What’s the most common and convenient way to receive your utilities? When it comes to gas, electricity, water, sewerage, internet connections and even television, the answer is obvious – underground pipes and cables. That’s led some to wonder why our waste is still stored and transported over ground. Surely someone could come up with a system in which waste is managed out of sight, doing away with all those polluting trucks and the problems of missing your collection.
Automatic transmission
In fact, someone did just that. Back in 1961, a Swedish company installed the first automated waste collection system (AWCS), allowing waste to be transported via underground pipes from the point of generation to a centralised waste collection station.
Although not yet common practice, AWCS installations are widespread. There’s even an operational example in the UK. There are currently 16 providers of AWC technology globally, of which Envac, the successor of the company that pioneered the technology, might be regarded as the market leader – closely followed by Finland’s MariMatic. Both companies report portfolios of over 800 installed systems worldwide. Other actors that have a strong regional presence include the Malaysian company Stream, Sweden’s Logiwaste and US-based TransVac.
An AWCS is typically installed as part of a new development, such as a high rise residential block or a hospital, but can also be retrofitted to serve existing buildings. While the underlying technology is much the same, each system will be configured to accept different waste streams depending on the local situation. Many systems (but not all) accept residual waste, some collect food and organic waste, and some collect one or more recyclable material streams.
Residents deposit their waste at above-ground inlet points (one for each waste stream), from where it drops into a chute. When the chute is full, a valve at the bottom can be opened and the waste is pulled into the pipe network. The suction comes from large pumps or fans, and the waste is pneumatically transported to a central waste collection station, which can be up to 2.5 miles away.
The use of separate inlet chutes, combined with sensors and control software, allows an AWCS to be configured to separately collect several waste streams, each of which ends up in a separate container at the central collection facility, ready to be transported (by more conventional means) to reprocessing facilities. However, this means the AWCS relies on residents to separate their waste, and to transport it to the inlet point. It’s a far cry from some of the more fantastic ideas about how this sort of system might work.
Miles better?
AWCSs appear to offer a number of environmental, aesthetic and practical advantages over conventional collection systems. Self-emptying underground storage means no more overflowing, smelly and unsightly bins, and a reduction in the litter associated with conventional waste storage. Meanwhile, industry studies have found that an AWCS system can reduce vehicle miles by over 90%, significantly reducing air pollution and CO2 emissions.
The industry also claims AWCSs can help improve recycling rates. Where a development has very limited space for bins, the small footprint of a chute system can enable a range of recycling facilities to be provided that might not otherwise be feasible. However, the only operational AWCS in the UK currently achieves a recycling rate around 40%. That’s 5% higher than the total for the London Borough of Brent where the development using the system is located, but less than many authorities achieve with conventional collections and still well below the 50% target for municipal waste.
As with more conventional collection systems, the recycling performance of an AWCS depends in part on the range of materials accepted – especially as there is little scope to physically limit the amount of residual waste capacity that residents have access to. That said, there are examples that use key cards to make the system “Pay As You Throw”, which would incentivise recycling. Although an AWCS can be designed to accept a wide range of materials, there are several waste streams that must still be handled in the conventional way either due to size restrictions or the limited number of waste streams accepted:
- Bulky waste and objects too large to fit in the inlets;
- Garden waste;
- Hazardous wastes including batteries; and
- WEEE, textiles and other potentially recyclable materials.
Additionally, while glass from residential premises is often accepted, commercial users generating large volumes of glass waste, (e.g. bars and restaurants) can often not use the systems, because the glass is abrasive on the pipes and may reduce their lifespan. These users would therefore need to arrange and pay for this waste stream to be collected separately.
Streets, chutes and leaves: AWCS can be a space efficient and aesthetic solution to waste management. Image: Inhabitat (CC BY-NC-ND 2.0), via Flickr.
Finally, the possibility of separately collecting different types of recyclable materials is limited by the number of separate waste inlets installed. Currently, most systems feature a maximum of four different types of inlets, which assuming residual and food waste is collected, leaves only two inlets for dry recyclables. The main factor limiting the number of inlets is the additional costs associated with the additional space required both for the inlets themselves and for additional storage bays at the central collection station. The number of separate waste streams that can be collected within a single system is also limited by the fact than only one waste stream can be transported through the main pipe at any given time.
Pushing down the price
When it comes to the spread of the technology however, the most significant barrier is the cost. AWCSs require upfront capital investment many times that of conventional collection systems. On the other hand, once a system is up (or more accurately down) and running, the maintenance and labour required for operations is minimal. The low operational costs mean the systems should, over time, pay for themselves and can offer significant cost advantages in the long-term. To recoup the investment associated with the installation, developers are typically looking at a payback period of at least ten years, with the systems themselves designed to last 50+ years.
However, with most UK housing development projects being funded by the private sector, saving councils money on waste collection is unlikely to be a powerful consideration. That may be why there has been little interest in AWCS in the UK; indeed, when Eunomia reviewed this topic recently, it was for an international client. However, the increasing value of land in urban areas might renew interest more locally. AWCS inlet chutes can take up less space than conventional waste storage, potentially making room for more desirable and profitable features such as commercial property or car parking. If that’s sufficient to offset the cost of installing the AWCS, it could make financial sense for a developer.
Flexible tube?
Despite its attractions, the long lifespan of an AWCS itself creates challenges. Although various initial configurations are possible, once it is installed there is little flexibility to deal with changes. Over the course of 50 years, one might hope waste collection will change quite a bit. New laws could require more materials to be collected separately. Increased waste prevention, increased use of producer take-back schemes, or the introduction of deposit schemes could change the amount and composition of waste being managed. New materials and production methods such as complex polymers and 3D printing may require new waste management techniques and solutions.
As a static, long-term waste management solution, AWCSs may not be able to adapt. The outcome of this could be large sunk investments if their operation ceases; however it is more likely that they would continue to be used, while functioning less than optimally. Either they will deliver worse outcomes than more flexible alternatives, or they will have to be supplemented by additional collection services – rather undermining the purpose of the investment.
Although there are operational environmental benefits to be had from installing an AWCS, many of these could equally be achieved by a transition to less polluting or even electric vehicles. The inflexibility of AWCSs, meanwhile, should give us pause for thought. If nothing else, the last 20 years of waste management should teach us to be cautious about predicting what the future might hold. Committing to systems that could limit our ability to respond to change could lead to negative environmental outcomes or wasted investments. So whilst developers may find the potential to devote less space to waste management deeply attractive, they may find that the environmental attractions of an underground AWCS prove rather superficial in the long run.
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