Extending our usage of renewable energy

How can we extend our usage of renewable energy?

Introduction: Renewable energy is something that is not new or unfamiliar to us. It has been around for many years already. However, these renewable sources all have their limitations, such as being too expensive to install, not having enough space to store, or not producing enough energy if the conditions to generate energy are not fulfilled. Hence, the key to making these sources of energy more prevalent and accessible is by finding a way to overcome these obstacles. Thankfully, the rapid advancement in technology has enabled us to have the solutions or at least some sort of solution to counter this limitation.

Body: The most widespread and practical sources of renewable energy come from solar and wind energy. Many of you would already know what these types of renewables consist of and are about generally. For reference, figure A explains the types of renewables and how it operates since it would not be the focus today. We will be covering the latest technology that helps to further extend our usage of these sources of renewable energy, rather than what they are. This further extends our implementation and utilization of more clean energy so that we can walk away from our traditional ways of energy production, which is fossil fuel burning that not only generates lots of emissions but also is a non-renewable commodity.

Figure A:

1.1: BESS (Battery Energy Storage Systems)

Body: When talking about the most practical renewable energy that we could potentially look to utilize, we talk about solar and wind, and solar especially. No matter which part of the world you go to, there will always be sunlight. It would be very wise to make use of this naturally occurring energy carrier we have been provided to the fullest. Traditionally, energy generated from solar panels cannot be stored and has to be used immediately. This creates some problems such as being unable to use energy during the night, providing enough time for this energy to be transported elsewhere, or being harvested for later usage in general. Hence, the key here would be finding storage systems to contain and channel our energy. Such systems are called BESS (Battery Energy Storage Systems).

There are many types of BESS, but the majority still stay within the up to 10 hours boundary for now. This is so because it is especially difficult to store energy generated in such an unfamiliar way. Thankfully, there are quite a few viable ways we can store both solar and wind-generated energy which we will be talking about further below. Though different types of BESS can be made up of different types of chemicals and materials, they still function the same way. BESS works by taking the energy produced by the solar panels in the form of Direct Current (DC) and converting it into alternating current(AC) for storage. Intelligent battery software is also encoded into BESS to take into account considerations like solar production and grid stability (grid refers to the wires that transfer electricity like overhead and underground wires, while stability usage refers to ensuring that areas with higher demands of electricity will be sufficiently supplied).

Some of the most commonly used BESS include lead-acid batteries, lithium-ion batteries, and flow batteries, mostly inspired by the usage of these systems in previous technologies like cell phones, computers, and many other high-tech. Usually, most solar panel developers would go for lithium-ion batteries as they can store more energy, and store for a longer period of time. They also help address the problem at hand which was grid stability and peak shaving (proactively addressing short-term demand spikes). There are longer-duration storage technologies currently still in progress development. One of them which could potentially store energy for more than 10 hours is the Tesla Megapack. The Tesla Megapack is a powerful battery storage infrastructure that requires only a relatively small amount of land and has the design of neat rows of several units. Each unit has the ability to store over 3Mwh of energy, which is enough to power 3600 homes for an hour. It also makes use of lithium-ion battery technology.

1.2: Thermal energy storage (TES)

Introduction: While battery storage is developing rapidly over the years, there are also alternatives we could take that help address the challenges that renewables face. One of them would be thermal energy storage. Thermal energy storage, in a nutshell, refers to heating or cooling a certain medium so that it can help store energy for later use. Many different technologies can be used for thermal energy storage. Depending on what type of thermal energy storage is used, excess energy can be stored for hours, days, or even months. Let's explore further how exactly thermal energy storage operates.

Body: Because renewable energy sources are intermittent, we need to harvest the energy during productive times for later use. Therefore, it is crucial that we find effective ways to store harvested energy. For thermal energy storage to work optimally, the medium that we use to store heat or cool needs to have certain properties, like having materials with high energy density, insulation for minimal heat loss, a chemically stable material, and a reversible process that can be done a countless number of times. These thermal energy storage systems are also known as thermal batteries. There is not just one type of thermal energy storage, but rather three - Sensible heat storage, Latent heat storage, and Thermochemical heat storage. We will be talking a little bit about what these 3 types of thermal storage systems are and how they differ.

Body: For latent heat storage, a Phase Change Material (PCM) is required. Essentially, a PCM refers to a special substance that stores and releases a large amount of energy as it transitions from one state to another. This is why it is known as a Phase Change Material, as the material undergoes a phase change process, while still retaining the same temperature. For example, when heat is absorbed by the medium, it changes from a solid to a liquid, or a liquid to a gas and stores that thermal energy meanwhile. However, it does not go over the point where it increases the temperature during the phase change. The characteristic of mediums used in latent heat storage enables the storage of energy. The ideal medium that would make the best candidate for a PCM would be silicon. Each material unit area of silicon can store 2.3 times more energy than a lithium-ion battery that BESS uses. Unfortunately, silicon is not the most practical candidate, thus other alternatives we use are paraffin wax and salt hydrates. Usually, the materials used have low boiling points.

