The offshore wind energy industry is all about clean power. All of the vessels that install turbines use conventional propulsion technology that is polluting and contributes to emissions, but that could change
Although a number of installation vessels have changed hands in recent months, there have been few orders for new ones, with the exception of Voltaire, a new vessel ordered by Jan De Nul, and a vessel ordered by Shimizu Corporation in Japan, based on a design from GustoMSC in the Netherlands designed to install offshore wind turbines of up to 12 MW. As the industry expands and goes global, more vessels will surely be ordered.
Apart from its ability to transport and install larger turbines, Voltaire is noteworthy for being a more environmentally friendly vessel than existing types. It is designed to comply with Euro Stage V regulations, which primarily regulate vessel operations in coastal service and on inland waterways.
Jan De Nul operates dredgers as well as turbine installers, and has a commitment to significantly reduce CO₂ emissions. One of the ways it is doing this is by using biofuel as a replacement for diesel derived from fossil fuels. It wants to reduce CO2 emissions from all of its dredgers by a minimum of 15% by 2022. Like the dredgers in the company’s fleet, Voltaire will run on gasoil, which is less polluting than diesel fuel, and be fitted with an advanced exhaust gas treatment system using a selective catalytic reduction system and diesel particulate filter.
The new installation ship has an additional class notation from classification society Bureau Veritas (BV) that reflects its ‘greener’ credentials. This takes the form of BV’s Ultra-Low Emission Vessel (ULEV) notation.
As BV global leader OSVs and tugs Eva Peno tells OWJ, ULEV notation demonstrates that a vessel has been fitted with additional equipment to go beyond the requirements of Marpol Annex VI, the environmental legislation most large ships need to meet. Normally, she explains, ULEV notation is used to demonstrate emissions reductions on vessels working in the vicinity of populated areas, ports or harbours – where the air quality is a particular concern – but its application to Voltaire means the ship will have lower levels of emissions than comparable vessels when in port and when operating offshore.
BV marine marketing and sales director Gijsbert De Jong tells OWJ that he anticipates more installation vessel owners will want to demonstrate they are also ‘going green’ or at least ‘getting greener.’
“It is already happening on other vessels for the offshore wind industry, such as service operation vessels and crew transfer vessels,” he says. On these vessels, hybrid battery propulsion systems are being adopted and alternative fuels such as hydrogen that produce less emissions are being proposed. Because of their size, changes to installation vessels may not be quite as easy to introduce, he told OWJ, but there are options owners could adopt right now.
In the offshore oil and gas industry, offshore support vessels (OSVs) serving that sector have been quite quick to switch to engines burning liquefied natural gas (LNG, which is less polluting than conventional fuel) and more recently have begun to be fitted with hybrid machinery that uses batteries to store energy and reduce emissions, but that might not be quite such an easy option for installation ships, Mr de Jong tells OWJ. This is because unlike OSVs with LNG propulsion, which usually operate in one area in which LNG supplies are known to be available, installation ships operate worldwide, and might not be assured of LNG availability. The capital expenditure involved in installing dual-fuel engines capable of burning conventional fuel and LNG, and the LNG tanks on a vessel, might also dissuade owners from this option, he says.
Mr de Jong and Ms Peno say there are really two important issues facing vessel owners: the first is reducing emissions of sulphur oxides (SOx), nitrogen oxides (NOx) and particulates; the second, which has come into focus more recently, is decarbonising shipping by reducing CO2 emissions. Ideally, shipowners need to address both. There are already ways to reduce SOx emissions, such as selective catalytic reduction, but reducing CO2 emissions requires new thinking.
“Alternative fuels will be part of the mix for future vessels,” says Mr de Jong. “LNG could be an option, but only if the supply chain can support it. Methane and hydrogen are potential options, as is ammonia in the longer term.” Biofuels could be an option for owners of vessels operating in a ‘green’ industry he believes, including, potentially, biogas produced using renewable sources. Interest is growing in using hydrogen to propel vessels and in countries such as Norway there is also growing interest in using green hydrogen, using electricity from wind energy, for vessel propulsion.
The designer of the Shimizu vessel, Gusto MSC, is a well-known designer of jack-up vessels. As the company pointed out recently, on an installation vessel, demand for power varies significantly, which makes applying energy storage technology potentially of interest as a way of reducing fuel consumption and emissions.
“Larger installation vessels designed to install larger turbines require significantly more propulsion power when in transit and dynamic positioning (DP) mode,” the company says, although power demands when idling, waiting for weather, loading in harbour and when installing wind turbines on site have risen only moderately. However, as the company also notes, significant improvements have been made in areas such as hull resistance in recent years, reducing power requirements for transit conditions, making the power required for DP a dominant driver.
Modes of operation such as DP which have high demand for power for a relatively short period, leading to a fluctuating power profile, are ideally suited to using energy storage systems, the naval architect believes, and as it notes, as demand for power has grown so energy storage technology has matured and costs have fallen. At the same time, their energy density and energy efficiency have increased significantly.
GustoMSC says it is important to take a case-by-case approach to assess the applicability of energy storage systems, but it believes that power requirements during DP and in other modes of operation such as when raising and lowering the legs on a jack-up mean batteries are a potentially attractive option.
“A turbine installation vessel usually arrives on site after several hours in transit with relatively predictable power consumption,” the company explains. “During this period, the batteries can be charged.
“Rather than install an extra generator set, batteries could be installed to meet the need for short-term peak power. In addition, batteries could supply instantaneous power, when required, so operators do not have to rely on a spinning reserve – that, is diesel generators running on standby to guarantee sufficient power is available to maintain position in the event of generator failure. What is more, a battery on standby is not using fuel or incurring running hours that will add to its needs for servicing and maintenance.”
In response to this potential application and others like it, GustoMSC has developed an integrated solution in which the jacking system and crane are combined with ‘DC grid’ and battery pack that could reduce running hours for diesel engines and reduce a vessel’s carbon footprint.