Battery storage: The answer to renewable energy intermittency

Big energy storage

Renewable energy technologies play a major role in mitigating pressing societal challenges such as climate change and resource depletion. Among the many renewable energy technologies, solar photovoltaic (PV) power and wind power have a particularly large potential for electricity generation due to their wide applicability and high efficiency. However, despite the many advantages, there remain major barriers that obstruct a more widespread implementation of grid-tied solar PV plants and wind power. As a result of the dependence of PV panels on solar irradiance, solar energy generation is only limited to daytime, depends highly on local weather conditions and fluctuates strongly over the course of the year. Moreover, the energy generated by wind turbines has a similar fluctuating nature due to its strong dependence on local wind speeds. This irregular generation of renewable energy is changing the dynamics of energy supply and demand and requires new innovative approaches for energy companies to stay on track.

Intermittency in the energy mix

Until now, because there was simply no efficient technology to store energy, most grids have been built on the just-in-time principle, in which energy is generated and almost instantly transported to the end user. Therefore, grid-operators cope with the intermittency from renewables by forecasting future load and including fossil fuel electricity generators to adjust to sudden rises and falls in the output from renewable energy. During this process, the electricity produced by generators is continuously increased and decreased, which is very inefficient and often results in an increase in emissions per kWh produced. Because, over the past decade, the portion of renewably generated energy in the energy mix has significantly increased, it has become much harder for grid-operators to foresee fluctuations in the total energy supply. Moreover, since renewable energy is on the rise and expected to become more dominant in the energy sector, some warn that its intermittency could eventually pose a serious threat to the stability of our electricity grids. In addition, energy companies are forced to deal with a larger number of small-capacity energy units, as a result of decentralized energy production from renewable energy and solar PV panels in particular.

The potential of energy storage

So are there any solutions to the upcoming threat from renewables to our power grid stability? According to Dunn et al (2011), energy storage would be very effective at smoothing out energy flows and balancing out electricity supply and demand. They argue that the storage of energy decouples the generation of energy from the supply of energy and therefore adds a time dimension to the picture. As can be seen in figure 1, whenever the solar supply is higher than the grid demand, energy storage could effectively store the excess energy for later use. In addition, it would enable energy companies to use the energy storage as a buffer and to only produce electricity when generation costs are lowest.

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Figure 1: This figure displays the benefit of energy storage of saving excess energy for later use. Source: https://www.renewableenergyworld.com/articles/2011/11/solar-intermittency-how-big-is-the-problem.html

Batteries are the answer

Over the past century, engineers have come up with different technologies to store energy after generation. However, apart from pumped-storage hydroelectricity, many have not been implemented on a large scale due to problems concerning scaling, price, and implementation. Recently, battery storage systems have been recognized to have a great potential in improving energy grid stability. While battery storage had always been too expensive and impractical for actual implementation in energy grids, the use of battery storage is becoming more and more attractive, as a result of lower product prices, smaller battery sizes and higher efficiency rates. Apart from this, batteries are known to have a lot of desirable features, since they have a long cycle life and low maintenance costs. Over the past decade, the price per kWh of lithium-ion batteries has even shown such a rapid decline, that innovative companies such as Tesla are currently producing battery storage systems for residences at competitive prices, while others are manufacturing gigantic storage systems capacities of 20-50 megawatt.

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Figure 2: Tesla’s revolutionary commercial home battery system: the Tesla Powerwall. Source: http://www.businessinsider.com/tesla-selling-powerwall-solar-panels-home-depot-may-help-business-2018-2

Increased flexibility with smart grids and battery storage

While the application of battery storage in our electricity grids by itself is very promising, it will have an even more important role in reaching the full potential of so-called ”smart grids”. While battery storage systems will slowly be implemented into our energy grids, smart management of electricity flows will become more and more important and will ultimately dominate the power network as it seeks to minimize costs and optimize the efficiency of power transport. Power will no longer flow in one direction from the energy company to the consumer, but instead will be highly dynamic, as computer-generated algorithms determine the flow of energy. In this process, it will be essential that the widely dispersed grid-connected battery energy systems are accessible to these “smart” systems, as they can collectively be treated as one big resource to fuel their applications. The use of batteries in “smart” systems is demonstrated in a recent research by the University of Delft, where they use charging algorithms to use electric vehicle (EV) batteries for storage and are able to optimally charge EV’s based on EV user requirements, distribution network constraints, energy prices, demand for ancillary services and solar forecast information.

