IEA report: bioenergy can meet 20 to 50% of world's future energy demand

In a new publication the International Energy Agency's Bioenergy Executive Committee highlights the potential contribution of bioenergy to future world energy demand. It summarises the wide range of biomass resources available and potentially available, the conversion options, and end-use applications. Associated issues of market development, international bioenergy trade, and competition for biomass are also presented. Finally, the potential of bioenergy is compared with other energy supply options.


In the document titled 'Potential Contribution of Bioenergy to the World’s Future Energy Demand', the analysts put the total energy potential for sustainably produced biomass at 1100 Exajoules (EJ) by 2050 under a most optimal scenario. In a more average scenario bioenergy's contribution to the world's future energy supply ranges between 20 and 50% (200 - 400 EJ), depending on different energy demand scenarios. Some 130-260 EJ of this amount would be made up of liquid biofuels, more than the world's current total mineral oil output. Over the longer term (2100), more land becomes available and the share of bioenergy increases (graph 1, click to enlarge). For this contribution to materialize, the development and deployment of perennial crops in developing countries is of key importance, as is the creation of international markets. The IEA Bioenergy Excom states that for many rural communities in developing countries such a situation would offer good opportunities for socio-economic development.

Current and future energy demand
The researchers note that global current fossil energy use totals 388 EJ. Energy demand is expected to at least double or perhaps triple during this century. At the same time, concentrations of greenhouse gases (GHGs) in the atmosphere are rising rapidly, with fossil fuel-derived CO2 emissions being the most important contributor. In order to minimise related global warming and climate change impacts, GHG emissions must be reduced to less than half the global emission levels of 1990. In addition, security of energy supply is a global issue. A large proportion of known conventional oil and gas reserves are concentrated in politically unstable regions, and increasing the diversity in energy sources is important for many nations to secure a reliable and constant supply of energy.

In this context, biomass for energy can play a pivotal role. Energy from biomass, when produced in a sustainable manner, can drastically reduce GHG emissions compared to fossil fuels. Most countries have biomass resources available, or could develop such a resource, making biomass a more evenly spread energy supply option across the globe. It is a versatile energy source, which can be used for producing power, heat, liquid and gaseous fuels, and also serves as a feedstock for materials and chemicals.

Due to rising prices for fossil fuels (especially oil, but also natural gas and to a lesser extent coal) the competitiveness of biomass use has improved considerably over time. In addition, the development of CO2 markets (emission trading), as well as ongoing learning and subsequent cost reductions for biomass and bioenergy systems, have strengthened the economic drivers for increasing biomass production, use, and trade.

The IEA Bioenergy ExCom notes that biomass and bioenergy are now a key option in energy policies. Security of supply, an alternative for mineral oil and reduced carbon emissions are key reasons. Targets and expectations for bioenergy in many national policies are ambitious, reaching 20-30% of total energy demand in various countries. Similarly, long-term energy scenarios also contain challenging targets.

Sufficient biomass resources and a well-functioning biomass market that can assure reliable, sustainable, and lasting biomass supplies are crucial preconditions to realise such ambitions. Relatively recently, international trade in biomass resources has become part of the portfolio of market dealers and volumes traded worldwide have increased at a very rapid pace with an estimated doubling of volumes in several markets over the past few years.

Global biomass potential
Various biomass resource categories can be considered: residues from forestry and agriculture, various organic waste streams and, most importantly, the possibilities for dedicated biomass production on land of different categories, e.g., grass production on pasture land, wood plantations and sugar cane on arable land, and low productivity afforestation schemes for marginal and degraded lands.

