This article could perhaps be more accurately titled "How some biofuels can warm our climate a bit less than some other biofuels", as that's the principle effect described. It's not clear that any net cooling below baseline is being described here - rather that switchgrass isn't as bad as corn. There's still a clear trend that ongoing deforestation to expand agricultural land globally is contributing to warming, and burning food crops seemingly isn't doing anything to fix this.
I'm not aware of any scientists currently advocating corn ethanol for BECCS. As far as I can see, corn ethanol was always a pork barrel politics move to nod through some politically useful agricultural subsidies under the guise of a climate change policy. As is typical of political intervention in climate, the action taken is usually about featherbedding vested interests, rather than actually doing anything. CCS is another prime example of this. A subsidy for a zombie industry, not a viable future technology. If governments wanted to actually DO something about climate, they'd put a carbon tax equal to the CDR cost on top of fossils. That's obviously not going to happen. The fossil fuels industry will die soon enough anyway, as cheap wind and solar will squeeze it out. We're already installing more generation capacity that's renewables than fossils, and the world’s cheapest electricity is AFAIK now Moroccan wind. Even in the gulf, solar is cheaper than gas fired generation. Expect a tax on renewables soon to "protect jobs" in the fossils industry. It's not unfair, you understand, just "levelling the playing field"... A PS obviously a personal view! On 20 Feb 2016 14:24, "CE News Site" <[email protected]> wrote: > DeLucia, Evan (2015): How Biofuels Can Cool Our Climate and Strengthen Our > Ecosystems. In Eos 96 (4), pp. 14–19. DOI 10.1029/2015EO041583. > > Critics of biofuels like ethanol argue they are an unsustainable use of > land. But with careful management, next-generation grass-based biofuels can > net climate savings and improve their ecosystems. > Miscanthus and switchgrass, two perennial grasses that could be used for > biofuels, grow in front of a corn crib. Credit: Evan DeLucia > > By Evan H. DeLucia <[email protected]> 22 December 2015 > > As the world seeks strategies to reduce emissions of carbon dioxide (CO2) > into the atmosphere, bioenergy is one promising substitute for fossil fuels > [*Somerville et al.*, 2010]. Currently, the United States uses the starch > component from roughly 40% of its corn harvest to produce ethanol for the > transportation sector (see the National Agricultural Statistics Service > website <http://www.nass.usda.gov/>). > Currently, the United States uses the starch component from roughly 40% of > its corn harvest to produce ethanol for the transportation sector. > Cornstarch production is technologically simple—a so-called > first-generation bioenergy technology. However, growing corn requires a lot > of fertilizer and field preparation that ultimately depend on fossil fuels, > tempering the net carbon savings. > > Because of this, researchers have focused on developing fuel production > using more advanced methods and second-generation bioenergy crops. These > methods make liquid fuel, primarily ethanol, from lignocellulose, which > composes the structural elements of plants, leaves, stalks, and stems. > Because many of these crops are perennials (they grow back year after > year), they often require less fertilizer and tillage, avoiding many of the > negatives associated with corn and other annual crops that need intensive > management. > > A challenge with second-generation energy crops, however, is that they > yield much less energy—lignocellulose produces less than one third of the > energy per unit mass compared to fossil fuels. Because of this low energy > density, the United States would need to invest a considerable amount of > land to meet a significant part of national demand, a land area almost the > size of Wisconsin to meet the Renewable Fuel Standard mandate for 32 > billion gallons of biofuel [*Hudiburg et al.,* 2015]. > Planting second-generation grass-based biofuel crops on marginal or > degraded land can reduce our carbon footprint and provide other beneficial > ecosystem services. The conversion of current land uses and management > practices to the cultivation of bioenergy crops directly affects the > climate system and is a fundamental process underlying the ecological > sustainability of bioenergy production, as well as the ability of bioenergy > crops to mitigate climate change. Where conversion of native prairie to > corn negatively affects climate by releasing CO2 and other greenhouse > gases to the atmosphere, planting second-generation grass-based biofuel > crops on marginal or degraded land can reduce our carbon footprint and > provide other beneficial ecosystem services. *Changing the Landscape > Changes Our Climate* Fig. 1. Terrestrial ecosystems affect