Is It Time to Consider 'Energy Sprawl' When Discussing Future Energy & Climate Policy?


Image: PLoS ONE

A new article published in the online journal PLoS ONE takes on the issue of energy sprawl -- namely how much land is required to produce energy from different sources -- under different potential US energy and climate policies in 2030. The researchers found that there is a three order of magnitude difference between available energy options:Energy Sprawl Only One Way to Evaluate Energy Options
Before we get to the results, though, I should point out the following, from one of the report's authors, the Nature Conservancy's Rob McDonald:

It's important to remember that energy sprawl concerns are only one of several ways to evaluate different energy production techniques, including climate change implications, cost efficiency, job creation, and issues of energy independence. Moreover, the environmental impact of much energy sprawl could be limited with proper siting, a philosophy The Nature Conservancy calls Energy By Design.

From the perspective of The Nature Conservancy, any new energy project that helps reduce U.S. emissions of greenhouse gases while avoiding impacts to sensitive species is a good project. We are not specifically advocating for any one energy production technology, just serious consideration of the potential environmental impacts of energy sprawl.

The reason I preface with that quote is to head off backlash against this statement:

Nuclear, Coal, Geothermal Have Lowest Sprawl - Biofuels Have the Most (By Far)
In decreasing order of land-use intensity (based on square kilometers of land needed to generate a terawatt-hour of power per year in 2030) the paper says the energy sources with the lowest impact are nuclear power (1.9-2.8), coal (2.5-17.0), and geothermal (1.0-13.9); the highest are corn ethanol (320-375), biomass-based electricity (433-654) and soy biodiesel (894). Wind power and solar power were both found to be in the middle of that range (72 and 37, respectively).

The report highlights the importance of energy conservation and efficiency in reducing these impacts: For each TWh decrease in electricity consumption, a decrease of 7.6-28.7 square kilometers of land impacted can result. For liquid fuels that goes up to 27.5-99.3 square kilometers.

Types of Impact, Longevity of Impact Vary
It's important to keep in mind what is meant by impact, in the context of this study:

Our definition of impact varies among energy production techniques, so a less compact way of generating energy does not necessarily mean that an energy production technique is more damaging to biodiversity, but simply that it has a larger spatial area impacted to some degree.

Moreover, many energy production techniques actually have multiple effects on biodiversity, which operate at different spatial and temporal scales. Biodiversity impacts that are likely to scale with areal impact include habitat replacement and habitat fragmentation.

Energy production impacts on biodiversity not related to land use intensity include impacts on air quality (e.g. acid rain, particulates), water quality (e.g. mercury, eutrophication), water consumption (e.g. irrigation water, evaporation from hydroelectric reservoirs), and water flows (e.g. dam-based hydroelectric).

Further, the longevity of the impacts described here varies. For example, radioactive nuclear waste will last for millennia, some mine tailings will be toxic for centuries, and other mines may be reclaimed for agriculture within decades.



Image: PLoS ONE. (A) U.S. energy consumption in 2006 and under four EIA scenarios. Energy conservation of liquid fuels and electricity, calculated relative to the Reference scenario, are shown as negative since they reduce consumption. (B) The total new area impacted because of development between 2006 and 2030. The new area impacted, or energy sprawl, is a product of consumption and the land-use intensity values in Figure 3. Energy conservation is calculated based on a scenario-specific weighted-average of the energy mix.
Energy Impacts New Land the Size of Nebraska by 2030
In total, regardless of policy, total new area in the US affected by energy production in 2030 is over 206,000 square kilometers -- an area larger than Nebraska. That includes expansion of biofuels, despite providing less than 5% of US energy supply under all scenarios studied. Under the study's Core Cap-and-Trade scenario that increases to move than 260,000 square kilometers.

In terms of habitats impacted, under all scenarios studied Temperate Deciduous Forests and Temperate Grasslands are the most affected -- with 95,000-229,000 sq. km. of forest impacted and 65,000-168,000 sq. km. under the reference scenario. Those figures increase under the study's Core Cap-and-Trade scenario.

Energy Conservation & Efficiency Paramount to Minimizing Impact
OK, so how to minimize impact. Here's report co-author Rob McDonald again:

  • Maximize energy conservation and energy efficiency as much as possible. Saving energy saves land by avoiding energy development.
  • Build incentives for the use of abandoned or degraded land. Particularly for biomass growth for liquid fuels or for electricity, natural habitat impacts could be minimized if the clearing of natural habitat was avoided.
  • Where possible site new energy development only where sensitive species will not be impacted.

Read more of Rob McDonald's comments on the paper: New Energy Production & Nature: What Will the Impacts Be?

The original journal article: Energy Sprawl or Energy Efficiency: Climate Policy on Natural Habitat for the United States of America
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