Batteries to store alternative energies have already been on the market for several years, however, despite their benefits, the cost has not allowed this class of products to become widespread in Latin America. by Duván Chaverra A.
Energy storage appears as an alternative between energy demand and its transformation capacity. There are different solutions on the market, on a small, medium and large scale that allow energy to be stored in all its forms. However, in Latin America its use is little, mainly because of the cost. To delve into this topic we invite René Ruano Domínguez, a professional with more than 35 years of experience in energy systems and equipment and who has done multiple jobs in projects, execution and services of General Energy Engineering. The guest will talk about the different types of batteries available for this purpose, the advantages and disadvantages, as well as the implementation of these systems in Latin America. - What are the advantages and disadvantages of energy storage systems?
The balance between energy demand and supply has always been a complicated problem everywhere and has had a strong impact on both energy costs and the efficiency of energy generation, transformation, distribution and use systems, including emissions generated by fossil energy. The advantages: If we store clean energy and can release it sectorally or as close to the consumer at peak demand hours, then clean kWh could replace dirty kWh and reduce generation capacities to peak hours, costs, CO2 emissions, transmission, transformation and distribution losses. This is the essential reason for accumulating energy and the advantages of its exploitation and diversification. In the HVAC sector, cold storage facilities are known as a way to manage energy, using tanks or containers of ice water, using polyalcohols (ethylene glycol) or ice. Unfortunately it is not a cheap system, hence it is not widespread, but it is very advantageous. In this case we move the kWh that cost the most, those of the rush hour, by the kWh that cost us the least, those consumed in the early morning. In addition, when the peak kWh are released, distribution and transformation losses are reduced in the network, as well as generation, in case these kWh have been generated by low-efficiency Peak Plants. Hydro pumping or compressed air is used on a large scale to accumulate clean energy, whether generated by a hydraulic, wind or solar source, although the reasons are different: a) In hydraulic generation (hydroelectric), we accumulate the kWh at dawn
hydraulic. At that time the generation exceeds the demand. Stored energy
it is delivered in the hours when the demand exceeds the generation.
b) If the generation is by solar panels or concentrators, we accumulate
energy in the day to deliver it at dawn in the hours without sun.
c) In wind generation, we accumulate energy during the early morning or day, to
deliver it at the times of greatest demand or when the wind does not blow. In the case of medium and small scale, for residential, commercial photovoltaic systems, accumulating solar energy is advantageous, as it ensures deliveries at night or days without sun. The disadvantages: I can summarize them in environmental, mainly. Large reservoirs or dams at levels above hydraulic generators can negatively impact the ecosystem. That is why investments of this type require in-depth studies of this subject. Another disadvantage is that these investments are large-scale, very expensive and of great financial volume, very typical of developed or developing economies.
- Do these batteries generate pollution?
In some types (I mention the one with the greatest presence, lead – acid), their materials can pollute the environment, but with the development of the recycling industry, these problems have been attenuated and depends a lot on personal care or individual or business interest to proceed with Good Practices. Many countries have established their own regulations that control disorder, pollution of the workspace and nature. - Why is the use of solar energy not massive in Latin America?
The main cause is price. It is unfortunate that these applications cannot be quickly extended in our countries, and I hope that soon this reality will change. In many, if not all, Latin American countries, solar energy can play a strategic role in sustainable development. There are many regions to be electrified, large areas difficult to access by electricity grids. Creating small- and medium-scale renewable electricity generating centers, without the need to extend electricity transmission networks, is a practical solution that can take electricity anywhere, with a significant social and environmental impact. - Why is it expensive to install a residential, commercial or business solar energy production system?
I said before that even these systems do not have attractive recovery times, mainly for small or medium-capacity pockets. It takes the will and government support for the market mechanism to work. In the U.S., the introduction of these technologies is promoted with federal aid and yet, when doing the math, the return is not at all stimulating. It is important to highlight the following: the price that has been historically established for energy carriers of fossil origin, in the international market, is contradictory with the economic and financial analysis of the investments of substitution of the same and with its polluting nature. The structure of formation of these prices takes into account lowering them as much as possible or subsidizing them, to avoid social collapses and brakes on development. It is a contradiction of the world market, it goes beyond the will that we all have to go to clean energy, to its rapid replacement. Therefore, we are facilitating the continued increase in CO2 emissions into the atmosphere. There is no brake possible. - What is the useful life of the batteries?