The potential for energy crops depends largely on land availability considering that worldwide a growing demand for food has to be met, combined with environmental protection, sustainable management of soils and water reserves, and a variety of other sustainability requirements. Given that a major part of the future biomass resource availability for energy and materials depends on these complex and related factors, it is not possible to present the future biomass potential in one simple figure. Table 1 (click to enlarge) provides a synthesis of analyses of the longer term potential of biomass resource availability on a global scale. Also, a number of uncertainties are highlighted that can affect biomass availability:
energy :: sustainability :: climate change :: fossil fuels :: bioenergy :: biofuels :: biomass :: energy crops :: bioconversion :: IEA ::

These estimates are sensitive to assumptions about crop yields and the amount of land that could be made available for the production of biomass for energy uses, including biofuels. Critical issues include:

• Competition for water resources: Although the estimates presented in Table 1 generally exclude irrigation for biomass production, it may be necessary in some countries where water is already scarce.
• Use of fertilisers and pest control techniques: Improved farm management and higher productivity depend on the availability of fertilisers and pest control. The environmental effects of heavy use of fertiliser and pesticides could be serious.
• Land-use: More intensive farming to produce energy crops on a large-scale may result in losses of biodiversity. Perennial crops are expected to be less harmful than conventional crops such as cereals and seeds, or even able to achieve positive effects. More intensive cattle-raising would also be necessary to free up grassland currently used for grazing.
• Competition with food and feed production: Increased biomass production for biofuels out of balance with required productivity increases in agriculture could drive up land and food prices.

Taking a more average estimate than the most optimal scenario, the researchers think future biomass production on different types of land could be broken down as follows:

Energy farming on currrent agricultural land
Energy farming on current agricultural (arable and pasture) land could, with projected technological progress, contribute 100 - 300 EJ annually, without jeopardising the world’s future food supply. A significant part of this potential (around 200 EJ in 2050) for biomass production may be developed at low production costs in the range of E2/GJ assuming this land is used for perennial crops.

Energy farming on marginal and degraded land
Another 100 EJ could be produced with lower productivity and higher costs, from biomass on marginal and degraded lands. Regenerating such lands requires more upfront investment, but competition with other land-uses is less of an issue and other benefits (such as soil restoration, improved water retention functions) may be obtained, which could partly compensate for biomass production costs.

Biomass wastes and residues
Combined and using the more average potential estimates, organic wastes and residues could possibly supply another 40-170 EJ, with uncertain contributions from forest residues and potentially a significant role for organic waste, especially when biomaterials are used on a larger scale.

In total, the bioenergy potential could amount to 400 EJ per year during this century. This is comparable to the total current fossil energy use of 388 EJ.

Key to the introduction of biomass production in the suggested orders of magnitude is the rationalisation of agriculture, especially in developing countries. There is room for considerably higher landuse efficiencies that can more than compensate for the growing demand for food.

The development and deployment of perennial crops (in particular in developing countries) is of key importance for bioenergy in the long run. Regional efforts are needed to deploy biomass production and supply systems adapted to local conditions, e.g., for specific agricultural, climatic, and socio-economic conditions.

Conversion options
Conversion routes for producing energy carriers from biomass are plentiful. Figure 1 (click to enlarge) illustrates the main conversion routes that are used or under development for production of heat, power and transport fuels. Key conversion technologies for production of power and heat are combustion and gasification of solid biomass, and digestion of organic material for production of biogas. Main technologies available or developed to produce transportation fuels are fermentation of sugar and starch crops to produce ethanol, gasification of solid biomass to produce syngas and synthetic fuels (like methanol and high quality diesel), and extraction of vegetal oils from oilseed crops, which can be esterified to produce biodiesel.

The various technological options are in different stages of deployment and development. Tables 2 and 3 (click to enlarge) provide a compact overview of the main technology categories and their performance with respect to energy efficiency and energy production costs. The ‘End-use Applications’ section discusses the likely deployment of various technologies for key markets in the short- and the long-term.

Current and projected performance data for transport biofuel production techniques

Current and projected performance data for bioenergy production techniques

Short-term represents best available technology or the currently noncommercial systems which could be built around 2010. Long-term represents technology with considerable improvement, large-scale deployment, and incorporation of process innovations that could be realised around 2040. This is also the case for the biomass supplies, assuming biomass production and supply costs around E2/GJ for plants which are close to the biomass production areas.

