The Fuel Route to Sustainable Aviation

Robert Whitfield, Envirostrat
robert@envirostrat.co.uk

Key words: Alternative fuels, biofuels, algae, halophytes, sustainability

Abstract: A combination of the high oil price, energy security and concern about global warming and climate change have lead to a major focus on finding alternative fuels for transportation and in particular for aviation. The main environmentally friendly solution in the short to medium term is provided by biofuels. The two main sustainable biofuel options are algae and halophytes, salt tolerant plants grown in wasteland and deserts and irrigated with saline or sea water. Whilst current alternative fuel studies include algae, the potential offered by halophytes is being overlooked. The urgency of developing and certifying fuels derived from sustainable sources is underlined.

1. Introduction

1.1. At various times a focus has been placed on seeking alternative fuels for aviation, driven by some combination of fuel price, supply of feedstock and level of import dependence. In recent years, a combination of an increase in the price of oil (prices have tripled since the PRESAV report in 2003)[i], concern about oil security and a rapidly increasing concern about global warming and climate change, has led to renewed interest and a new wave of innovation. There is an increasingly widely held view that the pressures are not going to go away and that cost effective solutions must be found.

1.2. In addition to concern within the airline industry and air-forces around the world, the issue is becoming increasingly political.

1.2.a. Following a NASA initiative in 2004, with support from Boeing and the USAF, a major stakeholder meeting in 2006 led to the launch of the Commercial Aviation Alternative Fuels Initiative (CAAFI)[ii], and Boeing launched an alternative fuels research programme with several partners. The FAA confirmed that they were determined "to work with our partners to find an alternative that strikes the balance between energy security and aviation’s environmental performance”[iii].

1.2.b. In the UK, Virgin have launched a major biofuels initiative[iv]; a Parliamentary committeerecommended that the Government take immediate steps to investigate the economic viability of using biomass as the feedstock for synthetic kerosene[v] ;and a biofuels study was launched within the knowledge network programme Omega[vi].

1.2.c. In Europe, there is widespread concern over climate change. Biofuels are seen as part of the solution, but the importance of the source being sustainable is stressed. In this context a major alternative fuels study Alfa-bird has recently been launched under the EU Seventh Framework research programme.

1.3. From an environmental perspective, any alternative fuel that is proposed as a serious candidate for aviation must satisfy two key criteria:

1.3.a. The fuel must be sustainable, that is to say with a low or zero Green House Gas impact, not placing serious pressure on other key resources including freshwater, farming land for food agriculture, and rainforests.

1.3.b. The fuel must be a ‘drop in’ and not require any major significant change to aircraft. Such fuels as Hydrogen and Methane might satisfy the first criteria, but they do not satisfy the second, due, in part to the need to cope with large volumes of fuel and heavy insulated tanks.

1.4. Most current first generation biofuels do not meet these criteria (e.g. ethanol and biodiesel made from conventional crops such as corn, oil-seed rape, sugar cane and palm oil). There are however two distinct types of sustainable biofuel feedstock (both missed in the PRESAV[vii] report) that do meet the above two criteria, namely algae and halophytes. Whilst the major alternative fuel research programmes are fully aware of the potential of algae, there is very limited awareness of the potential of halophytes. This paper outlines the nature of these two distinct pathways, assesses the current status of the broader alternative fuel research programmes, and makes some recommendations as to the way forward.

2. Algae

2.1. The potential of algae as an energy source is something that has been researched over many years, not least by the Aquatic Species Program (ASP), a programme from 1978 to 1996 run by the U.S. Department of Energy’s Office of Fuels Development. ASP was aimed at developing renewable transportation fuels from algae, focusing on the production of biodiesel from high lipid-content algae grown in ponds, utilising waste CO2 from coal fired power stations. This program, whilst not delivering its aim, made substantial progress in the basic science and engineering of micro-algae production systems.[viii]

2.2. The interest in algae derives from the fact that not only are algae organic, capturing their carbon from the air, or from waste products, but also oil can potentially be produced from algae at a rate of productivity 100-300 times the rate of production from soya beans.[ix] Such potential was not foreseen in the PRESAV report.[x]

2.3. In recent years, significant strides have been made in the development of micro-algae as a bio-feedstock, providing what is popularly called designer petrol. Start-up companies such as Amyris Biotechnologies, Codexis, Greenfuel, LS9, and LiveFuel have sprung up each with their own approach:

2.3.a. Amyris employs "synthetic biology ", using natural enzymes, slightly modified to make them work better, to turn living organisms into chemical reactors by assembling novel biochemical pathways within them[xi].

