In my last blog post, I discussed the prolific waste of pool pumps in the residential sector, but what about businesses waste? So I thought I would share example in that sphere.
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 2 million tonne p.a. sugar mill. This sugar mill would produce about 660,000 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 15MWe steam turbine generator which would be enough to cover most of its electricity use -, so they are self sufficient. That’s pretty green and is to be applauded.
However, I wanted to test our engineer’s knowledge… So I asked them how much electricity could this sugar mill produce if it was set up efficiently using the bagasse waste to produce electricity – assuming a typical steam turbine cycle efficiency of 30%. The answers came quick and fast; “30MW” said one. Quite a bold guess, 100% higher than at the existing operation. “Higher” I said. “50MW” another said. “Higher” I said. “100MW” said another which I could see was bordering on the ridiculous. Nevertheless I said, “higher”. But at that point someone cut in and said, “143MW”. Yep, that’s right, if the sugar mill ran for the duration of the crushing season it could produce 143MW of electricity 24/7 for 8 months. And if it was set up for 365 days a year, it could produce 95MW. So why are they making 15MW when they could make 143MW? In fact the boilers at sugar mills are designed brilliantly to be very very inefficient, to efficiently dispose of bagasse, and not useful heat. Why though? There are lots of reasons. Historically, electricity prices were low and no value was put on carbon emissions and so, no value was put on power that couldn’t be made available 365 days of the year.
Prolific energy waste is all around you.