the climate > system by influencing the exchange of greenhouse gases between the land > surface and the atmosphere (biogeochemical regulation) and by influencing > the exchange of energy (evapotranspiration and albedo) with the atmosphere > (biophysical regulation). Biogeochemical processes affect the concentration > of greenhouse gases in the atmosphere, influencing global climate on > decadal time scales or longer, whereas biophysical processes cause local > cooling or warming over days and months. Credit: Evan DeLucia > > Public discussion of climate change often focuses on the atmosphere. As > greenhouse gases (GHGs) like carbon dioxide, nitrous oxide, and methane > accumulate in the atmosphere, they warm the planet by absorbing infrared > radiation. But that’s not the whole picture: those greenhouse gases are > also constantly cycling between the atmosphere and the land (Figure 1). > Therefore, changes in land use, vegetation, and how we manage it affect > climate by altering that exchange. > > The metabolisms of plants and soil microbes help to regulate the exchange > of GHGs with the atmosphere, as these molecules or their precursors are > stored in biomass and soil. Clearing a native forest, for example, releases > large quantities of carbon stored in biomass and soil to the atmosphere > (“storage”; Figure 2). Indeed, creating and managing farmland contribute > more than 14% of the world’s GHG emissions (U.S. Environmental Protection > Agency <http://www.epa.gov/climatechange/ghgemissions/global.html>, > global greenhouse gas emissions data, 2015). > Fig. 2. (a) Biogeochemical climate services reflect the greenhouse gases > that would be released from land clearing and the change in ongoing > exchange with the atmosphere. (b) Similarly, land clearing affects > biophysical climate services, albedo, related to net radiation (Rnet), > and latent heat flux from evaporation (LE), related to changes in > evapotranspiration. Positive values represent a net cooling effect on the > atmosphere. (c) The sum of greenhouse gases and biophysical factors is the > climate regulating value (CRV) of an ecosystem. Values are normalized to > the warming potential of carbon dioxide (CO2) and are expressed relative > to bare ground over a 50-year time frame. Replacing an ecosystem with a > high CRV with that having a low value would have a net warming effect on > the atmosphere and vice versa. Reproduced from *Anderson-Teixiera et al.* > [2012]. Terrestrial ecosystems also affect climate on local scales by > regulating the exchange of energy between the land and atmosphere (Figure > 1) [*Davin et al.*, 2014; *Zhao and Jackson*, 2014]. Land covered with > vegetation generally absorbs more sunlight than bare soil, contributing to > local warming. Working against this, when water evaporates and passes into > the atmosphere from soil and vegetation (known collectively as > evapotranspiration), it carries heat away from the land, causing local > cooling. Thus, forest clearing would reduce the cooling effect of > evapotranspiration but would increase the reflectivity of the surface (or > its albedo), allowing it to reflect more radiation. > > However, global effects are complicated because evapotranspiration means > more moisture in the atmosphere, which can increase cloud cover, affecting > the global radiation balance. Also, when the moisture condenses into clouds > elsewhere, it releases its latent heat, which can cancel the local cooling > effect [*Pielke et al.*, 2002; *Snyder et al.*, 2004]. Unlike GHGs that > have a locally weak but globally strong effect on the atmosphere, albedo > and evapotranspiration affect climate locally [*Bright*, 2015]. > > By normalizing the warming (or cooling) potential of nitrous oxide (N2O), > methane, albedo, and evapotranspiration to the warming potential of CO2, > the contribution of different ecosystems to climate regulation can be > expressed as a single metric: the climate regulating value (CRV) > [*Anderson-Teixeira > et al., *2012]; this value provides an integrated index of the direct > effects of land clearing on the surface energy budget, where the greater > the CRV is, the greater the cooling effect is (Figure 2). > *Long-Term Strategic Planting* > > In native forests and other ecosystems with large carbon stocks, > biogeochemical processes—those processes that store and exchange GHGs with > the atmosphere—can play a larger role in regulating the climate than > biophysical processes such as changes in evapotranspiration and albedo > (Figure 2). The opposite can be true for perennial grasses that don’t store > much biomass but have high evapotranspiration and albedo. > > Therefore, displacing native forests, particularly tropical forests, with > annual or perennial crops for energy production will, in most cases, have a > net warming effect on the atmosphere, releasing large quantities of carbon > stored in biomass and soil (Figure 2). But replacing annual crops or > placing high-yield bioenergy crops on marginal land (that is, land that > cannot produce high-value crops) has a very different effect. > Replacing annual crops with perennial grasses would pull carbon out of the > atmosphere and return it to the ground. Replacing annual crops with > perennial grasses such as miscanthus > <https://en.wikipedia.org/wiki/Miscanthus> and switchgrass > <https://en.wikipedia.org/wiki/Panicum_virgatum> would pull carbon out of > the atmosphere and return it to the ground (Figure 2). These crops allocate > a large fraction of their biomass below ground in their root systems, and > they can rapidly build up carbon stores in soil, reversing losses > associated with frequent tillage, particularly on degraded or heavily > tilled soils [*Anderson-Teixeira et al.*, 2009, 2013; *Powlson et al.*, > 2011]. > > In terms of climate effects, this is doubly helpful. In addition to > displacing fossil fuels by providing a renewable biofuel, replacing low-CRV > annual crops with high-CRV perennial grasses would have a net cooling > effect on the atmosphere because of the changes in biogeochemical and > biophysical properties. In particular, the increased albedo from perennial > grass and the heat carried away by evapotranspiration can amount to a > considerable cooling effect compared to annual row crops [*Georgescu et > al.*, 2011]. > *The U.S. Midwest: From Carbon Source to Sink* > > Of the approximately 40 million hectares in the United States that are > planted with corn, mostly in the Midwest, only 8% of them directly feeds > humans; most of the rest (73%) is for feeding livestock and producing > ethanol (National Agricultural Statistics Service website, 2015). > Displacing corn currently grown for ethanol with high-yielding perennial > grasses would have enormous environmental benefits, without displacing land > used for food production. *Davis et al.* [2012] predict that replacing > ethanol-bound corn with perennial grasses would reduce emissions of GHGs to > the atmosphere while increasing soil carbon. The emissions of N2O in > particular would be reduced because perennial grasses require so much less > nitrogen than corn [*Smith et al.,* 2013]. Over the entire region, this > transition would convert soils in the Midwest from a net source to a net > sink for GHGs while simultaneously increasing fuel production and reducing > the contamination of groundwater by fertilizer-derived nitrate. > > Prime corn land is expensive. Restricting most bioenergy grasses to more > affordable marginal land would also drive a reduction in U.S. GHG > emissions, albeit a smaller one than replacing corn ethanol, and would > still meet the Renewal Fuel Standard’s mandate for 32 billion gallons of > renewable biofuel, with negligible effects on food crop production [*Hudiburg > et al*., 2015]. > > The biophysical processes will also help to regulate climate. > Evapotranspiration would increase slightly—less than 10% [*VanLoocke et > al.*, 2010]—but combined with an increased albedo, that’s enough to > provide an additional local cooling effect. > *The Promise and Challenges of a Bioenergy Landscape* > > In addition to displacing CO2 emitted from fossil fuels, the expansion of > perennial bioenergy crops in the U.S. Midwest will likely have positive > effects on the climate system. This, however, is not necessarily the case > elsewhere. In much of the United States west of the 100th meridian (a line > that roughly bisects the Dakotas and Texas), the ability of the atmosphere > to remove water (potential evapotranspiration) exceeds precipitation. > There, the irrigation necessary for energy crops would pose severe > environmental challenges. > > In Southeast Asia, displacing native forest with palm oil plantations, in > part for biodiesel, has increased the amount of atmospheric GHGs and hurt > biodiversity [*Danielsen et al.*, 2009]. Furthermore, by increasing grain > prices, displacing food crops with bioenergy crops may encourage > deforestation in the tropics for expanding agriculture [*Searchinger et > al.*, 2008]. > We must take care to avoid the unintended negative consequences of > expanding lignocellulosic bioenergy production. We must take care to avoid > these unintended negative consequences of expanding lignocellulosic > bioenergy production. But with appropriate financial incentives [*Dwivedi > et al.*, 2015], there are many strategies to use land sustainably to > contribute to the U.S. demand for transportation fuel: the use of marginal > or underproductive lands [*Gelfand et al.