Reassessing Bioenergy From The Ground Up
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Reassessing Bioenergy From The Ground Up as PDF for free.
More details
- Words: 1,955
- Pages: 4
by BYRON MILLIGAN
ENG + TECH
Reassessing Bioenergy from the Ground Up The global potential of abandoned agricultural lands. Imagine a future in which the world’s dire need for renewable energies is answered by biofuels. Cars and homes are completely powered by organic plant matter. Electricity is provided from energy crops, and nonrenewable fossil fuels are no longer relied upon.
Professor of Biology and Environmental Earth Science Chris Field is doing exactly that. With three other colleagues, he has conducted research analyzing the global potential for the production of bioenergy on abandoned agricultural lands. Using abandoned agricultural lands for bioenergy crop production is a solution that would potentially have a much smaller negative
Credit: sxc.hu
Credit: sxc.hu
Energy independence has moved from being an idea of the future to a guarantee of the present. A promising image such as this seems to be the blessing that these times so desperately need. Unfortunately, the solution is never so easy. Unanticipated carbon emissions from land use change
caused by bioenergy crop production are perpetuating global warming and harming out environment. Despite the world’s initial drive for biofuels, it has become clear that it is necessary to reconsider heading fullspeed towards a biofueled utopia.
volume VIII 25
Credit: sxc.hu
ENG + TECH
impact on the environment, by minimizing land-use change, carbon emissions, and biodiversity loss. Moreover, the use of these lands could potentially end the ever present fuel vs. food war that makes biofuels so controversial. The key issue initiating this research, however, is land-use change.
A Change of Scenery
With the inertia that has plagued the energy sector of the environmental cause, it is easy to want to invest in any renewable energy source that seems immediately viable. This tendency certainly surfaced with biofuels, as ethanol now supplies 40% of Brazil’s transportation fuel needs and American croplands become devoted more and more to supplying ethanol production. The fundamental point we must remember, however, is that the Earth only has a fixed amount of land resources. Such intensive production of biofuels inevitably taps into this fixed resource one way or another. That is, given current methods, production of biofuels must directly or indirectly lead to land-use change. Direct land-use change occurs when untapped land is cleared and converted to the croplands upon which biofuels will be grown. Indirect landuse change occurs when food crops are converted to fuel crops. Such conversion requires new land to be cleared in order to maintain the world’s production of food. And though this new land that is cleared may be an end result of many intermediate steps, the bottom line is that it will indeed be cleared. The problem with such land conversion is that in this change, tremendous amounts of carbon are released. As plant matter from forests or grasslands decays or is burned, the carbon that it has been storing for decades, or even centuries, is released into the atmosphere. Though biofuels crops do sequester carbon in the same manner that
26 www.stanfordscientific.org
forests or grasslands do, their capturing capabilities are nowhere near as high. For this reason, it will take a very long time for the carbon-sequestering advantage of biofuels to have a positive net effect on the atmosphere. Specifically, carbon sequestration from corn-based ethanol could take over 167 years to recapture the amount of carbon that has been emitted from the land conversion required to produce this ethanol. This means that emissions will be increasing for a 167 year period. That this setback is a product of a renewable energy source is a scary proposition indeed. Though biofuels may seem like a welcome change, the actual change in scenery that they cause may be more harmful for the environment than it is good. Professor Field, however, says that we should not give up on biofuels production completely. We simply must find a way to produce them sustainably. Only then can we journey forward with a true solution—or at least part of the solution—to the world’s impending energy problem.
Finding the Space
Field and his colleagues J. Elliott Campbell, David Lobell, and Robert Genova recognize that in order to develop a viable solution, it is critical to understand what one has to work with. It is for this reason that they conducted a study that was published in Environmental Science & Technology entitled “The Global Potential of Bioenergy on Abandoned Agricultural Lands”. In this study, they take a holistic approach in starting to understand what kind of a role biofuels can play in the future’s energy solutions. Says Field, “it is a way to get your arms around what kind of quantities we are talking about.” The study assesses how much abandoned agricultural land
ENG + TECH
is available globally, what the energy production from these lands would be, and how this production compares to the energy demands of the region. The idea of assessing the potential of abandoned agricultural lands arose out of their recognition that biofuel production must be protective of the climate, of biological diversity, and of the world’s food supply. Abandoned agricultural lands are lands that were once used for agricultural purposes but now are not. Using these lands for the production of biofuels, therefore, would eliminate most of the current problems associated with biofuels, especially since many of these problems are inextricably linked. Producing biofuels on these abandoned lands would not cut into food supply, as the lands are clearly not currently being used for the production of food. This, in turn, means that the production of biofuels on these lands would not impact available land area, and therefore should not lead to carbonreleasing land use change. Preventing such land-use change also helps to protect biodiversity. Finally, the use of these lands could also improve their quality by preventing erosion and restoring nutrients. This could enable the lands to be used again for food production at some point in the distant future. Quantifying the amount of this type of marginal land that is available, however, is much trickier than knowing the reasons why it should be used. This study was conducted on a global scale, and though Field jokes that “the computer really takes care of most of it,” there clearly was much to manage. Field set about finding the amount of land available globally by analyzing different preexisting land-use databases, such as HYDE, MODIS, and IGBP. Field remarks that abandoned-land data “is not something that people have tried to extract from these
historical land-use databases before, but it is hidden in them, waiting to be brought out.” The process of finding this information involved analyzing gridded maps providing “the fractional area of crop and the fractional area of pasture within each grid cell for each decade between 1700 and 2000. Abandoned areas were determined from each map grid cell that had decreasing agriculture areas over time.” This alone, however, was not enough to provide the accurate results desired.
