Sean Lumb, Ph.D. (Chemistry) posted this comment on the Squamish Reporter website. I dont think hed mind me reproducing it here. If you think the proposed Woodfibre LNG facility will be great for the area, just read what itll dump into our ocean. Then ask yourself: How much is such a thing worth to us in promised revenues and jobs? How much? I am Ph.D. Chemist and a resident of Squamish. I want to correct the misinformation being propagated in Larry McClennan’s post. It was I who spoke with Alex Brigden at the June 17th Open House, and I have since had an extended conversation with Woodfibre LNG via their Facebook site in relation to the cooling system. LNG has been very forthcoming with responses to my questions. Eoin is correct: Woodfibre LNG has indicated that it will require 17,000 metric tonnes of cooling water from Howe Sound each hour of operation to extract the heat from the natural gas liquefaction process. The cooling system is a once-through indirect system, which means seawater is sucked up and passed through a heat exchanger to extract the heat from a closed cooling loop connected to the liquefaction train. The heated water is then pumped back into Howe Sound. These facts have been provided by Woodfibre, Larry. This equates to 20 Brennan Park swimming pools’ worth of seawater each hour, or over 175,000 Brennan Park swimming pools’ worth of seawater each year. Brennan Park is Squamish’s local recreation centre and swimming pool. Woodfibre has also confirmed that the outfall temperature of the seawater returned to the ocean will be 10 Celsius higher than the ambient seawater temperature. Of course it has to be warmer: the heat from the liquefaction process has to go somewhere! That’s the whole point of once-through indirect cooling system. Environmental regulations require that the temperature be no greater than 1 Celsius 100 metres from the outfall. This requirement says nothing of the temperature within the vicinity of the outfall, nor what happens to the micro- and macro fauna within that 100m radius. Often eutrophication occurs with rises in seawater temperature, during which microfauna blooms exhaust the oxygen supply in the water, effectively killing the life-supporting water column. Effective temperature dissipation depends on a number of factors including convection, tidal churn and others. It’s not publicly clear that Woodfibre LNG will be able to meet the 1C temperature requirement 100m from the outfall, and it’s not publicly clear that they have assessed the thermodynamics of the heated water plume that will result from the cooling system outfall. If it is indeed clear and understood by Woodfibre LNG, then they should make the information publicly available to assuage the public’s concerns for the environmental effects of the heated outfall water. Woodfibre LNG has also confirmed that the seawater will be chlorinated as it is sucked up into the cooling system, to inhibit marine growth within the cooling system. This is often done electrochemically by using electricity to convert the natural salt (NaCl) in the seawater into sodium hypochlorite (NaClO, otherwise known as bleach). The use of this particular electrochemical generation technique has NOT been confirmed by Woodfibre LNG. Other chlorination options include injecting chlorine gas into the cooling water, but this involves the handling of dangerous chlorine gas. Hypochlorite is the same biocide that is used in municipal drinking water and swimming pools. Typical biocidal levels are 3-5 ppm total residual chlorine, and Woodfibre has confirmed they will be using this level of chlorine in their cooling system. Seawater cooling systems often use a pulsed chlorination technique to inhibit biofouling: this involves a timed periodic burst of chlorine over regular frequent intervals to prevent the growth of fouling marine organisms (e.g. molluscs and oysters). The use of this particular pulse technique at Woodfibre has not been confirmed by Woodfibre LNG. All emitters of total residual chlorine, which include municipalities and private companies or utilities, are required in BC to reduce residual chlorine emissions to below 0.5 ppm. This must be achieved chemically in some way: there to make the Cl- ion just ‘disappear’. The sodium hypochlorite is often turned into something else that is not hypochlorite but still contains a chlorine ion: usually with the addition of yet another chemical: sulfite, thiosulfite, or a number of other well-known “chlorite scrubbing agents’. The products of this chemistry are emitted into the ocean with the outfall. If you have 5ppm chlorite as a biocide, and reduce it to 0.5ppm with a scrubber, then you still have 4.5ppm of the scrubbing product, containing the scrubbed chloride, being emitted in every 17,000 tonnes of heated chlorinated seawater, every hour. What is the effect of this? Further complicating the situation, hypochlorite in seawater rapidly reacts with natural bromide (Br-) in seawater to form hypobromite (BrO-), and both of these chemical species react with dissolved organic compounds in seawater to form organic chlorides and organic bromides that are toxic to varying degrees to marine and land-based life. This is well-documented chemistry. In addition to heat and chlorination, seawater in cooling systems is also often treated with other chemical agents designed to prevent chemical corrosion (as distinct from biofouling) and to condition the seawater. I have no information from Woodfibre LNG on these other conditioning agents. One can’t look at existing, open-ocean based LNG facilities and say “well everything seems to work fine for them”. Howe Sound is not the open ocean. Wind and ocean currents, and tidal patterns are different. Larry, these are not grossly over-exaggerated assertions but rather facts confirmed by Woodfibre LNG, followed by research into the chemistry of these processes and aided by a little high school maths. I suggest you look at Woodfibre’s Facebook page for my conversation thread on this topic if you concerned with the veracity of these facts. squamishreporter/2014/08/06/mp-john-weston-unimpressed-with-west-vancouver-councils-stance-on-woodfibre-lng/?replytocom=16012#respond
Posted on: Sat, 09 Aug 2014 20:24:22 +0000
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