More haste, more waste: boosting biofuels

Jan 21, 2016

Biofuels offer the best chance for airlines to control their emissions at a critical juncture for climate change action. Other alternative fuels, such as hydrogen, are unfeasible for commercial aircraft, while improving engine efficiency cannot compensate for relentless expansion of the global fleet. Unfortunately, aviation biofuel production is still in an infancy protracted by haphazard government incentives, production hurdles and lack of finance. Alex Derber investigates.

From 2020 the airline industry is targeting carbon-neutral growth. Yet advances in aerodynamics and engine technology will not be enough to compensate for more aircraft in the skies. Boeing reckons there will be three times as many passenger aircraft by 2034 as today, growth that will sorely test aviation’s ability to expand within its present carbon footprint.

However unfeasible the goal of the Air Transport Action Group (ATAG) and International Air Transport Association (IATA) may be, biofuels and some form of carbon pricing system represent the best hopes of achieving it. That said, internationally-agreed, market-based measures for airlines’ CO2 output are still in limbo with the ICAO, while Europe’s controversial emissions trading system has been suspended for non-EU airlines and is in any case not set up correctly to control airline emissions.

That leaves biofuels. More than 20 airlines have now conducted test flights with a mix of drop-in biofuels and standard “Jet A” fuel, but even the most enthusiastic adopters still rely overwhelmingly on conventional, crude-oil-derived fuel. KLM, for instance, has operated hundreds of scheduled short- and long-haul services with a blend of used cooking oil and Jet A, but still counts on the latter for more than 99 per cent of its fuel requirements.

Since KLM is more engaged with biofuels than almost any other operator, it’s hard to see how Boeing’s ambition for airlines to use one per cent biofuel by 2016 can be achieved.

“The aviation biofuel market is still in its infancy and supply for sustainable biofuels needs to build up,” says a spokesperson for Dutch flag carrier KLM, part of Air France-KLM.

In fact, three issues need to be addressed before biofuels can start making a dent in Jet A use: volume, sustainability and price.

Europe’s Flightpath initiative – led by the European Commission, several major airlines and biofuel suppliers - wants an annual production of two million tonnes of sustainable aviation biofuel by 2020, which would equate to roughly one per cent of current annual jet fuel use by the global airline industry.

Such a modest goal should be achievable, and as volumes rise the price should fall, though KLM notes that biofuel remains two to three times more expensive than jet fuel. Price, however, is not an insurmountable obstacle, as airlines could in the future be rewarded for with carbon credits or other allowances for upping the biofuel blend in their tanks.

“Fuel sustainability is perhaps the most sensitive issue to get right as the negative consequences of a company marketing a fuel with less than ideal credentials would be disastrous,” says Jeremy Tomkinson, CEO of NNFCC, a biofuels consultant.

Picking a feedstock

Sustainable biofuel feedstock must not displace land used for growing food, must not be grown on deforested land and should produce at least half the greenhouse gas (GHG) emissions of conventional fossil fuels. Accordingly, land-based feedstocks such as camelina, jatropha and sugarcane can invite criticism, either because they occupy land that could be used for food or because they are grown in environmentally sensitive areas. Camelina and jatropha producers argue in response that they either use land unfertile for other crops, or that they plant between crop-growing cycles.

There are even stronger arguments in favour of fuels derived from algae-grown on water, though production hasn’t yet advanced from small-scale trials and the economics still present a significant challenge. 

For the present Boeing is pinning its hopes on green diesel, already produced in relatively large volumes and at an attractive price through subsidies in the US and Europe. Production capacity totals 800 million gallons per year for road use, and if a quarter of that was devoted to jet fuel it could meet Boeing’s one per cent biofuel target. International approval for green diesel’s use as aviation fuel is expected to arrive by 2016.

Finnair is evaluating the possibility of establishing a green diesel hub in Helsinki Airport in partnership with the Finnish Ministry of Transport and Communications, Finavia and Neste Oil.

