Solving the energy storage problem

Around the world, the use of wind and solar farms is increasing as the efficiency of panels and wind generators increase and production costs fall. In the global north, the large renewable energy plants feed power into national grid systems which means that we can reduce our carbon impact by using the gas, coal and oil fired power stations less. But, there is an issue. Whilst we can produce plenty of energy from energy farms, we have not yet really figured out how to store the megawatts of energy efficiently. During a cycle ride from London to Gibraltar last year, I passed through many wind farms in France and Spain. On windy days, there were times when only have of the turbines were not turning. So whilst we have all of this infrastructure, the maximum benefit cannot be realised as we do not have the technology to facilitate the mass storage of electricity.

For smaller solar systems like the ones we would use in the aid sector to power a school or a clinic, the same power storage problem exists. In most countries we store energy in lead acid batteries or some other variant. The use of Solar systems can reduce the carbon footprint, but at the same time we are producing a lot of environmental waste which is not good for the communities where the aid sector is meant to be “doing no harm”

The Battery Problem: The most widely used component in a small solar system is the lead acid battery. The same battery as we use in vehicles. In a vehicle, the lead acid battery normally lasts up to three years which is its expected life. This is because the engine will keep the battery charged. In a solar system the lead acid battery may last two years if we are lucky. Unlike in a vehicle, the battery will frequently be drained to less than 50% of its capacity. If this happens often, longer term damage occurs in the battery cells. The hot climates where NGOs operate also has a negative effect on the battery shortening its life further.

Given the short life span of lead acid batteries, the by-product of the green solar systems is a lot of toxic waste. This is can be a massive issue in developing countries where they are not geared up for recycling.

Lithium Ion batteries are often seen as a good alternative to lead acid batteries because they can hold more charge. But there are some major disadvantages. Lithium Ion batteries contain some very toxic chemicals and have a troubled history of catching on fire. Most airlines will not transport larger lithium batteries due to the fire risk.

An alternative approach:  There are better technologies and in the future we will see innovation come from the automotive industry.  Tesla and other manufactures of electric cars are working hard to develop battery technology which will allow electric vehicles to go much further than they can today. As vehicles move from petrol and diesel to electric, the mass production of new battery technologies will bring the cost of energy storage down. Where the automotive industry produces answers for energy storage, in the aid sector, we will be able to take advantage of new battery technology for our solar systems.

We have been using electric vehicles for many years and there are already battery technology we can use now to make our solar systems more sustainable. Schneider Electric uses Nickel Sodium batteries to store energy in its Vilaya range of solar systems.  

The Nickel Sodium battery (This example made by FZSoNICK) works in an interesting way. The battery need to be warmed up so that the salt inside melts. Once the battery is at its operating temperature, energy can be stored and discharged as needed. The lifetime of the battery is 13-15 years. At the end of life, the waste product is a block of salt and some associated electronics.

The FZSoNICK has the ability to store 10 KWH of energy in this single unit. The cost for one battery is roughly $10,000. It’s a big upfront costs, but there is a return on investment over time. So let’s take a closer look at the numbers.

A good quality deep cycle 90AH battery will cost around $(US)250 and can store 1KWH of energy. Taking in account that we don’t want to discharge a lead acid battery than 40%, then we need to buy more batteries than the stated capacity to ensure that we can store and use the 10KW without damaging the battery bank. So for this example, we would need to buy 14 lead acid batteries at a cost of  $3500. As the lifetime of the battery is likely to be two years or less, over the course of 12 years, we would need to change the batteries 6 times, which comes to a total of $21,000 or more. This does not include other costs such as installation and shipping.  

So whilst there is a higher start-up costs, the return on investment is significant. But there are other advantages which you will see in the following summary:

  • Cheaper to run over a long period
  • Batteries take up much less space which means less cables are needed for installation.
  • No fire risk from gasses such as hydrogen
  • End of life waste is smaller as this technology does not use as many materials as other batteries. The main waste product is a block of salt.
  • Battery is stable and safe to transport
  • Good return on investment

Deployment example: Nickel Sodium batteries are built into complete systems such as the Villaya solar system from Schneider Electric. The solar plant is transportable with electronics installed and fixed to the walls of the an ISO container. This approach is great for disaster preparedness due to its mobility.  

This system can produce enough power to run a small office. In addition to the power circuits, communications technology can also be fitted inside the container so that internet connectivity can be provided in addition to electricity.

The Villaya system is designed with the appropriate systems to protect the circuits from lightning, which means that this system is very well suitable for topical and sub-tropical locations such as Africa.

For disaster response, where it may be difficult to move a container quickly, it’s possible to design the same system into other  formats which can be broken down to smaller shipping units for future assembly at a disaster site.

Sustainability: We know that solar panels have a long life if looked after. Nickel Sodium Batteries also have a long life which means that a system built on this technology will be sustainable, but technology is not the only area we need to make sustainable. We need to build peoples capacity. As we adopt new sustainable technology, with built in monitoring systems, these systems will become more complex. We need to initiate a training programme to build the skills of the people who will source, install and maintain solar energy systems.  NGOs will have a massive role to play here as they work in very remote locations. If they can adopt green energy systems instead of generators, other sectors might do the same.

In my next article, I will discuss how we in the aid sector should establish teams within our organisations to take ownership of environmental affairs and build the skills in house to help reduce the carbon footprint.  

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