Biomass environmental FAQs
What are SEPA’s expectations in relation to the
environmental impact assessment of particulate
material?
SEPA has requested that the Environmental
Impact Assessment (EIA) should include an assessment of the impact
from emissions including particulate matter (including the
PM10 and PM2.5 fractions as a
minimum). There are defined air quality standards (AQS) laid
out in legislation – The Air Quality Standards (Scotland)
Regulations 2007 and the amended Air Quality Limit Values
(Scotland) Regulations – for a number of airborne pollutants
relevant to these processes, as well as domestic objectives
(contained within the Air Quality (Scotland) Regulations.
Particulate material has an AQS / domestic
objective for PM10 (being material less than 10µm in
diameter) and PM2.5 (being material less than 2.5µm in
diameter). As part of the EIA the applicant is required to take
into account the background pollutant levels coupled with any
increase from the development to ensure that there would be no
breach of AQS and that BAT will be implemented. Further information
on the application of air quality standards and domestic objectives
on this type of development is available at: www.scotland.gov.uk/Publications/2001/10/10153/File-1
(page 51)
Note that the Scottish Government is currently
consulting on Draft 2010 Air Quality Standards (Scotland)
Regulations, which will introduce a Scottish PM2.5 AQS –
the consultation and draft regulations are available at:www.scotland.gov.uk/Publications/2010/01/25153504/0
If locations have already been
designated as Air Quality Management Areas for particular air
pollutants, eg particulates or NOX – how can new industrial
developments which would emit more of those pollutants be allowed
to go ahead?
Air Quality Management Areas (AQMAs) are
designated for locations which have levels of air pollution that
exceed the recommended exposure limits that have been set to
protect human health. A key part of our response to the S36
consultation will be our view on whether the operation of the
biomass plant would be acceptable or not in terms of any additional
contribution to the existing air pollution levels in the local
area. This would be based on our opinion as to whether the
additional pollutant contribution from the development would be
likely to lead to breaches of air quality standards and
objectives.
However, a new development within an AQMA does
not necessarily mean that the development will have a detrimental
impact on local air quality. For example the AQMAs in Dundee and
Edinburgh have been designated because the concentrations of
nitrogen dioxide (emitted from road traffic) are exceeding the
annual mean air quality objective, although the high concentrations
of nitrogen dioxide will only exist close to the source and fall to
safe concentrations within several metres from the side of the
road.
Environmental Protection UK has published an
excellent document that provides advice relating to planning and
air quality. The document states: “The designation of an Air
Quality Management Area does not mean that there will be a complete
ban on all development in that area...rather it means that greater
weight must be given to the consideration of air quality impacts
and their mitigation.” The document, Development Control:
Planning for Air Quality (2010 Update) can be obtained free of
charge from:
www.environmental-protection.org.uk/publications/default.aspx
This very issue is considered in detail in paragraphs 4.14 -
4.21.
The proposed biomass plants outlined by Forth
Ports are likely to have a single stack that will discharge
emissions 100m above the ground, where they will be rapidly
dispersed by the wind. The emissions plume will typically take the
shape of a cone, the tip of which appears at the point of
discharge. This is also the point at which the concentration
of emissions will be at their highest. The diameter of the plume
will then grow in size as it moves away from the stack; this
effectively spreads the pollutants over a larger area and so the
concentrations decrease rapidly. The plume can move in any
direction and its shape and direction of travel will be influenced
by factors such as wind speed, wind direction, the temperature of
the air and the temperature of the gases leaving the stack. We can
predict how the plume will disperse using complex computer
modelling packages.
Unlike traffic pollution, the emissions from
the biomass plant do not have any physical barriers to confine them
to a particular location, as the plume will be carried in which
ever direction the wind is blowing instead. Consequently, for the
biomass plant to have a significant impact on the levels of
pollution at a roadside location, the emissions must fall on that
particular section of road, where the pollution is already high –
and it must do this repeatedly – before it will influence the
annual mean concentration. Several short-term increases in
nitrogen dioxide will not affect the annual mean concentration.
The situation relating to particulate matter
is slightly different, in that the majority of the material
suspended in the atmosphere is made up of 'background material'
(material that has not been generated by other sources
locally). The emissions of particulate matter from the biomass
plant will be considered and every effort will be made to minimise
the impact that the biomass plant will have on the localised
concentrations of particulate matter.
What are the potential levels of
dioxins generated from the different types of wood that may be
burnt at the facility?