“We have identified renewable bio-based diesel as a potential alternative to kerosene, due to the lower investment required for continuous production, and therefore lower costs,” says Outi Merilä, manager of environmental management at Finnair.

But questions about sustainability persist despite green diesel’s 50-90 per cent GHG savings over fossil fuel. Although waste cooking oil and animal fats do go into green diesel, it also relies on virgin palm oil, the cultivation of which has led to massive deforestation in Southeast Asia.

One of the most exciting new avenues is the conversion of solid waste from landfills and forestry residue into biofuel. Solena Fuels and British Airways are partnering to build a plant capable of recycling more than 500,000 tonnes of solid waste, while United recently invested $30m in Fulcrum BioEnergy to have plants up and running by 2017.

After removing any glass and metal, these plants pulverise remaining feedstock into refuse-derived fuel (RDF), which is burned via gasification to produce carbon monoxide and hydrogen, rather than the carbon dioxide and H2O that results from normal combustion. The CO and H can then be converted into fuel, while any residue is used for building materials. Fuel conversion itself relies on the Fischer-Tropsch process pioneered in Germany in 1925 and then used throughout the war to produce synthetic fuels.

Given such proven chemistry, the obvious benefit of recycling landfill waste and its limitless supply, one would expect gasification to be more popular. The problem is that Fischer-Tropsch has traditionally been deployed by states on a large scale for conversion of coal, a known substance.

For private biofuels suppliers the goal is to have small production facilities dotted around landfill sites, and capable of producing reliable RDF from an assortment of different rubbish.

“It’s an expensive process that’s never been done before [using landfill waste] so you need buyers at the end of the chain if you are are going to get lenders on board,” comments Tomkinson. Hence the involvement of airlines like United and British Airways.

Chip fat flyers

Possibly the strongest sustainability credentials are attached to used cooking oil (UCO). Companies such as SkyNRG, Neste Oil and Honeywell have been refining UCO into a drop-in bio-jet fuel using the Hydrotreated Esters and Fatty Acids (HEFA) process, which converts oil to hydrocarbons via deoxygenation with hydrogen. Although some companies also produce biofuel from primary sources, such as palm oil, using the same process, UCO has proved by far the most popular feedstock for airlines.

Chemically near-identical to Jet A, UCO biofuel does not offer much better tailpipe emissions than standard fuel (although its one to three per cent higher energy density produces some small savings). Like other biofuels, however, it offers huge lifecycle benefits, as the carbon dioxide emitted by burning it has already been sucked out of the atmosphere by the plants grown to produce the cooking oil in the first place.

Most of UCO’s carbon footprint, then, stems from collecting and processing it. KLM estimates that its UCO-derived fuel offers 80 per cent greenhouse gas savings over normal jet fuel. It has also monitored wear on engines using the biofuel and found it to be either the same or less than those using fossil fuels.

Despite its obvious merits, however, supplying UCO in quantity is time-consuming and expensive without dedicated infrastructure to harvest UCO from the thousands of restaurants, takeaways and food manufacturing plants that expel it as waste.

“UCO is sustainable and technically feasible, but volumes are limited and could only cover part of aviation demand if prices would reach parity,” comments KLM.

To encourage biofuel production the UK government issues renewable transport fuel certificates (RTFCs) per litre of biofuel that suppliers blend with petrol and diesel. Excess certificates can be sold to suppliers who don’t meet minimum blending thresholds, and these currently trade for about 12p per RTFC. Conversely, suppliers are fined for every litre of fuel that doesn’t contain at least five per cent biofuel.

This carrot-and-stick approach is a sensible way to promote biofuel use, but there are problems. Firstly it doesn’t apply to aviation, so refiners prefer to produce biofuel for cars or even electricity over bio-jet fuel, especially since use of waste products like UCO attracts double certificates.

“At the moment there’s no point making [UCO] biofuel for aviation because you’re losing £250 for every tonne of fuel you make,” comments Tomkinson.

Secondly, the higher market value of waste feedstocks has led to rumours of fraud at certain European ports, where boatloads of virgin oils have become ‘used cooking oil’ at the stroke of a pen.

