The current news cycle, particularly from July up to date, has been dominated by a variety of unprecedented and widespread global warming anomalies. The month July of 2021 has been declared the hottest month ever on record; the records started some 142 years ago.
I certainly became very wary when I got to know that July was the hottest, while ferocious wildfires were scorching large swaths of land almost simultaneously in the USA, Canada, Russia, Turkey, Greece, Algeria, Morocco and France.
It is also quite frightening to imagine the dire consequences associated with the diminishing water levels in rivers Euphrates and Tigris as well as Hoover dam in the USA. Can we find a better solution at the next climate change meeting COP26 at Glasgow in November to reverse our steady slide into the point of no-return?
Capacity Factor: A Measure of Effectiveness
To deepen our understanding about capacity factors, CF, for our discussions today, let’s refer briefly to our previous discussions on CF. It was shown that a CF of a given option is calculated from its actual generated electricity per year, divided by the product of its installed capacity and 8760 hours in a year.
In this way, we found CFs for the 4 low-carbon energy sources of interest, which are hydropower, (HP), solar power (SP), wind power (WP) and nuclear power (NP) in 3 different geographical areas, namely the USA, Germany and China.
In all the 3 geographical areas, SP had the lowest CF, followed by that of WP and then that for HP. Out of the 4-given low-carbon energy sources, NP stood out as the option with the highest CF. Its CF of 94.2% in the USA, implies that it can work at its rated power for 8252 hours in a year (using the calculation 8760 x .942 = 8252), as compared CF of 22.1% for SP, corresponding to working at its rated power for only 1936 hours in a year. Hence, this is a clearer indicator that NP is more effective option than SP in producing electricity.
Table 1: Capacity Factors in Percentages in Three Geographical Areas
Capacity Factor: Energy Performance
All the CFs discussed in the previous episode, are put in Table-1 to enable us to compare them more closely to one another. It is also interesting to compare Table-1 with Fig1, where CF is described, interestingly, as “energy performance”. Note that the figure was introduced to our discussions a while ago when we briefly talked about CFs. Let’s compare Table-1 with Fig1, limiting our attention only to NP, SP and WP, due to the most contentious issues, including pitting NP against WP and SP for the pivot role as the principal source to produce abundantly clean, reliable and affordable electricity in the anticipated future of low-carbon economy that is necessary if we are to effectively mitigate the adverse effects of climate change.
Let’s also note that, the most polluting energy source, coal, which has to be phased out, has a pretty high CF of 80%. Hence, an 1000MW coal-fired plant with CF of 80% can produce in a year, about (1000MW x 8760hours) x 0.8 = 8760GWh x 0.8 = 7008GWh of electricity. When we replace the above-given coal power plant with 1000MW power reactor with CF of 90%, it would produce in a year 8760GWh x 0.90=7884GWh of electricity, which is more than what the coal plant of the same wattage can produce.
On the other hand, using CF of 25% for an onshore 1000MW WP, and CF of 15% for 1000MW SP, they can produce annually about 2190 and 1314GWh of electricity respectively. It is clear from the annual amounts of electricity generated by WP and SP that, they cannot adequately replace coal.
It can be found from the above generated electricity that, the energy performance of coal for generating electricity is about 3.2 and 5.3 times higher than WP and SP respectively. It is also worthy to note that NP’s energy performance is 3.6 and 6 times higher than WP and SP respectively.
Negative Externalities of Energy Sources for Power Production
There are some negative externalities or environmental impact from energy sources used to generate electricity that must be considered. Several studies, performed by competent institutions, find NP to be the cleanest energy source, a position shared with only HP and WP. In the EU’s first External Cost Studies, under the auspices the EU-15, the results showed that even in the temperate areas, NP is more environmentally friendly than HP.
It has been well established here that NP, with the highest energy performance out of the 4 low-carbon energy sources, NP, HP, WP and SP, is the realistic option to replace coal or fossil fuels in power production. Furthermore, NP has the least external cost or lowest carbon footprint. Due to the urgency and the enormity of the global warming problems, related to energy, only NP is the option that can be steeply accelerated to meet such problems.
The Major Limitations of Wind and Solar Power
In comparing WP and SP with NP, we have learned that whereas NP is the most concentrated energy source, WP and SP are the least concentrated. We have also learned that NP is more effective or has a much higher energy performance than WP and SP, and that is why it produces abundantly reliable electricity, while the little amount of electricity produced by WP and SP is not reliable for the grid, or simply ‘non-dispatchable’ in technical terms.
With the exception of only WP and SP (based on solar panels), all conventional and renewable energy sources for power generation are dispatchable. Since WP and SP produce variable electricity intermittently, they cannot be used as a stand-alone power source. Hence, the better way to utilize WP and SP is store their generated electricity in batteries and use them later as required. As a result, new batteries, or the relevant device to store WP or SP energy, should not be only affordable, but also highly efficient.
Surely there are several many types of energy storage which are on drawing board, but the only practical one in use is a Pumped Hydropower-Energy Storage (PHS), made up of 2 reservoirs, where the upper one is vertically above the lower one. Electricity produced by WP or SP is used to pump water from the lower reservoir to the upper one, where it is stored and used when necessary. If the efficiency of the PHS is about 70%, it follows that the amount of electricity, produced by WP or SP will be reduced by approximately 30% before it is used.
However, using WP and SP to power the grid is made possible by backing them with dispatchable energy sources. Ideally, HP is so flexible that it can be readily ramped up or down to meet demand, but there is not enough installed capacity of HP to serve as the back-up for WP and SP, the fastest glowing energy sources. Again, since natural gas, the next suitable option to serve as back-up for WP and SP is too expensive, coal is ironically used to back up WP and SP which are used to replace coal. A vicious cycle indeed!
This is the big dilemma that continues to fuel the climate challenges as witnessed across the nations over the last few weeks. A collective engagement of the citizenry is required so that we do not get to the point of no return when it comes to the preserving the earth. That requires honest conversations about the potential of NP as the most effective, efficient, clean and affordable source of energy that will help us address today’s global climate challenges.