Sustainable bioenergy is fundamental to the decarbonisation of the energy system and plays an essential role in the IEA’s long-term climate scenarios, making key contributions in several sectors that are difficult to decarbonise by other means, such as aviation. In addition to cutting CO₂ emissions, the best-practice use of bioenergy also has other benefits such as job creation, rural development and enhanced waste management.

The IEA is fully aware of the debate regarding the sustainability of certain forms of bioenergy. Some concerns relate to air pollutant emissions from residential biomass heating, lifecycle emissions and land use change associated with some conventional biofuels, and deforestation.

Unsustainable bioenergy deployment has justified these concerns in some cases, which has undermined confidence in across the full bioenergy spectrum. In other cases, however, negative perceptions of bioenergy are not based on scientific grounding. In addition, these misperceptions about modern bioenergy are sometimes confused with the traditional use of biomass, which is entirely different.

This refers to the use of local solid biomass resources by low-income households that do not have access to modern cooking and heating fuels or technologies. Solid biomass, such as wood, charcoal, agricultural residues and animal dung, is converted into energy through basic techniques, such as a three-stone fire, for heating and cooking in the residential sector. Such consumption occurs principally in emerging economies and developing countries.

This use of biomass resources tends to have very low conversion efficiency (5-15%) and, as local demand can also exceed sustainable supply, can often result in negative environmental impacts. In addition, high particulate matter emissions and other air pollutants are produced. When combined with poor ventilation, such pollutants result in household indoor air pollution, which is responsible for a range of severe health conditions and is a leading cause of premature deaths. As a result, policy attention focuses on reducing the traditional use of biomass and encouraging the adoption of more sophisticated heating and cooking technologies.

Therefore, even though traditional use of biomass is a renewable source, it is outside the scope of our analysis and is excluded from our renewable energy accounting. Renewables 2018 only focuses on modern bioenergy technologies, such as the use of biomass resources for electricity generation, for industrial applications and in the production of biofuels for transport.

Because bioenergy sustainability is a complex topic, each application must be judged on its own specific circumstances, and generalisations regarding the sustainability of bioenergy feedstocks, fuels and technologies can be misleading.

For bioenergy applications to be used to greatest effect in decarbonising the electricity, heat and transport sectors, they must be employed in a best-practice manner, providing net lifecycle GHG emissions reductions while avoiding unacceptable social, environmental or economic impacts. Bioenergy is not unique in this regard, as sustainability challenges associated with scaling up deployment of fossil-based and other renewable energy technologies must also be managed.

Policy makers must ensure suitable frameworks are established to deliver sustainable bioenergy. The first step to ensuring best practices is to understand the criteria used to assess sustainability. The Global Bioenergy Partnership (GBEP), an intergovernmental initiative that brings together 50 national governments, the IEA and other international organisations, has produced a set of sustainability indicators for bioenergy organised under overarching environmental, social and economic pillars. 

The GBEP criteria are recognised among stakeholders as representing the key issues that need to be managed to ensure the best-practice employment of bioenergy applications, and they can form the basis of policies and regulations to support sustainable deployment.

There are already examples of established frameworks to ensure sustainability, such as:

• The EU sustainability criteria for biofuels and bioliquids, which demand minimum lifecycle GHG emission reduction and stipulate the types of land on which crop feedstocks for biofuel production cannot be grown. In 2016, 98.7% (by energy) of reported biofuel consumption was compliant.
• Policies that facilitate demand for biofuels with the lowest lifecycle GHG or CO₂ emissions such as California’s Low Carbon Fuel Standard, which takes into account emissions from land use change, and Brazil’s forthcoming RenovaBio program. 
• Brazil’s forest code which requires a legal reserve for natural habitat, and green protocol to eliminate in-field burning of sugarcane residues in São Paolo state.
• The Roundtable on Sustainable Biomaterials (RSB), which outlines principals and criteria on how to produce biomass, biofuels and biomaterials in an environmentally, socially and economically responsible way, as well as certification to demonstrate sustainable performance.

Robust governance is required to ensure that such policies and regulations are adhered to. When suitable monitoring and control mechanisms are in place, policy makers can establish policy support for bioenergy in the confidence that it will deliver beneficial outcomes. These mechanisms include third-party certification of biomass fuel supply chains to ensure they are sustainable, and comprehensive assessments of lifecycle CO₂ emissions for different biomass fuel production pathways.

In keeping with the bioenergy focus of Renewables 2018, the potential to scale up several bioenergy applications has been assessed -- including aviation biofuels from waste oil and animal fat feedstocks; biomass and waste in cement production; and the use of in-field sugar cane residues for co-generation in the sugar and ethanol industry. These applications highlight the potential to use untapped waste and residue biomass resources that generally offer low lifecycle GHG emissions and mitigate land use change concerns, and they can also deliver waste management and air quality benefits.