Conclusion

While this all may sound a bit futuristic, the technology regarding battery systems is advancing faster than we think and will be key to working around the intermittent nature of renewable energy. Especially in combination with smart grid technology and the use of advanced meters for data collection, battery systems could enable a more flexible grid with interconnections between different energy users, energy companies and perhaps even countries. This will be essential in building up a sustainable and renewable energy dominated power system.

Sources

1. Chen H, Cong TN, Yang W, Tan C, Li Y, Ding Y. Progress in electrical energy storage system: A critical review. 2009;19(3):291–312.

2. Dunn B, Dunn B, Kamath H, Tarascon J. Electrical energy storage for the grid for the Grid!: A Battery of choices. 2011;334(6058):928–936.

3. IRENA. Battery Storage for Renewables!: Market Status and Technology Outlook. 2015. 60 p.

4. The National Energy Technology Laboratory. ENERGY STORAGE–A KEY ENABLER OF THE SMART GRID. 2009. 16 p.

 

 

 

5 thoughts on “Battery storage: The answer to renewable energy intermittency

  1. This looks like an interesting solution to the intermittency problem. However, batteries are rather damaging to the environment. How will this problem be tackled if we want to apply batteries on such a large scale?

    Julian

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  2. Thanks for your blogpost! I just have two questions. First, you did not mention the negative sides of batteries. As far as I know, the production of batteries requires a lot of energy but is also very polluting. Do you know if the newer-generation batteries are less damaging to the environment? Second, you say that solar and wind and desirable due to their high efficiency and applicability. But doesn’t the physical efficiency of solar panels reach max 30% or so? Or by efficiency do you mean in relation to other energy source where losing energy through the process of production to reaching the consumer is not a problem for renewables as we basically have an infinite amount of energy to start with?

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  3. Yes Julian you are right, maybe I should have mentioned something about the environmental issues surrounding battery storage. It is true that a lot of batteries and lithium ion batteries in particular contain substances that are bad for the environment if released. However, I personally believe there are ways to work around this. For example, Tesla mentioned that they will be setting up an onsite recycle program capturing nickel, aluminum and lithium for use in new battery cells. Why would they do this? Well there might also be an economic incentive for companies to recycle batteries after use, as recycling could save them money. Also if battery storage becomes more and more popular, policies could be made to regulate the process of recycling and mining for battery substances to bring the pollution to a minimum. Hope this answers your question.

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  4. Good point. I hadn’t really thought about the production costs of batteries until now (more about the pollution after use). The mining of substances such as Nickel is known to be responsible for about 20% of the total production costs, while 80% is due to the processing of these substances in order create the final battery. However, we should not forget that the commercialization of large batteries (also for EV’s) is still at its beginning phase and that due to economies of scale and new production methods it is likely to become a lot less polluting very soon. So newer-generation batteries will probably become less damaging for the environment. When talking about efficiency I mean the process from absorbing a particular form of energy (wind energy, sun energy) and transferring it to electrical energy, which for wind power and solar is a very efficient process relative to other renewable energy technologies.

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  5. Hi,

    Thank you for your post, Very interesting and I agree with you that batteries could form a viable alternative to tackle the intermittency in renewable energy sources. And I do think that the environmental impact of the mining and production for these batteries are more manageable compared to the CO2 emitted by fossil fuel power plants.

    The impact of mining can be narrowed down to very specific locations by which processes can be implemented to reduce the impact. However, as of now, these processes are costly. A solution to that problem could be to divert funding from fossil fuel plants to research. In order to divert this funding, the energy mix needs updating and the grid especially.

    To tie into the point made on the efficiency of solar PV, there is a maximum efficiency of 23% at the very moment. Most panels are centred at around 15-20%. The real problem lies in the loss of electricity in storage. So when that problem is addressed and the loss is minimised, batteries can form as a reliable aspect in the energy transition towards renewable energy sources. I am not sure whether new batteries will reduce that loss, or how different other processes are able to contribute to the innovation, do you know?

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