So what can be done to raise the supply of UCO biofuel for airlines? Britain’s carrot-and-stick approach is problematic because airlines might avoid the country due to higher refuelling costs. Instead, Tomkinson suggest a pure incentive-based approach.

“You could hand out the certificates but not fine those who don’t blend. I believe the Dutch government has done it and that would accelerate the output of aviation biofuel,” he says.

Power plants

In 2011 – the same year that US standards body ATSM allowed passenger flights to use an up to 50 per cent blend of biofuel – Iberia trialled a biofuel produced from the camelina plant. Part of the mustard family, camelina’s seeds are harvested either once or twice a year and processed via HEFA into jet fuel. As with UCO (or jatropha), its tailpipe emissions are similar to fossil fuel, but lifecycle analysis indicates that camelina has a 66 per cent smaller CO2 footprint than Jet A.

Like UCO, though, supplies of camelina are limited. “Several airlines are engaged in pilot projects to demonstrate renewable fuel use but none are willing to substantially raise their costs by paying higher prices for large volumes of fuel,” says Rob Natelson, a postdoctoral researcher at North Carolina State University (NCSU), which receives US Department of Energy funding to enhance camelina productivity under a programme called Plants Engineered to Replace Oil.

Via HEFA about 3kg of camelina seed are needed for one litre of jet fuel, which equates to about one hectare of land for every 300 litres, according to NCSU. “If yields are further increased, through technologies such as breeding, genetic engineering, and optimal farm management, then one hectare would produce around 750 litres,” comments Natelson.

To put that in context, US airlines use about 85 billion litres of jet fuel every year. To supply them exclusively with camelina would require at least 100 million hectares of land – an area more than twice the size of California.

Of course, biofuels – of which camelina is but one feedstock – are only intended to replace a portion of petroleum-based fuel. Even so, refining capacity for camelina is extremely limited, with only the REG refinery in Louisiana currently able to convert it into jet fuel. In Los Angeles a company called Altair is building a refinery that could eventually produce up to 272 million litres of camelina-based biofuels. However even if devoted purely to jet fuel, Altair’s plant would only satisfy a fraction of a per cent of US airline demand.

To encourage biofuel production the US government has several subsidy and grant schemes. These include: the Biomass Crop Assistance Program, which assumes some of the costs of harvesting and transporting agricultural residue unsuited to purposes other than biofuel; loan guarantees of up to $250 million to build biorefineries; US Navy, Department of Agriculture and Department of Energy funding totalling $510m to support the development of drop-in biofuels; and the Renewable Fuel Standard, which requires fossil fuel producers or importers to buy renewables certificates generated by the production or import of biofuels. At present one gallon of camelina oil generates 1.7 RIN certificates.

An integrated system

No single biofuel will provide the pathway to sustainable aviation, just as biofuels alone can’t stabilise emissions. Market-based measures such as the EU ETS and California’s cap-and-trade scheme are, in theory, excellent ways to encourage biofuel use, as every tonne of CO2 saved equates to a carbon credit for airlines to sell.

Unfortunately the ETS was poorly implemented, and has been suspended from non-European airlines. In any case, too many emission credits were handed out for free and the carbon price collapsed, leaving little incentive for polluters to change behaviour. California sensibly set a minimum price, but its scheme does not yet apply to airlines.

Thus the world waits on the ICAO to agree its own solution, which won’t come into effect until near 2020 and which many expect to be toothless given decades of reluctance to tackle aviation emissions by the UN body.

Thus it falls to states to incentive sustainable sourcing, production and use of biofuels for aviation. As stated above, there are various initiatives around the world, but investors still back away from biofuels and other renewable energies because of ephemeral and haphazard government backing.

“Governments should develop a stable framework of sustainability criteria and support incentives. This will provide the airlines and the biofuel supply chain partners clarity needed to invest in continuous production, secure feedstock and to generate significant demand to further reduce the price of biofuel,” says KLM.

In the Netherlands it seems the government is listening. Let’s hope the rest of the world follows suit.