Most engines installed in generators comply with Stage IIIA emissions standards, and so the leap forward to Stage V has a big impact. Also, generators – in the main – require constant- rather than variable-speed engines, which in turn requires different technical solutions. As constant-speed machines account for only a small percentage of the overall industrial engine market, that means progress towards Stage V compliance has been slower.
However, Atlas Copco has been working with its partners on Stage V solutions for generators for several years. These conversations have focused on areas such as the design and packaging of after-treatment systems. These considerations will have an impact on the size, performance, fuel efficiency and cost of Stage V-compliant machines, and all of these factors are currently being assessed in ongoing trials.
With a wide technological gap between Stage IIIA and Stage V, Atlas Copco has thought long and hard about how to implement a smooth transition towards the phased adoption of the new standards in 2019/20. One solution has been the development of the flagship QAS 5 generators, which come with optimised Stage IIIA engines. QAS 5 Stage V-compliant engines will become available in the near future, offering a clear pathway to Stage V adoption and beyond.
The QAS 5 range represents a technological leap in its own right. The first five models – new versions of the QAS 80, 100, 120, 150 and 200 generators – all include the optimised Stage IIIA engines, a high-capacity fuel tank and integrated variable-speed drive motor to power the cooling fan. These features combine to provide users with a more than 5 per cent reduction in fuel consumption compared to the industry average for equivalent models, resulting in a lower carbon footprint. The QAS 5 generators deliver a significant reduction in noise levels, with one-fifth lower noise perception than comparable generators, which is an important consideration when excessive noise generated by portable energy equipment is becoming increasingly unacceptable in urban environments.
On other ranges – such as QES – similar complementary strategies are being employed, resulting in the use of transition engines in certain power ranges, with Stage V-compliant models set to follow in the short term.
Meanwhile, in certain power outputs, Stage V compliance could be achieved through the use of highly innovative dual-power strategies. Here, big power nodes could be covered by two smaller engines working in tandem. Atlas Copco already has extensive experience of this technology, having launched its TwinPower operating principle in 2016, based around the concept of two generators, with two independent engines, fitted inside one box.
The QAC 1450 TwinPower, launched in April 2018, is the latest model, featuring two compact 725 kVA generators, powered by V8 engines with double bearing alternators. This configuration, with its fast-paralleling system, allows the two generators to work independently or in parallel with each other. This provides far more flexibility, contributing to fuel savings and a lower overall cost of ownership, as well as a 15 per cent reduction in carbon footprint compared to a single-engine generator. TwinPower offers a sound strategy for Stage V compliance at the upper end of the power outputs, while the engine manufacturers decide on new engine architectures for their largest and most powerful constant-speed models.
In order to overcome the potential low load issues on Stage V engines like wet stacking or after treatment saturation, which impacts the performance of the generators, Atlas Copco has also seized the opportunity to launch the first ever variable-speed generator called QAS VSG. The unique technology QAS VSG works between 950 and 2550 rpm integrating an Energy Storage System to increase Peak power capabilities by 70% and will ensure that the power pack works at the optimum speed level regardless of the load. In addition to reliability and performance under Stage V, QAS VSG will bring several end-user benefits, including 40% fuel savings, 40% less CO2 emissions, +70% Peak power capabilities vs nominal power, high fleet utilization, low noise under low loads and compact footprint. This is an important consideration in space-constrained metropolitan building sites. Whatever the outcome of ongoing technical discussions, Atlas Copco has in place the required depth of range and the technical expertise to ensure that customers are provided with a smooth transition to Stage V across the power range. Ultimately, customer needs will be met through sustainable productivity and increased operational flexibility, along with compliance with environmental and regulatory obligations – whatever the model choice.