How can we keep the lights on?
10th October 2022
Author: Christopher. J. Parker
I have never had to revisit and amend an article as much as I have with this one. Every time it comes to the proofread and thumbs up to go, another news story breaks confirming a hypothesis I have discussed or adds so much weight to one side of an argument that they become obsolete. I half expect to return to the keyboard again before this publication (Edit: I did!).
For those of us in the UK you will have recently noticed an influx of news articles such as:
The UK’s full emergency plans for a winter gas shortage, from blackouts to battle rhythms:
Blackouts on way unless we act now, say experts:
How your car and dishwasher could earn you money and stop blackouts:
We trust public to cut energy use, says minister
Blackout fear as gas supply could be cut
Homes face winter power cuts in worst-case scenario, says National Grid
These stories are the culmination of several key events over the past two decades.
- First and foremost is Russia’s War in Ukraine and the sanctions imposed on the former. The sanctions have directly led to an increase in the global price of natural gas and restricted global sources as Russia holds 24% of the worldwide supply.
- In 2011, the UK’s import of natural gas as liquified natural gas (LNG) for the first time exceeded home production, a result of the policies of the previous decade. These policies sought the reduced use of Natural Gas for electricity generation and source a lower cost supply. An environmental and economic driven policy.
- The combination of more energy efficient processes across the board has reduced the UK’s electricity demand since 2000 by 15%.
- Likewise, the phase out of historic power generation plants and the uptake of renewable energy sources has reduced the UK’s overall electricity production by 20%.
- The rapid expansion of wind farms on and offshore from 2000 until 2014 was the outcome of environmentally conscious energy policies. However, the inherent flaw of wind generation highlighted an energy security issue (they only produce electricity when the “right” wind is available) and so the former policy of reduced natural gas use was reversed.
- Natural gas turbines are quick to install, modular in design and relatively easy to operate. They were a logical, rapid response to the sudden energy security scare in the early 2010’s and provided a short-term solution. However, the previous policies that oversaw the gradual reduction and phase out of home production could not be reversed so easily, and with the precedent shifted towards importing the fuel, the quantity and reliance on imported natural gas increased rapidly post 2013. We in the UK may remember the fracking exploration and controversies a few years ago. These were on the table to reintroduce home production of new natural gas demands.
- The failure to introduce fracking and the reason why natural gas rather than coal was the chosen energy vector was due to the environmental education and conscience developed in the UK. Natural gas is seen as less “dirty” than coal. Some may say the decision was directed by our international treaties and commitments but there are work arounds.
- The new natural gas demand was intended to be a temporary, short-term solution while renewable energy production gradually increases. Therefore, the 2010’s Government’s gradual phase down of fossil fuel assets, including natural gas storage facilities continued unhindered.
- The COVID-19 pandemic did introduce a gap in production and transportation of LNG, like all industries. As global demand for LNG increased during the period, global stockpiles have reduced, leading to a drop in supply and increasing the difficulty in sourcing the fuel.
- All the meanwhile, natural population increases, construction of new buildings expanding villages, towns, and cities across the UK has stretched the current infrastructure to capacity. What do I mean by at capacity?
- There is a finite amount of electricity that can be transmitted down a length of wire. Building more electricity generation plants will not be enough. The infrastructure requires expansion as well.
In summary, our environmental driven policies have seen the reduction of fossil fuel extraction, refinement, and use in power generation until the energy security risks posed by renewable energy was realised in the 2010’s. Improved energy efficient processes and historic power plant closures have reduced the UK’s overall electricity consumption and production. In 2014, a reverse decision on using natural gas to produce electricity was implemented but home extraction and refinement was not, firmly increasing our reliance on imported LNG. Despite the increase in LNG usage, the UK’s storage facilities continued to be phased out in line with long term environmental strategies. Russia’s War in Ukraine has seen the implementation of sanctions against the Russian state whose position, as the world’s leading supplier of natural gas has led to the global increase in natural gas prices and reduced the accessible global supply.
The compound impact of these events has led to the UK’s energy security being at its greatest risk since the Winter of Discontent in 1979. Radical ideas are being posed by the current Government including a full policy reversal. Oil fields may reopen in the North Sea (Edit: New North Sea drilling licencing round has been announced.)Refinery and storage facilities may reopen, reducing the reliance on imported LNG (Edit: The Rough site is due to reopen). The controversial fracking ban, implemented less than a decade ago, has been lifted.
The Great Renewable Energy age may have to wait while the UK aims to become self-sufficient on fossil fuels while the renewable sector gradually expands.
These are, however, only ideas and may not come into fruition (I thought I’d leave this sentence from the first draft of this article, in September. This has been a rapid development). From the linked articles and latest news stories, the current strategy is to maintain the status quo but provide taxpayer financial support where needed and relieve the pressure on LNG imports through strategic blackouts and revive home production. I suspect this is the short-term reaction while a long-term solution is worked out. The extreme of which was previously described.