Body: As for sensible heat storage, they make use of a similar concept. Sensible heat storage induces heat on mediums such that they increase their temperature, but not with the intention of changing their states, which is why PCM materials are not used. The material absorbs heat and increases temperature or can lose heat and decrease in temperature. Thus, the temperature is directly proportional to the amount of heat supplied to it, while latent heat storage maintains the same temperature throughout.

Body: In thermochemical heat storage, the concept of reversible changes applies as well. Essentially, what occurs is that a substance, usually gas or vapor reacts with a chemical known as the reactant to form a new compound. This new compound holds the ability to store heat energy, and when energy is needed, it undergoes a reverse chemical reaction and releases energy in the process. When we compare the 3 types of storage mechanisms, it is observed that thermochemical energy storage can yield the highest heat storage capacity without producing any thermal losses at all during its period of storage. The reaction, suffice to say, requires 2 substances. A simple example would be ammonia and water. Ammonia is able to absorb heat when it reacts with water and forms ammonium salts. However, the use of chemicals differ for different industries depending on situation.

1.3: Pumped Storage Hydropower (PSH)

Introduction: Pumped storage hydropower is also one other common storage system apart from battery storage. This type of storage takes electricity generated by intermittent sources to be saved for use during periods of high demand. PSH can be characterized into 2 different types, open-loop or closed-loop PSH. PSH can be characterized into 2 different types, open-loop or closed-loop PSH. Open-loop PSH has reservoirs that connect to a naturally flowing water body while closed-loop PSH has reservoirs that are not continuously connected to a naturally flowing water feature.

Body: The way that the PSH works with respect to the demand for electricity is this: When the sun shines and the wind blows, electricity is in high supply. So, water is pumped from low reservoirs to elevated-leveled reservoirs. During night-time or unproductive days for the various renewable energy sources, water is released from the elevated reservoir back to lower reservoirs, thus filling in the gap during peak demands and generating electricity. Pumped storage is the most dominant form of electricity storage for electric grids today. It is by far the largest capacity form of grid storage today. A report made by the United States Department of Energy Global Energy Storage Database (GESDB) states that the PSH accounts for around 95% of active storage installations worldwide, with 29GW of energy already installed in the U.S., and over 181GW of throughput capacity installed worldwide. The energy efficiency of PSH varies from 70 to 80%. Though hilly environments are ideal for installations of PSH, the global greenfield pumped hydro atlas lists more than 600,000 potential sites suitable for installation around the world, which is about 100 times more than needed to support 100% renewable electricity. Most of them are closed-loop systems located away from rivers, and other natural water bodies as part of preserving scenic beauty and tourist destinations.

1.4: Policies and regulations

Introduction: One effective way we can ensure that those carbon emission rates drop is by making all emitters drop their production of CO2. This can happen if governments rightfully make use of their power to ensure that carbon dioxide is not overly emitted and harm the environment. Governments are the people who impose laws regulations, policies, taxes fines, etc. Doing their part and helping in the pursuit of ecological balance, especially during these times, could potentially change things significantly.

Body: The power that the government holds plays a vital role in really bringing down emission rates. Apart from advocacy work and making investments in research and development of technology, governments can also implement supportive policies which would help incentivize the adoption of renewable energy. A Nationally Determined Contribution (NDC) is known as a national plan each nation must submit which involves climate-change mitigation, in terms of climate mitigation targets for greenhouse gas emission reductions.

Body: NDCs are at the heart of the Paris Agreement, an agreement that requires each party to prepare, communicate and maintain successive milestones that each country targets to obtain. This way, countries keep each other accountable and pressure each other to improve in their journey to reducing greenhouse gas emissions.

Body: Carbon pricing is referred to two types of policies, carbon taxes, as well as cap-and-trade schemes. Under the cap-and-trade system, companies are required to purchase a certain number of permits, known as carbon credits. These carbon credits represent your right as a company to emit a certain amount of greenhouse gases. These permits are tradable; hence companies can buy or sell them in the market. So, if a company finishes all its carbon credits, it could trade or buy extra credits so that they do not face the fines imposed for those who exceed their credits. On the other hand, carbon taxes impose a price per ton of CO2 emitted. This forces emitters to pay for their fair share of carbon emissions. Carbon taxing is typically favored by economists as a tax in such a scenario is the usual prescription from the economic theory. In addition to carbon taxes, many countries have also opted for trade-and-cap systems to be implemented, as trade-and-cap systems are often considered more flexible.

Body: On top of all this, there are also other policies that had a significant effect in reducing the emissions in specific sectors. The sector which has had the greatest impact so far is the power generation sector. Renewable Portfolio Standards (RPS) is a set of regulations that aims to increase the supply of renewably-obtained electricity by requiring commercial electricity producers to source a portion of electricity from renewable energy sources.

Body: Feed-in tariffs (FiTs) are yet another policy mechanism that offers a fixed, guaranteed price per unit of electricity generated by renewable energy sources. The rate is typically higher than usual retail electricity prices to encourage renewable energy investments as a financial incentive. Feed-in tariffs often involve long-term contracts which usually last from 10-20 years.

Ending: There are a lot more ways that the government can influence a country to shift greener, from home energy-efficiency requirements to fuel taxes and land-use regulations. Many of the ways the government can support this is by making use of its power of control rightfully. Overall, by implementing policies and regulations, governments cause companies and organizations to transition to cleaner alternatives.

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