In March 2017 the following presentation on Milk Cooling was delived to a Northland branch meeting of Smaller Milk and Supply Herds Association (SMASH)
In April 2015 I presented to some South Island meetings run by SMASH on practical aspects of dairy shed energy use. See the presentation here: SMASH: Efficient Energy Use
The benefits of projects with co-benefits – a chilling example
Often we get frustrated that we come up with great energy savings projects with good paybacks but still can’t get plant management to run with them. One trick is that rather than continue to bash your head against a brick wall, hunt out opportunities that have multiple benefits. I was reminded of this recently when I was reading a case study of a frozen foods plant which made some pretty basic improvements to their refrigeration plant . These changes involved a variable speed drive on one compressor and adopting floating head pressure control. These two relatively simple measures will provide them with significant energy savings but equally valuably it frees up additional capacity for large parts of the year. This latter benefit is achieved because the lower head pressure gives increased compressor capacity when the ambient conditions are less extreme than the design conditions - which is most of the time. (If you operate refrigeration plant and you think this might be worth looking at for you, please contact us to discuss a review)
There is no doubt that plant and utility managers are more likely to support projects which give additional non-energy benefits, particularly if those other benefits are more closely aligned to their performance measures.
Don’t be put off by what you don’t know
A common comment what people start thinking about energy efficiency is “we don’t have enough energy metering to be able to manage energy”. This sometimes leads to a big capital expenditure request going to senior management who then throw it out due to lack of guaranteed return on investment.
A few weeks ago I read an article in an energy newsletter written by P Monaghan of Enerit Ltd and this really struck a cord with me. The basic premise was to start simple and you’ll be surpised how much of the energy- use picture you can build up with a bit of “guesstimation”. Then you can direct your early efforts to those areas that have real potential. Rather than try to summarise this short paper, I’ll leave to you to read it yourself:
It’s not all about capital spend
Often we look for the big glamour projects to deliver energy savings then grizzle that the money mandarins decide there are better things to spend the company money on. But, you shouldn’t despair as there are a lot of energy savings to be had in just being smarter in how we run our plants. A colleague referred to this aptly as sweating the assets. This is particularly fruitful in the food processing industry with many batch processes and where even “continuous” processes need to be taken off line for cleaning very regularly.
Here there are big savings to be made in reducing the amount of unproductive running. This is the time that the processing line is consuming energy but without any productive output - it may be awaiting input material, held up by a breakdown, or going through a start-up or shutdown cycle. Look at all these elements critically and try to shave some time out of each element. If the plant is capacity limited then freeing up a bit more production time is sure to get the plant manager on side and then he might be more amenable to looking at your bigger projects!
Energy Champions need to dig around, ask questions, and challenge old habits. There is no textbook here telling you how to do it or even where best to look. One of the biggest impediments may be the new-age managers who insist technical staff only work on fully scoped and approved projects with specific deliverables.
How often need we audit?
Recently I read an article about energy audits which stated that just under half of the companies surveyed were doing annual energy audits. The article implied that this was an indication that we still had a long way to go with commitment to energy efficiency.
But really, is the mere fact of whether a company does an energy audit each and every year a useful indicator of a company’s commitment to improvement? I think not - in my view annual audits are too frequent and a waste of money. The energy efficiency gains come from projects and actions taken as a result of the audit and not from the mere fact of doing more audits. If a company can scope and implement all of the projects which arise out of a single audit within the first 12 months then that company is super-human ( or whatever the company version of that phrase might be) or the audit was too superficial in the first place.
A good quality audit need be done about once every 3 years and that should throw up enough ideas to fill the project pipeline for a couple of years. If you find that an energy audit finds new inefficiencies just 12 months later then perhaps the company has bigger management problems.
So, I would argue that even if only 33% of companies do an energy audit every year then there is a good commitment to improving energy efficiency provided the recommendations are implemented.
If only we could harness that power …
Like many people, I have been enjoying watching the Tour de France over recent days. This led me to thinking on how much power those guys generate. It turns out there is quite a lot of information on various sports science websites suggesting that the riders sustain energy outputs of over 400 Watts on a climb. As one who struggles to maintain 200 Watts for even 5 minutes on a rowing machine at the gym, they have my admiration.
This then got me thinking on how we value human energy compared to fuels. If our rider maintained his 400 Watts on a 25 minute climb, he would expend about the same amount of energy as contained in one litre of petrol. Now my medium-sized car will travel around 10-12 km of general around-town driving on that amount of fuel . While we all like to grizzle about high petrol prices, would you rather ride a bike up a mountain or push a car around town for ½ hour than pay a couple of dollars for a litre of petrol?
When Statistics overtakes Common Sense
Just this week I was reading a recent conference paper about using regression analysis to generate an energy-use model as a basis for comparing energy use before and after a process change. It was a good paper but one element of it did grate a bit. That was in the way the authors had introduced a number of parameters into the regression analysis in an effort to maximise the statistical fit of the model equation without too much thought as to what would really be driving energy use.
In particular I was surprised by the introduction of power functions of production into the model equation, i.e. production squared and production cubed. Few process energy situations would need power functions in the equation. Adding such additional factors may well improve the R2value (a measure of the statistical fit) but that will be the case over a narrow range.
My experience is that regression analysis is a powerful tool for energy analysis and for developing energy budget models. It is a must-have in the suite of energy management tools and fortunately Microsoft Excel makes it straightforward enough to apply for amateur statisticians like me. But you must always view the results critically and ask yourself; Does each component of the model make sense given what I know about the process? Can I explain each parameter in simple terms such that plant staff will nod and say “that makes sense”. It is a balancing act because we must still have statistical confidence in the model equation and there are lots of traps for the unwary.
It is very much a case of process understanding being just as important as statistical prowess.
Resourcing of Energy Monitoring Programmes
In the various energy newsletters that land in my in-box, I see a lot of fancy-looking energy monitoring systems being offered onto the market. These go under various guises and names such as energy monitors, dashboards, etc. There are some very good systems being offered and they have an important place in the energy management suite of tools. The old adage that if you can’t measure it, you can’t manage it is a very true one.
But don’t get drawn into buying a bit of software and just assuming that the energy savings will automatically follow. The savings are unlocked only once you start to do something with the results of that reporting. I would suggest that the energy savings accrue 10% from the software and 90% from (human) brainware – no matter what the vendors may claim of their smart monitoring. I am also a firm believer in trying a few things in spreadsheets first, especially if your process is complicated. Learn what works and what is useful and then you are much better placed to interrogate the technical specs of the systems on offer.
Most importantly you need technical and operational people with the nous to look at the energy use data and trends and ask why is it that way? Why is it higher today than yesterday? Is “normal” good enough? Why is the energy use 10% less this week than last week? In these days of lean technical staffing I fear we don’t allow people enough freedom to just look at monitoring, to compare it with benchmarks, and to challenge practices. The easiest and cheapest energy savings come from simply being smarter in what we are doing today. Unfortunately that doesn’t fit the pattern of discrete projects which can be wrapped in all those layers of project approval and resource allocation.