To move away from depleting fossil fuel energy, the world seeks to upscale the use of renewable sources of energy. This goal is enshrined in Sustainable Development Goal 7 to substantially increase the deployment of renewable energy in the global energy mix by 2030. In response to this, the EU has set ambitious targets for the deployment of renewable energy in the recently updated Renewable Energy Directive. The EU has committed to derive 32% of its primary energy consumption and 14% of its road and rail transport from renewable energy sources by 2030. While renewable energy is generated from a number of technologies in the EU, such as hydropower, wind power and solar, most (61%, see Fig. 1) renewable energy in the EU comes from biomass.
The term biofuels can refer to liquids and gases only or also include solids. Sometimes the physical state of biofuels is made explicit, i.e. “liquid biofuel” or liquid and gaseous biofuels can also be referred according to their function, i.e. “transport biofuel”. The transport biofuel refers only to liquid and gaseous biofuels, but not all liquid and gaseous biofuels are “transport biofuels”. For example, syngas and pyrolysis oil are only intermediate fuels that can be used in power stations and need upgrading to become usable in transport vehicles.
Fig 1. Showing the shares of primary production of energy from renewable energy sources based on Mtoe in 2017. Source: Eurostat (nrg_bal_c)
For road and rail transport, biofuels are seen as the primary renewable energy source by which the EU can achieve its targets. First-generation biofuels, such as biodiesel or bioethanol based on oil and starch crops have been the most commonly deployed biofuels so far. In 2017, the EU produced 2.42 Mtoe of bioethanol, 12.23 Mtoe biodiesel and 0.44 Mtoe of other biofuels. However, the use of first-generation biofuels is controversial: they compete with food production; the energy performance is questioned; and its expansion is limited by biophysical constraints (i.e. the availability of land, water, solar radiation and soil) and economic constraints (e.g. capital and labour). Hence, the increasing demand for biomass for fuel may trigger competition for the biomass, increase pressure on natural and economic resources, and entails consequences for land use and land-use change. In response to such concerns, the transport target envisions to achieve 7% of its target through the use of so-called ‘advanced biofuels’. These biofuels are made from wastes and residues rather than crops and are seen to ease the pressure on land.
Despite this, the transport sector has found it challenging to increase its use of renewable energy. In 2016, only 3.8% of the energy consumed in the transport sector came from renewable energy sources. Furthermore, questions remain surrounding the impacts of biofuels on natural and economic resources and the availability and potential of wastes and residues to meet the transport targets.
To answer these questions, we look at the potential of first-generation biofuels such as bioethanol and biodiesel from starch and oil crops and advanced biofuels from crop residues and animal manure. We take examples from the Netherlands and the EU as case studies.
What is the potential of biomass to meet EU renewable energy transport targets?
What is the potential of first-generation biofuels?
First-generation biofuels are biofuels that are made from dedicated crops. Typically, these are biodiesel (which can be made from rapeseed, soya and palm) and bioethanol (which can be made from maize, wheat, sugar cane and sugar beet). For our case study, we looked at the case of the Netherlands, which has one of the highest levels of production of biofuels per capita (Fig 1). We assessed the impacts in terms of water, energy, land, labour and greenhouse gas emissions to support this large production per capita.
Figure 2. Local production of biodiesel and biogasoline per capita in road transport (MJ/per capita) in several EU countries in 2016. Data source: Eurostat [nrg_110a]
We find that if the Netherlands had to produce 10% of its end-use gasoline and replace it with bioethanol from wheat, it would require 80% of the arable land in the Netherlands. This indicates that 1st generation biofuels cannot be the primary mechanism by which transport fuel is replaced.
What is the potential of bioethanol?
Bioethanol is an advanced biofuel that can be made from conventional crops such as wheat and maize as well as from the residues of these crops, such as wheat straw and maize stover. Our case study for bioethanol was calculated at EU level. Currently, most advanced biofuel plants remain in the research or demo stages rather than at the commercial stage.
