IEEE Power & Energy Magazine - November/December 2020 - 71

Wind
PV + Wind

PV
Total

Power (MW)

400
300
59.97%

200

PV Capacity:
107.1 MW

100
0
Wind Capacity:
198 MW

CO2 Emissions (t/MWh)

500

0.8

0.75

0.7

0 2 4 6 8 10 12 14 16 18 20 22 24
Time (h)

(a)

(b)

Diesel Engine

Gas Turbine

Steam Turbine
(c)

Combined Cycle

figure 6. (a) Generating curves for wind, PV, and total energy produced on 19 May 2019 (record instanteous generation at 4:20 p.m.); (b) evolution of carbon emissions per MWh produced; and (c) detail of the generating curves for each
conventional power technology on 19 May 2019.

Tenerife: The Record for Renewable
Electricity Injected Into the System
As of October 2019, Tenerife held the record for the highest instantaneous penetration of renewable energy (59.97%)
for a power system without any storage capacity (no pumping, batteries, or any other storage system serving the power
grid) in the Canaries. This was recorded on 19 May 2019
at 4:20 p.m. (Figure 6). As expected, the CO2 emissions
per megawatt hour generated by conventional power units
increase when the renewable supply reaches its highest values, but they grow by only a few percentage points compared to other time intervals when the generating activity
is mostly supported by conventional power units. That is
partly because of the time intervals required by conventional
generating units to reach hot starts and ramp-ups (Table 4).
Lower CO2 emissions per kilowatt hour produced can be
expected if new dispatchable power units with faster starts
and ramps replace the current conventional power units. In
fact, EU Directive 2010/75, which covers industrial emissions, limits the operating hours of many important conventional power units. Some of these are retrofitted, but others
will be decommissioned and replaced by new firm capacity.
In addition, the future of renewable energy in the Canary
Islands will be connected to the development of Royal
Decree 244/2019 about energy self-consumption (including
net metering and selling surplus energy to the power system). This regulation covers all of Spain, but it is particularly
important for the Canary Islands, which constitute the Spanish region with the greatest solar irradiation rates and the
highest cost of electricity. The decree includes individual and
november/december 2020

table 4. The conventional power units' average
flexibility in Tenerife.
Technology

Hot Start (min)

Ramp-Up to Full
Load (min)

Steam turbine

285

Diesel engine

23-68

4-11

Combined cycle

330

Gas turbine

community self-consumption, and the connection between
production and consumption sites can be used in an internal
grid as well as the distribution grid, considering some very
innovative rules about the distance between feeders and consumption locations. The regulation is very simple for distributed generation that has a nameplate capacity in kilowatts
peak of fewer than 10, 15, or 100.

El Hierro: The Highest Penetration of
Renewable Electricity in the Canary Islands
There is general consensus in the Canary Islands that large
amounts of storage capacity are needed to increase the share
of renewable energy and reach a 100% renewable power
system. At this time, however, there is discussion about the
introduction of pumping systems and/or batteries (stationary and those used by electric vehicles). The Gorona del
Viento hydro-pumping system on El Hierro island, which
has been operating since mid-2014 (Figure 7), plays a central role for the first option. The system includes five wind
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