“It is a way to get your arms around what kind of quantities we are talking about.” Chris Field
Field and his colleagues also looked at other datasets to determine if land that was once used for agriculture had truly become abandoned, or if it had been converted to some other purpose. They called upon satellite maps to determine if land truly is abandoned agricultural land, or if it has become converted to forest or urban environments. Using two different sets of assumptions, one being lower and more conservative, they estimated the global area of abandoned agricultural land to be between 385 and 472 mega hectares. Knowing this is a terrific insight indeed. But it is only one step in the research that Field and his colleagues conducted. Field says that what they really want to do is to frame the issue of biofuels and their potential on a global scale. To do this, they discovered not only the amount of abandoned agricultural land available, but also what it means for the future of energy.
The Story in the Soil
It is hard to see what this quantity of land represents in terms of energy production. Field and his colleagues went on to assess how much biomass these abandoned lands are capable of producing, and how much energy demand that biomass could fulfill. Doing so, of course, required another simulation model.
volume VIII 27
Credit: sxc.hu
“Every serious student of the future energy environment has concluded that there is no single technology that is going to solve the problem.” - Chris Field This second model uses satellite information and data sets that form calculations of biomass production based on sunlight, water, soil nutrients, temperature, and historical growth. By looking at this information globally, Field and his colleagues could determine that the 385 to 472 mega hectares of abandoned agricultural land could potentially produce between 1.6 and 2.1 billion tons of above ground biomass per year. They then determined the energy content of this much biomass, and found it to be 32 to 41 exajoules. It is important to note, however, that just as certain regions of the world will contribute more to the total biomass produced by abandoned lands annually than others, this energy content will vary geographically as well. Nevertheless, from a global perspective, this tells us the amount of energy that could be provided by producing biofuels in a sustainable manner. Perhaps most importantly, it means that the amount of energy demand satisfied by biofuels coming from abandoned agricultural lands is 7-8%. This may not seem the like the miraculous number that we would hope for. It certainly is not an all-encompassing solution that will completely revolutionize the future of energy. Field acknowledges this, and even says that of this 8%, we will only be able to actually employ a smaller part of it. There will be challenges, due to many variables, ranging from conservation values to degraded land quality to efficiency issues. But even if we could only satisfy 1% of the global energy demand with biofuels from abandoned agricultural lands, Field still feels it is still extremely significant. “I think almost
every serious student of the future energy environment has concluded that there is no single technology that is going to solve the problem.” When it comes down to it, we are going to need everything we can get. Do not let this information seem too dreary though. Sitting in the office of an eco-friendly building, Professor Field seems wonderfully optimistic. And it isn’t only about raw numbers. There are other positive impacts of producing bioenergy crops on abandoned lands. Field hopes they will help to restore the quality of the land and prevent erosion. But even from the perspective of how much energy these lands will supply, it may be more significant than the overarching numbers indicate. Though the potential of bioenergy from abandoned agricultural lands may not be tremendous on the global scale, regionally it can be much more significant, especially in areas with high biomass yields and low energy demands. Finding exactly where these areas are and how to utilize them, however, is an entirely new aspect of this study that Field hopes to pursue. But for now, we have a starting point, or perhaps even a re-starting point. We have a new way to think of biofuels and their sustainable production. The need for change is pressing, and the problems we face seem to be accelerating toward us quickly. But it has been made clear what will happen if we proceed too hastily and without caution. To proceed properly, we must be informed and prepared. This research brings us one step closer.