For bioethanol, we calculated two kinds of crop residues: wheat straw and maize stover. The total amount of crop residues available for the use of bioethanol is 65.3 million tonnes (dry) for 2017. Using these residues would result in a gross amount of 470 PJ bioethanol. This would replace 3.44% of the EU’s final energy consumption in the transport sector for 2017. This is still far away from the 7% target of advanced biofuels by 2030, especially considering that our case study is the theoretical potential. In reality, it will be difficult and expensive to gather all the wheat straw and maize stover in Europe and take it to nearby biorefineries. Currently (2017), Europe only produces 1.3% of this theoretical potential!
What is the potential of biomethane?
Biomethane is also an advanced biofuel. It is an upgraded form of biogas that can be injected directly into a gas grid or compressed and liquefied and used in vehicles. Biomethane can be made from the digestion of many types of biomass, one of which is manure. Our case study for biomethane was calculated for the Netherlands due to its intensive livestock sector and widespread availability of manure. We calculated the amount of biomethane that would be available if all cattle and pig manure was turned into biomethane. The potential is 37.2 PJ of biomethane, which is 8.75% of road and rail transport in the Netherlands. However, this is the theoretical potential and in reality, manure will be difficult to collect while some manure must remain on the soil to maintain soil fertility. Furthermore, many biogas digestors require still subsidies to build and maintain. Currently, no biomethane from the digestion of manure is being used in the Netherlands. Biomethane from other forms of wastes such as municipal organic wastes and sewage sludge accounted for 0.1% of all transport energy in 2017.
More results will be made available, particularly in relation to the impacts on water, energy, land, labour and carbon.
So why biofuels?
Given the above, one may ask, why do biofuels still feature as an important part of the decarbonisation of transport in EU policy? To answer this question, we dig further into how the innovation process itself is handled through a variety of means.
First, we review the scientific literature on biofuels and find that while scientific experts often agree that there are biophysical and economic trade-offs across the nexus for biofuels, there was disagreement about the solutions. Scientific experts recommended different solutions to the nexus issue of biofuels, such as planting on marginal lands and using advanced feedstocks. We also asked scientific experts to assess the coherence of policies that govern biomass in the EU and find that EU policies surrounding biofuels can struggle with balancing multiple goals, such as waste management and energy generation. Often, waste biomass is directed towards energy purposes to avoid issues of food-fuel competition and indirect land-use change. However, this often went against the waste hierarchy, which argues it is more resource-efficient to use waste biomass for material purposes before energy.
Several stakeholder engagements confirm that there is disagreement as to which problem are biofuels meant to solve. For example, in our recent, engagement with energy policy and modelling experts (see the link to EMP-E engagement below), many felt that biofuels could not work as a primary source of energy in transport. Biofuels represent only part of the puzzle for the decarbonisation of transport and therefore more wide-scale solutions will have to be pursued; finding other sources of energy as much as reducing consumption in the transport sector. Engagements with scientific, policy and energy experts often meant that more questions remained to be asked, such as:
• First-generation biofuels can come with big impacts on water, energy, land and labour. Should this be the basis of decarbonisation for the transport sector?
• Are crop residues or manure really free? Can crop residues and manure be considered a waste or a co-product of the agricultural system? In a circular bioeconomy, should crop residues and manure be valued differently?
• Crop residues and manure can be expensive and bulky to transport. Will this mean biorefineries within short distances? Should subsidies mitigate production costs of bioenergy? Or should consumers assume the cost?
• The sustainability of residues depends on site-specific criteria, such as climate and field management. How can we determine the sustainable use of residues?
From calculating absolute theoretical potentials, we can already see that it will be difficult to meet our renewable energy targets. Are biofuels a solution or will another renewable energy source be needed for transport?
- Video: Are biofuels a solution to climate change?
- Scientific article: The battle for biomass: A systematic review of food-feed-fuel competition
- Nexus Times article: Meeting EU biofuel targets: the devil is in the detail
- Nexus Times article: Can Europe utilize bioenergy without compromising sustainability?
- Nexus Times article: Why it is so difficult to measure biofuel emissions
- Nexus times article: Biofuels at a crossroads: the concerns are stacking up
- EMP-E 2019 focus group: WEF Nexus in Energy Models - The Case of Biofuel