Recent climate policy successes have left some American observers concerned about a knock-on effect: transitioning to a clean energy economy will take up a huge amount of land. One group, Net Zero America, claims the transition will require up to 590,000 square kilometers of land devoted to clean energy production. Ezra Klein noted that this is the equivalent of “the land mass of Connecticut, Illinois, Indiana, Kentucky, Massachusetts, Ohio, Rhode Island and Tennessee put together.”
But is this accounting correct? If we dig into the projections, we find a wide range of energy scenarios that don’t require such obscene amounts of land. While the maximalist projections assume a special focus on wind and solar, there are far more tools available to us that can reduce both cost and land use. And innovation in heating technologies could also change the calculus. In other words, our likely energy future won’t necessarily rely on wind farms covering the Great Plains.
Instead, we’re much more likely to solve our emissions problem through a range of new technologies, like heating innovations and changes to industrial equipment.
Projections that rely only on renewable energy lean heavily on wind to meet electricity demand at night. Although the physical footprint of wind turbines is tiny, their total area is enormous compared to other technologies. The tower and roads only use 0.75 acres per megawatt, better than many estimates for nuclear power plants. But turbines need wide spacing to prevent interference, roughly 80 acres per megawatt.
Source: Our World in Data
As a result, these projections would cover most of the Great Plains with wind farms, and require massive amounts of politically contentious long-distance electricity transmission to move power from the Great Plains to population centers in the east.
What if we pushed for an energy system that was driven by renewables, but incorporated other energy sources as well? The National Renewable Energy Laboratory (NREL) models many cases beyond pure renewables. A recent NREL study incorporated hourly regional energy demand and costs like transmission infrastructure to estimate the future price of energy resources, then computed the market share that minimizes costs. The resulting projections suggest that a market-friendly approach to decarbonization can be successful. Wind generation has a minor market share in most cases, only two to three times our current installed capacity. In scenarios that allow natural gas, wind’s total area would be slightly larger than West Virginia.
In these projections, local generation prices out additional wind electricity because transmission lines are expensive, and wind production on the Great Plains tends to be correlated, leading to wasted output. Solar reaches much higher market shares because of its alignment with daily electricity demand patterns and battery storage. Renewables exceed 80% market share with natural gas at $6.50 per thousand cubic feet (MCF), but wind generation is around one-eighth of what wind and solar dominant scenario groups like Rewiring America propose.
NREL’s study assumes only a 50% increase in electricity usage, which would cover projected economic growth and the electrification of transport. But it’s not adequate for the electrification of heating and industry. Moving to zero emissions in those sectors will require substantially more electricity. Groups like Rewiring America assume wind energy will be required to cover these sectors, leading to massive land usage projections. But what if other technologies are better equipped to electrify heating and industry?
If you assume that electric heating and air-source heat pumps will fulfill most of American heating needs, you need a massive amount of wind and solar energy. Heating demand is the highest when solar panels are the least productive: at night, at high latitudes, and during the winter.
Air-source heat pumps lose efficiency as air temperature decreases, causing electricity demand to skyrocket during extreme weather. The grid needs extra wind farms and transmission lines to meet peak demand.
However, multiple new and resurgent technologies are available to reduce emissions in housing. A combination of natural rollovers in housing stock, ground-source heat pumps, district heating, and geogrids can get us most of the way to clean energy without heavy land use.
Residential and commercial buildings made up 13% of U.S. greenhouse gas emissions in 2019. New homes roughly halve the heating usage of old homes, even with more square feet. We’ll see a significant reduction in fossil fuel heating usage through the natural rollover of housing stock.
Ground-source heat pumps are another technology gaining prominence, as they don’t lose efficiency as the temperature falls. They use about half the electricity in colder climates but are more expensive upfront. The extra cost might be well worth it for regions that would otherwise require new power plants to meet peak heating demand.
Geogrids are a variation on ground-source units. A neighborhood shares the underground pipes instead of each house having a system. Geogrids can be even more efficient because some users might still be cooling (like a restaurant with a freezer) and dumping heat into the grid. Geogrids are clever because they allow existing gas utilities to convert to geogrids, preserving jobs. They especially make sense where gas piping is beyond end-of-life and needs replacement. The utility can subsidize new customer appliances and recover the cost over time through monthly bills.
Industrial emissions pose a unique challenge to clean energy goals. Efficiency boosting technologies like heat pumps aren’t as effective because of the high temperatures industry requires. Cost is also a barrier because fossil fuels are good at producing high temperature heat. Natural gas at $5 per MCF is equivalent to $17 per MWh. Transmission cost alone could exceed typical industrial natural gas prices. Luckily, there are other options.
Deep geothermal may struggle to generate competitive electricity, but it has a comparative advantage in generating steam for process heat. It could produce much of our industrial steam at much lower costs than electrification.
If industry electrifies instead of choosing geothermal steam, onsite renewables, like solar, will be a more practical option than far away wind. A factory can install solar panels on its extra land to heat materials like graphite blocks during the day. That heat can make steam throughout the night, allowing 24/7 process heat. Rewiring America assumes industry will pay at least $20 to $40 per MWh for electricity, the equivalent of $6 to $12 per MCF natural gas. Prices at those levels would be debilitating for industry. Onsite solar that avoids transmission costs and volatile wholesale electricity prices might be as low as $10 to $15 per MWh, comparable to $3 to $4.50 per MCF natural gas.
The story is similar for industries like steel that might use hydrogen to replace coal for reducing iron ore. Hydrogen is expensive to transport and requires onsite production. It will be cheaper to generate electricity for electrolyzers onsite and have a small hydrogen storage buffer. A company that has decarbonization goals could meet them immediately by using onsite generation instead of waiting for the grid to clean up. In the vast majority of the U.S., that onsite generation will be solar instead of wind.
What’s more, projections for the amount of land solar will take up continue to fall. In the last ten years, the efficiency of standard solar panels has roughly doubled. Incremental improvements and tandem cells could deliver another 50% increase over the next decade. New concepts like Erthos’s tightly packed solar farms could cut land use by two-thirds for utility-scale installations.
Current estimates require around 6.5 million acres of solar to meet our total needs, assuming 20% efficient panels. Usage decreases to 2.2 million acres if we assume a 50% demand bump and account for new technology. There are roughly four million acres of rooftops that could reduce our total further. That is less area than the land we’ve mined for coal, and a fraction of the 50 million acres we use to produce biofuels like ethanol today. Two million acres is a tiny corner of a state like Kansas, and we will use less than that to supply the grid (because solar won’t provide 100% of our electricity).
Groups like Rewiring America are working backwards from goals of near 100% wind and solar, rather than investigating the full spectrum of clean energy solutions. When looking at our wide array of clean technologies, there’s tremendous cause for optimism. We can reach net zero emissions without devoting hundreds of thousands of square kilometers of land to energy farms.