It wasn’t very long ago that the first domestic biogas unit went on the market in Britain. More common in other countries, it would allow households to generate cooking gas from food waste. But what about all the other rubbish the household generates?
Lots of ‘black bin’ waste is already used for generating power. It’s carted off and burned in an incinerator, or put through a gasification unit. What if you could miniaturise that process and do it at home? You’d cut out bin collections, waste processing, the emissions from transporting waste. People would benefit directly from the energy created, with no transmission losses.
That’s some of the logic behind the Home Energy Resources Unit, or HERU. This domestic pyrolysis unit has been developed by British inventor Nik Spencer, and it’s currently trialling in a couple of ordinary homes.
The HERU would be fitted in a kitchen or utility room, much like a washing machine or drier. You stick your waste in the top – anything except metal and glass. Don’t worry if it’s not full, it’s a hybrid and will top up from the gas mains if required. The machine then runs overnight, raising the temperature and removing oxygen until the material is effectively turned into charcoal. It is then burned to make hot water, with the emissions scrubbed before release. Come the morning, you have a hot shower and a teaspoon of ash that has already been swirled down the drain. Here’s a recent news piece that shows it in action:
There’s no doubt that the HERU is a clever idea. But how does it stack up environmentally?
In the video, we see the machine being crammed with ‘problem’ waste such as nappies or used coffee cups. Great – that’s waste not going to landfill. We also see fabrics and plastic milk bottles going in, which are recyclable. Less good presumably?
Or not – there’s no question that recycling is better than landfill, but it has a big carbon footprint of its own, especially since recyclate is often shipped across the world for processing. An independent lifecycle assessment showed that pyrolysing waste at home with a HERU generated a third of the emissions of mixed recycling collection. Since you’re replacing the natural gas that would normally be used to heat water, there’s a carbon saving there too. In theory, the average household would save 1.2 tonnes of CO2 a year.
According to the the inventor, if it was adopted by all 27 million households in Britain, it would result in “carbon savings of 32.4 million tonnes, equivalent to 8.8% of the UK’s total carbon output.” That’s a significant contribution, but what other consequences might follow?
Let’s imagine that they become as common as washing machines, and most households in Britain have one. Glass and metal recycling continues, but all plastic and paper is now in the machine – those recycling industries have been killed. With less recycled material on the market, there is increased pressure on virgin stocks – more timber for paper and card, more oil or gas for plastic. Perhaps food waste is going into the HERU too, reducing food waste to landfill, but also reducing material available for compost or biogas.
Universally applied, the HERU would be a better way of dealing with our waste problem, but it might remove the incentive to reduce waste in the first place. Our waste would disappear like magic, and it would be easy to forget that we were literally vaporising the earth’s resources in our kitchens. That’s definitely a downside.
Then again, it’s not likely that we’ll have one of these in every home. Not anytime soon. I suspect that the HERU will be picked up at the commercial level first. Waste is a more direct cost for businesses than it is for households, and the savings will be more obvious. The HERU could make a big difference, and while mine is a cautious welcome, I look forward to seeing how the technology develops.
- Feature image by Bas Emmen