Waste to energy

John Skinner, ceo of the Solid Waste Association of North America, pointed out that it is important to distinguish between existing technologies, as opposition to some of them has stopped their development, while for newer technologies, he said there is a lack experience and risk data.

James Thompson, president of Waste Business Journal, added that this is important due to the high funding requirements for such plants, and environmental concerns mean a focus on recycling while from the public’s point of view, ‘no-one wants to see a new smoke stack’. He emphasised that there is a need to educate the public  about  the different technologies.

Susan Robinson, federal public affairs director at Waste Management Inc, explained that the time taken for such technologies to become commercial is usually due to the higher than expected complexity of the waste mix. The impact in terms of extended timescale makes investors sceptical about funding such projects, while legislators, a key audience,  also need to be educated.

WTE projects can also face pressure from environmental groups that in some cases have shut down projects even when relevant permits, contracts and plant fabrication have been obtained or are already under way. Pete Johnson, vp at Dynamis Energy, described how a batch waste gasification project near Boise, Idaho, failed despite public support as a result of a targeted environmental campaign based incorrectly on it being an incineration project, and despite compelling scientific evidence that the project was safe.

The project failed at such a late stage that most of the plant equipment had already been produced and is now stockpiled hopefully, he said, for use in future projects.

According to Gershman, there is a general public perception that waste-to-energy plants are just incinerators and  this view has resulted in increased amounts of MSW going to landfill in many parts of the US, rather than being used to produce energy in an environmentally safe way while reducing landfill demand. ‘There is a need to educate the public, and to be honest and realistic about how plants work,’ he said.

Another key issue is feedstock preparation for which there are four basic business parameters that need to be considered when embarking on WTE projects, according to Nathaniel Egosi, president and ceo of RRT Design & Construction. These are: the supply of raw feedstock, which varies seasonally and is affected by a host of other factors, including  moisture content; the choice of equipment to prepare the feedstock, including grinders, crushers etc; the logistics of the operation, including the management of the waste coming into the facility and its supply in a suitable form as a feedstock, which can account for 70% of the overall cost; and the market for the processed feedstock, eg for energy production.

Currently in the US, 96% of food waste goes to landfill, according to Ljupka Arsova, a consultant with GBB, who describes it as ‘a huge resource’. Anaerobic digestion (AD) offers immense potential for processing this resource, she added, noting that it is already an important solution in Germany. In the US,  there are only 19 AD plants , ranging from pilot to commercial scale facilities. This compares with around 500 sites that accept food waste for composting, and many more plants operating in waste water treatment plants.

There are around 1600 AD plants elsewhere in the world, according to Dieter Korz, vp of business development, municipal waste, at Anaergia, with most of those plants being located in Europe where he said waste separation is developed to a higher level. Anaergia has recently commissioned an AD plant in Dagenham, the first of its kind in London, UK.

The challenge for AD is that it can only handle organic waste, but as Mel Kurtz, president of the Quasar group, which specialises in AD equipment, this can range from food waste to biofuel processing residuals, and he estimates that the quantity of organics that currently end up in US landfills or incinerators as 33.8m t/year, worth $165m. He believes the importance of AD is that ‘everything to do with AD costs less, compared with other approaches’. Quasar makes significant cost savings by using fuel produced by AD facilities to power its truck fleet, for example.

The American Chemistry Council (ACC) has been promoting energy recovery, but as Craig Cookson, director of sustainability and recycling within the ACC’s plastics division, pointed out, part of energy recovery is the conversion of plastics waste to oil.

Out of a total of more than 62m t/year of plastics waste generated annually in the US, part of a global total of 187m t, only 8% is currently recycled, according to estimates by the EPA. After traditional recycling in the US, more than 90% of the total plastics waste goes to landfill or is incinerated, noted Jay Angin, vp of business development at Agilyx, an oil-to-plastics technology provider.

As Anjin added, this is a relatively new industry but one that is on the rise, and his company claims to be the first in the world to install commercial scale technology to produce refinery grade crude oil from used plastics, producing and selling over 500,000 gal of its synthetic crude oil so far. The company is currently involved in developing a next generation continuous feed, self-cleaning pilot plant, following the construction of five first generation 50t/day facilities in three US states, while planning a number of projects worldwide. A key aspect of this current development is the use of partners to handle construction,engineering etc, leaving the company to focus on developing the technology.

This partnership approach represents a major change from earlier plastics-to-oil developers and their subsequent failures as the technology was not fully understood from feedstock right through to final product, according to Jay Schnabel, ceo of RES Polyflow. The focus needs to be moved away from just ‘getting rid of polymers’ towards harvesting polymer waste as a feedstock that replaces crude oil.

