Memorandum submitted by the Resources
Research Unit, School of Environment and Development, Sheffield
Hallam University
Report No. 27/1
ENERGY AND GREENHOUSE GAS BENEFITS OF LIQUID
BIOFUEL TECHNOLOGY OPTIONS
by N D Mortimer, M A Elsayed and R E Horne
1. This submission concerns the evaluation
of the net benefits of producing liquid biofuels from alternative
crops in the United Kingdom in relation to the depletion of energy
resources and the emission of principal greenhouse gases, in the
form of carbon dioxide, methane and nitrous oxide. As a basis
for evaluating these net benefits, it uses results from earlier
work conducted by the Resources Research Unit of Sheffield Hallam
University for the Department for the Environment, Food and Rural
Affairs, and the Department of Trade and Industry Renewable Energy
Programme. This earlier work refers to baseline results for 18
biofuel technologies relevant to the United Kingdom. The results
of new work are also presented for the estimation of net benefits
from the production of biodiesel from oilseed rape and bioethanol
from wheat using renewable energy in processing.
2. The background to this area of work is
described briefly. The methodology for deriving results is outlined.
In particular, the application of a transparent and standardised
method of producing and presenting results is demonstrated and
an example of this is provided in the Annex. Basic results show
positive net savings in energy resource depletion, and carbon
dioxide and greenhouse gas emissions for all these biofuel technologies
in comparison with conventional energy sources that they could
replace. In terms of liquid biofuels, net savings of 65% in energy
resource depletion, 71% in carbon dioxide emissions, and 53% in
greenhouse gas emissions could be realised by replacing ultra
low sulphur diesel with biodiesel produced from oilseed rape.
Net savings of 61 per cent in energy resource depletion, 70% in
carbon dioxide emissions, and 64% in greenhouse gas emissions
could arise from the substitution of unleaded petrol with bioethanol
produced from wheat. Bioethanol produced from lignocellulosics,
in the form of wheat straw, saves slightly more than all the primary
energy required to produce the unleaded petrol it could replace.
This is due to the use of renewable energy sources, in the form
of lignin and unfermentables, in processing of bioethanol from
lignocellulosics which means that this liquid biofuel could be,
effectively, "carbon neutral" and provide 84% net savings
in greenhouse gas emissions.
3. The effects of using renewable energy
sources in the processing of biodiesel from oilseed rape and bioethanol
from wheat are also investigated. In particular, the use of rape
straw and wheat straw as fuels in biodiesel and bioethanol processing,
respectively, are considered. Results show that these modifications
could enable the production of biodiesel from oilseed rape and
bioethanol from wheat to achieve similar net benefits to the production
of bioethanol from lignocellulosics. Net savings in energy resource
depletion of 83%, 99% and 102% could be possible from the use
of biodiesel from oilseed rape, bioethanol from wheat and bioethanol
from lignocellulosics, respectively. Similarly, 86%, 99% and 100%
net savings in carbon dioxide emissions could be realised from
the use of biodiesel from oilseed rape, bioethanol from wheat
and bioethanol from lignocellulosics, respectively. Finally, net
savings in greenhouse gas emissions of 78%, 92% and 85% could
be achieved from the use of biodiesel from oilseed rape, bioethanol
from wheat and bioethanol from lignocellulosics, respectively.
4. It is concluded that, provided renewable
energy sources are used in processing, similar substantial net
savings energy resource depletion, carbon dioxide and greenhouse
gas emissions can be realised from production and use of biodiesel
and bioethanol, regardless of the particular source of biomass
and the details of the technology. It is, therefore, suggested
that these essential issues are taken into consideration when
examining the net benefits which might arise from expanding liquid
biofuel production in the UK and the potential contributions from
the use of liquid biofuels to sustainable development.
March 2003
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