It is now more than two years since Ros Roca entered the UK anaerobic digestion (AD) market, and Ros Roca Envirotec is now well established as one of its leading suppliers. Last year, following an intensive evaluation process, Biffa Waste Services chose the company as its preferred supplier of AD and mechanical biological treatment technology in the UK. This will entail them working together to develop a number of large-scale biogas plants in the UK and jointly tendering for a number of PFI projects.
Biffa based its decision on Ros Roca Envirotec’s extensive experience in designing large-scale industrial AD plants throughout Europe. The company has built more than 21 plants since 2000 of varying sizes and handling a variety of waste feedstock – from source-segregated food waste and municipal waste through to agricultural feedstocks such as energy crops and manures.
The partnership has begun with the construction of a 4MW 80,000 tonnes a year AD plant at Biffa’s Poplars landfill site at Cannock, Staffordshire. Work started on-site early this year and the first biogas is expected to be produced at the start of 2011. When completed, this plant will be the largest merchant facility in the UK and will be a flagship for the industry, encompassing all the latest technology.
“In Scandinavia, biomethane is used extensively to fuel municipal vehicle fleets”
So how is the biogas created from these AD plants to be used? Ros Roca is an enthusiastic champion of using biogas from the AD process to create vehicle fuel and has first-hand experience of the adoption of this approach. In 2005, the company completed a 23,000 tonnes a year plant in Vasteras, Sweden, which was an EU Demonstrator project. One of the main objectives of the project was to demonstrate the cost-effectiveness of using biogas for vehicle fuel.
The AD plant uses Ros Roca gas cleaning/upgrading plant to produce biomethane. The gas is piped to the city centre bus depot, where both buses and refuse vehicles are fuelled. Just outside the depot is a gas tank station, where the compressed gas is used by the public. It has been so efficient at producing biomethane that the plant is generating excess fuel, which is now being transported to Stockholm for use. Of the seven plants that have been built using Ros Roca’s biogas upgrading technology, five are generating biomethane for use as a vehicle fuel.
But the situation in Sweden is far from representative of how biogas is used elsewhere in Europe. Although its example supports the use of biomethane both from the point of view of the supply of the necessary technology (AD and biogas upgrading) and also the manufacture of refuse vehicles capable of running on biomethane, for the moment biomethane for vehicle fuel is the least preferred option in most European countries, behind electricity and natural gas production.
In the UK, there is a bias towards using biogas to generate electricity. Conversely, in Germany they often upgrade biogas for injection into the natural gas grid. Strategically, Ros Roca will continue to promote the production of biomethane for use in vehicles, but accepts that Europe-wide adoption is still a long way off. This is particularly true in the UK and the contract with Biffa reflects current thinking.
The biogas produced from the AD plant at Cannock will be used to generate 4MW of electricity and heat. The electricity will be eligible for double Renewables Obligation Certificates (ROCs) and will be sold back into the national grid. Ros Roca is working closely with Biffa to develop a number of other AD plants in the UK. It is likely that the additional plants will have a larger capacity than Cannock, but in each case it is still likely that the biogas will be used to generate electricity.
At the moment, Biffa intends to generate electricity but it continues to evaluate the potential for upgrading the biogas to virtually pure methane by using Ros Roca’s biogas upgrading plant. The biomethane could then either be injected into the national grid’s gas network or compressed for use as a vehicle fuel. Simply from an energy efficiency point of view, upgrading the biogas to biomethane is a much more efficient use of the biogas because typically the heat generated from using on-site CHPs to generate electricity is often wasted.
Undoubtedly, the availability of double ROCs for electricity produced by biogas is a significant commercial incentive that has transformed the economic viability of AD in the UK. However, there is also no doubt that it distorts the evaluation of using biogas for other purposes, such as vehicle fuel and/or injection into the gas supply network. Until there is an equalisation of incentives for the various uses, electricity production will inevitably remain the main biogas output use.
Although there is considerable political appeal in utilising the biomethane for use as a vehicle fuel, we are not at the point yet when it makes economic sense. But there is still considerable interest in creating fuels for vehicles.
Local authorities are keenly aware of the experience in Scandinavia, in particular where biomethane is used extensively to fuel municipal fleets. In a ‘green’ political climate, this is an attractive course of action. During the current round of PFI contracts that Ros Roca has been involved in, it is fair to say that all the respective authorities have recognised the role biomethane might play as a vehicle fuel during a typical 25-year PFI contract.
Dennis Eagle is currently carrying out research into dual-fuel and biofuel technology. If this type of energy becomes commonplace for vehicles in the UK, we will be in the unique position of being able to offer a closed-loop system for customers in the UK. AD offers an effective means of reducing waste to landfill and cutting our use of fossil fuels and, as we move towards a low-carbon future, it will be interesting to see how AD develops in the UK.
Ian Handley is Ros Roca Envirotec UK general manager