need for excess capacity, redundancy, and storage, all of which would be required to cover times when the sun doesn’t shine, thus requiring even more land. Still, my estimate gives some idea of the size of the task.

Before you boggle at the size of the task, think of our current power generating infrastructure and how long it took us to create it. In 2014 there were an estimated 7,644 power plants in the USA.

https://www.eia.gov/tools/faqs/faq.cfm?id=65&t=2.

The first generating stations supplying power to the public were built in 1882, meaning that it took us 132 years to get to where we are now.

https://en.wikipedia.org/wiki/Power_station.

We have a big job in front of us, but if we give it our best effort, could we, would we, cover that much land with solar panels? I don’t know. But what if you relied on distributed solar photovoltaic power? What if you put solar panels on the roofs of buildings all across America? I will look at that next.

Figure 1. Source: U.S. Energy Information Agency.

Climate change results from greenhouse gas (GHG) emissions. Inventories of U.S. GHG emissions consistently show that the majority of our emissions consist of carbon dioxide (CO2) from burning fossil fuel to create energy. This post looks at state emissions of CO2 from burning fossil fuel to create energy. Missouri did two GHG inventories in the early 1990s, but hasn’t done one since. Thus, this data is as close as we can come to assessing Missouri’s progress in reducing GHG emissions. The most recent data is through 2013.

Figure 1 shows that in Missouri CO2 emissions from burning fossil fuel to create energy grew 13% from 2000-2005, then began a decline through 2012 that reversed most of the growth. In 2013 they began increasing again. In 2013, CO2 emissions were 4.3% above the 2000 level.

Figure 2. Data source: U.S. Energy Information Administration.

Figure 2 shows similar data for Missouri and 4 neighboring states: Arkansas, Illinois, Iowa, and Kansas. Kansas and Illinois have reduced their emissions, though only by a small amount. The other states have increased emissions, Arkansas the most at 6.6%.

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Figure 3. Data source: U.S. Energy Information Administration.

Figure 3 shows change in CO2 emissions from 2000 to 2013 for all 50 states plus for the USA in total. Only 13 states have increased CO2 emissions over that period. The other 38 (list includes District of Columbia) have reduced CO2 emissions, in some instances by more than 25%. Nationwide, CO2 emissions are down 9.6%.

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Figure 4: Data source: U.S. Energy Information Administration (a and b).

Figure 4 shows 2013 CO2 emissions from Missouri by Sector. The blue columns show the raw data. CO2 emissions from generating electric power dwarf those from any other sector. Electric utilities, however, don’t generate electricity for their own consumption, they generate it for others to use. The EIA keeps data on the sectors into which utilities sell their electricity, and it can be used to distribute their CO2 emissions to their end use sectors. Almost all of it goes to the Commercial, Residential, and Industrial Sectors. The red columns show the results.

The data suggest that converting electricity generation to renewable sources would probably be the the single most effective way to reduce Missouri CO2 emissions. To reduce CO2 emissions by reducing energy consumption in end use sectors, the Residential, Transportation, and Commercial sectors would all be of similar importance.

The Intergovernmental Panel on Climate Change estimates that we need to make significant reductions in CO2 emissions – 50% or more – if we are to avoid the worst effects of climate change. All states have a long way to go; most appear to have made some progress. Not Missouri.

In the coming weeks, I’m going to offer some posts that suggest that completely converting to renewable energy would require covering huge amounts of the country with wind and solar farms, without even considering the need for redundancy, excess capacity, and storage, all of which would be required. It would be a huge task.

That notwithstanding, Missouri’s performance on this metric is shameful. The fact that it is a huge, difficult task means that we aren’t going to be able to accomplish this transition overnight. We need to get cracking, and there is no excuse for avoiding it. I fear we will pay a heavy price for our inaction.

Sources:

United States Energy Information Administration. 2016. Table 1: State Energy-Related Carbon Dioxide Emissions by Year (2000-2013). http://www.eia.gov/environment/emissions/state/analysis.

United States Energy Information Administration. “Sales and Revenue, 2013.” Form EIA 826 Detailed Data, Electricity. http://www.eig.gov/electricity/data/eia826/#salesrevenue.