Sensor solutions for energy from waste

Materials World magazine
1 Apr 2009
mixed waste

The need for an online system to measure the biomass content in solid recovered fuel (mixed waste) was outlined at a seminar held in London, UK, on 24 February.

The UK’s Sensors and Instrumentation Knowledge Transfer Network (KTN), which organised the event, is planning to create a working group to explore the possible funding sources and technologies to address the ‘instrumentation challenge’ for producing energy from waste.

The demand for such a system stems from the Renewable Obligations Order (ROO), which requires licensed electricity suppliers in the UK to source an increasing proportion of electricity from renewable sources. This is designed to enable the UK to meet its target for at least 15% of its consumed energy to come from renewables by 2020.

The Environmental KTN has billed energy from waste as a priority technology area, with a market potential of about £17bln/yr and the possibility to address energy needs as well as divert waste from landfill.

Up until now, however, the technology has not benefited from the Renewable Obligation Certificates (ROCs) Scheme, which provides Government funding credits to support compliance with the ROO. This is due to the lack of instrumentation to directly determine the biomass (renewable) content of mixed waste fuel.

As of April, the Department of Energy and Climate Change (DECC) has updated the legislation in a new ROO, which outlines how ROCs can now be claimed for 50% of municipal mixed waste, as it can be ‘deemed’ to have at least half biomass content.

This will rise to 60% from 2013-2018 and 65% from 2018, in line with the predicted change in the composition of municipal waste as recycling increases.

To claim ROCs for the remaining proportion of the solid recovered fuel, a direct measurement system is still required.

Money talks

Gaining this extra Government investment becomes particularly important as the new ROO ‘introduces banding – which involves increased support for emerging technologies and less for mature technologies,’ explained Alasdair Grainger of the DECC.

This subsequent decline in support for co-firing homogenous biomass and coal, and the fact that many coal-fired stations will be decommissioned by 2015, suggests an opening for energy from waste, said Steve Cornwell of RWE npower, headquartered in Swindon, UK. But this is only possible, he noted, if the funding can be secured to help build dedicated plants for heterogeneous waste. This needs a larger capital than co-firing due to the nature of the advanced conversion technologies and the need to comply with the EU Waste Incineration Directive.

‘Direct continuous measurement would be fantastic,’ said Cornwell. ‘It can be built into the planning of the plant to claim ROCs.’

He added, ‘The current system of claiming ROCs based on delivery sampling and offsite analysis is admin intensive’.

System analysis

At the event, speakers presented a number of possible sensing solutions, which included X-ray adsorption spectroscopy and hypersectral mapping. However, delegates concluded that a system that combined a number of analytical techniques was required, posing a considerable challenge.

Luke Hares of product solutions provider Cambridge Consultants Ltd, UK, said, ‘We need a detailed specification with regards to what the regulatory bodies would accept and what type of plant it would be retrofitted to’.

Robustness, accuracy, power consumption and compliance with manufacturing standards are key parameters.

Some delegates therefore questioned whether the cost of developing and implementing such a system might outweigh the funding gained from claiming the extra ROCs.

The Sensors and Instrumentation KTN will begin to look more closely at the field and is inviting interested partners to be involved in the process.

Further information: E-mail Robin Higgins, or visit Sensors and Instrumentation KTN