Energy recovery from cruise ships' wastewater
Why this challenge?
For each and every boat, whether a cruise ship or not, on-board waste management is a real problem. Among the waste produced on board wastewater represents, in average, a daily volume of 1900 m3 for a middle-sized cruise-ship.
In order to limit discharges into the sea (indeed permitted at a certain distance from the shore), regulation requires at least a dedicated storage tank or at best, an on-board waste water treatment facility. Similarly, ports also have the obligation to have wastewater reception facilities.
In case a port doesn’t have a waste water treatment plant (WWTP) on-site, the waste water has to be transported to a WWTP, usually by truck, generating an important flow of trucks, inducing atmospheric emissions as pollutants and GHG.
As regulatory constraints are becoming more stringent, the volume of wastewater to be managed by ports is raising. Despite, the energy potential that is entailed in wastewater is yet untapped: actually wastewater can be valorised locally in different forms and be transformed in different energy carriers (heat, bio-gas, electricity) and thus, serve to different end-uses not only bounded to the port activity, but also serve neighbouring city-district.
Such a local treatment and valorisation of wastewater could, not only minimize off-shore discharge, but also directly reduce greenhouse gas emissions related to the wastewater transport to out-bound treatment plants. Moreover, such produced energy could be valorised locally, replacing imported fossil fuel based energy needed for the port activity.
To answer to such challenge, different aspects have to be considered:
First of all, the overall theoretical and technically exploitable energy potential from wastewater reaching the port has to be assessed. Not only are overall annual capacities to be estimated, but also its temporal dimension has to be addressed: the docking of cruise ships is rather irregular and undergoes strong seasonal changes. This needs a careful modelling of the source availability and its flows.
Once this has been estimated, the challenge has to address the definition of adequate energy systems to exploit such a source. In particular, it will be necessary to juxtapose to potential energy systems to the actual energy-uses: the objective is to favour an on-site valorisation of the produced energy or energy carriers and thus, answer to a “self-consumption” model for the port, reducing energy imports. This should contribute to the amelioration of the environmental footprint of the port in terms of emissions and pollutants.
Finally, it will be necessary to build a suitable business model for the developed solution. The challenge is to imagine a model which on one hand, favours the waste-water treatment and on the other, minimizes the wastewater discharge at sea. The driver of such value creation, could be related to financial, environmental or regulatory aspects or even be a combination of those.
The developed solution should:
- minimise off-shore wastewater discharge by proposing an adapted solution to cruise ships operators
- maximize the production of low-carbon energy and its local valorisation via self-consumption
- reduce the overall environmental and carbon footprint related to the treatment or transport of wastewater
Trial, resources and co‑innovation
Perimeter & Experimentation
The experimentation perimeter for the challenge will be the Grand Port Maritime de Marseille and more particularly, the eastern area which is almost completely dedicated to cruise ships.
The scope of the assessment should not only focus on cruise or passenger ships, but also be enlarged to other types of vessels, which could potentially contribute in increasing the volume and the regularity of wastewater supply.
There is no constraint concerning the type of energy system to be proposed for the wastewater valorisation. The energy system could be for instance comprehend following technologies:
- waste-heat recovery via a district heating network (high or low temperature) associated to heat pumps
- a digester system for biogas (methane) production for grid injection or associated to a co-/tri-generation plant
- a thermal valorisation of dry-sludge via an incineration plant w/o an ORC system
- a combination of such technologies
- or any other suitable energy conversion or storage system.
The energy consumption perimeter should remain within the port’s boundaries, promoting local self-consumption. A circular economy system in which cruise ships themselves become end-users of the produced energy is not excluded.
It is foreseen to work in a “co-experimentation” mode among the candidate company, the challenge leader EDF and the port authority, including also cruise-lines companies such as MSC Cruises.
The so composed team will be able to provide the needed know-how, tools and data, necessary to fulfil the challenge’s objectives.
The EDF team, specialized in low-carbon energy solution, will be able to support the candidate company on energy system related aspects.
The port authority and cruise-companies will be able to support the candidate by providing data and know-how concerning the wastewater potential assessment and shipping related aspects.
Profile for the expected startup
To meet the proposed challenge, several business profiles can be considered for a candidate company:
- A start-up/SME offering innovative wastewater energy recovery solution to be adapted in a port environment.
- A start-up/SME specialized in modelling and/or engineering, able to provide flow modelling of the wastewater potential and/or energy system design.