It depends on your technology and the practice of your operation. Lead-Acid has a short life: about 3 or 4 years. In practice, they must be replaced in about 4 years. The tubular ones last up to 8 years. In new technologies we find data that promise up to 20 years, for Vanadium (Redox) batteries and new systems. - What is the storage capacity of batteries vs. the capacity needed in a home?
It's an estimate. The autonomy of the system decides and weighs on the value of the initial investment. The autonomy is equivalent to the days we want to ensure renewable electricity, considering cloudy, rainy or sunless days. In isolated systems, where the electricity grid does not reach, a greater number of days of autonomy are assumed. We will take two days as a factor of autonomy. To the extent that we assume the factor mostly, more security will be, but more batteries and with it, the system will be more expensive. This data decides when sizing the battery bank. The average installed electrical load that a small, typical home can have, without considering air conditioning, micro wave, (including washing machine, appliances, lighting), can be on the order of 1,000 Watt in AC. That typical household could consume about 5,000 Wh/day, between 150 and 200 kWh per month.
Consumption is made between 8 and 10 hours a day and is variable. With this basic information, the size and amount of the initial investment can be estimated. The payment of the bill of this consumer can be in the order of US $ 20.00 to US $ 40.00 thinking of a price of the average kWh between US $ 0.13 and US $ 0.20. Considering about 5 hours of average solar radiation per year, 1,000 Wh/m2, standard panel efficiencies 0.9, inverter and regulator 0.85, a panel of 12 VCD / 118 W / Isc= 9.3 / Imax 8.9 to 9.0 etc, system at 24 VCD, batteries of 250 Ah / 24VCD, with a VB discharge voltage of 2 volt and a maximum depth of discharge of 80% (Pmd= 0.8), the cost of these batteries is us $ 280 to US300 each and panels between US $ 90 and US $ 100 / panel of 100 watt. It is necessary to include the rest of the components, the load inverter, the regulator, the wiring, the means of measurement or meter, the supports and hardware to hold and be able to reorient the panels, the cost of the installer, the conditioning of the premises where the components of the system will be installed, that makes the estimated investment of about US $ 7,000. There are those who decide and the assembly is done by oneself and obtains its advantages, but still considering
kits, where we buy everything at once and HUM, the amount is between US $ 6,000 and US $ 7,000. - In which sectors is this investment competitive?
Where the electricity grid does not reach. Their competitiveness is also stimulated in countries that provide incentives and aid, or there is the exchange of coal quotas, or a combination of the previous two and thus enhance the introduction of renewable sources. On our website www.energianow.com there are several publications about the photovoltaic system, which describe the system, its components and offer comparative data between these technologies. To highlight
Types of batteries
- Lead - Acid BATTERIES PD. (Deep Click): they are on the market and are the lowest priced. They are used to form battery banks. Life cycle: between 4 to 6 years. They are batteries that withstand deep discharges, equal to or greater than 80%, which makes them different from automotive batteries, with small discharges. - Lithium-ion battery: higher energy density but much more expensive, compared to the Lead-Acid (PD) battery, even with the tubular type. Of the dry battery type, the electrolyte is formed by a paste of lithium salt, of very low humidity. They have a high load density (less mass per unit - power) and are being produced on a large scale, due to the demand in electric motor vehicles, so a reduction in their costs is expected in the medium term.
- Molten Salt Batteries (liquid sodium batteries): they offer high energy density and delivery power. They are used to store the energy contained in molten salts (cathode) that when released react with nickel electrodes (anode). They are known from sodium-sulfur and lithium-sulfur salts. - Ultra or super capacitors: this system stores electrostatic energy. Compared to standard batteries, they have very low density, so they store less energy, but have a high discharge power and perform charge/discharge cycles quickly. They are currently operating in solar installations. It is an expensive technology, and now they begin to be produced commercially, looking to lower price. It has a scope of application in vehicles, residential photovoltaic systems and others. - Flow Batteries: to store large amounts of photovoltaic energy, (Large capacities). The operation is similar to that of a traditional battery. The great advantage of these systems is that the energy storage capacity is limited exclusively by the capacity of the tanks that store the electrolytic solution. Iron electrodes are being studied for this type of dynamic battery, which will lower the cost per kWh, as iron is much cheaper than other metals.
