In my last blog post, I discussed the prolific energy waste of pool pumps in the residential sector, but what about energy waste in industry? So I thought I would share an example in the sugar industry.
When I was with the Ensight Energy Solutions team at the Richards Bay operation a few weeks back, I also asked them about the energy waste of a typical 4,6 million tonne p.a. sugar mill. This sugar mill would produce about 1,6 million tonnes p.a. of a waste product called “bagasse”. The sugar mills burn the bagasse and generate steam and electricity with it. A sugar mill of that size may have a 30MWe steam turbine generator which would be enough to cover most of its electricity use, so they are self-sufficient in electricity. That’s pretty green and is to be applauded.
However, I wanted to test my project engineers’ knowledge of the energy waste in the sugar industry… So I asked them how much electricity could this sugar mill produce if it utilised its bagasse efficiently to produce electricity – assuming a typical steam turbine cycle efficiency of 30%. The answers came quick and fast; “60MW” said one. Quite a bold guess, 100% higher than at the existing operation. “Higher” I said. “80MW” another said. “Higher” I said again. “100MW” said another which I could see he thought was bordering on the ridiculous. Nevertheless, I said, “higher”. But at that point someone cut in and said, “140MW”. “Higher”, I said, then out of frustration, I said, “Enough is enough, 329MW is the answer”.
Yep, that’s right, if the sugar mill ran for the duration of the crushing season it could produce 329MW of electricity, 24/7 for 8 months each year. And if it was set up for 365 days a year, it could produce 220MW. So why are they making 30MW when they could make 329MW? In fact, the boilers at sugar mills are designed brilliantly to be very, very, inefficient. Wasting a conservative US$75 million per annum in fuel equivalent or a present value of US$750 million of lost opportunity. That is a big loss for any country let alone a company. The sugar mills are designed to very efficiently dispose of bagasse. Why though? There are lots of reasons. Historically, electricity prices were low, electricity utilities made it difficult for sugar mills to export excess power and no value was put on carbon emissions and so, no value was put on the opportunity cost of shadow electricity that could have produced. How many sugar mills are there around the globe that are running 90% below what is possible.
Prolific energy waste is all around you.