Market development and international trade
Biofuel and biomass trade flows are modest compared to total bioenergy production but are growing rapidly. Trade takes place between neighbouring regions or countries, but increasingly trading is occurring over long distances.

The possibilities for exporting biomass-derived commodities to the world’s energy markets can provide a stable and reliable demand for rural regions in many developing countries, thus creating an important incentive and market access that is much needed. For many rural communities in developing countries such a situation would offer good opportunities for socio-economic development. Sustainable biomass production may also contribute to the sustainable management of natural resources.

Importing countries on the other hand may be able to fulfil cost-effectively their GHG emission reduction targets and diversify their fuel mix.

Given that several regions of the world have inherent advantages for producing biomass (including lignocellulosic resources) and biofuels in terms of land availability and production costs, they may gradually develop into net exporters of biomass and biofuels.

International transport of biomass (or energy carriers from biomass) is feasible from both the energy and the cost points of view. The import of densified or pre-treated lignocellulosic biomass from various world regions may be preferred, especially for second generation biofuels, where lignocellulosic biomass is the feedstock and large-scale capital intensive conversion capacity is required to achieve sound economics. This is a situation comparable to that of current oil refineries in major ports which use oil supplies from around the globe.

Very important is the development of a sustainable, international biomass market and trade. Proper standardisation and certification procedures are to be developed and implemented to secure sustainable biomass production, preferably on the global level. Currently, this is a priority for various governments, market players, and international bodies. In particular, competition between production of food, preservation of forests and nature and use of land for biomass production should be avoided. As argued, this is possible by using lignocellulosic biomass resources that can come from residues and wastes, which are grown on non-arable (e.g., degraded) lands, and in particular by increased productivity in agricultural and livestock production.

Demonstration of such combined development where sustainable biomass production is developed in conjunction with more efficient agricultural management is a challenge. However, this is how bioenergy could contribute not only to renewable energy supplies and reducing GHG emissions, but also to rural development.

Biomass and bioenergy in the world's future energy supply
What contribution can biomass make to future global energy (and bio-products) demand? A wide diversity of projections of potential future energy demand and supply exist. Typically, scenarios are used to depict uncertainties in future developments and possible development pathways. The ‘Special Report on Emission Scenarios’ (SRES) developed in the context of the Intergovernmental Panel on Climate Change (IPCC) is based on four storylines that describe how the world could develop over time.

Differences between the scenarios concern economic, demographic, and technological development and the orientation towards economic, social, and ecological values. The storylines denoted A1 and A2 are considered societies with a strong focus towards economic development. In contrast, the B1 and B2 storylines are more focused on welfare issues and are ecologically orientated. While the A1 and B1 storylines are globally oriented, with a strong focus towards trade and global markets, the A2 and B2 storylines are more regionally oriented.

Graph 2 shows the total energy demand for secondary energy carriers (such as transport fuels, electricity, gas, etc.) in four distinct years of the four scenarios. Clearly, the various scenarios show large differences in demand and energy mix, as a result of variations in population dynamics, and economic and technological development.

Total primary (the presumed mix of fossil fuels, renewables and nuclear) energy demand in 2050 varies between about 800 EJ and 1,400 EJ. As discussed previously, the total primary biomass supplies in 2050 could amount to 200-400 EJ. This is conservative relative to the increased availability of primary biomass for the different SRES scenarios, shown in graph 1. The circled lines depict the total primary energy demand per scenario, corresponding with the projected energy consumption data in graph 2. All scenarios project a gradual development of biomass resource availability, largely corresponding to the (potentially) gradually increased availability of land over time.

Assuming conversion to transport fuels with an expected average conversion efficiency of 65%, this would result in 130-260 EJ of fuel. This is up to double the current demand and a similar range to the expected demand in the SRES scenarios discussed above.

