Why dedicating land to bioenergy won’t curb climate change

WRI

Corn_ethanol_plant_-_Iowa_-_Macomb_Paynes_-_cropped
A new WRI working paper recommends against dedicating land to produce bioenergy. Photo by Macomb Paynes.

How does bioenergy contribute to a sustainable food and climate future?

A new WRI paper finds bioenergy can play a modest role using wastes and other niche fuelstocks, but recommends against dedicating land to produce bioenergy. The lesson: do not grow food or grass crops for ethanol or diesel or cut down trees for electricity.

Even modest quantities of bioenergy would greatly increase the global competition for land. People already use roughly three-quarters of the world’s vegetated land for crops, livestock grazing and wood harvests. The remaining land protects clean water, supports biodiversity and stores carbon in trees, shrubs and soils—a benefit increasingly important for tackling climate change. The competition for land is growing, even without more bioenergy, to meet likely demands for at least 70 percent more food, forage and wood.

Competition for Land

Opportunities do exist to grow more food on the same land and to reinvigorate some degraded, highly underutilized land. But meeting food and timber needs without clearing more forests will already require full use of this potential. Providing just 10 percent of global transportation fuel from biofuels in 2050 would require roughly 30 percent of the total energy in all the crops people harvest today.

rsz_biofuels_figure3

Turning to so-called cellulosic energy crops such as fast-growing grasses would not avoid this land use competition. On cropland, even with optimistic estimates, such energy crops will struggle to produce even the same amount of ethanol per acre (hectare) as corn ethanol does today. Growing these crops on pasture or forest land would sacrifice food and carbon storage benefits.

Some institutions have called for producing 20 percent of human energy needs from bioenergy of all sorts by 2050. That would require an amount of biomass equal to all the plants harvested annually across the entire world today: all the crops, crop residues, wood and grasses eaten by livestock. The world does not have the room.

Biofuels_figure4

Beneath these global figures is an even simpler truth: every time we dedicate land to bioenergy, we sacrifice the opportunity to use that land for some other human need, ranging from food to carbon storage. The trade-off is a bad one because bioenergy is an inefficient use of land. Even ethanol from sugarcane in Brazil only converts around 0.2 percent of the energy in the sun’s rays to usable energy, and cellulosic ethanol would optimistically only be a little better.

Bioenergy Isn’t Carbon-Free

This opportunity cost of land also explains why bioenergy will rarely reduce greenhouse gas emissions. Studies that find bioenergy reduces greenhouse gases incorrectly view plants as a carbon-free fuel and ignore the very real carbon emitted by burning them. The theory has been that the original growth of the plants absorbs enough carbon to offset the carbon released when they burn. But if those plants were going to grow and absorb carbon anyway – and typically they would – then diverting them to bioenergy does not remove any additional carbon from the atmosphere. Instead, bioenergy comes at the expense of some other uses of those plants. When the expense is food or agricultural land, the effect is poorer nutrition. When the expense is forests or woody savannas, the effect is less stored carbon.

Some alternative sources of bioenergy still exist without dedicating land for bioenergy. Municipal waste and some forest and crop residues provide potential. But because of limited quantities of such potential biomass, ambitions need to remain modest. Replacing traditional but inefficient use of fuel wood or charcoal with improved bioenergy would also be a net gain.

Solar Cells Offer an Alternative

The good news is that standard solar cells available today can generate more than 100 times as much usable energy per acre (hectare) as bioenergy even using optimistic projections for bioenergy’s future. When used with electric engines in cars with more efficient batteries, solar benefits can rise to 200 or 300 times the efficiency biofuels. And unlike bioenergy, solar energy works great in deserts and on rooftops without competing for fertile land.

Solar energy will need a variety of improved storage techniques to realize its full attention to meet human energy needs, and there are unlikely ever to be electric airplanes. But the world can boost solar production enormously even with today’s technology, and promising storage technologies are emerging for the future.

The ultimate challenge is that land, particularly fertile land, is a finite resource that becomes ever more valuable as the world becomes more crowded. Using solar technologies to produce more of our energy and cropland to produce our food is the wiser, more efficient and food-secure path to a sustainable food and climate future.

 

Source: World Resources Institute. Reproduced with permission.

Comments

9 responses to “Why dedicating land to bioenergy won’t curb climate change”

  1. suthnsun Avatar
    suthnsun

    Solar power on existing or rebuilt structures is our natural ‘budget’ for land use, efficiency of energy use makes it feasible as a complete solution.

