De-risking the market for EfW operators

Building and operating an energy-from-waste plant is not without its risks. Mark Higham argues that a strategic approach could reap benefits for potential operators

The waste-to-energy market has been a major emerging industry in the UK over the past decade. This form of renewable energy generation has been driven by the Government’s Renewables Obligation (RO), which has been imposed on the UK electricity industry and requires that up to 15.4% of the electricity that energy suppliers generate must be from renewable sources by 2015.

On top of this, the Landfill Directive has driven the need to seek alternative means of waste disposal; as a result, the incineration of waste to generate power is becoming more commonplace across the country.

Potential operators of energy-from-waste (EfW) plants have a number of important issues to consider, ranging from project financing, site planning, plant design, build, operation and, hopefully, economic success – the latter often to be achieved over a 25-year-period or more. Because of this, the efficient operation of the plant (its lifetime cost) has a major bearing on its overall profitability.

While traditionally looked at separately, it could be argued that bringing together some of the various components involved – especially the important plant control and automation technology – under the auspices of a single supply, could simplify procurement, design and build, and consequently drive operational savings.

EfW plants typically adopt a modular approach to plant elements, such as raw materials handling, the furnace/boiler, steam turbine, pollution control, emissions monitoring and any other remaining issues around the running of the plant. This approach can often pose a major challenge for contractors and plant operators, who are looking for a coherent system which will allow the consistent and efficient running of the entire plant.

The challenge of co-ordinating how package plant – the different plant elements – is controlled and bringing a degree of standardisation across these elements lies mainly with the main contractor. However, increasingly, the end-customer or plant operator is not prepared to accept a non-standardised control strategy as they typically have to run the plant with this set up for the next 25 years or more, which is the typical minimum life of an EfW plant.

The solution lies in the provision of a standardised approach to automation technologies which incorporate open communication networks such as Profibus or Profinet. These networks greatly simplify the task of integrating different areas of package plant and products such as process instrumentation, intelligent motor controls and variable speed drives. The benefit to operators is that such technologies will enable entire plant-wide diagnostics with which informed, predictive maintenance decisions can be made. This will increase plant availability and lead to lower overall running costs.

Process automation comprises a number of control system solutions including Distributed Control Systems (DCS), Programmable Logic Controllers (PLC), field bus networking, along with all the peripheral equipment such as motor control and process instrumentation. It allows these control systems to give optimal control of the plant.

Taking optimisation one step further, important aspects such as the measurement of calorific gas values produced from burning waste in support of renewable obligations certificate responsibilities, can form a small, but important part of any integrated system approach.

Likewise, the process improvements obtainable via in-situ gas analyser technology can assist EfW operators to meet environmental obligations, as the sector uses abatement consumables such as lime and urea to clean up emissions from the combustion process that produces power or heat. Rather than deploying a separate emissions monitoring and reporting system, solutions which are fully integrated with the control system are being implemented thereby reducing capital cost and simplifying maintenance.

Other important areas, aside from the plant control and automation elements, need to be factored into a successful plant operational design. These will include energy management, water management technology, power transmission and distribution, and fire and security solutions. A holistic and integrated approach can contribute to the plant’s overall operational efficiency. Integral to this broad range of potential operational solutions is a partnership approach, which enables sound engineering advice.

For the enterprises that will go on to operate these plants, the importance of the control and automation system to influence shareholder value should not be underestimated. Labour costs, consumable/energy costs, asset utilitisation and environmental/regulatory constraints all have an impact on the business’ value.

A poorly conceived plant control and automation system will create unnecessary complexity. This leads to increased need for labour and a dependence on higher skilled labour, as well as reduced plant control and production flexibility, which in turn means higher consumable/energy costs and poor asset utilitisation.

The EfW market has improved its operational efficiency and become more profitable. Most contractors taking on design, build and operating contracts, such as those found in the EfW market, are now attaching higher importance to a standardised approach. By doing so on the back of a standardised, integrated philosophy this approach can only help support the overall drive for operational success.

Mark Higham is general manager for Siemens

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