Waste-to-energy: Answer to the Dome Valley landfill blues?

Posted at 9:16am Tuesday 18 Feb, 2020

The Copenhill waste-to-energy plant in Copenhagen is topped by a ski slope. Photo, Ehrhornhummerston.

For many Mahurangi residents, the proposed landfill is as welcome as a “bullet hole in the head”. 

Craig Lord made it clear where he stood on the proposed Dome Valley landfill at a mayoral candidates' meeting last year.

One alternative to Waste Management's plans to put a much-despised landfill in the Dome Valley is to have our trash sent to a waste-to-energy plant instead. James Addis takes a look at the pros and cons …

It was a feisty mayoral candidates' meeting in the Warkworth Town Hall last September. Protesters waved placards and candidate Craig Lord got a huge cheer when he suggested that Waste Management be politely told to “b*gger off”. At stake was the Chinese-owned company's plans to build a landfill in our backyard – or more precisely, the Dome Valley – something about as welcome to many local people as a bullet hole in the head.

Objections to the landfill are well known. It will mean hundreds of waste trucks trundling up the Dome Valley – an already dangerous and clogged section of highway. And critics claim leachate from the landfill will end up polluting our waterways and beloved Kaipara Harbour, presenting an environmental hazard for possibly centuries to come.

To paraphrase Lord and fellow candidate John Tamihere, putting a landfill in the Dome is nuts. The solution surely lies in waste-to-energy plants (WtE), where rather than being dumped in landfill, waste is incinerated and the energy generated becomes a handy source of power that could perhaps light up 50,000 homes.

Lord's message may have gone down well at the Town Hall, but it made no impact at the polls: WtE sceptic Phil Goff was re-elected mayor by a landslide. But did Mr Lord and Mr Tamihere have a point?

Wouldn't a WtE plant, which are common in many parts of the world, make a lot more sense than another landfill? On paper, it would certainly seem so. For starters, there is no leachate from a WtE plant. The volume of waste is typically reduced by 95 per cent or more, and the ash that is left behind can be reprocessed for use as road aggregate. Landfills require a large area to successfully handle waste to manage environmental and sanitary hazards; WtE plants, on the other hand, have a much smaller footprint. Many in Europe are happily located in residential areas – highlighting, advocates say, their clean and green credentials.

Strangely though, some of New Zealand's greenies are not so easily impressed. For example, the decision to grant an Overseas Investment Office consent to allow Waste Management to purchase land in the Dome Valley for a landfill was made by Green MP and Conservation Minister Eugenie Sage. In defending her decision, Ms Sage poured cold water on WtE, claiming the plants were expensive and required consistently high volumes of waste as “feedstock” to make them viable. To meet this demand, material that would be far better off being recycled would end up being incinerated instead. She added the plants released harmful gasses, which effectively risked turning the atmosphere into a kind of gas landfill.

Mahurangi Wastebusters founder and waste minimisation guru Trish Allen is equally scathing. While finding the prospect of a landfill in the Dome Valley “unacceptable”, Ms Allen says replacing it with a WtE plant simply replaces one bad idea with another.

She says incinerators don't do away with the need for landfill. Landfills are still required to dispose of the plant's waste product – a highly toxic ash. In this case, fly ash, which can't be used in roading projects. Ms Allen says given the planet's finite resources, we instead need to adopt a zero-waste mentality.

“We need to design products and materials that can be re-processed to keep the resources in the system, not destroy them by burning them and creating toxic residue,” she says.  

Unsurprisingly, WtE companies approached by Mahurangi Matters – Veolia, Fichtner and New Zealand-based Global Olivine, paint a more positive picture. None of the companies see any difficulty in securing enough feedstock to justify a plant. New Zealand business development manager for Veolia Keith Martin says Auckland alone could support a WtE facility, though a regional plant, taking waste from, say, Hamilton, Coromandel, Bay of Plenty and Tauranga, in addition to Auckland, would make more economic sense and would likely be best located in Huntly or Meremere.

The companies are equally adamant WtE poses no significant environmental hazards and in this respect, are an enormous improvement on landfill. Mr Martin says any emissions are treated and meet very high standards, which is why they can be safely located near housing. A WtE plant in Copenhagen is even topped by an artificial ski slope – the last place one would locate such a facility if there were any fears that the atmosphere was contaminated.

Veolia is also emphatic that recycling is an essential component of waste management and recycling is preferable to incineration where possible. But Mr Martin says there are limits. “We can only recycle a piece of cardboard or plastic a certain amount of times before it is unable to be recycled any more,” he says.

“A WtE facility allows that end of life material to be completely destructed and its energy used for the production of heat and power.”

And let's not forget the potential environmental benefits of that power. Holger Zipfel, a consulting engineer associated with Fichtner, says the dairy industry mostly uses coal to fire boilers to process milk, but a WtE plant could supply the power instead, and thereby eliminate the need for burning fossil fuels.

But is Trish Allen correct, in what is surely a devastating claim, that WtE does not actually eliminate the need for landfill and therefore all the problems associated with landfill remain? Both Veolia and Fichtner concede landfills are still required to dispose of residual waste from WtE. But Mr Zipfel says this waste is a tiny fraction of what would be going to landfill if we were dependent on landfill alone and the reduced quantity of this waste is consequently far easier to contain and manage. Moreover, even the fly ash can be detoxified if necessary, though admittedly this would incur an extra cost.

Meanwhile, Global Olivine boldly claims that its version of WtE, what it calls a “sustainable resource recycling facility” (GO-SRRF), would not require any associated landfill at all. They say every single scrap of waste can be recycled into functional products such as electricity, glass, plastic and useful chemicals. Though it's perhaps important to note that while the different technologies involved to achieve this are all proven, they have yet to be combined in a single plant. There is no GO-SRRF facility anywhere in the world that demonstrates that it actually works.

Leaving that uncertainty aside, and assuming we accept all the other arguments of the WtE companies, what's stopping us? Why not build a WtE plant in Huntly, put any associated landfill there, and boot Waste Management out of our precious Dome Valley, as Mr Lord suggested all along? Well, one thing that might stop us is the cost. Mr Martin says a WtE plant is likely to cost between $300-370 million and the cost of processing the waste would be around $120-140 per tonne. That compares to about $25-30 per tonne to simply dump it in a landfill. The only way WtE could compete is if landfill taxes were dramatically increased, making WtE an attractive alternative. In short, we'd have to pay a lot more to get rid of our rubbish. So it comes to this: If we want to do right by our environment, are we willing to pay the price?

Where are we at with the landfill?

Waste Management lodged a resource consent application to build a landfill in the Dome Valley in May last year. It is expected the resource consent will be publically notified in the first half of this year. Consent documentation can be viewed at the Wellsford War Memorial Library or Council's Warkworth Service Centre, 1 Baxter Street.


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