A continuous target of product design has been the optimal use of materials. This is reflected in the development of power-to-weight ratio and increased time between overhauls as well as the improved lifetime of the components.
The cost of fuels can be a major component in the operating costs of a ship, which highlights the importance of reducing fuel consumption when considering costs and emissions levels. One way of reducing fuel consumption and thus the amount of waste created is to raise the engine’s combustion pressure. Development of the piston-ring-liner combination has achieved low lubricating oil consumption and long change intervals, supplemented by systematic co-operation with oil companies to extend the useful life of the lubricating oil. Minimal waste during operation has been Wärtsilä’s aim when designing the lubricating and fuel treatment system. To do this, Wärtsilä has moved away from using disposable insert filters to self-cleaning automatic filters.
Wärtsilä Oil and Gas Cube power plants are a good example of the optimization of the raw material use. These plants have an extremely high degree of prefabrication, modularity and standard components, which considerably reduces the amount of installation work at site and thus also plant costs. The concept also improves installation quality and reduces environmental impacts due to the smaller amount of on-site construction waste. Similarly, space requirements are considerably lower than for traditional solutions.
Waste is generated during the construction of a power plant, mostly soil and rock derived from earthworks, wastes created while building the foundations, or packing materials. Since the components, including the wall and roof structures, for Wärtsilä’s turnkey power plants are delivered in the specified sizes as ready-to-install elements, power plant construction does not create significant amounts of other wastes. The waste that is generated is sent to a local waste disposal site for disposal or utilized according to local conditions.
Most of the environmental impact of a Wärtsilä power plant during its lifecycle comes from the operation of the plant. Operation of an engine-driven power plant normally generates only small amounts of waste. Most of the materials classified as waste are replaced spare parts, used lubrication oil and oily sludge from the fuel. Other wastes include small quantities of replaced filters and wear parts as well as normal office wastes.
Replaced metal parts are normally reprocessed to produce metal products locally. Procedures for oily wastes, including used lubrication oil and oily sludge, vary considerably. One option is to incinerate them, whether at the site or at an external facility. Another is to send them to the oil supplier for producing new oil products, or to local industry for energy production according to legislation and local regulations.
Exchangeable filters, oily rags and similar waste containing oil or solvents are either incinerated along with other oily waste or delivered to an external facility for appropriate treatment or final disposal. Flue gas cleaning creates its own challenges for waste management at power plants. The catalyst material of an SCR and the oxidation catalyst must be changed at intervals. These elements can contain hazardous and even dangerous compounds that are damaging to health and the environment. On the other hand, they also contain precious metals that can be re-used if suitably processed. They are normally sent back to the supplier of the unit for reprocessing to produce new catalytic material.
The re-usability and final disposability of the end-product created when reducing particulate and sulphur emissions must be evaluated as precisely as possible during the environmental impact assessment of a power plant. Wärtsilä has conducted studies of the typical composition of these end-products, applied a range of accepted methods and performed standard-compliant tests in order to help its customers evaluate such issues. These tests can determine the basis for classification of wastes into hazardous or normal wastes. The figure below illustrates the reduction achieved in sulphur and particulate emissions in the end-products when operating a 50 MW power plant using a certain fuel.
