US Researchers Build Wastewater Energy Generator
A new technique that combines two forms of renewable energy—using bacteria and saltwater—generates more electricity than either alone, while cleaning wastewater at the same time. Researchers at Pennsylvania State University recently built the prototype device that both generates electricity from wastewater while simultaneously treating it.
The technique could be adopted in developing countries to provide clean water and power for homes, according to the team.
Domestic wastewater contains nine times more chemical energy than the energy required to treat it—an amount that would be nearly enough to maintain the entire US water infrastructure, according to the researchers.
Similarly used reverse electrodialysis (RED) systems have been applied to generate renewable energy along coastlines, using fresh water and seawater to generate an electrochemical charge between two intermittent chambers separated by membranes. The problem with that process is that it requires a large number of membranes and must be located by the sea.
The new technology, however, reduces the number of membranes used and uses organic matter to create the electric current—in this case wastewater. Using microbial fuel cells (MFCs), the system bypasses the need for salt water by using ammonium bicarbonate solution as a substitute, allowing it to be used in areas far from the ocean.
Using waste heat from local industries, the ammonium bicarbonate would be constantly recycled in the system.
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"If we treat waste water in just a microbial fuel cell, we don't create much power and it takes a long time," lead researcher Professor Bruce Logan told BBC News. "In our process, we have the MFC part which is treating waste water and creating energy, and we have the RED stack which is just boosting that process, it's making it happen more efficiently."
Though the technology offers promising solutions to developing countries in terms of clean water and power generation, it would initially be used to treat water in inland areas while gaining a bit of extra energy from wasted heat.
Major move forward for UK’s nascent marine energy sector
Although the industry is small and the technologies are limited, marine-based energy systems look to be taking off as “the world’s most powerful tidal turbine” begins grid-connected power generation at the European Marine Energy Centre.
At around 74 metres long, the turbine single-handedly holds the potential to supply the annual electricity demand to approximately 2,000 homes within the UK and offset 2,200 tonnes of CO2 per year.
Orbital Marine Power, a privately held Scottish-based company, announced the turbine is set to operate for around 15 years in the waters surrounding Orkney, Scotland, where the 2-megawatt O2 turbine weighing around 680 metric tons will be linked to a local on-land electricity network via a subsea cable.
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Described as a “major milestone for O2” by CEO of Orbital Marine Power Andrew Scott, the turbine will also supply additional power to generate ‘green hydrogen’ through the use of a land-based electrolyser in the hopes it will demonstrate the “decarbonisation of wider energy requirements.”
“Our vision is that this project is the trigger to the harnessing of tidal stream resources around the world to play a role in tackling climate change whilst creating a new, low-carbon industrial sector,” says Scott in a statement.
The Scottish Government has awarded £3.4 million through the Saltire Tidal Energy Challenge Fund to support the project’s construction, while public lenders also contributed to the financial requirements of the tidal turbine through the ethical investment platform Abundance Investment.
“The deployment of Orbital Marine Power’s O2, the world’s most powerful tidal turbine, is a proud moment for Scotland and a significant milestone in our journey to net zero,” says Michael Matheson, the Cabinet Secretary for Net-Zero, Energy and Transport for the Scottish Government.
“With our abundant natural resources, expertise and ambition, Scotland is ideally placed to harness the enormous global market for marine energy whilst helping deliver a net-zero economy.
“That’s why the Scottish Government has consistently supported the marine energy sector for over 10 years.”
However, Orbital Marine CEO Scott believes there’s potential to commercialise the technology being used in the project with the prospect of working towards more efficient and advanced marine energy projects in the future.
“We believe pioneering our vision in the UK can deliver on a broad spectrum of political initiatives across net-zero, levelling up and building back better at the same time as demonstrating global leadership in the area of low carbon innovation that is essential to creating a more sustainable future for the generations to come.”
The UK’s growing marine energy endeavours
This latest tidal turbine project isn’t a first for marine energy in the UK. The Port of London Authority permitted the River Thames to become a temporary home for trials into tidal energy technology and, more recently, a research project spanning the course of a year is set to focus on the potential tidal, wave, and floating wind technology holds for the future efficiency of renewable energy. The research is due to take place off of the Southwest coast of England on the Isles of Scilly