Competing markets for biomass?
Biomass cannot realistically cover the whole world’s future energy demand. On the other hand, the versatility of biomass with the diverse portfolio of conversion options, makes it possible to meet the demand for secondary energy carriers, as well as biomaterials. Currently, production of heat and electricity still dominate biomass
use for energy.

The question is therefore what the most relevant future market for biomass may be. For avoiding CO2 emissions, replacing coal is at present a very effective way of using biomass. For example, co-firing biomass in coal-fired power stations has a higher avoided emission per unit of biomass than when displacing diesel or gasoline with ethanol or biodiesel.

However, replacing natural gas for power generation by biomass, results in levels of CO2 mitigation similar to second generation biofuels. Net avoided GHG emissions therefore depend on the reference system and the efficiency of the biomass production and utilisation chain. In the future, using biomass for transport fuels will gradually become more attractive from a CO2 mitigation perspective because of the lower GHG emissions for producing second-generation biofuels and because electricity production on average is expected to become less carbon-intensive due to increased use of wind energy, PV and other solar-based power generation, carbon capture and storage technology, nuclear energy, and fuel shift from coal to natural gas.

In the shorter term, however, careful strategies and policies are needed to avoid brisk allocation of biomass resources away from efficient and effective utilisation in power and heat production or in other markets, e.g., food. How this is to be done optimally will differ from country to country.

The use of biomass for biomaterials will increase, both in well established markets (such as paper, construction) and for possibly large new markets (such as bio-chemicals and plastics) as well as in the use of charcoal for steel making. This adds to the competition for biomass resources, in particular forest biomass, as well as land for producing woody biomass and other crops. The additional demand for bio-materials could surpass the current global biomass use (which is some 10% of the global energy use).

However, increased use of bio-materials does not prohibit the production of biofuels (and electricity and heat) per se. Construction wood ends up as waste wood, paper (after recycling) as waste paper, and bio-plastics in municipal solid waste. Such waste streams still qualify as biomass feedstock and are available, often at low or even negative costs.

Cascading biomass over time in fact provides an essential strategy to optimise the CO2 mitigation effect of biomass resources. The IPCC (2007) reports that the largest sustained mitigation benefit will result from a sustainable forest management strategy aimed at maintaining or increasing forest carbon stocks, while producing an annual sustained yield of timber, fibre, or energy from the forest. This could for example involve conventional forests producing material cascades (e.g., solid wood products, reconstituted particle/fibre products, paper products) with wood or fibre that cannot be reused/recycled being used for energy.

Comparison with other energy supply options
State-of-the-art scenario studies on energy supply and mitigation of climate change agree that all climate-friendly energy options are needed to meet the future world’s energy needs and simultaneously drastically reduce GHG emissions.

Intermittent sources such as wind and solar energy have good potential, but their deployment is also constrained by their integration into electricity grids. In addition, electricity production from solar energy is still expensive.

Hydropower has a limited potential and commercial deployment of geothermal and ocean energy, despite their large theoretical potentials, has proved to be complex.

Biomass in particular can play a major and vital role in production of carbon-neutral transport fuels of high quality as well as providing feedstocks for various industries (including chemical). This is a unique property of biomass compared to other renewables and which makes biomass a prime alternative to the use of mineral oil.

Given that oil is the most constrained of the fossil fuel supplies, this implies that biomass is particularly important for improving security of energy supply on the global as well on a national level.

In addition, competitive performance is already achieved in many situations using commercial technologies especially for producing heat and power. It is therefore expected that biomass will remain the most important renewable energy carrier for many decades to come. Conversion to power with an assumed average efficiency of 50% logically results in 100-200 EJe, also a similar range to the expected future demand.

Additional future demand for (new) biomaterials such as bio-plastics could add up to 50 EJ halfway through this century.

