Land, in common with many other resources, is in limited supply to
meet an array of human and environmental needs. The constraint
will only tighten with growing global population. Re-envisioning the
picture of technology in the landscape reveals ways to make more
Biomass produced on non-traditional land shifts demand
from agricultural land for other products, creating a net increase in
available land without compromising other use. More flexibility in
processing technology facilitates adaptation and robustness against
larger climatic and market variations. Innovation in bioenergy production technologies makes these possible and can mitigate strain on land and other resources.
Discussions of land use for bioenergy focus naturally on the feedstock production part of the picture. But, the technologies transforming biomass into fuels intersect with land everywhere along the supply chain. Those connections provide several strategies to minimize land use.
Do a better job
The low-hanging fruit: simply increasing the amount of product from each acre, by decreasing process losses and increasing efficiencies in various process stages. Assessments of first generation biofuels processes suggest that there is room for up to a six-fold improvement in process efficiency. Land needed for a liter of sugarcane ethanol dropped by a factor of three over 30 years, building on improvements in crop productivity and process yields. Ongoing improvements in boiler technologies in cane ethanol facilities are further increasing the energy yield per unit land. Adding emerging cellulosic fuel technologies could nearly double that.
Create a less demanding alternative
Many resources are drawn from land, some grown, some extracted. Another route to reduced land intensity is to create a product or co-product to replace something that uses more land, or uses it inefficiently.
Tracking the flow of nutrients through the cycle illustrates several options feeding into the biofuels supply chain at different points:
-- Downstream, one co-product from some feedstocks is a protein-rich animal feed, such as distillers grains from corn or wheat ethanol that can release from 40-120 percent of the land used to produce an equivalent mass of grain to feed livestock. Replacing components within the production cycle is also possible.
-- Mid-stream, the nutrient loop can be closed by recycling nutrients to support the growth of the fermenting or enzyme production organisms.
-- Alternatively, those nutrients can be used upstream if returned to the field as effluent, ash, or compost from wastewater treatment after recovery. Doing so decreases use of synthetic fertilizers produced by mining and refining, activities themselves intensive in both land andother resources and for which only limited footprint data is available to use in comparing pathways.
A low-input bioenergy crop like some of the energy grasses dodges the land (and other resource) impacts of fertilizer production. Even for lignocellulosic feedstocks with minimal protein, such as Miscanthus x giganteus or sugarcane bagasse, yeast protein from fermentation could be a feed supplement co-product, potentially providing up to eight times the crude protein of grass pasture.
From a land use perspective, the best of these, or other similarly inter-connected options, isn’t transparent. Only detailed analyses incorporating regional factors will decide. Generating the data for those comparisons is an important priority.
Find a different source
There are large land resources currently not being captured. For example, about 20 percent of cultivated lands globally is degraded. Roughly a tenth of that is chemically damaged, and another quarter of it is over-salinized. Some damaged lands, particularly those with metal poisoning, will never be usable for human or animal consumption but can grow energy crops. Cleaning the soil with a bioenergy crop that draws the contaminant into the biomass it produces, phytoremediation, is an option in other cases.
There are also “overlooked" parcels, like highway verges or riparian protection zones where the bioenergy crop might be used to capture agricultural chemical runoff. These land resources become viable with flexible technologies. The processes need to be robust against greater variation in biomass carbohydrate composition or the additional compounds taken up by the plant, or be able to use highly variable feedstocks mixed from smaller collection lots.
Microbes with a higher tolerance to salts, catalysts that are less sensitive to impurities, better gas-cleanup technologies, homogenizing pretreatments, fermenting organisms that can utilize all of the sugars simultaneously... there are many opportunities for development already being pursued.
Make it multitask
Sustainable landscapes support many services for people and the environment with a dynamic balance of functions whose connections allow additional benefits. Moving beyond historical boundaries with this in mind introduces synergies, such as integrating two key services—food and energy production—to increase effective land productivity.
In some areas of India, for example, a third of the harvest can be lost to spoilage in the heat. For each acre of land, 1/3 of an acre is lost, wasted (along with all of the inputs used for that acre). Converting a portion of that 1/3 to biofuel to drive a generator for cooling would save the rest of that 1/3, essentially equivalent to adding the land needed to compensate for losses, but without actually adding land. This isn’t technically challenging; the systems just need to be deployed—an innovation in perspective, perhaps, that recognizes both that sectors can be connected and that the best implementation will be strongly location-dependent.
Innovation in bioenergy and biofuels in these ways can create win-win implementations that decrease strain on valuable resources. How such options play out for land, water, nutrient, labor, and other resource use isn’t necessarily obvious. Some, such as improving process efficiency, are unambiguous improvements; others need detailed evaluation. This is not a trivial task, and additional research is critical.
The comparisons require gathering more data and tuning methodologies for assessing the impacts of multiple-product systems that span sectors. The best option—the one with the most benefits—will differ by region and resource. In some cases, the least intensive option won’t be the most economical and may need support, and some of the most high-tech highest-benefit options aren’t feasible in areas lacking necessary infrastructure. It’s not a one-size-fits-all, but a best-size-fits-each calculation.