Concluding remarks and perspectives on the future of energy systems using biomass - Biomass as Energy Source: Resources, Systems and Applications - page 263

large scale plants are more economic, but as the risk with these are higher it may as well be a fea-
sible strategy to develop more small scale solutions, that can be afforded also by less capitalized
investors like villages or even single persons. Even if these investments may have longer pay-back
time it may still be more feasible as you may eventually have to pay taxes, distribution costs etc. if
you produce for yourself. Then instead it should be technical demands on the equipment to avoid
emissions of pollutants. Even if biomass is an excellent energy resource, we have to be aware of
that if it is combusted in a bad way it will give very strong negative effects on nature, although
perhaps not on the global warming.
There are some basic principles regarding the evaluation of the environmental aspects of various
treatment methods. For instance, the combustion processes produce remarkable amounts of ashes,
which might contain heavy metals and other harmful pollutants. Therefore, any such process plant
should include also a plan for the treatment of all fractions of the outlets, not only the volatile
emissions.
The utmost potential of the microorganisms could be exploited for the management of the
xenobiotic compounds within the dry waste or wastewaters (Slater and Bull 1982). Microbiolog-
ical pretreatments could be effectively used for lowering the environmental and health hazards
related to later process steps of treating the mixed wastes or sludges.
In a Dutch review on the climatological effects of the energy production, various methods
for lowering the carbon emissions are summarized (Okken et al. , 1989). One potential method
presented there is the storage of carbon dioxide in the oceans (de Baar and Stoll, 1989). For
example, in this case most of the bacteria in the seas are free-living and utilizing dissolved organic
carbon (DOC) rather than carbon in the particles as a food source. Therefore, the route of sinking
water masses in the sub polar ocean regions is suggested for the biological carbon fixation.
Other carbon dioxide capture and storage methods have been overviewed e.g. in (Benson and
Surles, 2006).
The above-mentioned example is showing clearly that the global environment cannot be divided
into separate segments but needs to be considered as an entity. For example, the environmental
load to the Baltic Sea is the heaviest from Poland, corresponding to 34% of the total phosphorus
and 27% of the total carbon. The same figures for the Russian impact are 19% and 14%, and
for the Finnish organic pollution 10% and 11% (Poutanen, 2010). Carbon is often not estimated
in these models directly, but it contributes to the oxygen demand in the waters. Moreover, the fate
of the carbon residues in the water ecosystems is related also to the proportion of anaerobic niches
to the aerobic ones. In the Baltic Sea 1/7 of the sea bottom is completely deprived of oxygen. In
fact, it could be much better to treat and recycle the wastes in a sustainable way including the
microbiological and biotechnological solutions, than by just discharging the organic loads into
the water and maritime ecosystems, or to the atmosphere.
Therefore, nothing is only good or bad, but depends on how it is used!
This fact that nothing is absolute can also be illustrated by the following example of ethanol
production from wheat in the region close to Västerås city. The data on input to energy from
production of cereals comes from the farmer Gustaf Forsberg, who is operating a 450 ha farm
with mostly cereals; 350 ha are used for cereals in the calculation below:

• Harrowing twice in autumn with cultivator, 6 ha/h. 350 ha/6 = 60 h × 2 = 120 h

• Harrowing 1-2 times with smaller fingers, 10 ha/h. 350/10 = 35 h × 1.5 = 50 h

• Sowing 3-4 ha/h including filling seed + fertilizer. 350/3.5 = 100 h

• Spraying 1-2 h/y (herbicides-outsourced. 24m width. Very fast. Can neglect)

• Total hours 270 h × 40 L/h = 10 800 L × 10 kWh/L = 108MWh

• Harvesting 2.5 ha/h including transport machines, emptying etc. 350/2.5 = 140 h × 32 L/h =

4480 L × 10 = 45MWh

• 130 kWh/tonne

• Production of wheat 5 tonne/ha × 350 ha = 1750 tonne cereals per year
• Energy input for drying: 1750 tonne × 0.130 kWh/tonne = 230MWh
• Addition of fertilizers/nutrients: 150 kg N/ha + 30 kg P-K/ha.

Drying from 20% to 13% moisture = 13 L/tonne × 10 =