Environmental Engineering Reference
In-Depth Information
8.7
Social and legal aspects
When planning a biogas installation, the social and legal conditions of the
plant site must be integrated in the project approach. Public acceptance of a
biogas project is important, but usually not an easy achievement. People are
very concerned about impacts such as odour, noise and undesired landscape
changes and the appearance of bad examples in the media amplifies these
fears. During the permission procedures, objections from the population can
slow down or even prevent a project. To avoid such difficulties, the
population concerned should be informed at an early stage of the project.
Willingness to discuss and taking apprehensions seriously help to prevent
and reduce problems during the permission procedures, as well as during
operation of the plant.
The regulations concerning biogas plants are different from one country
to another, and regional regulations must also be considered. Early contact
with the municipality and the permission authorities can be helpful. In
particular, zone conformity and distances to buildings, forests, rivers, lakes
or sources must be respected. Emission regulations or compensating
measures are other possible constraints.
8.8
Practical challenges and future trends
Since the growth of the biogas sector in the late 1990s, mainly in Germany,
knowledge about biogas plant design and engineering has constantly
improved. The technology has developed strongly and new and optimised
solutions have been proposed. Today, the technological options are vast and
the main challenge is choosing the best option for a specific situation.
Problems in biogas plants are primarily due to human failures or negligence,
either during design and engineering or during operation. Problems such as
pipe clogging, material abrasion, floating layers and sedimentations in the
digester frequently happen due to technology that is not adapted to the
feedstock or to feedstock that is not adapted to the technology.
In the field of plant design, the challenges mainly concern economic
optimisation. Technologies allowing lower investment and operation costs
are of great interest in the biogas market. In countries where subsidies and
feed-in tariffs are low, projects can be viable only if costs go down.
Furthermore, substrates that are at present economically uninteresting for
anaerobic digestion could become attractive. Some further trends and
developments are as follows.
.
Mixing optimisation. Mixing of the digester content is a process with
high electricity consumption. The challenge is to adapt mixing intervals
and intensity in order to minimise energy consumption but still fulfil the
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