Evolving the Grid

In my article on July 17th I explained what is a grid and how it works at a high level. It was not intended to make you an electricity engineer, but to give you a greater appreciation of what it is and what is involved to maintain it for us to have stable electricity. So let’s look at where we are now and where we hoping to go. We are adding renewable energy to the grid and more specifically we are adding solar and a little wind. The first thing we need to appreciate is the type of renewable energy we have chosen is intermittent. However, it’s the best choice for us because it is available in unlimited quantities, but not necessary readily available when we need it. As we all know the sun only shines during the day and it can be reduced by clouds during the day. Wind is seasonal and is available day and night, but it still can stop or slow down without warning. So we can agree these sources of energy are intermittent.

Now if you remember in the article on the grid. The utility company has a challenging task of predicting variation in demand and they use a number of techniques to respond to those changes. They are able to do this because they can control the generation of electricity. In one instance they can use spinning reserves in the baseload generators. So they basically keep a little extra electricity available from the generator to respond to a sudden increase in demand and if that is not enough they can fire up the turbine generators that come up to speed quickly to meet the demand. Both methods are using a predictable energy source that they control. This is known in the industry as firm source of energy.

So let’s bring in an intermittent source of energy on to the grid and look at a real world scenario to understand the possible impact. We have a 10MW solar farm supplying half of the electricity for your neighbourhood. Then without warning a 0.5MW spike in demand occurs at the same time a big dark cloud passes over your solar farm and production drops to 8MW. This would mean you now have a 2.5MW increase in demand that you need to respond too. What do you do? This is a serious challenge that the utility company has to consider as they allow more and more renewables on the grid. Now in this scenario the utility company would have to maintain enough firm energy on the grid to be able to respond to such a rapid large demand change. Now this should give you some insight into why the utility company always appears to be overly conscious of allowing large amounts of intermittent renewable energy. I don’t believe the utility is appose too renewable but just rightfully conscious on how and how much is bought on to the grid without any mitigating work on the grid.

Please don’t get concern now and believe we can’t go 100% renewable. It is very possible to do so but it must involve the Utility company at every step and as we contemplate adding more intermittent energy we have to also include an intermittency mitigation plan. This challenge is not unique to Barbados and technology is evolving rapidly to come up with different ways of addressing this. However, you would be please to know that the utility company has already develop a plan to address this and the Barbados Renewable Energy Association (BREA) has also been looking at this challenges for a while. The current mitigation techniques available are to include some firm renewables like Biomass/Biogas using waste to energy or Anaerobic digesters in the mix to go 100% and storage which allows us to have energy when the intermittent sources are unavailable.

Moving toward renewable energy is the right thing for Barbados and doing it as fast as possible is also the right thing. The questions we need to ask ourselves are; how fast is fast? Should we go with large scale solar, distributed or a mix? Should we be going 100%, 80% or 60% renewable? I would expect the answers to these questions to be in our national energy policy, which is long overdue.

So after reading this article I would want you to take-away three things; 1) an awareness of what is really involved when considering moving Barbados to renewable energy and recognizing it is not an easy consideration, but a necessary consideration. 2) a better understanding of the utilities role and that they have an obligation to ensure that the grid remains stable as we include more and more renewable and 3) The importance of a national energy policy that considers all the pros and cons of the various options and set the guidelines and frame work for us to transform our country.