The winter of 2010 was characterized by low temperatures and low wind speeds. It was considered a 1 in 10 year i.e. a year like this comes around roughly once in ten years. But there are long term cycles which determine temperature in Europe. The North Atlantic Oscillation (NAO) is the dominant mode of winter climate variability in the North Atlantic region. A negative NAO results in low temperatures and weaker storms and a positive, vice versa. The NAO oscillates between positive and negative every few decades and there are hints of a transition to a negative NAO at the present time. This could mean that we are entering a cold and calm period in the coming decade with weather much like the winter of 2010.
So what will this mean for Ireland's energy strategy ?
Along with the amount of installed wind capacity (currently 2,200MW which needs to be at least doubled by 2020 but may well be trebled) there are two main factors which determine whether or not Ireland meets its renewable targets :
- The strength and frequency of the wind blowing during the year (I will use the term capacity factor¹) and
- Annual demand for electricity (total electricity consumption over the year).
Capacity FactorIn 2010, according to Eirgrid, average capacity factors for wind was 24% (see page 33 here) well below the average of 31%. Long cold periods usually bring calm weather and this would be a disaster for the wind industry and Ireland's energy policy. The wind farms would receive less income from the market and some would go bankrupt.
So could they increase the PSO Levy to save them from bankruptcy ? Well the simple answer is no. The PSO Levy exists to bring the income they receive from the market (about € 50 per MWh) up to the subsidized REFIT level (€ 80MWh). So the less power a wind farm produces, the less it receives from the market and the less it receives from the PSO Levy. Payments from the PSO Levy are directly linked to the power a generator produces. It cannot be used to generate additional income over and above what a generator produces.
Electricity DemandEirgrid explain :
The actual amount of renewable energy this requires will depend on the demand in future years, the forecast of which has decreased due to the economic downturn.The renewable targets essentially depend on the outcome of a simple equation - total wind output divided by total electricity consumption or demand. The higher the demand the smaller the renewable generation percentage and vice versa.
(Eirgrid Capacity Statement 2015)
A long cold period will create higher demand for electricity (peak demand hit 5,100MW during the winter of 2010) :
Temperature has a more significant effect on electricity demand, as was particularly evident over the two severe winters of 2010 and 2011, when temperatures plunged and demand rose (Eirgrid Capacity Statement 2015)
So basically, if the NAO becomes negative for a prolonged period, wind output goes down, demand goes up, and the percentage of wind relative to our electricity needs goes down, meaning our renewable energy targets will be next to impossible to meet regardless of how much wind capacity we install.
There will be alot of head scratching should this happen. Perhaps we shouldnt have put all our eggs in one basket we will most likely be told by journalists who will have suddenly become experts but refused to listen to anything other than the official line at the time².
¹Capacity factor gives the amount of energy actually produced in a year relative to the maximum that could have been produced, had a generator been generating at full capacity all year.
²There have been notable exceptions - economist Colm McCarthy for example