aireg - biofuels

8/10/2019 Aireg - Biofuels

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Feedstocks

German aviation is committed to reaching a ten percent share of biofuels domestically by 2025, which will require 1.1 million tonnes of sustainable fuel

per year. The required amount of energy derived from alternative sources is set at 190 petajoules (PJ). The feedstock requirements increase accordingly

in proportion with this figure. However, it is still difficult to estimate the global biomass potential reliably as research is still underway. In 2010, the

German Federal Ministry of Transport, Building and Urban Affairs (BMVBS) delivered one of the first major contributions. It produced a comprehensive

study, reporting on the global and regional biomass potentials in the categories of energy crops, forest biomass and residual materials.


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What's clear is that we will not be able to rely on one single feedstock in the future. Much more must be done to ensure all feedstock options are

examined and every possibility considered and utilised.

Energy crops

Energy crops are renewable feedstocks that yield biomass to generate power and heat and to produce fuels. These include grain, silage maize, rape

and oil palm. There are also crops such as camelina and jatropha, which are not used for food production. The study from the German Federal Ministry

forecasts that Russia, Brazil, the United States and Indonesia will likely be key countries for biomass production.

Forestry biomass

Forests cover 3.95 billion hectares, or roughly 30 per cent of world-wide land area. According to the study by BMVBS, forest area can be expected to

decrease by up to 310 million hectares by 2020. However, the potential to obtain feedstock from forestry biomass will not be completely exhausted by

2020. Forestry biomass is a promising raw material for future biofuels

taking into account the required forest management. However, the followingchallenges must first be addressed:

Statistical basis: The available data on production and consumption of woody biomass is in many cases based solely on estimates or projections thatare not yet accurate enough. A reliable set of data must be created in order to be able to make long-term forecasts.

Sustainability: According to the calculation, raw timber consumption would be higher than the raw timber potential in some countries. The consequenceof this would be that more wood would be imported or more raw timber would have to be used from native forests than would be available sustainably.The overuse of forest resources must be avoided in the medium to long term.

Availability: Russia, North America and Brazil have large feedstock potentials. In order to tap their full potential, several technological, ecological andeconomic challenges must be addressed, which will require an intersectoral approach.


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Residual materials

Residual materials include all biogenic by-products, residues and wastes from which energy can be extracted. The global biomass potential for residualmaterials is around 30,000 PJ per year. Straw and wood residues have the greatest potential with 13,000 PJ and 10,000 PJ per year, respectively. The

worldwide population growth points to an increase in the volume of residual materials. However, due to their low energy densi ties and in part

unfavourable substrate properties, importing residual materials as energy sources will play only a minor role. In most cases, local utilisation or

processing makes more sense from an economic and environmental standpoint.


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Algae

Algae can also be considered as a promising feedstock option for the production of biofuel. Their cells contain high amounts of chlorophyll, meaning they

are five times more efficient in converting sunlight into biomass than many other plants. The yield per hectare of up to 25 t onnes per year is significantly

greater than that of rapeseed, which produces only 1.8 tonnes. However, the production of biomass from algae is still very cost-intensive. In order to

change this, research and development must be accelerated and large-scale production facilities must be constructed. For this reason, it is not currently

possible to reliably estimate their biomass potential. Therefore it is expected that algae will initially only make a small contribution towards aireg's ten

percent goal.

Production

Only a small number of production pathways are currently available for the large-scale production of alternative aviation fuel. Therefore, the aviation

industry, fuel producers and scientists are collaborating on pioneering work to bring additional processes to market. Internat ional evaluation criteria such

as the Fuel Readiness Level (FRL) test provide the basis for a classification of technological maturity.

The production of biofuels requires not only peak performance in terms of research and development, but also an effective infrastructure. At present,

Germany does not yet have any advanced biorefineries however even today it would already be technically and ecologically feasible to built and run

biorefineries fed either on a vegetable oil or biogas. This is where politics come into play: politicians must work to support aviation by establishing the

required infrastructure as quickly as possible.


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Hydro-processed esters and fatty acids (HEFA)


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To produce biofuels on the basis of hydro-processed esters and fatty acids (HEFA), any form of native fat or oil can be used. Apart from waste fats left

over from the food industry vegetable oils and fatty acids from oil and fat refining processes are the most common forms used.

In the first stage of production, the oils and fats are hydrogenated and in the second stage, they are refined, in a very similar process as is used with

fossil fuels. The relevant production process is already fully developed and has been certified by the international standardisation organisation ASTM

since 2011. Even today, increased amounts of HEFA jet fuel are already being used for testing purposes in scheduled passenger flights. Therefore, the

production of biojet on a HEFA basis is rated at 9 on the FRL scale.

Nevertheless, the expansion of production capacity is progressing too slowly. There are currently only four large-scale biorefineries in the world that

specialise in the production of certified fuels from vegetable oil

including alternative aviation fuel.

Gas to liquid (GtL)


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Biomass of very different origin and/or composition is initially converted into a biogas using biochemical processes. Using physical processes, this gas

can be used to obtain biomethane (among others). In the subsequent gas-to-liquid process, this biomethane is converted into carbon monoxide (CO)

and hydrogen (H2). Then it is converted into hydrocarbons using what is known as Fischer-Tropsch synthesis from which it is ultimately turned into jet

fuel.

Alternative aviation fuel has not yet actually been produced via the GtL process. However, GtL technology has already been applied for years in

conventional refineries and has met the international ASTM standard since 2009. Since biomethane and fossil methane are chemically identical and the

technology has been used successfully for natural gas on an industrial scale, straightforward production is considered possible. Unfortunately, there are

high costs associated with the production of alternative aviation fuels using the GtL method. This method is rated at 7 on the FRL scale.

Biomass to liquid (BtL)


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To produce alcohol-based biofuel (Alcohol to Jet, AtJ), hydrocarbon chains are produced from the alcohols with the aid of thermo-chemical reactions,

and then the jet fraction is separated in a final step. In doing so, the required alcohols can be produced in a number of ways: One approach, for

example, is to convert carbon monoxide into alcohol using micro-organisms. In another method, a sugar-containing solution is initially obtained from

biomass and then the solution is subsequently converted into alcohol in a fermentation process. It is also possible to leave out the alcohol phase entirely

One example is the direct sugar to hydrocarbons (DSHC) method in which micro-organisms are used to process sugar molecules so that they can

subsequently be converted directly into C15 hydrocarbons via hydrogenation.

Some companies are already developing the production of biojet on an AtJ basis beyond the demonstration phase. Given the limited number of

production sites, so far there have still been no major breakthroughs made regarding the large-scale deployment of such technology. Alternative aviation

fuel from AtJ production processes is in the testing phase with regard to the certification processes; certification is expected by the middle of 2014. Due

to the early stage of development, AtJ methods are assigned an FRL rating of 2.

aireg - biofuels

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