To Learn More
For more information, visit the website of the Department of Global Ecology at dge. stanford.edu
28 www.stanfordscientific.org
Credit: sxc.hu
ENG + TECH
ENG + TECH
Reassessing Bioenergy from the Ground Up The global potential of abandoned agricultural lands. Imagine a future in which the world’s dire need for renewable energies is answered by biofuels. Cars and homes are completely powered by organic plant matter. Electricity is provided from energy crops, and nonrenewable fossil fuels are no longer relied upon.
Professor of Biology and Environmental Earth Science Chris Field is doing exactly that. With three other colleagues, he has conducted research analyzing the global potential for the production of bioenergy on abandoned agricultural lands. Using abandoned agricultural lands for bioenergy crop production is a solution that would potentially have a much smaller negative
Credit: sxc.hu
Credit: sxc.hu
Energy independence has moved from being an idea of the future to a guarantee of the present. A promising image such as this seems to be the blessing that these times so desperately need. Unfortunately, the solution is never so easy. Unanticipated carbon emissions from land use change
caused by bioenergy crop production are perpetuating global warming and harming out environment. Despite the world’s initial drive for biofuels, it has become clear that it is necessary to reconsider heading fullspeed towards a biofueled utopia.
volume VIII 25
Credit: sxc.hu
ENG + TECH
impact on the environment, by minimizing land-use change, carbon emissions, and biodiversity loss. Moreover, the use of these lands could potentially end the ever present fuel vs. food war that makes biofuels so controversial. The key issue initiating this research, however, is land-use change.
A Change of Scenery
With the inertia that has plagued the energy sector of the environmental cause, it is easy to want to invest in any renewable energy source that seems immediately viable. This tendency certainly surfaced with biofuels, as ethanol now supplies 40% of Brazil’s transportation fuel needs and American croplands become devoted more and more to supplying ethanol production. The fundamental point we must remember, however, is that the Earth only has a fixed amount of land resources. Such intensive production of biofuels inevitably taps into this fixed resource one way or another. That is, given current methods, production of biofuels must directly or indirectly lead to land-use change. Direct land-use change occurs when untapped land is cleared and converted to the croplands upon which biofuels will be grown. Indirect landuse change occurs when food crops are converted to fuel crops. Such conversion requires new land to be cleared in order to maintain the world’s production of food. And though this new land that is cleared may be an end result of many intermediate steps, the bottom line is that it will indeed be cleared. The problem with such land conversion is that in this change, tremendous amounts of carbon are released. As plant matter from forests or grasslands decays or is burned, the carbon that it has been storing for decades, or even centuries, is released into the atmosphere. Though biofuels crops do sequester carbon in the same manner that
26 www.stanfordscientific.org
forests or grasslands do, their capturing capabilities are nowhere near as high. For this reason, it will take a very long time for the carbon-sequestering advantage of biofuels to have a positive net effect on the atmosphere. Specifically, carbon sequestration from corn-based ethanol could take over 167 years to recapture the amount of carbon that has been emitted from the land conversion required to produce this ethanol. This means that emissions will be increasing for a 167 year period. That this setback is a product of a renewable energy source is a scary proposition indeed. Though biofuels may seem like a welcome change, the actual change in scenery that they cause may be more harmful for the environment than it is good. Professor Field, however, says that we should not give up on biofuels production completely. We simply must find a way to produce them sustainably. Only then can we journey forward with a true solution—or at least part of the solution—to the world’s impending energy problem.
Finding the Space
Field and his colleagues J. Elliott Campbell, David Lobell, and Robert Genova recognize that in order to develop a viable solution, it is critical to understand what one has to work with. It is for this reason that they conducted a study that was published in Environmental Science & Technology entitled “The Global Potential of Bioenergy on Abandoned Agricultural Lands”. In this study, they take a holistic approach in starting to understand what kind of a role biofuels can play in the future’s energy solutions. Says Field, “it is a way to get your arms around what kind of quantities we are talking about.” The study assesses how much abandoned agricultural land
ENG + TECH
is available globally, what the energy production from these lands would be, and how this production compares to the energy demands of the region. The idea of assessing the potential of abandoned agricultural lands arose out of their recognition that biofuel production must be protective of the climate, of biological diversity, and of the world’s food supply. Abandoned agricultural lands are lands that were once used for agricultural purposes but now are not. Using these lands for the production of biofuels, therefore, would eliminate most of the current problems associated with biofuels, especially since many of these problems are inextricably linked. Producing biofuels on these abandoned lands would not cut into food supply, as the lands are clearly not currently being used for the production of food. This, in turn, means that the production of biofuels on these lands would not impact available land area, and therefore should not lead to carbonreleasing land use change. Preventing such land-use change also helps to protect biodiversity. Finally, the use of these lands could also improve their quality by preventing erosion and restoring nutrients. This could enable the lands to be used again for food production at some point in the distant future. Quantifying the amount of this type of marginal land that is available, however, is much trickier than knowing the reasons why it should be used. This study was conducted on a global scale, and though Field jokes that “the computer really takes care of most of it,” there clearly was much to manage. Field set about finding the amount of land available globally by analyzing different preexisting land-use databases, such as HYDE, MODIS, and IGBP. Field remarks that abandoned-land data “is not something that people have tried to extract from these
historical land-use databases before, but it is hidden in them, waiting to be brought out.” The process of finding this information involved analyzing gridded maps providing “the fractional area of crop and the fractional area of pasture within each grid cell for each decade between 1700 and 2000. Abandoned areas were determined from each map grid cell that had decreasing agriculture areas over time.” This alone, however, was not enough to provide the accurate results desired.
