Renewable Energy – The Vital Missing Link

This blog was written by BSRIA's Henry Lawson

This blog was written by BSRIA’s Henry Lawson

For years, renewable energy, especially solar power and wind, has offered the tantalising prospect of almost zero carbon energy; tantalising because, even as costs fall, solar and wind are inherently unreliable, especially in temperate climates such as those that we ‘enjoy ‘in regions like Western Europe, and much of North America not to mention most of the developed world.

While a lot of progress has been made in demand response, which manages the energy that we need to match that which is available at any given time, we need a cheap, safe and efficient way of storing electrical power. Up until now, storage of electrical power in particular has been expensive and inefficient, and sometimes a bit scary.

The electrical vehicle market of course already faces this problem in spades. Electric cars are never likely to become main-stream so long as they need to go through a lengthy recharge process every 200 miles or so. It is therefore no surprise that much of the running is being made by manufacturers of vehicle batteries.

Tesla’s announcement that it is moving into the home energy storage market could represent a significant step. Being able to store electrical power not only makes local wind and solar power generation more practicable, it could also be invaluable in the many areas of the world where the grid is unreliable or virtually non-existent.

The biggest barrier, at least initially,  is likely to be the price tag. The 7kW battery which could, for example power a laptop for two days, or run one full cycle of a washing machine, or boil 10 kettles, will cost $3,000 to buy: That’s a very pricey home laundry service, and a frighteningly expensive cup of coffee, especially if you only need to use it occasionally.  The 10kW version represents slightly better value.

At this stage this is surely going to appeal only to wealthier individuals living away from a reliable grid, or those willing to pay to make a green gesture.  However, as with other technology initially aimed at the ‘smart home’ we may well find that much of the demand is actually from businesses. If you are running a business, even a small one, then any loss of service can do you immense damage. If an investment of a few thousand pounds or dollars can help guarantee that you will keep running, then it may well seem like an attractive return on investment.”

A further significant sign is Tesla’s announcement of an alliance with the international Energy Intelligence software supplier EnerNOC, which already has a presence in the USA, Canada, Germany, the UK, Switzerland, Ireland, Brazil, Australia and New Zealand.

Ultimately, success for energy storage in buildings, as in vehicles is likely to hinge on the two Cs: cost and capacity. It is a familiar catch 22 situation with most new and emerging technologies, where the market is waiting for the price to fall, but, other things being equal, production costs will only fall once you have achieved  real economies of scale.  The other factors that could influence the market are regulation, requiring builders or building owners to make provision for storage, or someone willing to take a loss leading initiative.

Safety concerns will also need to be allayed, given problems that have occurred with various types of battery technology, whether in laptops or vehicles. Storing a lot of energy in a very small space, inside the home is always going to raise concerns. And while batteries may offer the most promising option at the moment, other forms of energy storage might prove more effective in the end.

Still, the paradox is that sometimes problems get solved precisely because they are so big. The whole direction that the world is moving in, the growing realisation that we need to slash CO2 emissions,  demands cheap, efficient, safe energy storage. It seems likely that companies like Tesla, along with the other major energy companies involved in energy storage  will continue to concentrate their fire power on this until a viable solution emerges. And for the first few who get this right, or even approximately right, the potential returns are huge.

For then we really will have found the missing link.

Refrigeration Part 1 – Choosing the right refrigerant

Salim Deramchi, Senior Building Services Engineer at BSRIA

Salim Deramchi, Senior Building Services Engineer at BSRIA

Refrigerants are a key component for air conditioning and refrigeration. Since the 19th century there have been many refrigerants developed and used but none of them has as yet become the industry standard.

As an industry we should not consider reducing F-Gas emissions as just complying with legislation to meet government set targets, but reducing them will also have a positive effect on operating costs.  We can make cost savings through efficient operation and we can also help enhance market reputation by being more environmentally friendly.

To have a good understanding of this we need to look at:

  • Available refrigerant types
  • Our selection criteria
  • How we evaluate the available refrigerants

Traditionally commercial businesses have been using R12, a CFC, and R502a CFC/HCFC. In addressing the ozone depletion problem, most manufacturers have adopted either R404A a HFC blend or R134a. However, both are potent greenhouse gases (Nicholas Cox).

So the industry needs to look at future solutions which might be natural refrigerants, although some design change might be required on the equipment used. The following refrigerant replacements all require system and operational changes to current practice:

20140213_132647_resizedIsobutane (R600A) is a hydrocarbon , and hence is flammable. The thermodynamic properties that are very similar to those of R134a. Isobutane presents other advantages, such as its compatibility with mineral oil and better energy efficiency and cheaper than that of R134a. The use of isobutane requires minimal design changes, such as the relocation of potential ignition sources outside of the refrigerated compartment. Operational changes will also be required.

Propoane (R290). With a boiling point of -42C, propane is an excellent alternative to R22 as it requires similar working pressures. An added advantage is that except for added safety measures because of its flammability, virtually no design change is required in systems when switching from R22 to propane. The combination of its good thermodynamic and thermophysical properties yields systems that are at least as energy efficient as those working with R22. The use of propane is increasing in countries where regulations allow it.

Ammonia (R171). Ammonia has been continuously used throughout modern refrigeration history. Despite its numerous drawbacks, it is toxic and flammable in concentrations between 15.5% and 28% in air. It is not compatible with copper, thus requiring other materials of construction. Its thermodynamic and thermophysical properties also yield very efficient refrigeration systems. Because of its acute toxicity, stringent regulations apply for ammonia systems, which require close monitoring and highly skilled engineers and technicians.

20140213_132339_resizedCarbon dioxide (CO2) is not a new refrigerant. Rather, it was ‘rediscovered’ in the early 90’s. The use of carbon dioxide as a refrigerant has gone back well over a century. Its application was abandoned in the mid-50s, with the widespread use of the CFC refrigerants, which were more efficient, more stable and safer. Due to its low environmental impact, low toxicity and non-flammability, CO2 is now regaining popularity from refrigeration system designers when an alternative to fluorocarbons is being sought. (Ahmed Bensafi and Bernard Thonon)

So there are alternatives on the market and technology development is tackling this issue it is now up to the designers and operators to specify something new to move the industry forward. With F-Gas regulation 2 coming we need to get ahead of the game.

We have tried to cover some of the available refrigerants seen in the market and we will be evaluating and discussing the selection criteria in our future blogs.

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