It is clear, therefore, that biomass can make a very large contribution to the world’s future energy supply. This contribution could range from 20% to 50%. The higher value is possible when growth in energy demand is limited; for example, by strongly increased energy efficiency.

Opportunities for bioenergy
Biomass is a versatile energy source that can be used for production of heat, power, and transport fuels, as well as biomaterials and, when produced and used on a sustainable basis, can make a large contribution to reducing GHG emissions.

Biomass is the most important renewable energy option at present and is expected to maintain that position during the first half of this century and likely beyond that. Currently, combined heat and power (CHP), co-firing and various combustion concepts provide reliable, efficient, and clean conversion routes for converting solid biomass to power and heat.

Production and use of biofuels are growing at a very rapid pace. Although the future role of bioenergy will depend on its competitiveness with fossil fuels and on agricultural policies worldwide, it seems realistic to expect that the current contribution of bioenergy of 40-55 EJ per year will increase considerably.

A range from 200 to 400 EJ may be expected during this century, making biomass a more important energy supply option than mineral oil today – large enough to supply one-third of the world’s total energy needs.

Bioenergy markets provide major business opportunities, environmental benefits, and rural development on a global scale. If indeed the global bioenergy market is to develop to a size of 300 EJ over this century (which is quite possible given the findings of recent global potential assessments) the value of that market at E4-8/GJ (considering pre-treated biomass such as pellets up to liquid fuels such as ethanol or synfuels) amounts to some E1.2-2.4 trillion per year.

Feedstocks can be provided from residues from agriculture, forestry, and the wood industry, from biomass produced from degraded and marginal lands, and from biomass produced on good quality agricultural and pasture lands without jeopardising the world’s food and feed supply, forests, and biodiversity.

The pre-condition to achieve such a situation is that agricultural land-use efficiency is increased, especially in developing regions.

Considering that about one-third of the above-mentioned 300 EJ could be supplied from residues and wastes, one-quarter by regeneration of degraded and marginal lands, and the remainder from current agricultural and pasture lands, almost 1,000 million hectares worldwide may be involved in biomass production, including some 400 million hectares of arable and pasture land and a larger area of marginal/degraded land. This is some 7% of the global land surface and less than 20% of the land currently in use for agricultural production.

There are rapid developments in biofuel markets: increasing production capacity, increasing international trade flows, increased competition with conventional agriculture, increased competition with forest industries, and strong international debate about the sustainability of biofuels production.

Biomass is developing into a globalised energy source with advantages (opportunities for producers and exporters, more stability in the market) and concerns (competing land use options, sustainability).

Biomass trading and the potential revenues from biomass and biomass-derived products could provide a key lever for rural development and enhanced agricultural production methods, given the market size for biomass and biofuels. However, safeguards (for example, well-established certification schemes) need to be installed internationally to secure sustainable production of biomass and biofuels. In the period before 2020 substantial experience should be obtained with sustainable biomass production under different conditions as well as with deploying effective and credible certification procedures.

Especially promising are the production of electricity via advanced conversion concepts (i.e., gasification, combustion, and co-firing) and biomass-derived fuels such as methanol, hydrogen, and ethanol from lignocellulosic biomass. Ethanol produced from sugar cane is already a competitive biofuel in tropical regions and further improvements are possible.

Both hydrolysis-based ethanol production and production of synfuels via advanced gasification from biomass of around E2/GJ can deliver high quality fuels at a competitive price with oil down to US$45/ barrel.

Net energy yields per unit of land surface are high and GHG emission reductions of around 90% can be achieved, compared with fossil fuel systems. Flexible energy systems, in which biomass and fossil fuels can be used in combination, could be the backbone for a low risk, low-cost, and low carbon emission energy supply system for large-scale supply of fuels and power, providing a framework for the evolution of large-scale biomass raw material supply systems.

References:
IEA Bioenergy Executive Committee: Potential Contribution of Bioenergy to the World's Future Energy Demand - September 2007.