*, 2013] or replacing > intensively managed corn for ethanol with high-yielding, low-input > perennials. When annual crops that require intensive management are > replaced with high-yielding perennial plants, bioenergy crops can > simultaneously reduce the emission of GHGs to the atmosphere and improve > the health of agricultural landscapes [*Werling et al.,* 2014]. > ------------------------------ > References > > Anderson-Teixeira, K. J., S. C. Davis, M. D. Masters, and E. H. DeLucia > (2009), Changes in soil organic carbon under biofuel crops, *Global > Change Biol. Bioenergy*, *1*, 75–96. > > Anderson-Teixeira, K. J., P. K. Snyder, T. E. Twine, C. V. Cuadra, M. H. > Costa, and E. H. DeLucia (2012), Climate-regulation services of natural and > agricultural ecoregions of the Americas, *Nat. Clim. Change*, *2*, > 177–181, doi:10.1038/NCLIMATE1346. > > Anderson-Teixeira, K. J., M. M. Masters, C. J. Black, M. Zeri, M. Z. > Hussain, C. J. Bernacchi, and E. H. DeLucia (2013), Altered belowground > carbon cycling following land-use change to perennial bioenergy crops, > *Ecosystems,* *16*, 508–520. > > Bright, R. M. (2015), Metrics for biogeophysical climate forcings from > land use and land cover changes and their inclusion in life cycle > assessment: A critical review, *Environ. Sci. Technol.*, *49*, 3291–3303. > > Danielsen, F., H. Beukema, N. D. Burgess, F. Parish, C. A. Brühl, P. F. > Donald, D. Murdiyarso, B. Phalan, L. Reijinders, M. Struebig, and E. B. > Fitzherbert (2009), Biofuel plantations on forested lands: Double jeopardy > for biodiversity and climate, *Conserv. Biol.*, *23*, 348–358. > > Davin, E. L., S. I. Seneviratne, P. Ciais, A. Olioso, and T. Wang (2014), > Preferential cooling of hot extremes from cropland albedo management, *Proc. > Natl. Acad. Sci. U. S. A.*, *111*, 9757–9761. > > Davis, S. C., W. J. Parton, S. J. Del Grosso, C. Keogh, E. Marx, and E. H. > DeLucia (2012), Impact of second-generation biofuel agriculture on > greenhouse-gas emissions in the corn-growing regions of the US, *Front. > Ecol. Environ*., *10*, 69–74. > > Dwivedi, P., et al. (2015), Cost of abating greenhouse gas emissions with > cellulosic ethanol, *Environ. Sci. Technol.*, *49*, 2512–2522. > > Gelfand, I., R. Sahajpal, X. Zhang, R. C. Izaurralde, K. L. Gross, and G. > P. Robertson (2013), Sustainable bioenergy production from marginal lands > in the US Midwest, *Nature*, *493*, 514–520. > > Georgescu, M., D. B. Lobell, and C. B. Field (2011), Direct climate > effects of perennial bioenergy crops in the United States, *Proc. Natl. > Acad. Sci. U. S. A.*, *108*, 4307–4312. > > Hudiburg, T. W., W. W. Wang, M. Khanna, S. P. Long, P. Dwivedi, W. J. > Parton, M. Hartmann, and E. H. DeLucia (2015), Impacts of a > 32-billion-gallon bioenergy landscape on land and fossil fuel use in the > US, *Nat. Energy*, in press. > > Jobbágy, E. G., and R. B. Jackson (2000), The vertical distribution of > soil organic carbon and its relation to climate and vegetation, *Ecol. > Appl.*, *10*, 423–436. > > Pielke, R. A., et al. (2002), The influence of land-use change and > landscape dynamics on the climate system: Relevance to climate-change > policy beyond the radiative effect of greenhouse gases, in *Capturing > Carbon and Conserving Biodiversity: A Market Approach*, edited by I. R. > Swingland, pp. 157–172, Earthscan Publ., London. > > Powlson, D. S., A. P. Whitmore, and W. W. T. Goulding (2011), Soil carbon > sequestration to mitigate climate change: A critical re-examination to > identify true and false, *Eur. J. Soil Sci.*, *62*, 42–55. > > Searchinger, T., R. Helmlich, R. A. Houghton, F. Dong, A. Elobeld, J. > Fabiosa, S. Tokgoz, D. Hayes, and T.-H. Yu (2008), The use of U.S. > croplands for biofuels increases greenhouse gases through emissions from > land-use change, *Science*, *319*, 1238–1240. > > Smith, C. M., et al. (2013), Reduced nitrogen losses after conversion of > row crop agriculture to perennial bioenergy crops, *J. Environ. Qual.*, > *42*, 219–228. > > Snyder, P. K., C. Delire, and J. A. Foley (2004), Evaluating the influence > of different vegetation biomes on the global climate, *Clim. Dyn.*, *23*, > 279–302. > > Somerville, C., H. Youngs, C. Taylor, S. C. Davis, and S. P. Long (2010), > Feedstocks for lignocellulosic biofuels, *Science*, *329*, 790–792. > > VanLoocke, A., C. J. Bernacchi, and T. E. Twine (2010), The impacts of > *Miscanthus > x giganteus* production on the Midwestern US hydrologic cycle, *Global > Change Biol. Bioenergy*, *2*, 180–191. > > Werling, B. P., et al. (2014), Perennial grasslands enhance biodiversity > and multiple ecosystem services in bioenergy landscapes, *Proc. Natl. > Acad. Sci. U. S. A.*, *111*, 1652–1657. > > Zhao, K., and R. B. Jackson (2014), Biophysical forcings of land-use > change from potential forestry activities in North America, *Ecol. > Monogr.*, *84*, 329–353. > *Author Information* > > Evan H. DeLucia, Department of Plant Biology, Institute for > Sustainability, Energy, and Environment, Energy Biosciences Institute and > Carl R. Woese Institute for Genomic Biology, University of Illinois at > Urbana–Champaign; email: [email protected] > > *Citation:* DeLucia, E. H. (2015), How biofuels can cool our climate and > strengthen our ecosystems, *Eos, 96,* doi:10.1029/2015EO041583. Published > on 22 December 2015. > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