“It is a way to get your arms around what kind of quantities we are talking about.” Chris Field
Field and his colleagues also looked at other datasets to determine if land that was once used for agriculture had truly become abandoned, or if it had been converted to some other purpose. They called upon satellite maps to determine if land truly is abandoned agricultural land, or if it has become converted to forest or urban environments. Using two different sets of assumptions, one being lower and more conservative, they estimated the global area of abandoned agricultural land to be between 385 and 472 mega hectares. Knowing this is a terrific insight indeed. But it is only one step in the research that Field and his colleagues conducted. Field says that what they really want to do is to frame the issue of biofuels and their potential on a global scale. To do this, they discovered not only the amount of abandoned agricultural land available, but also what it means for the future of energy.
The Story in the Soil
It is hard to see what this quantity of land represents in terms of energy production. Field and his colleagues went on to assess how much biomass these abandoned lands are capable of producing, and how much energy demand that biomass could fulfill. Doing so, of course, required another simulation model.
volume VIII 27
Credit: sxc.hu
“Every serious student of the future energy environment has concluded that there is no single technology that is going to solve the problem.” - Chris Field This second model uses satellite information and data sets that form calculations of biomass production based on sunlight, water, soil nutrients, temperature, and historical growth. By looking at this information globally, Field and his colleagues could determine that the 385 to 472 mega hectares of abandoned agricultural land could potentially produce between 1.6 and 2.1 billion tons of above ground biomass per year. They then determined the energy content of this much biomass, and found it to be 32 to 41 exajoules. It is important to note, however, that just as certain regions of the world will contribute more to the total biomass produced by abandoned lands annually than others, this energy content will vary geographically as well. Nevertheless, from a global perspective, this tells us the amount of energy that could be provided by producing biofuels in a sustainable manner. Perhaps most importantly, it means that the amount of energy demand satisfied by biofuels coming from abandoned agricultural lands is 7-8%. This may not seem the like the miraculous number that we would hope for. It certainly is not an all-encompassing solution that will completely revolutionize the future of energy. Field acknowledges this, and even says that of this 8%, we will only be able to actually employ a smaller part of it. There will be challenges, due to many variables, ranging from conservation values to degraded land quality to efficiency issues. But even if we could only satisfy 1% of the global energy demand with biofuels from abandoned agricultural lands, Field still feels it is still extremely significant. “I think almost
every serious student of the future energy environment has concluded that there is no single technology that is going to solve the problem.” When it comes down to it, we are going to need everything we can get. Do not let this information seem too dreary though. Sitting in the office of an eco-friendly building, Professor Field seems wonderfully optimistic. And it isn’t only about raw numbers. There are other positive impacts of producing bioenergy crops on abandoned lands. Field hopes they will help to restore the quality of the land and prevent erosion. But even from the perspective of how much energy these lands will supply, it may be more significant than the overarching numbers indicate. Though the potential of bioenergy from abandoned agricultural lands may not be tremendous on the global scale, regionally it can be much more significant, especially in areas with high biomass yields and low energy demands. Finding exactly where these areas are and how to utilize them, however, is an entirely new aspect of this study that Field hopes to pursue. But for now, we have a starting point, or perhaps even a re-starting point. We have a new way to think of biofuels and their sustainable production. The need for change is pressing, and the problems we face seem to be accelerating toward us quickly. But it has been made clear what will happen if we proceed too hastily and without caution. To proceed properly, we must be informed and prepared. This research brings us one step closer.
To Learn More
For more information, visit the website of the Department of Global Ecology at dge. stanford.edu
28 www.stanfordscientific.org
Credit: sxc.hu
ENG + TECH
Related Documents
Reassessing Bioenergy From The Ground Up
June 2020 3
Venice From The Ground Up
May 2020 11
Washington From The Ground Up
May 2020 7
Bioenergy
November 2019 5