In her thesis work at VTT Technical Research Centre of Finland, climate change
expert Johanna Kirkinen has studied the impacts on climate change of various
biomass-based and peat-based fuels used in Finland. The impact of forest
residues proved to be the least important. In her thesis, Kirkinen presents a
new and exceptional approach to life cycle calculations of fuels for assessing
their greenhouse impacts.
Combating climate change requires a significant reduction in greenhouse gas
emissions. Biomass-based fuels are considered to be a means of achieving these
emission reductions. However, biofuels are not carbon-neutral or
emission-free, as is often believed. They cause an effect that heats the
atmosphere when the entire life cycle of the fuel’s production and use is
taken into consideration. The greenhouse gas impacts and possible emission
reductions of the fuels must, therefore, be proven clearly and comprehensively.
In her thesis work, Kirkinen studied the greenhouse impacts of the following
fuel chains: forest residues, reed canary grass, coal, natural gas, and peat.
Diesel fuels studied included the forest residues and peat-based
Fischer-Tropsch diesel, Jatropha diesel, and fossil diesel. During the work
on her thesis Kirkinen developed the Relative Radiative Forcing Commitment
(RRFC) assessment method, which illustrates the significance of the greenhouse
impacts. It shows the heating effect of greenhouse gases as a concrete ratio
compared to the energy generated by the fuel chain.
Forest residues has the smallest climate impact
Over a hundred-year time span, forest residues cause the least climate impact,
but they still heat the atmosphere by 20–40 times compared to the amount of
energy it produces. The atmospheric heating is caused by radiative forcing,
which is a result of the increased greenhouse gas concentrations, caused by
greenhouse gas emissions. Reed canary grass has a slightly greater impact than
forest residues (climate impact between 20 and 50). Natural gas heats the
atmosphere 100–110 times and coal 170–190 times the amount of energy they
produce. The use of peat has a slightly larger or smaller greenhouse impact
than coal, depending on the type of peat bog it was collected from.
According to Kirkinen’s thesis, there is considerable justification in forest
energy remaining clearly the most important source of renewable energy in
Finland, in line with the scenarios presented in the government’s foresight
The role of climate impact assessment will increase
The climate impact of fuels must always be comprehensively examined, taking
into consideration the entire life cycle of the fuel chain, and emissions at
different stages. In her thesis, Kirkinen presents a new and exceptional
approach for assessing the greenhouse impacts of fuel life cycles,taking into
consideration the reduction of thermal radiation from Earth to space. The
assessment method is dynamic, allowing the calculation of the greenhouse
impact for each year studied. The climate impact was assessed using radiative
forcing, which is especially well suited to the assessment of the greenhouse
impact of biomass-based fuels, when emissions and/or sinks are considered over
a time period of several decades. This is often the case, for example, with
land use and resulting emissions.
If one wishes to limit global warming to 2–3 degrees, the consideration of
time spans in the assessment of greenhouse impacts is emphasised, as emissions
must be drastically reduced as early as during the next couple of decades. The
timing of the greenhouse effect will thus be a very important factor when
considering the sustainability of biofuels.
The role of assessing and reporting the greenhouse impacts of products and
services will increase when moving towards a low-carbon society. Clear and
definite information is required, not only for the support of effective
climate change reduction strategies, but also for increasing awareness.
Emissions should not be assessed merely at the end of an exhaust pipe or a
smokestack, but taking into consideration the overall climate impact of
production and use.
Photograph for media use: Johanna