Thursday, 29 January 2015

More on the Energy Bubble

Figure 1: How generating capacity has increased since 2006. East West Interconnector included in 2013 and 2014, also Great Island CCGT included in 2014 and retired oil plant on same site taken out

The above graph, Figure 1, shows the levels of electricity generation capacity for the Republic of Ireland at the end of 2014. We are now approaching the 10 GW mark, the highest ever in the State. If you really want to know why your electricity bills are so high then you only need to look no further than the above graph. All the above power stations and wind farms have to be financed through our bills, even though we only use on average less than a third, and at peak times less than half, of this capacity in electricity. The key to understanding this graph is looking at the gap between the blue (average demand) and black line (total capacity including wind) and the red (peak demand) and black line in 2006 and then comparing this gap with the current gap in 2014 (See Figure 2). As you can see, it has gone out of control. Consider that back in 2006, when the economy was booming, there were no blackouts . The level of back up capacity was sufficient but now that we have over 2GW of wind, it appears that more back up capacity is required to maintain a stable and reliable system.

Total Capacity
/ Average Demand
2.0 times
3.2 times
Total Capacity
/ Peak Demand
1.3 times
2.0 times
Figure 2: Total Capacity is now over 3 times that of average demand and double that of peak demand

There is an argument put forward by the Greens that this excess capacity will be required when everyone switches over to electric cars and electric heating systems as this will lead to a surge in average and peak demand. But there is a major flaw in this argument. You would still need enough dispatchable plant (i.e. plant that can be switched on and off at the touch of a button rather than when the wind blows) at least equal to the peak demand under this scenario, no matter how many wind farms there are. Otherwise, what would everyone do on a calm day like the 11th October 2014 ? Cycle the 10 or 20 miles or more to work ? Or perhaps wear extra woolly jumpers ? So you would still need to build more power stations to cover the surge in demand under this scenario and wind turbines would still result in excess capacity just like in the above graph.

Fuel Mix 2013 - another historic milestone

Figure 3: Fuel Mix 2013 with UK imports broken down into original fuel sources

Figure 3 shows that in 2013, Ireland used nuclear power for the first time. 2% of the electrons going into your electric socket in 2013 came from nuclear stations in the UK. I have broken down the power consumed here through UK imports into their energy sources and added that to the fuel mix provided by SEAI to arrive at the above chart. UK coal power accounted for 40% of our imports with gas at 25% and nuclear at 21%. The 10GW or so of UK wind provided just 6% of imports. So we are still very reliant on gas and coal power - almost 70% of the electrons entering your home in 2013 came from gas and coal power. (not including spinning reserves or back up generation)

But when we look at SEAI's original chart it tells an interesting story :

Figure 4: SEAI Fuel Mix 2013

While on the face of it, wind power did well, one has to put the output of a generator in the context of its generating capacity. The following table (Figure 5) shows the share of generating capacity each energy source had in 2013, so for example, gas plants made up 44% of the entire power plant and wind farm fleet in 2013.

Ireland's Power Generation Mix
Figure 5: Generating mix 2013

Definitions used :

Grid Acceptance Rate (GAR): the rate at which when power becomes available from a generating source that it is accepted by the grid. So wind power has a grid acceptance rate of 1:1 because it has priority dispatch, meaning when wind power is available it is automatically taken by the grid. Gas has a GAR of between 1:0.8 - 0.9 because when wind becomes available it pushes gas off the grid. I will assume 1:0.85 for this analysis. Coal and Peat are assumed to have a GAR of 1:0.95 as they are occasionally pushed off by wind

Fuel / Capacity Ratio : the position of a fuel source in the fuel mix relative to its position in the generating capacity mix. So a fuel source that makes up 50% of the capacity and 50% of the fuel mix will have a fuel / capacity ratio of 1:1.

Gas power gave just over 1MW power for 1MW share of capacity so had a fuel / capacity ratio of 1:1. Peat gave over twice as much power as capacity (2:1) while coal gave approx 1.6MW power for 1MW capacity (1.6:1). It is no surprise that the highest emitting power sources produced the most power relative to their size. This is because coal and peat store higher concentrations of energy than other fuel sources having formed over millions of years. Oil power, representing 12% of capacity, had a negative fuel / capacity ratio because these plants were lying idle most of the time. Oil plant are mostly used for "peaking" , i.e. when peak demand goes above normal which doesn't happen very often nowadays. So it had a significantly low Grid Acceptance Rate (somewhere around 1:0.01), whereas gas, peat and coal had GARs very close to 1:1 (between 1:0.85-0.95)

So how did wind do? Well, it had a negative output relative to its share of capacity. It comes out at 0.8MW of power for each share of MW installed. This is despite it having priority dispatch i.e. when the wind blows, the power is taken straight away by the grid. So levels of other power sources - mostly gas, and sometimes coal and peat - are reduced when wind is available. Applying the above definitions, this means that wind had the best Grid Acceptance Rate of all fuel sources i.e 1:1, but had a negative fuel / capacity ratio of 0.8:1. So wind and oil came out the worst, but oil had the lowest Grid Acceptance Rate, whereas wind had the highest. What this shows is that wind is a poor storage of energy when compared to coal, gas, peat and oil and storage solutions cannot solve this problem, rather it simply transfers the storage of this energy from one hour to another. What is required is a renewable source that contains higher concentrations of energy

And herein lies the problem with wind energy - you can't run a reliable grid if you install power plants that almost always give a negative fuel / capacity ratio. If you install 1,000 MW of wind, and demand hits 1,000MW, the power from the wind will almost always be less than 1,000MW so you have a blackout. This problem means that wind energy can never replace conventional plant and so competitiveness goes out the window