That’s the national overview. What can the niche refrigeration industry do to reduce its energy intensity and reduce its operation costs (that are passed onto the end customer) to boot? Do our part if you will.
The direction taken by a large proportion of refrigeration users has been to transition to low global warming potential natural refrigerants, for various reasons that can be summarised as the business’ environmental policy. System modelling and empirical data has consistently indicated that R-744 (carbon dioxide) refrigerant systems are more energy intensive than synthetic refrigerant counterparts in the low to middle latitudes regions of the world. Advances in R-744 technology and system design has reduced the energy gap but generally, they are still more energy intensive. Despite this, R-744 aligns with business’ environmental policy and has seen large roll outs.
With the latest energy crisis no longer on the horizon but firmly with us, and part of everyday life, it is our responsibility as engineers to develop the next evolution in technology and strategy to alleviate the energy demand on our creations.
This is no different to what we have already been doing.
Some will remember images like this during the 2010’s highlighting how much cold spill and wasted energy was being lost in retailer cabinets through spillage. Thankfully, the adoption of doors is being taken up in response. This is not only reducing wasted energy but lowering the duty capacity on refrigeration systems thereby reducing energy consumption. Brilliant! Now what else can we do?
Refrigeration as a process is inherently inefficient. We are acting against nature. The Zeroth Law of Thermodynamics states that:
And The Second Law of Thermodynamics states that:
Taken together, thermal energy will always move from a hot object to a cold object until they are of equal temperature. Refrigeration systems do there best to reverse this therefore, an uphill battle.
We can, however, use our knowledge of these systems and our laws of thermodynamics to operate refrigeration systems with a reduced electricity demand. Based on the above laws, it can be deduced that refrigeration systems, which reject heat to external ambient will require less energy when the external ambient is closer to the target temperature of the controlled environment.
During a typical day-night cycle, it is cooler at night than during the day. Therefore, the refrigeration system will require less energy when operated at night. Excellent, but what about the day? Can we just switch of the system? Well, if there is enough “thermal mass” or enough substance at low temperature within the controlled environment then you could get away without operating the refrigeration system (subject to calculations). Okay, so why are we not doing that? Well, most refrigeration systems control a storage environment. The products in storage will need to be moved eventually. Sometimes daily, or hourly. There are very few applications where the storage items are held for a protracted period without human interaction in the environment.
So, during the day, personnel will typically enter the controlled environment through a portal, introducing warmer air to the environment. The personnel will radiate body heat, increasing the air temperature, and product or thermal mass may be removed from the environment therefore, our refrigeration system needs to remain active to maintain the environment’s target temperature.
Over the decade various strategies have been adopted to reduce the influx of heat sources into the control environment. Rapid portals reduce the volume of external air entering the environment. Thermal clothing reduces the personnel thermal radiation, and the introduction of LED lighting has reduced the heat generated by light sources.
I believe (yes, an opinion) further technology and operational strategy will enable refrigeration systems to only require night-time operation and avoid the less efficient day time running hours. Phase Change Materials (PCMs) have been proposed previously and with the right operational strategy, they can reduce the overall energy consumption of the system.
Notice, I wrote energy, not power. There is a fundamental difference. The introduction of PCMs does increase the power demand on the system. Additional cooling duty is required to maintain the temperature of the environment, products, and PCMs but, as a dedicated thermal mass that does not require moving, optimum placement of the PCMs will absorb the thermal energy ingress and maintain the control temperature in the various micro-climates. When the PCMs have absorbed their maximum quantity of heat, if sized correctly, the refrigeration system can reactivate to remove the PCM stored thermal energy. Despite the increased cooling duty, the improved efficiency of night operation versus daytime operation and reduced operating hours would reduce the overall energy consumption. As a double up, the cost for electricity is typically lower during the night period as well, therefore, reducing operational costs.
I have written a paper published by the Institute of Refrigeration, discussing this exact and controversial topic DOI: 10.18462/iir.iccc2022.1172. There are limitations of the technology and the study that have been discussed, and these should be addressed in future considerations.
The exploration of introducing PCMs and a functional operation strategy is just one idea that can be used to reduce the impact refrigeration has on the UK’s National Grid. Other strategies may include the adoption of adiabatic cooling systems for ambient rejection systems, transition to alternative refrigerants or some other yet to be mentioned technology. Either way, all options should be explored to see what is compatible with specific businesses. We could just go to the Winchester, have a nice cold pint, and wait for all of this to blow over, or take a proactive stance and evolve our existing and future refrigeration systems to a reduced energy consuming model.
We cannot resolve the energy crisis. It is larger than the impact the refrigeration industry can have, but failure to act would be a moral travesty.