2.3.b. Codexis employs "molecular evolution” to design enzymes in the way that normal evolution designs organisms, producing enzymes that can perform chemical transformations unknown in nature. These enzymes are applied to molecules chemically similar to petrol, such as biocrude, in order to make biopetrol, where each batch can be relied upon to be identical (in contrast to the variations found with petrol itself)[xii].

2.3.c. GreenFuel Technologies focuses on the development of algae bioreactor systems that recycle some of the carbon dioxide emissions from power stations into clean renewable biofuels.

2.3.d. LS9 also uses synthetic biology to produce biocrude by controlling the pathways that make fatty acids; the final stage of the synthetic pathway will clip off the oxygen atoms to create pure hydrocarbons[xiii]

2.3.e. Livefuel eschews the use of photobioreactors (too expensive)and the use of geneticmodification, and is focusing ongrowing large amounts of biomass very cheaply in open ponds and developing biocrude.[xiv]

2.4. The current costs from the Boeing study are not publicly available, but there is anecdotal evidence that the algae start-up companies are struggling to reduce their costs to the level required. Some algae developers believe their business will be like the semiconductor business, where, with significant investment in capital equipment, a very cheap product is ultimately produced[xv]. John Melo, CEO of Amyris Biotechnologies suggested that in their first project on a drug, artemisinin, they had to generate a million-fold improvement in yield. Using that base technology platform, they now need to generate a three- to four-fold improvement on top of that to be cost competitive with fossil fuel.[xvi]

3. Halophytes

3.1. Halophytes are salt tolerant plants (including salt-tolerant algae). They may be grown in desert or waste land, irrigated with saline or sea water. There are over 2000 natural halophytes and since World War II, research has been undertaken to determine which halophytes are most appropriate for agriculture. Whilst irrigation with brackish water inland is one option, the approach offering the greatest potential is that of seawater irrigation of halophytes in coastal deserts and waste lands.

3.2. A crucial attribute of halophytes is that they may be developed in a manner that makes no demands upon the world’s rapidly diminishing freshwater supplies, nor on land fit for farming. Halophytic agriculture works best in sandy soils and there is no danger of virgin forests being cut down to grow halophytes.

3.3. Research and development of halophytic agriculture is being undertaken in at least twenty countries across the world. In the US, key centres have been established at the Universities of Arizona and Delaware. These centres have focused particularly on cultivation of two oil-seed plants, Salicornia and Seashore Mallow respectively. The scope for growing halophytes with saline / seawater irrigation and using them to produce biofuels has been well documented in the literature, including Glenn,1992, Hodges 1993, Glenn 1998, Bushnell 2006, and the forthcoming Hendricks and Bushnell 2008. A fuller bibliography can be found within these sources.

3.4. Examples of how integrated seawater farming can be deployed to grow Salicornia can be seen in the Seaforest in Eritrea and in Seawater Farms Bahia Kino (SFBK) in SonoraMexico[xvii]. In Eritrea for example, 100 hectares of Salicornia were established as part of an integrated seawater farm, together with 100 hectares of seawater forest, a shrimp farm shipping one metric tonne of premium shrimp a week to Europe or the Middle East and a 60 hectare wetland with 200 bird species - overall employing almost 800 people. By March 2008, SFBK will have established a similar farm ten times the size. In 2003, the Eritrean enterprise suffered from a change of political climate, affecting both the availability of staff and the management of the shrimp farm and underlining the need for the careful assessment of political stability, when determining the location of seawater farms.[xviii]

3.5. Large scale seawater farming, along the lines described above, offers potential scope for management of the water table, bringing seawater inland and helping to reduce the level of sea rise - but that is beyond the scope of this paper.

