Biomass energy and the implications for climate and food

Abstract

Many experts have concluded that, if greenhouse gas concentrations are to be limited while the world’s energy demands are nonetheless met, biomass energy will be an indispensable resource. At the same time, climate change is expected to affect agricultural productivity adversely—and 15 percent of people in developing countries, according to the UN’s Food and Agriculture Organization, already suffer from extreme food insecurity. Authors from three countries—José R. Moreira of Brazil (2014), Roberto Bissio of Uruguay (2014), and Ethan B. Davis and Tom L. Richard of the United States—explore how the potential climate mitigation benefits of devoting arable land to the production of biomass energy can be achieved without further undermining food security in the developing world.

Reconciling the need for enhanced food security with the need for low-carbon energy is among the most pressing challenges facing the world today. Growing populations and high global consumption patterns are increasing demand for both food and energy, placing additional pressures on agricultural and natural resources that are already stressed. This food-versus-energy dilemma ultimately plays out at the intersection of land productivity and land scarcity. Keeping pace with anticipated demand for food and energy may be possible through productivity gains on existing arable land—but to address continuing yield shortfalls, especially in the developing world, more effective management practices and better deployment of agricultural inputs will be needed (Tilman et al., 2011).

At a time when climate change is already limiting crop yields (Funk and Brown, 2009), it is not clear that substantial increases in production of biomass energy are possible without expansion of land area dedicated to agriculture. But converting forests and grasslands to agriculture, whether for food or energy, could increase greenhouse gas emissions, forgo future carbon sequestration, and drain precious reservoirs of biodiversity. Current food and energy choices are already driving climate change, land degradation, habitat destruction, and eutrophication (Food and Agriculture Organization, 2006; Intergovernmental Panel on Climate Change, 2012). Against this backdrop, resolving food insecurity and energy insecurity hinges on sustainably intensifying agricultural production on existing managed lands, on reducing waste, and on dietary choices.

Food and energy crops are often portrayed as competing for land, but this portrayal is not always accurate. While wholesale substitution of energy crops for food crops can cause higher food prices, exacerbate food insecurity, and drive indirect land use changes, the strategic integration of energy crops and food crops can create synergies that increase overall yields while generating multiple ecosystem benefits. For example, perennial grasses retain nutrients and increase organic matter in soil while also improving water quality and sequestering carbon; intercropping perennial grasses with annual crops and establishing riparian buffers are two ways of incorporating energy grasses into agricultural landscapes without significantly decreasing food crop yields. Double cropping—growing food during summer and crops for energy during winter—can produce significant amounts of bioenergy while food production is maintained. Double cropping also decreases erosion and nutrient loss.

There are other ways in which feedstock for bioenergy can be produced without contributing to food insecurity. Degraded or marginal lands unfit for food production could be used for perennial biomass crops, potentially meeting 10 to 50 percent of the world’s demand for liquid fuel (depending on assumptions related to land availability and yields). Other noncompetitive resources include wood and crop residues. Less than one-quarter of available residues could supply 5 to 15 percent of current demand for transportation fuel.

These sustainable synergies in production systems for food and bioenergy have tremendous potential, but they are not a panacea for the world’s food and energy problems. Within the constraints of the current system, bioenergy probably cannot satisfy very large-scale energy demand (say, 25 percent of primary energy supply) without either forcing agriculture’s footprint to expand or creating conflicts with food security goals. Instead, to free up land for bioenergy, systemic changes are necessary in the food sector—changes that would transform supply, demand, and utilization efficiency.

On the supply side, pastureland represents the biggest opportunity for restructuring food production to free up land for energy crops. Globally, pastureland covers roughly twice as much area as cropland—but supplies only about 5 percent of the world’s protein and 2 percent of its caloric intake. According to studies carried out in Africa, Central America, and Brazil, improved pasture and livestock management could increase animal yields per hectare by between 144 and 600 percent, depending on forage type, cattle breed, and previous degradation (Angelsen and Kaimowitz, 2001; Thornton and Herrero, 2010; World Bank, 2012). Even if just a fraction of this potential yield increase were realized, pasture intensification could spare significant amounts of land from use as pasture, potentially liberating this land for energy crops while also increasing food supply.

On the demand side, meat consumption has important implications for land use. Increased food consumption, particularly meat, is often seen as an inevitable corollary of higher income. And while technological innovations have resulted in higher yields over recent decades, most of the new production has been offset by dietary changes (Kastner et al., 2012). Thus dietary choice often seems more powerful than innovation and intensification.

But income and diet do not march in lockstep. From 1960 to 2010, China’s income multiplied 45 times and meat consumption increased 14 times; but in India, though incomes multiplied 15 times over the same period, the country still exhibits some of the lowest meat consumption in the world (Ausubel et al., 2013). And importantly, the types of meat that people eat vary widely from country to country. Globally, producing a kilogram of beef requires 10 to 15 times more feed and 15 times more land than chicken or pork (Wirsenius et al., 2010). Most of China’s increased meat consumption has been accounted for by pork. And in the United States, three decades of price signals coupled with health concerns about red meat have reduced beef consumption by about 40 percent, or to about one-third of total meat consumption, while chicken consumption has more than doubled. The key points are 1) that the developed world needs to reduce its current food footprint, and is already doing so for health and economic reasons, and 2) as income levels rise globally, the type of meat consumed is just as important as the total amount of meat in determining how large the developing world’s food footprint becomes.

Substantial opportunities exist to create a more efficient food system through reduction of food waste. Globally, food losses and waste are estimated to amount to one-third of production, with developed and developing countries squandering roughly the same percentage of food (though for different reasons). Reducing food losses is possible through improvements in harvest techniques, infrastructure, and logistics. Such strategies could have a significant impact on food security and land requirements per unit of food.

Identifying constraints to efficient food and bioenergy production is essential to ensuring that unsustainable paths in food and energy are not pursued. Balancing food and energy production on limited amounts of agricultural land is a matter of concern—but expansion of agricultural land is a concern as well. Expansion of land devoted to palm oil, which is used for both food and energy, is a major driver of tropical deforestation in Asia. If energy crops are not carefully integrated into agricultural systems, food prices could increase and malnutrition could be exacerbated.

Cautionary tales abound about conflicts between bioenergy and food production—and lessons must be taken from these conflicts. But it is equally important to highlight potential solutions to problems and demonstrate how to get bioenergy right. Systemic, synergistic approaches are available for sustainably integrating food and bioenergy. Many of these strategies require substantial changes to conventional food and agricultural systems; some are more easily implemented than others. But business as usual, whether for food or bioenergy, is not sustainable. Given that the world’s food and energy problems must both be resolved, even solutions that seem improbable should be explored seriously. Indeed, given the depth and recalcitrance of the world’s food and energy crises, the improbable may become necessary.