Monday, November 17, 2014

Question of the Week: Do we need energy storage?

7 November 2014 by Patrick Smith , 

WORLDWIDE: Following the news that Siemens is developing a system to store thermal energy in rocks, Windpower Monthly asked experts whether there is a need for large-scale energy storage.

Siemens believes storage is necessary for greater integration of renewable energy
Siemens believes storage is necessary for greater integration of renewable energy

Question: Will utility-scale energy storage be necessary for the greater integration of wind energy?

Bentham Paulos - Principal, PaulosAnalysis

Grid-scale storage will have a lot of competition to provide integration services. This flows from the most basic fact of grid operations: everything backs up everything else. There is no need to have one thing dedicated to backing up one other thing (for example battery to solar panel, gas turbine to wind turbine) because every generator and every source of load is connected.
This results in a long list of tools that grid operators can deploy. For starters, they simply rely on the  power of statistics to reduce variations in both supply and demand. In a bigger sample size, variations are less likely to correlate with each other, making a smoother curve. A bigger pool also reduces the consequences of any one thing failing. A more interconnected grid is itself a solution to variable generation.

Next, from the perspective of the grid operator, supply and demand are increasingly interchangeable. With demand becoming more controllable, storage will have to compete not just with generation, but also with increasingly sophisticated demand response.
Add to this more flexible fossil generators, better wind forecasting and more frequent dispatch, and most of the problem is solved. Storage will have to be very cheap to compete.

David Elzinga - Senior project manager, International Energy Agency

Shares of variable renewable energy in power systems have increased dramatically in some countries, and the value of the flexibility that electricity storage technologies can provide will rise as the share of variable renewables in electricity systems increases.
Under current market structures, however, cost and performance is a major barrier to deployment of storage. IEA analysis, as featured in our Energy Technology Perspectives 2014, finds that storage, in itself, is unlikely to be a transformative force. Frequency regulation, load following and off-grid applications for electricity storage represent the most attractive deployment opportunities for storage in the near to medium term, and could spur cost reductions.Iin most markets, however, storage will be deployed only after maximisation of more economic solutions, such as thermal generation, thermal storage, transmission and distribution grid development, or demand response.
But our outlook also highlights two potential situations that could affect the use of storage in a low-carbon electricity system. The first is the use of batteries in electric vehicles (EVs). The cost of batteries for EVs is primarily paid by the buyer in return for acquiring mobility. In reality, most passenger EVs will be parked for most of the time (95%) and will spend much of that time connected to the grid. EVs can therefore provide flexibility to the grid through effective charging strategies. The cost for the EV storage asset, from a grid perspective, can be assumed to be relatively low since it is primarily paid for by the owner for car propulsion.
Also, in regions without access to electricity, especially in poor communities, small-scale battery services (such as for lighting) can help eradicate energy poverty and are already a cost-effective alternative to grid extension.

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