Schnabel pointed out that Polyflow has developed a process that can utilise all forms of mixed dirty polymer waste, without sorting or cleaning, to produce a liquid that can be converted into fuel and petrochemicals normally produced from crude oil. He believes this offers a unique business case for converting a low cost, widely available, local raw material into a high value end product, while complementing existing recycling activities.

Municipal authorities are not the only US organisations to be looking at converting waste into energy. US food retail group Kroger, sees food waste as ‘an asset not as garbage’, according to its logistics sustainability manager, Ashley White. This view is reinforced by California regulations which prohibit food waste from being landfilled.

Kroger is producing biogas using AD, from out-of-date products that are returned by stores to the distribution centre. The biogas is used to generate 20% of the centre’s total energy demand, noted John Winkels, senior director, logistics engineering and network strategy. In the Pacific North West, White believes such an approach could facilitate the replacement of 25% of Kroger’s existing diesel truck fleet with gas-powered vehicles.

At Shaw Industries, the world’s largest producer of carpet, hardwood and laminate flooring, a partnership with Siemens has seen the development of a gasifier, using hardwood dust and carpet trimmings previously sent to landfill, to create a product stream that can be used to set the colour in carpets. Jay Henry, director of operation support at Shaw believes the company is the world’s largest carpet recycler and has the world’s first energy plant fully fuelled by carpeting, both post-consumer product and trimmings, as a result of a second major investment.

Gershman believes that the US public sector has adopted a low risk approach, encouraged by a perception that the technology still needs further development, especially AD, and thermal technology .

However, US states are increasingly adopting legislation that encourages this approach to waste utilisation, driven by fears that land fill capacity will run out. There is an opportunity here for private industry to partner with municipalities , especially in the US West and Northeast as well as Florida.

But Ralph Avallone, secretary general of the International Green Energy Council, identified a specific  potential US market: Native American tribal lands, many of which he said had closed landfill sites and which generated their electricity using diesel generators. Mobile waste to energy facilities could offer an ideal solution, well within the financial resources available.

Meanwhile, John May, managing director of Stern Brothers, summed up the current situation saying that this industry sector is at a crossroads: ‘Will it explode or not? There is a need to challenge current assumptions... we have to realise that to invent or re-invent an industry, it takes longer to develop the technology and the supply chain than envisaged.’

This view was echoed by Robinson who said ‘it is taking longer than we[in the industry] even thought it would because we didn’t fully understand the complexity of the waste stream, and this has not been helped by the general economic situation. Once we see technologies being taken up then the sector will move faster.’

When the Solid Waste Authority (SWA) of Palm Beach County in West Palm Beach, Florida, US, realised in 2005 that it would run out of land fill capacity by 2025, it started looking at possible alternative land fill sites. When public consultations started, there was the expected resistance, but the positive support was unexpected – and it was for a second waste to energy facility, involving the combustion of household waste.

The SWA handles over 2m t/year of MSW as well as 250,000t/year of vegetative waste at its renewable energy park in Palm Beach county. Facilities here  include a waste-to-energy (WTE) plant, landfill, composting recovered materials processing, ferrous processing, household hazardous waste, paper and plastics handling and a biosolids pelletisation facility. Its current 2,000t/day WTE plant generates sufficient electricity to power the site as well as 30,000 homes, and the site recycles 136,000t/year.

Following the positive public support, in 2008 the SWA committed to expand the facility with a second mass burn WTE facility, with a capacity of 3,000t/day, which it was hoped would extend the life of the existing land fill capacity on the site to beyond 2045. Construction began in 2012 and the plant is scheduled for completion in early 2015, bringing total power generation at the site to provide power for over 60,000 homes.

The Vero Beach, Florida, facility of Ineos Bio adds biocatalyst fermentation and distillation onto a gasification plant that processes around 150,000t/year of municipal, garden, wood and vegetable waste, as well as waste tyres and coal and automobile shredder residue, into some 8m gal/year of ethanol and 6MW of electric power. The power generation part of the facility came on stream in Q3 2013, and ethanol production began in July 2013 with the whole facility becoming fully operational in 2014.

According to Ineos business manager Dan Cummings, the plant is the result of over 400,00 hours of laboratory time and 10 years of integrated pilot plant operations. Ineos believes this is the first such plant in the world to achieve commercial scale with true feedstock flexibility, thereby providing a total waste conversion solution.

Gasification technology is not new, however, having been around since the 1970s, according to Gershman. It is usually described as partial combustion in an air-controlled environment, to produce syngas from a variety of feedstocks including biomass, municipal waste and even medical waste; a variant, plasma gasification, utilises a plasma arc as the heat source.

In the UK, Bruce Leonard, director of corporate development at Westinghouse Plasma, noted the Tees Valley plasma gasification facility in North East England, operated by Air Products, was the first of its type, and a second identical plant representing an investment of $350m, was ordered in November 2013 for completion in 2015.

The first plant was a partnership project with Statoil and funded by Air Products, which was begun in 2007.