Stena Line is seeking novel, cost-effective approaches to recover energy from exhaust gases from ship engines and to transform it into a more useful energy form (e.g., electricity to supply hotel loads on board the ship).
Stena Line said that it is especially interested in industrial-scale applications of thermoelectric generators (TEG) that use the temperature difference between the exhaust gas and the ambient air to directly transform waste heat into electricity. The company is also interested in efficient turbine systems that generate electricity from the kinetic energy from the massflow and velocity of the exhaust gases.
Currently, combustion engines onboard ships have an efficiency of 50% or less. If a ship consumes 10,000 tonnes of fuel in one year, then less than 5000 tonnes is transformed into “usable” energy. These energy losses are primarily radiant heat loss and the sensible heat of exhaust gases. About 30% of the total energy available is lost through the exhaust gases. Typically, the temperatures of the exhausts are in the region of 250-350 ˚C.
Ideally, Stena Line would like to convert a significant portion of this waste heat directly into electricity in a cost-effective manner.
Stena Line said that today there are different solutions for capturing the energy, including exhaust gas boiler that generate steam to drive a turbine and direct exhaust gas turbines. However, these are capital-intensive, energy-inefficient, and costly to maintain. As a result, interest in investment in these kinds of systems is limited in the marine industry.
Also, a 1MW engine produces a mass flow of about 7 tonnes/hour. Stena Line is also interested in approaches to transform a portion of the kinetic energy of this exhaust stream into electricity.
Criteria for proposals include:
Technical Viability. Solutions proposed must be based on sound scientific principles and have pilot scale data that demonstrate efficacy. Also, the associated equipment must be able to withstand the harsh environment inside an exhaust stack.
Scale-up Potential. Solutions proposed must have a clear pathway to be application on commercial ships within 1-2 years. Solutions already practiced in marine markets have higher value. The ideal partner would be able to lead the design and installation of full-scale systems.
Capital and Operating costs. Solutions would need to provide reasonable return on investment, consistent with the 30% energy losses experienced today. The return on investment assumptions for any proposed solution should include a full life-cycle analysis (including capital/installation costs, maintenance costs, installation time, etc.)
Ship Operations. Solutions should not impact the normal operation of the ship engine. The equipment space and weight must be able to be retrofitted onto existing vessels. Moreover, the equipment should not increase back pressure to the point it affects engine performance.
Ownership. Solutions covered by patents have higher value. At a minimum, proposed solutions must not be prohibited by other patents in the field.
Intellectual Property Requirements. None required when using exiting solutions; however, where Stena takes technology and creates a bespoke applied solution then patents and IP may need to be sought.
The company is looking for concise, non-confidential proposals. The proposal should describe the technical approach and should ideally include information on the technological readiness of the proposal, any proof of concept data, reference to any peer reviewed publications, and potential route to commercialization.
The companies comprising the Swedish-based Stena Sphere represent one of the largest private shipping groups in the world.