Solvang’s total emission control
Our goal is to minimise operational and indirect emissions, and strive for zero spills to the environment. This is how Solvang deploys all systems to minimize our operational footprint on the environment and climate.
How we clean the exhaust
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Solvang's total emission control system
Solvang runs a low-pressure exhaust gas recirculation system for NOx-TIR III control on main engines, combined with an exhaust gas cleaner (EGC/scrubber), in order to convert the sulphur in the fuel into sea salt. We use a hybrid exhaust gas cleaning system with electrostatic particle filters (WESP) for SOx and particle control onboard five vessels, and scheduled for installation on seven VLGC newbuildings.
A pioneer of OCCS - onboard carbon capture
In 2023, Solvang received a grant of MNOK 80 from the Norwegian Climate and Energy Fund, in order to apply OCCS in operation. At the turn of the year, OCCS was being installed onboard the LPG carrier Clipper Eris. The system captures CO2 from the 7 MW main engine, before it passes through the exhaust outlets. Inside the smokestack, carbon gas is being separated, then refrigerated into liquefaction and transferred to deck storage. The installation is set to capture 70-80 percent of carbon dioxide from the main engine and auxiliary engines’ outlet, dramatically improving the ship’s environmental performance.
Solvang's EGC (scrubber) and low-pressure EGR setup
Solvang commenced its low-pressure EGR project with former gas tanker Clipper Harald in 2015, which showed continous HFO operation below NOx TIR III levels, without the use of urea. In 2019, the setup was extended to four 21,000 cbm ethylene carriers and one 80,000 cbm gas tanker.
The concept has been further developed to cover seven VLGC newbuildings scheduled for delivery from 2026.
The figure below shows an historical fuel burning reduction of 60 percent, NOx and particles reduction of 90 percent, and SOx reduction of 99.8 percent, respectively.
Scrubber pro's
- CO2: Reduced "well-to-wake”
- SOx: Reduced to LNG level
- High-value energy from low-cost residual oil
- Engines already fit for HFO
- Makes cheap fuel pay for NOx cleaning with LP-EGR
- Catches toxic particles in addition to MGO particles
- Prepares for ECO-EGR, TIR II NOx operation with EGR
Scrubber con's
- High investment costs
- Nickel and vanadium accumulation in enclosed harbours
Converting sulfur to sea salt
Solvang utilises calsium carbonate in a seawater scrubber to convert sulphur oxides into sea salt. The sea water flue-gas desulfurisation process (SWFGD) exceeds 98 percent in efficiency, and it yields no by-products. The flipside is a 2-3 percent rise in fuel (HFO) consumption, increasing CO2 emissions correspondingly. The alternative, to crack HFO in an onshore refinery, would increase CO2 emissions by 10-15 percent.
Alstom Sea Water Flue-Gas Desulfurisation process
Sea water salt content
The current natural concentration of calcium sulfate in seawater is 2.7 g/l. If all vessels in the world use fuel oil with scrubber for another 150 years, the concentration of calcium sulfate will rise to approximately 2.701 g/l.This means a seawater scrubber can be regarded as a reactor converting sulfur into sea salt.
Washwater management and sampling
Solvang closely monitors the level of risk posed to humans and nature by our operations. The washwater from exhaust cleaning is analyzed according to PEC/PNEC and Norwegian criteria for metals, PAH components, hydrocarbons, nitrate/nitrite, turbidity and PH, in total 41 components plus PH and turbidity for each sample.
Solvang samples inlet sea water and outlet washwater from the EGC. The method follows IMO guidelines for the vessels' IAPP certificates, and the results show similar figures for the predicted effect (PEC) and no-effect concentration (PNEC). Which indicated that washwater discharges do not affect the surrounding water at this distance or likely anywhere beyond. See Marintek report MT2016 F-152 ("Clipper Harald operation with scrubber").