Dioxins are formed by the burning of materials
that contain chlorine. The amounts of dioxins which can be
generated, if not adequately prevented, are dependent on the amount
of chlorine in the fuel source. Dioxins are prevented from forming
by controlling the temperature and other factors in the combustion
process. This is done by detailed specification of the initial
design of the combustion plant, temperature control, abatement
system and other parts of the process. As part of the PPC permit
determination, SEPA sets emission limits to prevent or minimise all
those emissions to air, water or land which have the potential to
harm the environment or human health regardless of the fuel source,
and would also set out what measurements and monitoring of the
emissions must be undertaken.
Research by the Food Standards Agency has
shown that, since 1992, there has been a 70 per cent reduction in
the amount of dioxins and PCBs released into the environment. as a
result of a combination of improved technology, and stricter, more
effective regulations. The concentrations of dioxins found in
individual foods in a study in 2001 were all below EU safety
limits.
Will it smell?
Odour is one of the potential impacts
considered by SEPA when considering our Section 36 consultation
response and our determination of a PPC application. SEPA would
object to the S36 application and would not grant a permit to a
facility if the applicant could not demonstrate that satisfactory
steps could be taken to prevent / control odour and specific
controls would be imposed to limit odorous emissions if considered
necessary. Once a plant became operational, regular checks for
odour, dust and litter at the process boundary will be carried out
both by the operator and by SEPA officers.
Will modelling be carried out to
include the effect of the haar?
The weather affects how discharges from the
chimney stack are distributed in the local environment and SEPA
takes this into account when setting discharge limits. The operator
must carry out modelling, which aims to predict how the discharges
will react in different weather conditions, at the proposed
location. This includes models to predict the effect of the sea
mist, known as the haar, which is of particular importance at some
coastal locations. SEPA have therefore advised that the Leith
and Dundee modelling work should be carried out using two modelling
systems to increase the robustness of the study.
Will there be any waste or by-products
produced by the process and how will they be dealt
with?
Wastes from the process are described in the
application but will mainly comprise waste ashes from the
combustion system. There are two main types of ash; ‘top ash’ or
‘fly ash’ which is normally trapped by the air abatement equipment,
and ‘bottom ash’, which drops out of the main combustion unit. As
part of the PPC permit determination, SEPA will consider whether
the application proposes to use the Best Available Techniques
(BATs) for the storage and handling of wastes.
What are SEPA’s views on the mixing of
top and bottom ashes?
SEPA’s position would be that mixing of hazardous and
non-hazardous residues would not generally considered to constitute
BAT unless a robust justification for this activity was put
forward. Fly ash/abatement plant residues are liable in most
circumstances to constitute absolute hazardous waste (ie regardless
of chemical analysis) and as such the mixing with other potentially
non-hazardous wastes (bottom ash) would render the whole volume
hazardous.
What are the toxicity controls on and
methods of disposing of ash?
As part of any PPC permit conditions, SEPA
would require chemical analysis (including speciated metals, dioxin
content and leachate produced) of the various residues created from
such a process, including minimum sampling frequencies. This data
would be utilised to classify the waste as being hazardous,
non-hazardous or inert. Most types of waste may be disposed of via
landfill, however the EU Landfill Directive 1999/31/EC1 requires
that landfill sites must now be classified as hazardous,
non-hazardous, or inert with strict criteria on the chemical
acceptance of wastes dependant on the classification. Depending on
the nature of waste pre treatment may be required to meet the waste
acceptance criteria, this is generally carried out at offsite waste
treatment sites which are subject to separate SEPA control.
Further information on acceptance of waste to
landfill is available on our website: www.sepa.org.uk/waste/waste_regulation/landfill.aspx
From the initial EIA scoping opinion SEPA
understands that the applicant intends to review the potential for
reusing ash within the construction and fertiliser industry, or
where no market exists, dispose of the material to landfill. From a
sustainability perspective SEPA would be keen to reduce the amount
of residues disposed of as landfill, but only where it could be
demonstrated that the material was suitable for use, a ready market
existed and there would be no greater impact when using the residue
than with a comparative virgin raw material (ie fully recovered and
no longer considered as a waste). SEPA has a protocol for
demonstrating this which is available at: www.sepa.org.uk/waste/waste_regulation/is_it_waste.aspx
How will the heat
from the new power stations be used?
Combined heat and power will play an important
role in delivering a low carbon economy, and offers an opportunity
to significantly increase energy productivity from the power
sector. SEPA believes that new energy generation should be
heat recovery ready, with a heat plan, in accordance with the
Scottish Government guidance on thermal power stations in
Scotland (see section 3.6- 3.14). This requires developers
to carry out a CHP feasibility study in line with our thermal
treatment guidelines, even those with non-waste fuel sources. Power
stations should be suitably located and scaled in order to maximise
the heat usability from the installation, and assess their
potential to meet current and future heat demands.