Energy Price Crisis

With costs for electricity and gas having gone up, and predicted to go up again by large amounts, we have taken down our advice on energy bills and switching supplier. Switching is now all but impossible as suppliers are not taking on new customers. Currently (January 2022) the advice from such as money-saving expert Martin Lewis is to sit tight on the capped energy price, as this is the best deal available.

WREN members make electric cars (EV) a normal sight in Wadebridge

The Observer newspaper says that EVs will now become more common nationally - http://www.guardian.co.uk/environment/2012/dec/29/electric-car-sales-prices - but they are already becoming a common sight in Wadebridge. Five WREN members have now taken advantage of recent price reductions on EVs (and some have also received a £200 cash-back in the local currency - the Wren).

In addition to carbon savings, they have therefore opted to pay all or most of their motoring costs up front. The only running cost for those with renewable generation is insurance (relatively cheap) and maintenance costs are minimal.

As Wadebridge moves towards powering itself on local renewables, we can expect EVs to catch on both for transport, and for storing electricity. Drivers of EVs have noticed a new psychological phenomenon. When they sit silently in a traffic jam they become acutely aware that they are breathing the fumes from the exhaust of the car in front . It must have been like this for the minority of non-smokers in 1960s pubs. It won’t be long before drivers of EVs are as popular as those who first started effective campaigning against passive smoking. Some people do fume when they are stuck in traffic jams. Passive fuming will one day become as much an historical curiosity as passive smoking.

Washing machines

There is a considerable price range in washing machines, and that, plus the list of features, is the main purchasing criteria.  However, if we look at the whole life cost of one of these machines, the decision as to which one to buy could be different.  There is a huge variation in build quality, and thus expected life of the machine, and also the energy used to run the machine.  As an example, average annual running costs can vary between £40 and £60 in terms of energy and water used.

Most machines available today are at least ‘A’ rated, but there are several machines with multiple pluses after the ‘A’ which use much less energy, and therefore have lower associated carbon emissions. Overall, you could be forgiven for thinking that there is not an enormous difference in running costs as stated, but a cost which is not so obvious relates to the design life of the machine – as an example, you might have to allow for the price of 2 or 3 Hotpoint machines in the life of 1 Miele or Siemens machine.  Also, with some of the cheaper machines you will have to pay a high price to extend the warrantee beyond 1 or 2 years, whereas a Siemens machine, for example, comes with a free 5 year warrantee.

Tumble Dryers

Clearly, the lowest carbon method of drying washing is air drying, either outside if you are confident enough to risk the weather, or inside if you have the space and time – an old fashioned Sheila Maid is excellent for this, especially if you have high ceilings.  That said, many people are forced to opt for the tumble dryer at least some of the time. As a running cost comparison, annual cost can vary between £27 and £91 for the same amount of drying.

So, we can see a much bigger difference in energy use here, with the most efficient machine using not much over a quarter of the energy of the least efficient.  The difference in price between the most efficient and least efficient examples would pay back in less than 7 years in saved energy costs.  The same discussion on build quality and warrantees applies to these machines as mentioned for washing machines above.

Televisions

Not many people actually think about the power consumption of their television, leaving it on with impunity when not even in the room, and taking no notice of the wattage clearly stated on the label on the back when purchasing a new model.  We are told that picture quality and other features play a more important role.  As an example, running costs on TVs in the 37” to 42” range can vary between £9 and £32 per year to run.
A key point here is that the annual running cost for a plasma TV is 50 – 60% higher than that of the equivalent sized LED TV.  Also, if you are prepared to sacrifice a small amount of screen size, there are options that are much cheaper to run – for example a 37” LED TV can have less than half running cost of a 42” LED.

What is hydro power?

Most of us are familiar with large scale hydro power – huge dams creating an artificial lake, where the water passing through the dam does so through large turbines that generate electricity.  What follows concentrates on smaller scale hydro, but the basic principles are the same. Hydro schemes qualify under the government’s feed in tariff.

Micro and pico hydro power

This is the modern equivalent of the old water wheel.  The term ‘micro’ refers to systems up to 50kW, and ‘pico’ to systems up to 5kW.  Turbines used at this scale are usually Impulse Turbines, where the turbine is driven by a concentrated jet of water released under high pressure to drive the wheel of the turbine.  These ‘turgo’ wheels usually have a series of spoon shaped blades, which are driven by the water pressure. 

Gravity

A ‘head’ of water is required in order to create the necessary pressure – basically, the surface of the body of water has to be higher than the turbine wheel.  The process converts the gravitational energy contained within the body of water into kinetic energy at the point of impact with the wheel.
The amount of electricity produced is dependent on the height down which the water falls (the head), and the speed the water is flowing when it reaches the turbine.  In both cases, the bigger the number, the more electricity can be produced.

