‘Vast’ energy value in human waste – UN
Biogas from human waste, safely obtained under controlled circumstances, is a potential fuel source powerful enough to generate electricity for up to 138 million households, says the ‘Valuing Human Waste as an Energy Resource’ report, produced by the UN University’s Canadian-based Institute for Water, Environment and Health (UNU-INWEH).
It estimates that the biogas potentially available from human waste worldwide would have a value of up to $9.5billion (£6.3 billion) in natural gas equivalent.
According to the report, once human waste has dried and charred, it is similar in energy content to coal and charcoal, with the potential to produce two million tonnes of charcoal-equivalent fuel, which in turn can help reduce the destruction of trees.
In addition, the report emphasises that biogas is approximately 60 per cent methane by volume and can be generated through the bacterial breakdown of faecal matter through anaerobic digestion (AD).
Human waste not a liability but ‘improving our environment’
The global health and sanitation benefits that would come from using human waste for energy are also explained in the report. It reads: “The large energy value would prove small relative to that of the global health and environmental benefits that would accrue from the proper universal treatment of human waste.”
Figures released by the UN show that 2.4 billion people lack access to improved sanitation facilities and almost one billion people do not use toilets at all, instead going in the open.
Using these figures, the report states: “If the waste of only those practicing open defecation was targeted, the financial value of biogas potentially generated exceeds $200 million (£132 million) per year and could reach as high as $376 million (£250 million).”
The energy value of this could, it is hoped, generate enough electricity for around 10-18 million households. If processing the residual faecal sludge, meanwhile, it is estimated that it would yield the equivalent of 4.8-8.5 million tonnes of charcoal, which could then be used to power industrial furnaces.
'Multi-dimenstional financial case' to be made for deriving energy from human waste
UNU-INWEH Senior Research Fellow Chris Metcalfe, who co-authored the report, added: “We recycle the nutrients in human waste effectively via agriculture in many places, yet the potential energy value of human waste has been given much less attention to date.
“Challenges are many but clearly there is a compelling, multi-dimensional financial case to be made for deriving energy from waste.”
The report, ‘Valuing Human Waste as an Energy Resource’ says: “Rather than treating our waste as a major liability, with proper controls in place we can use it in several circumstances to build innovative and sustained financing for development while protecting health and improving our environment in the process.”
Waste to Wealth
The Waste to Wealth national framework is one of a number of pilot projects in Africa for the systematic collection of human waste to provide energy.
Funded by Grand Challenges Canada and UNU-INWEH in partnership with the Ugandan Ministry of Water and Environment, the Waste to Wealth framework aims to help bridge the financial gap for sanitation in Uganda through the efficient reuse of human faeces.
The Waste to Wealth project focuses on the potential of using human waste in rural growth areas, small towns and high density institutions such as schools and prisons. The project hopes that through using the biogas and residual material left from the faeces as an economic resource, they can then provide a return on investment in bioenergy technologies.
The project consists of two phases. The first if to identify value in human waste and provide incentives to use toilets in areas where such facilities are uncommon.
The second phase of the project is proving the success of the concept through a series of proposed initiatives. One of these includes equipping a Ugandan prison with a £66,000 system requiring approximately £3,500 in annual operating costs, expected to pay for itself through fuel cost savings within two years.
Biowaste buses used in UK
Animal faeces are already being used as valuable biofuel, although on a much smaller scale to that suggested by the UN-INWEH. Reading Buses currently has a fleet of 34 vehicles running on biomethane compressed natural gas (CNG) recovered from cow manure.
With only a few cities across the UK implementing the use of biogas in public transport, Bristol’s Bio-Bus last November has been the first human faeces-fuelled addition.
Bristol’s aptly-named ‘Number 2’ bus, decorated with images of people sitting on toilets, successfully transports up to 40 passengers across the city while running on the gas recovered from human waste.
Commenting on the research behind this, Mohammed Saddiq, Managing Direcor of GENeco says: “In terms of the biogas, we knew that biomethane could be used as a fuel, and when we started research the applications in which it could be used, we found that it could be used in buses.”
Read the full report ‘Valuing Human Waste as an Energy Resource’.