Seasonal Energy Storage using Bioenergy Production from Abandoned Croplands

by Christina Whalen

Producing electricity from biomass could potentially provide a back-up storage source for the intermittency that accompanies wind and solar energy production. Biomass electricity also provides a carbon-negative and efficient method for bioenergy production, which is important because of mandated restrictions on carbon emissions. Furthermore, biomass electricity also provides an efficient method for providing renewable transportation energy that could replace current liquid fuel approaches. Although bioenergy may be important in producing electricity and developing energy storage mechanisms, the economic and environmental effects are unclear. Studies have been conducted on abandoned agricultural lands to try to find a path of producing bioenergy that has reduced land impact. Campbell et al. estimate at county level, the magnitude and distribution of abandoned agricultural lands in the United States and attempt to quantify how much potential energy storage could be produced by the provided bioenergy. Continue reading

Topographic and Soil Influences on Root Productivity of Three Bioenergy Cropping Systems

by Christina Whalen

Root production in plants plays a vital role in ecosystem carbon, nutrient, and water cycling, but researchers have not made much progress in further understanding this issue. It’s important to understand the impacts of environmental conditions on root production because it aids in the development of a sustainable bioeconomy. However, scaling root productivity estimates for cropping systems beyond plot scales poses a great challenge to researchers. Whether the bioenergy plants are annual or perennial influences the biogeochemical cycling and the ecological benefit of the systems. The foundation of the study is based on previous research of the response of root growth to variations in soil properties at multiple spatial scales. Roots of plants generally respond to different soil types by growing into nutrient patches, but this depends on the species and nutrient demands or limitations. Ontl et al. measured the response of root productivity of three different bioenergy cropping systems across a topographic gradient with variation in typical agroecosystem soil conditions. The hypothesis is that root dynamics would vary by cropping system and position of the landscape across a hillslope. If landscape alone was not a good enough indicator, they predicted that root productivity would be related to differences in soil. Continue reading

Hemp: A More Sustainable Annual Energy Crop for Climate and Energy Policy

by Christina Whalen

Growing concern about greenhouse gas (GHG) emissions and climate change due to fossil fuel dependency has led to the consideration of more attractive energy sources, especially bioenergy sources. In Northern Europe, the two crops that have worked the most effectively are Miscanthus and willow, two perennial energy grasses that have proven to be sustainable energy crops due to high yields of biomass from low inputs. Farmers are fairly attracted to cultivating these crops because of the declining farming market and the future promise of a biomass energy market. Farmers use break crops to control for disease and weeds, a technique that also increases wheat production. Currently sugar beet and oilseed rape are used in Northern Europe, but because of reduction in the sugar beet industry, hemp has been predicted to be an effective break crop because its root system aids soil structure. Various studies have demonstrated that it produces high yields of biomass with no agrochemical input and very little fertilizer use. It offers the potential of being an effective break crop as well as an energy crop. Finnan et al. compare hemp with other annual and perennial energy crops, economically and as a way to mitigate GHG emissions. Continue reading

Sustainable Bioenergy: Evolving Stakeholder Interests

by Christina Whalen

The diversity of stakeholders’ interest and values complicates the decision-making process involved in the future of sustainable bioenergy production. Johnson et al. explores the different stakeholder perspectives and then examines how this diversity affects research on the subject. Biofuel production has been brought to the public’s attention because of the need to mitigate greenhouse gas (GHG) emissions, increase energy security, support farm production, and improve economic growth in rural areas. The recent increase in biofuel consumption has resulted in stakeholders questioning environmental, economic, and social benefits of using agriculture to produce ethanol and biodiesel. As a result, policy makers have passed legislation and modified regulations about renewable fuel production in order to promote the use of alternative biomass feedstocks. The general research community is looking for ways to convert this feedstock to a usable fuel source in vehicles. The expansion of biofuel production coincides with Continue reading

Farmers Think Hard Before Planting Biofuel Crops

by Christina Whalen

Using Kansas as an example, White et al. (2012) examine the various factors that influence farmer decision-making during this controversial era of climate change and energy conservation. A conceptual model for understanding farmer’s decisions was developed from interviews conducted with a diversity of farmers and key informants. Interestingly enough, results demonstrate that most farmers hold a positive perception of the natural environment and don’t have a strong concern about climate change issues. The guiding factors of farmer’s decisions about whether or not to cultivate biofuel crops are the relative advantages of the practice and the ability to discuss the practice with a social network. There is a strong need to create a renewable energy market in the U.S. because of its potential to reduce greenhouse gases and increase production benefits; biofuel crops pose one plausible solution. The paper addresses the following question: considering global climate and energy concerns, what are the main influences on farmer’s decisions regarding land use, specifically the decision to cultivate biofuel crops? Continue reading

Saving Land and Water by Cultivating Miscanthus

Due to government mandates in response to climate change, ethanol production has steeply increased since 2009, and there are now for 79 billion liters of cellulosic biofuels yearly by 2022.  Cellulosic crops such as maize, switch grass, and Miscanthus have been determined to be viable biofuel sources. In order to meet the biofuel target in 2022, cellulosic crop cultivation needs to be expanded and intensified. The impact on land and water use needs to be considered as well. Zhuang et al. (2013) present a data-model assimilation analysis assuming that maize, switchgrass, and Miscanthus can be grown on available U.S. croplands.—Christina Whalen
 
Zhuang, Q. Qin, Z. Chen, M. 2013. Biofuel, land, and water: maize, switchgrass, or Miscanthus. Environ. Res. Lett. 8, 015020.