Siting

There are thousands of potential hydro sites in the UK – anywhere a stream passes close to a building could have potential.  The advantage of these small-scale systems is that the water is always returned to the same stream, thereby having very little impact.  Design and siting is a specialist activity, and all systems are bespoke.  It is easy to price the kit itself (approx £4500 per kW at this scale), but there is usually a considerable amount of civil engineering work, which is site specific and can be expensive.

Output

For illustrative purposes, a continuous output of 1kW would require a head of 23m and a flow rate of 10 litres per second, assuming an average efficiency for the turbine itself.  The beauty of hydro power is that it can be continuous and predictable, as long as your source of water doesn’t dry up.  Thus a 1kW system could generate up to 8760kWh in a year (compared to 1000kWh for 1kW of PV).

Limitations

Obviously the need for a suitable stream with a good head and potential flow rate is important.  Another limiting factors is proximity to the building – the closer the better to reduce cable runs.  The seasonality of the water flow is important – often hydro systems are running less effectively in the dryer months, and if the source is overestimated, this could lead to the system not working at all for periods of time.
Durability of the kit can also be an issue – breakdowns are common due to all sorts of factors, such as leaks in the system and worn bearings. Systems can be easily damaged due to poor installation – there is a lot of force in the water required to drive these turbines.

Summary

  • Hydro is a continuous and predictable source of energy to make electricity.
  • The cost and output of a hydro scheme depends on the site and the head of water available.
  • You will need an ‘extraction licence’ from your local water authority.

How do heat pumps work?

  • Step 1:  Collecting the Heat
    Heat collection for GSHP is achieved by installing a series of pipes in the ground – the ground loop. They are buried a metre deep and contain a water-glycol mix at a low temperature. The surrounding soil is naturally at a higher temperature, typically 10-13oC, and gently warms the glycol mix as it is pumped around the ground loop.
    A temperature increase of the ground loop fluid of just 3 or 4 degrees is all the heat pump requires. The returning warmed liquid is fed into a heat exchanger/evaporator.
    For ASHP, heat is collected from the air by a series of pipes running through fins – similar to the fins on the back of a fridge that are used to dissipate heat collected from inside the fridge.  The method of heat collection is the only major difference between GSHP and ASHP.
  • Step 2: The Evaporator
    The purpose of the Evaporator is to take the collected heat out of the ground loop liquid and return it cooled to the pipe for the next cycle. It does this by using a refrigerant that boils at approximately -10oC, the act of boiling turns the refrigerant into a vapour, which is then moved into the Compressor.
  • Step 3: The Compressor
    In the Compressor the vapour is compressed in volume and as its volume reduces, its temperature increases. Temperatures of between 75 and 125oC are achievable and the gas is then fed through a heat exchanger.
  • Step 4: Condenser/heat exchanger
    Feeding the hot gas through a condenser allows the refrigerant to turn back into a liquid. As it condenses it cools and releases its heat through a heat exchanger into the hot water and central heating system.

What are the limitations?

Heat pumps will be at their most efficient in applications where high levels of insulation have already been installed, and are generally used only where no mains gas is available.  Although the high efficiency might seem attractive, electricity costs are considerably more than gas for the same output, so installing a heat pump where gas is available might not save money.  Heat pumps really only work well if the house is well insulated, and heated by an underfloor heating system or has oversized radiators.

How much will I save?

How much you can save will depend on what system you use now, as well as what you are replacing it with. In order to calculate potential savings you will need to consider:
a) cost of installation including upgrading radiator system or installation of underfloor heating,
b) how much you currently spend on fuel, savings will be greater where you are reliant on more expensive fuels such as electricity, oil or LPG.  

Our installers will be able to give you an idea of savings achievable and possible payback times. You may be able to receive payments for the heat you generate using a heat pump through the government’s Renewable Heat Incentive. Heat pumps also qualify for financing under the government’s Green Deal scheme.

Do I need planning permission?

Heat pump installations may be considered Permitted Development, in which case you will not need planning permission, but to be sure it is always a good idea to check with your local planning office or talk to our approved installers.

Summary

  • Heat pumps are renewable technologies for heat for central heating and/or hot water.
  • Heat pumps need electricity to run but use less electricity than other forms of electric heating.
  • A Heat pump will only save money and carbon if you have a really well insulated house and perhaps an underfloor heating system.
  • In most houses around here gas is cheaper (if it is available!)
  • You may qualify for payments through the Renewable Heat Incentive.