The Holyrood Thermal Generating Stationís wastewater treatment plant treats the
wastewater resulting from the combustion of fuel and run-off from the solid
waste landfill. Components of the wastewater from the plant are measured and
compared to regulatory limits. Once all aspects of the wastewater meet
provincial regulatory requirements, the wastewater is released into the
environment. In 2005, 6.29 million litres of wastewater were treated and
discharged, which is a slight decrease from the 6.74 million litres of
wastewater processed in 2004.
Hydro relies on both hydroelectric and thermal generation to meet customer
needs for electricity. The operation of the Holyrood plant is highly dependent
on the availability of water in our hydroelectric reservoirs. Water levels in
our reservoirs vary annually with the amount of precipitation and runoff. When
water levels increase in the reservoirs, the demand on thermal generation
decreases, as does associated air emissions. The opposite is also true.
Total emissions were lower in 2005 than 2004 as a result of a greater
percentage of hydroelectric as opposed to thermal generation enabled by
increased inflows in the reservoirs. Concentrations per unit of fossil
generation increased on account of lower average unit output levels. System
emission ratios, with the exception of NOx,
decreased due to greater hydroelectric production and greater purchases of
energy. The NOx emission ratio did not decline
because of a significant increase in the calculated NOx
emissions from small diesel plants in isolated areas in the province.
As part of an agreement with the Department of Environment and Conservation,
Hydro conducts stack testing for the rate of particulate emissions at the
Holyrood plant biannually. Testing conducted in April 2005 indicated the
emission rate for particulate was 30.7 grams per second (g/s). This is the
average emission rate for all three units from stack emission testing
conducted. This is considerably higher than the average emission rate
identified in 2003 (10.6 g/s) and is more comparable to average particulate
emission rates recorded in 2001 (23.5 g/s) and 1999 (38.1 g/s). The increase in
particulate emission rate compared with 2003 is partly
attributable to testing of a fuel additive on one of the generating units
during the winter of 2004/2005 that may have added to the particulate
emissions. However, particulate emissions from all three units were higher in
2005 than in 2003.
In 2005, Hydro made a decision to burn cleaner fuel at the Holyrood plant. The
maximum fuel sulphur content will be reduced from two per cent to one per cent
by mid-2006. The decision will significantly improve on air emissions from the
plant. The cleaner fuel is expected to decrease the annual sulphur dioxide
emissions by 50 per cent and reduce particulate emissions by 40 per cent. The
cost for cleaner fuel will be marginally higher, but Hydro believes it is the
right investment for the plant, stakeholders in surrounding communities, and
the environment and tom facilitate compliance with regulatory requirements.
Stack emission testing, conducted every two years, was performed on the three
generating units at Holyrood during April 2005. The tests monitor total
particulate, particulate particle size, metals, sulphates, SO2,
NOx, CO and CO2
in the exhaust-gas.
Test results are reported to the Department of Environment and Conservation to
satisfy an existing agreement, and are used for on-site evaluation, the annual
report on air emissions, exhaust-gas modeling, and reporting to Environment
Canada through the
National Pollutant Release Inventory and Greenhouse
Gas Emissions Reporting. The results also provide data on our initiatives to
improve overall unit performance and efficiency.