Solvang submits EGC water samples to maritime authorities for IMO
There has been a discussion about the negative impact from open loop EGCS in port and/or special areas. It seems to be large variations in methodology and results regarding water samples from EGC. IMO has therefore asked for validated data to ensure high quality risk assessment regarding possible impacts from the EGCS. An EGC uses the alkalinity in seawater to convert the sulfur in the fuel to sea salt. Basically, EGC is a reactor which converts sulfur into sea salt.
Inflated sample output
Following IMO’s request for data, Solvang has compiled five years of sampling results from 13 vessels. In general, the results show that the EGC contamination is between a 5,000th and 10,000th fraction of the contamination suggested by another dataset recently being submitted to the IMO.
In general, these “tricky” measurements require experience and good procedures to get validated results. The detection limit is in the scale microgram per liter. To understand the scale, with 1 microgramme per liter we need 1 million liters to get one gramme of an element. The emission factor established, is on a scale, 1 million less than standard emission factor to air from ships engine.
In the IMO documents, Solvang has discussed the element measured in the water together with a detailed description of the complete water system, from the sea chest to overboard. The dataset and methodology have been validated by Sintef.
News release: Solvang refutes inflated washwater sampling figures
Nickel, vanadium and copper
The water samples have been compared to Norwegian water quality standard published by Miljødirektoratet.
All metal elements are natural in ambient seawater. Solvang cannot see any particular concern to the use of open-loop EGC at sea and in open ports. The only thing to be aware of is the possible accumulation of nickel and vanadium in closed ports. For copper, a smart control of marine growth system would very easily bring the values within acceptable limits. For a shorter period and in closed ports, MGP could also be switched off.
As part of the unburnt fuel (THC) in exhaust, PAH is being condensed in the scrubber and contained in sea water instead of being released to the atmosphere. Well-maintained diesel engines running on HFO or MGO emit 0.1-0.2 g/kWh. Shipping is estimated to contribute 0.5 percent of the total PAH emissions in Norway (newest data from 2015). Whether PAH emissions with the use of HFO is higher or lower than MGO and 0.5 % HFO we don’t know. In any case, the values are negligible.
Solvang's washwater analyses show less than 10 percent of the maximum ∆PAH levels. PAH carceniogenics are close to or below detection levels.
Read more
Marine Scrubbers vs. Low Sulphur Fuels: A Comprehensive Well-to-Wake Life Cycle Assessment
Exhaust gas scrubber washwater effluent | US Environmental Protection Agency
Washwater criteria for seawater exhaust gas SOx scrubbers (Marintek report MEPC 56/INF.5)
Polysykliske aromatiske hydrokarboner (PAH) | Miljøstatus (NO-2018)
Automotive PAH emissions | Concawe. Environmental science for european refining
Polycyclic Aromatic Hydrocarbons (PAHs) | US Environmental Protection Agency
Polycyclic Aromatic Hydrocarbons | European Commission
Turbidity and Water | USGS.gov
Marintek report MT2016 F-152 ("Clipper Harald operation with scrubber")
WESP - Wet electrostatic filter
The Wet Electrostatic Precipitator (WESP) solution leads the exhaust from the main engine outlet through a honeycomb structure rigged with high voltage electrodes. The ensuing electrical field is able to filter up to 80 to 95 percent of particulate matter (PM), which is attached to the tube electrodes and flushed by water for cleaning onboard. According to WESP manufacturer Wärtsilä, the technology is incremental to Solvang's onboard carbon capture and storage (OCCS) technology.
The WESP in action (activate audio)
GHG reduction for different shipping fuels
The figure below illustrates the cost of reducing the emission of one ton GHG gas.
The calculation strongly support our work for making HFO clean. It is a very cost effective solution to reduce the GHG emissions. Actually it is the only available technology with a negative abatement cost. I.e. reduce cost and GHG emissions at the same time.
Well-to-wake emissions from different fuels
Total energy input WTW/delivered propulsion energy
Abatement costs per tonne GHG
The calculation strongly support our work for making HFO clean. It is a very cost effective solution to reduce the GHG emissions. Actually it is the only available technology with a negative abatement cost. I.e. reduce cost and GHG emissions at the same time.
