Page 48 - European Energy Innovation - spring 2019 publication
P. 48
48 Spring 2019 European Energy Innovation
BIOFUELS
Renewable jetfuel pathways
By Jeffrey Skeer (pictured), International Renewable Energy Agency (IRENA)
There are two main ways to There are several promising biojet advanced processes to ethanol and
reduce carbon emissions feedstocks and technologies. First then upgraded to jet fuel in an extra
from aviation – better there are oilseed crops, such as process step.
efficiency and better fuel. neem seed in India, rapeseed in
The International Civil Aviation Europe, and possibly oil palm – a Feedstock costs are potentially
Organisation (ICAO) has found that very high yielding plant – provided it very low for energy crops – due to
to cut aviation emissions in half can be certified as sustainably grown their high yield per hectare – as
by 2050 (from 2005 levels), half of on existing farmland. Next there are well as for wood residues of which
the lifting can be done by efficiency wood residues – such as tree tops large amounts are left in the forest
improvements (in technology, and branches from logging (“slash”) because they have low value. But
operations and infrastructure). But and sawdust from processing the oil crops have many alternative
the other half will have to be done by lumber which is extracted from uses, which tends to keep their
renewable biofuels. forests to displace use of cement costs somewhat higher. Feedstock
in buildings; it is better to convert costs are very important, since
IRENA analysis shows that biofuels them to fuel than to have them decay they account for up to 80 percent
can sharply reduce carbon emissions to carbon dioxide uselessly. Finally of total fuel cost when conversion
if they are produced from sustainable there are carbohydrate crops, such technologies are mature. So we need
feedstocks on existing farm land or as maize, sugar cane and high yield to consider which feedstocks are
existing managed forest, so that no energy cane, which can be converted cheapest in each place, and allow for
increase in greenhouse gas emissions by a mix of conventional and jet fuel to be traded.
arises from land-use change. The
associated resource potential is very Comparative Costs of Renewable and Fossil Jet
large – from sources like greater use Fuel with Crude Oil Prices of $50-100 per barrel
of agricultural residues, restoration
of degraded lands with wood crops, Unit total cost, 10% discount rate (without carbon values)
and freeing up land for energy crops
by raising food crop yields, raising 3.50
livestock on less pastureland, and
reducing waste and losses in the food 3.00
chain. While fossil kerosene emits 3
or 4 kg of CO2 per litre, biojet emits 2.50
just 1 or 2 or even less.
US$ per litre 2.00
1.50
1.00
0.50
0.00
Vegetable oils Corn and sugarcane Wood residues
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