August 22, 2011. The Green Piece Column.
With electric cars inching ever closer to a mainstream reality, questions are raised as to how the grid will cope with increased demand.
One of the potential answers appears to be energy storage. In 2009, for example, the US Stimulus Plan helped finance research into energy storage with smart electrical grids. Here we take a closer look at the concept and why it is needed.
Why store electricity?
As electricity is transferred in a closed circuit it cannot be stored as electrical energy. Therefore even though power plants seemingly generate all of the energy we need, any changes in demand could not be accommodated without either reducing demand elsewhere or by storing the electricity in another medium.
With the world’s population growing and electric cars about to emerge, there are increased environmental and economic pressures placed on the use of fossil fuels, with alternative energy from renewable sources becoming more important. However, renewable energy is arguably even more reliant on energy storage to make it efficient.
To illustrate the point, wind blows intermittently and so some form of storage is needed for periods of calm; while solar energy is not available on cloudy days or during the night-time, and so must be stored to compensate for the loss of sunlight. As an example, in June, California experienced an 1800MW drop in electricity production during one hour due to wind fluctuations.
So what is the answer?
There have been many potential solutions for energy storage discussed over the last three decades. In the 1980s, for example, a number of manufacturers looked into thermal energy storage to meet the growing demand for air conditioning during peak hours and today several companies manufacture these systems. One of its most popular forms is ice storage as it can store more energy in less space than water storage – it works by creating ice at night when electricity is less costly and then using this to cool the air in the buildings during hotter periods.
When most of us think about energy storage, we think about batteries – and they were also one of the earliest solutions for storing energy for electrical purposes. However, they have been previously limited in their use in electric power systems because of their relatively small capacity and high cost. However, since the start of the 21st Century there have been significant advancements in battery technology and capacitors are well-equipped to deal with the intermittency issue of solar and wind power.
In terms of the United States grid however, pumped hydro is seen as the incumbent technology, followed by compressed air and then the relatively new concepts such as flywheels and electrochemical batteries. The newer technologies are more expensive but also more flexible to deploy.
There is also the idea of grid energy storage which allows energy producers to send excess electricity over the electricity transmission grid to temporary electricity storage sites which become providers when demand for electricity is at its greatest. There is also the vehicle-to-grid variant, where modern electric vehicles will be plugged into the energy grid and can release the stored electrical energy from their batteries back to the grid when needed.
Added pressures
With the increase of renewable energy portfolio standards, the need for energy storage is gathering momentum.
Though not a major issue today, by the time renewable sources constitute 20-30 per cent of energy generated on the grid, there will be no guarantee of continuous supply without storage. This could place the US in particular in a stand off between the Federal structure of the markets, renewable implementation goals and the power producers that generate energy for the grid.
Our verdict – Where there is chaos there is opportunity
Changing grid architecture will create incredible opportunities in the marketplace.
Most developed countries are only storing four-five per cent of their energy; with the USA even less at 2.2 per cent. As such energy storage will need to play a firm role as a new market for electric cars is developed.
Its influences can already be seen in countries such as China, which has made energy storage a fundamental part of its five-year renewable energy plan; Mexico, which is adding a 1GW energy warehouse to improve its reliability; India, which is deploying an energy storage plan to address the 1.2 per cent loss in its GDP due to unreliable power; and in the state of Abu Dhabi, which is implementing a 1.35GW storage system with the intent of peak load shifting.
As such, the emphasis should now be placed on serious research and development into energy storage – and not only energy storage itself, but also into the systems that will make it more efficient, such as secondary life batteries and how to incorporate vehicle fleets into grid storage solutions. Only with the correct systems in place, and suitable investment into energy storage infrastructure, can we be confident of meeting the demands of electric car use in the most efficient and environmentally friendly way.
Faye Sunderland.