Continue reading

Setbacks of Using Agricultural Crops and Natural Ecosystems as Energy Sources

The currently growing concerns around the world about foreign oil dependency and growing climate change, have contributed to an increasing interest in using bio-fuels as an alternative to fossil fuels such as coal, gas, and oil. The study conducted by Graeme I. Pearman (2013) demonstrates that bio-fuels and bio-sequestration can only make a minor contribution to lowering carbon levels and minimizing net emissions of carbon into the atmosphere. This is done through examining available solar radiation and observing how efficient natural and agricultural ecosystems are in converting that energy to usable biomass. The 11 countries compared in the study are Australia, Brazil, China, Japan, Republic of Korea, New Zealand, Papua New Guinea, Singapore, Sweden, United Kingdom, and United States, with a main focus on the researcher’s homeland, Australia. The objective of the study is to answer the following question: from a biophysical perspective, can using bio-fuels or bio-sequestration of carbon significantly contribute to the future of energy and the reduction of greenhouse-gas  (GHG) emissions?—Christina Whalen

                  Pearman, G. 2013. Limits to the potential of bio-fuels and bio-sequestration of carbon. Energy Policy 59, 523-535.

                  The first part of the study focuses on comparing annual rates of solar radiation and respective energy consumption for each country. The results group countries into 3 groups. Group 1, Japan, Korea, and Singapore had energy consumption around 1 en dash 10% of incident (surface) radiation. Group 2, China, U.K., and U.S. had energy consumption around 0.1% and Group 3, Australia, Brazil, New Zealand, Papua New Guinea, and Sweden had energy consumption around 0.1 en dash 0.001% of incident radiation. These comparisons demonstrate the limits that deriving energy from the sun has on meeting national expectations for energy consumption. We can consume much more energy than the sun could ever provide us.
                  Photosynthetic efficiency is another limit to the use of bio-fuels or bio-sequestration. The pigments in the chloroplast are only activated by certain parts of the solar spectrum, leaving much of the solar radiation unutilized. In addition, more than 50% of photosynthetic products (sugars) are lost through photorespiration. The whole process is only 3.3% efficient in C3 plants and 6.7% in C4 plants.
 The study then continues to examine the limitations of bio-fuels regarding energy efficiency captured from natural vegetation and from global crops. Net primary production (NPP) is how much carbon (or energy in this case) remains after the photosynthetic organism has used it for growth and other metabolic functions. In natural environments, a large portion of captured solar energy is used within the community and is vital for a functioning and healthy ecosystem. Thus, human use of this energy will no doubt have negative impacts on preexisting ecosystems. Agricultural ecosystems are constructed for the purpose of providing biomass for human consumption. The main difference between the two types of ecosystems is that a cultivated system inputs fossil fuels, which needs to be considered when accounting for the net production of energy. Comparisons within each of the countries were then made between energy captured annually as net primary production and the national solar radiation and energy consumption rates. The comparison demonstrates the inefficiency of the biochemistry involved in photosynthesis and is also influenced by temperature and water availability. The comparisons also conclude that modifying the NPP of the biosphere could be possible when global scale changes occur to temperature, rainfall, and carbon dioxide concentrations.
Photosynthesis can be more efficient in agricultural crops when there is plenty of water and fertilizer and crop management is most favorable during the peak growth rates. In the study, multiple samples were taken from various countries and locations in order to accurately compare the relative efficiencies of different cropping systems. This is called “tradable production” because the net production is calculated after discarding the roots, leaves, and stems of plants. Sugar cane and wheat crops have the potential to contribute significantly the nation’s energy demand, but have some economic and political setbacks that are not discussed in detail in the paper.
Though natural and agricultural biomass have the potential to provide energy for human use and to offset carbon emissions from fossil fuels, this study demonstrates that there are major limiting factors to this solution including the availability of solar radiation and the efficiency of photosynthesis needed to convert the energy into feedstock. Another limitation is how efficiently biomass can be converted into fuels that are appropriate for existing feedstocks, conversion systems, and applications. Solar radiation on land accounts for 1700 times the amount of energy consumed by humans, but the radiation and the energy demands are not evenly distributed geographically, so this process depends on the redistribution of energy. It also depends on how efficiently solar energy can be converted to meet the demands of humans, which is where photosynthesis becomes a limiting factor. In comparison, agricultural crops may be more efficient at converting solar radiation to a more usable form of energy, but the study demonstrates that wheat, rice, and corn crops have low efficiency rates that are similar to those of natural ecosystems. The only crop that shows a decent amount of efficiency is sugar cane.
                  The analysis conducted in this study is not meant to completely reject the idea of using crops and natural ecosystems as bio-fuel and bio-sequestration of carbon, but  is meant to illustrate that this would require a huge amount of increase in land utilization and/or altering existing crops. Investors in these types of activities and governments seeking policy implementation need to be aware of these so-called “attractive” energy efficiency solutions.
                  The paper summarizes 12 criteria of assessments of issues raised by the possibility of using bio-fuels as a future energy source and for the bio-sequestration of carbon. The first issue that needs to be examined is the potential for agricultural and forestry capacity to deliver to energy demands and emissions reduction. Another one is evaluating the co-benefits or dis-benefits of developing policies about bio-fuels such as soil productivity, job creation, economic opportunities, international balance of trade, security of energy supply and so on. There also has to be enough net energy to cultivate crops for fuels, to produce fertilizer, transform the energy into chemical energy, and for transporting the subsequent fuel.  Another issue to keep in mind is the continuously changing climate and its affect on which bio-fuels are appropriate. Other issues include timing, production location, strategic carbon & nitrogen budgeting, human capacity to convert the energy, competing use of land, costs of production, and social and political realities.
                  The conclusion of the paper does little to provide the answers to the various questions raised throughout the study, but rather implies that “we” have the knowledge to develop a system to produce bio-fuels and bio-sequestration of carbon from agricultural crops and natural ecosystems, but now we need more efficient biomass that will provide us with the tools we need to power that process.