Cutting carbon emissions while meeting the growing energy needs of an expanding global population requires innovative, pioneering solutions. One such solution is micro-grids powered by renewable energy.
Among the solutions ABB championed at the recent COP22 climate change conference in Marrakech was micro-grids. These small-scale grids are exceptionally flexible, bringing power to remote communities and facilities that might otherwise have to wait years or even decades for a grid connection. They are also ideal as back-up power sources for grid-connected installations in places prone to power outages.
Integrating multiple distributed generation sources
Micro-grids enable the integration of conventional diesel and gas, and/or renewables such as solar photovoltaic (PV), wind, hydroelectric, tidal and even thermal schemes like combined heat and power (CHP), together with energy storage. A micro-grid provides the overall control to coordinate these resources to meet the requirements of industrial, residential or consumer loads.
Enormous potential in Africa
In sub-Saharan Africa where two-thirds of the population – 620-million people – live without power, microgrids could dramatically speed up economic development.
Experience shows that when a community gets electricity, the benefits start to be realised almost immediately. Productivity goes up because people are able to work at night and avoid searing daytime temperatures. Children were able to study after dark, and the number attending school doubled in two years. Electricity also replaced kerosene, lowering fossil fuel emissions, reducing the danger of fires and easing health problems.
They lend themselves perfectly to island communities and remote villages and towns. A notable example is the Azores island of Faial in the Atlantic, population 15 000, which has a self-contained microgrid powered by five wind turbines and six oil-fired generators. A similar solution is being installed at a remote windfarm called Marsabit in northern Kenya, where the population of 5000 relies exclusively on a wind- and diesel-powered microgrids.
Others include the solar- and diesel-powered microgrids in the remote towns of Marble Bar and Nullagine in Western Australia. Thanks to grid stabilising technology, which enables high solar-energy penetration, the towns now obtain close to 60% of their power from solar generation, saving approximately 400 000 litres of diesel and 1100 tonnes of greenhouse gas emissions each year. Optimisation of this complex energy mix was made possible by ABB’s flywheel grid stabilising system that extends battery life, balances intermittencies from the wind farm, and reduces diesel consumption.
Important applications in industrial and commercial sites
Micro-grids help to ensure power availability and quality. If they are connected to the main power grid, they also help to improve grid resiliency and reliability, for instance during extreme weather events. In cities affected by frequent power cuts, they are a clean and efficient alternative to diesel generators, which are highly polluting and expensive to run, pushing up the cost of doing business. In Kenya, for instance, 57% of businesses own generators, according to the World Bank.
Renewables-powered microgrids also use diesel for back-up power when the wind stops blowing or the sun goes down. However, thanks to advances in energy storage technology it is now possible to store excess renewable energy, further reducing the need for diesel fuel.
For instance, ABB has delivered its containerised PowerStore solution which included a battery energy storage system for an integrated solar-diesel micro-grid at its own premises in Johannesburg, South Africa. The micro-grid can seamlessly disconnect and reconnect to the main grid in case of outages. It can run entirely on solar power, and has resulted in a reduction of over
1000 tonnes of CO2 per year.
The ability of micro-grids to seamlessly separate and isolate themselves from the main grid when needed is an increasingly important consideration, especially for humanitarian organisations. The International Committee of the Red Cross (ICRC) recently asked the company to supply solutions for a micro-grid at its global logistics centre in Nairobi, Kenya, which experiences frequent outages and suffers from power quality issues. Here again, the company is providing a containerised battery energy storage system that works in parallel with the on-site solar/diesel generation, seamlessly disconnecting and reconnecting to the main grid in case of outages. This ensures a reliable power supply for the centre, which delivers food and other essential items like medicines and relief supplies across the African continent.
As these examples demonstrate, the technology needed for the deployment of micro-grids is now readily available. In addition, the cost of key technology components, such as solar photovoltaic and battery storage, will continue to decline as a result of the economies of scale and innovations in materials and manufacturing. Renewable energy is, in many cases, the most economical solution for electrification, with the levelised cost of electricity (LCOE) being lower than diesel, provided the latter is not heavily subsidised.
Some countries have incentive-driven renewables programmes, but very often no framework specifically for micro-grids. This is starting to change: the US Department of Energy, for instance, which is working to encourage the development and deployment of micro-grids, is promulgating federal and state policies to end regulatory uncertainty, which is in turn expected to unlock the level of investment required to scale up the industry.
With the right financing and business models which take account of the regulatory environment, micro-grids could help to trigger development in rural areas, improving the lives of hundreds of millions of people, while helping to meet national and global emissions targets.
Contact Regula Niehus, ABB, Tel 010 202-6156, email@example.com