  2. Don Chambers Avatar
    Don Chambers

    Food to feed the increasing global population cannot be grown at the capacity required without liquid fuels to plant and harvest crops. Energy and fuel crops like agaves grown on marginal lands must be part of the future to support food production.

  3. Shaun Colley Avatar
    Shaun Colley

    I have some sympathy for the intentions of the writer of that report but unfortunately they have used out-dated assumptions and refer to very old technology. The latest (and far more efficient) conversion technology combined with utilisation of degraded or desertified non-agricultural land demonstrate far higher energy output than assumed here. Should be utilised alongside solar.

  4. Sebastian Klein Avatar
    Sebastian Klein

    By focussing on Bioenergy crops that displace arable land the author sets up BE to lose the argument. A one sided article that fails to see the bigger potential for renewable resources grown in ways that complement and enhance existing agricultural production.

  5. Chris Baker Avatar
    Chris Baker

    The author makes the intriguing statement that bioenergy isn’t carbon free. Well of course, but that misses the point, and implies that that would be the claim of supporters of biofuel. The significance of burning fossil fuels is that it releases carbon that would otherwise remain sequestered in the ground. The burning of biofuels releases carbon that was in the atmosphere quite recently and is just being cycled without adding an additional carbon load to the atmosphere. For me an important point about biofuels is that the same piece of land can be used year after year to produce fuel that would replace fossil fuels. To be going on with it seems a useful strategy to me. As we see the increased use of electric cars and eventually trucks, transportation will need less and less liquid fuel, and the use of bioenergy during this transition could be helpful.
    Also odd is Searchingers claim that there are unlikely ever to be electric airplanes — he need look not further than the pages of this website to see not only an electric plane, but a solar powered one at that.
    Dedicating land to bioenergy seems like a useful transition strategy to me just now to give us some breathing space while we learn better ways to provide for our energy needs. Perhaps we will even begin to understand our role on the planet, and treat ourselves and the planet with more respect.

  6. atwork Avatar
    atwork

    Deserts and fertile well watered land vary so much that lumping them as one and talking about food versus fuel is meaningless. Trees grown for bioenergy on the same land as crops or pasture will not only store carbon faster and longer but will also replace fossil fuels. Thinking carefully about land use requires segmentation – for example – grazing land, crop land, land likely to be stressed by higher temperatures, change rainfall and developing vegetation options linked to profitable markets. Belts of trees grown for jet fuel based on 20 years of careful consideration provides a practical example of how land could be allocated to bioenergy in Australia’s wheat sheep belt.

  7. john Avatar
    john

    Converting the Carbon in plant material to usable fuel can be efficient however using old pot still methods that are shall we say thousands of years old is not the way to go.
    One has to convert all of the available Carbon in the material to usable fuel which yes will then be burn to produce CO2 however using pot stills that emit CO2 is not exactly very smart or for that matter cost effective.
    Using cellulosic conversion to utalise all of the available C5 and C6 is what should be used.

  8. Matthew Dawes Avatar
    Matthew Dawes

    If bio-energy is used to produce “bio-char” it could be carbon negative.

  9. Ben Rose Avatar

    I disagree with the Author’s premise that all biomass for energy must necessarily compete with land for food crops. He does not understand that landscapes are variable are not all of the land is suitable for crops or even grazing. There are steep, stony waterlogged or deep sandy areas that produce much better under trees. I have studied and written papers on growing oil mallee for energy in the WA sheep belt (350 – 600) mm rainfall and 10% under trees would not reduce agricultural production – it can even improve the surrounding land by reducing water logging and wind erosion.

    Here in New York State USA where I have been living for 9 months, this is even more noticeable. There are huge areas of swampy land and quartz / shale ridges that are pretty well useless for agriculture but produce good trees or switch grass. Wood and straw can be burned directly in thermal power stations, preferably with heat cogeneration. It can also be pyrolized to produce liquid fuels.

    What the Author also misses is that there are sub-zero temperatures and very little sun through all of northern US, Canada, Europe, Russia and China for 3 – 5 months of the year (over a billion people live in these areas). A fair bit of fuel energy has to be used at least during that period. It is either maximize biomass or use nuclear. They are not addressing this issue of sustainable fuels for freezing winters in the US, where they are very vulnerable.. Nuclear is going backwards (NIMBY), coal is being regulated out and there’s little being done with bioenergy. And electric heating and batteries aren’t the solution they are in Australia – heat pumps don’t work too well when it’s 10 C below outside – there’s not much heat to pump and not much sun to generate solar.

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