3.6. A recent report on water management in agriculture by the Consultative Group on International Agricultural Research (CGIAR) identified the potential for seawater agriculture using Salicornia and concluded that irrigation of coastal deserts with seawater toproduce biomass for carbon sequestrationand renewable energy may represent a majorfuture use of saline water resources. Thelikely environmental, economic and socialimpacts, however, remain to be quantified.[xix]

3.7. A significant additional commercial feature of halophytic biofuel feedstock exists where it is produced as part of an overall system, such as in Eritrea and SFBK. Such systems may have CO2 / GHG benefits well in excess of the basic fuel substitution. That is to say the other elements of the system may for instance capture CO2 but no credit is attributed to that sequestration. This notion gives rise to the idea that when an aeroplane burns say a 20/80 halophytic biofuel / Jet A blend, a portion of that Jet A burnt could be considered as offset - and maybe the entirety. This concept is powerful and deserves serious consideration.[xx]

4. Spreading the risk, exploring the options

4.1. The very real threat to the world’s forests posed by first generation biofuels is clearly demonstrated in UNEP’s latest Global Environmental Outlook (GEO4)[xxi]. In the two scenarios particularly addressing global warming, it shows that expanding the use of first generation biofuel feedstocks will seriously threaten the very forests whose burning is causing 25% of the problem. A switch to algae or halophytes as the biofuel feedstock is therefore essential.

4.2. Algae have not yet been established as a realistic competitive option. They have great potential, but, quite apart from the challenges in producing an acceptable ‘drop in’ aviation fuel, significant further development is required in both algae farming / harvesting and the transformation at scale to the desired fuel, before algae can be accepted as a commercial solution. For example, great care needs to be taken to prevent indigenous algae from overwhelming the high-tech varieties.

4.3. One could argue that if algae meet the environmental criteria, then there is no need to look at any other option, particularly one with lower productivity projections. This would be to miss two key issues however, namely the spreading of risk and the complementary nature of the two options. Furthermore, the very act of pursuing more than one viable option diversifies the risk: it increases the biodiversity of fuel.

4.4. The complementary nature of algae and halophytes reflects the fact that

4.4.a. The production of algae, particularly the potentially unstable high-tech varieties, would initially be more suited to the developed world, with introduction to the developing world at some time later

4.4.b. The production of halophytes, on the other hand, tends to be somewhat lower technology, quite labour intensive and more suited to the developing world.

4.5. Whilst high tech algae are quite distinct from halophytic oil-seed plants grown as part of a systems approach, algae are in fact a form of halophyte and can be grown in the developing world as well as the developed world. The plans for the SFBK project include algal ponds in due course. If at some stage the halophytic biofuel production was proving uncompetitive compared to algal biofuel, then the halophyte crops could be turned over to food production and the seawater farms could focus more on algae production.

5. Are current studies addressing both halophytes and algae?

5.1. Whilst the science is available and demonstration sites have been developed, there is little evidence that halophytes are yet being considered as a serious option. A wider understanding of their potential is essential.

5.2. Neither the current Boeing study nor the CAAFI[xxii] appear yet to be considering halophytes, but are certainly both addressing algal options. In Europe, the Omega study includes synthetic fuels manufactured from biomass as well as biofuels made from agricultural crops[xxiii]. There is no mention of algae or halophytes specifically however. The full scope of Alfa-bird (see 1.2c) remains to be seen.

5.3. The Boeing study sees biofuels as a mid term option, but only as a minority blend with synjet fuels, most likely based on coal or natural gas. The bio-feedstocks are expected to remain varied, with the oils most likely provided from several sources to form a pre-blend of bio-kerosene that has to be further refined to biojet.[xxiv] This projected use of biofuels is to be welcomed, if from sustainable sources. It would appear, however, that there is more work to be done before the goal of being able to fly with 100% biofuels is reached – and what mid-term means in reality, remains to be seen.

6. Conclusion

6.1. Finding a sustainable new aviation / transportation fuel is extremely urgent. One algae developer likened the challenge to the Manhattan project: it took 3 years, they will take 4. Whether four years is the right period remains to be seen – but the analogy is not so far fetched. Climate change requires at least a Manhattan project approach. The development of sustainable and cost effective biocrude for aviation and other transport industries is a key part of that Manhattan project. The current lead times talked of in the industry do not reflect this level of priority.

6.2. Non algal biofuels tend to be treated en bloc when discussing concerns over their impact on farming, farm land, forests and freshwater. Whilst the concerns are well placed, they do not apply to halophytes, a fact that has been largely missed up to now.

6.3. The two main sustainable options, algae and halophytes, both need to be properly assessed, and means found to rapidly complete their development and implementation.

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