Gardens by the Bay a test site to convert rubbish into hot water, soil conditioner
The pilot system at Gardens by the Bay can process up to one tonne of waste per day.
SINGAPORE — As a step towards zero-waste and lower carbon emissions, national utilities provider SP Group (SP) has teamed up with Gardens by the Bay to use a system that will turn waste at the garden into thermal energy and soil conditioner.
The plan unveiled on Thursday (June 6) is to convert up to one tonne a day of plastic, food and general waste produced at Gardens by the Bay into thermal energy and into biochar, a type of carbonised biomass that could be used to make soil better for plants to grow in.
This process involves compact gasification technology. A container truck is fitted with machines that carry out the process of transforming waste into thermal energy, to be used to generate hot water for use at the garden’s food and beverage (F&B) outlets.
Gasification is an alternative to incineration and it reduces waste to only 5 per cent of its original volume. There is also no need to sort plastics from general or food waste.
Ideally, all waste disposal will be done on-site, so there will be no need to transport waste to the incinerator, easing traffic conditions and reducing carbon emissions.
The project has the backing of state investment firm Temasek Holdings.
At a media briefing, Mr Jimmy Khoo, chief executive officer of Singapore district cooling at SP Group, explained that while this technology is not new, it is a decentralised and compact district-level solution that could solve some of the problems Singapore faces with waste disposal.
“Earlier on, this solution is not so common, but we think that this is a good fit for Singapore because of landfill challenges and we are highly urbanised.” Mr Khoo said.
Mr Thomas Seow, senior director for research and horticulture at Gardens by the Bay, explained the benefits of biochar as a soil conditioner: “Biochar helps the plants to retain nutrients better, retain water better. It is like charcoal to soil. Some gardeners add charcoal to plants, hoping that the plants will retain such (things).”
However, biochar is yet to be used on the plants, as more research would be needed on the composition that would ensure optimal growth of the plants. It is understood that biochar may be used on plants later this year.
“The study and research is not very conclusive as yet, so now we are gathering data to ensure that we get robust results.” Mr Seow said.
The main aim of the system is towards a zero-waste solution, one in which almost nothing will be wasted but is continuously used instead.
Mr Khoo added: “(The) idea is trying to harness different components of the waste — 5 per cent (of biochar) is a lot less, but even at 5 per cent, it is a useful product, rather than it going to the landfill.
"Overall, because of this process, it reduces carbon dioxide emissions and energy can be harnessed, which produces the hot water, that otherwise will need electricity to produce. It saves energy because the same energy from the system is used to produce that.
"Finally, it also reduces the filling up of landfill.”
The conversion process starts by loading a bag of waste into the gasification chamber, where the waste will be converted from solid to carbon monoxide and hydrogen. After that, heat released can be used to sustain the gasification process, also known as the exothermic process.
The combustion process can be used to generate more heat to make hot water.
Although the process is at the pilot stage, both Mr Khoo and Mr Seow have been encouraged so far and are confident of the project.
“Beyond Gardens by the Bay as a pilot, this can be deployed in other areas as well, like on campuses and hospitals, where there is waste.”
For now, the machine operates eight hours a day, processing about 320kg of waste. If the machine is to operate for 24 hours, it is capable of processing one tonne of waste.
The agreement between SP Group and Gardens by the Bay was signed at the Ecosperity Conference 2019, witnessed by Mr Masagos Zulkifli, Minister for the Environment and Water Resources.
The project has been underway since last year and trials started at Gardens by the Bay only in early May this year.
