Study of non-fossil power sector scenarios in the Czech Republic (part 1)

In 2017, the Czech Republic acceded to the Paris Climate Agreement, which calls for the economy to be fully decarbonised by 2050.Some countries with favourable geographical conditions can have an energy mix predominantly based on renewable energy sources (RES). However, the Czech Republic is not among them, due to the climatic conditions of an inland country in densely populated central Europe, with limited options for energy storage. Therefore, from both an environmental and economic perspective, it is not efficient to base the Czech power sector on RES as the main source of electricity, as the Realistic Energy and Ecology association has long pointed out.

An analysis of statistical data on electricity consumption and generation using a mathematical model of energy mixes shows that, after the shutdown of all coal-fired and nuclear power plants, the Czech Republic would face irregular grid outages (blackouts) during periods of winter inversions (cloudy, windless conditions) and on winter nights, even if investment of CZK 4 trillion increased the current capacity of solar photovoltaic power plants (PV) 25-fold and wind power plants (WPP) 99-fold, while installing CZK 1 trillion worth of batteries. Due to a similar energy mix in neighbouring countries, energy imports would not be available in adverse weather, and the capacity of gas-fired power plants would therefore have to be increased up to fourfold to serve as backup when RES output declines (see the 96% RES scenario).

In addition to the high investment required to build RES and the need for backup fossil gas-fired power plants, the costs of disposing of materials after RES reach the end of their operating life must also be considered. Due to their low energy-flux density, RES consume several orders of magnitude more construction materials than other power plants with the same annual electricity output, and their lifetimes are much shorter. Under a circular economy, it would be necessary to recycle large quantities of waste every day: approximately 1,200 tonnes of photovoltaic panels and one 100 m-high wind turbine.

A significantly more rational option is the State Energy Policy scenario, which strengthens the role of nuclear power plants that are virtually free of greenhouse-gas emissions. This scenario makes it possible to efficiently use several times more RES capacity and leads to Czech self-sufficiency in electricity generation. Further development of the scenario would reduce the carbon footprint of the power sector by up to ninefold compared with today and meet the EU Green Deal climate agreement target (the 62% nuclear + 35% RES scenario).

The results presented in this article were obtained using the Energetika.m mathematical model in the Octave.org environment, which is freely available to all interested parties. The stated emissions values are the sum of the emissions values for each source, based on a conversion factor analysing the full life-cycle carbon footprint of energy sources according to the study. The conversion factors used are also employed by ourworldindata.org, supported by the University of Oxford. Those relating to mortality and material damage resulting from the use of energy sources are based on global statistics and are shown in the charts.

Gas emissions include potential methane leaks from extraction, transport and storage. Although emissions of other pollutants (fly ash, NO_x, SO_x) from gas are much lower than from coal, greenhouse-gas emissions are only 40 % lower. If natural gas leakage exceeded one percent, the equivalent emissions of gas-fired sources could be higher than those of coal-fired sources, because unburned natural gas (primarily methane) has a greenhouse effect 25× stronger than the products of its combustion. Germany therefore introduced emissions allowances of EUR 25 per tonne of CO_2,eq for natural gas in January 2021 and seeks to promote this approach to natural gas as a fossil energy source throughout the European Union.

Decarbonisation of the power sector

The Czech Republic acceded to the Paris Climate Agreement, which calls for the economy to be fully decarbonised by 2050. Assuming the rest of the world does the same, this would stabilise the global temperature increase at +1.5 ^oC compared with the pre-industrial climate. As global emissions, despite half a century of international negotiations, continue to grow by 1.5 % per year, keeping the temperature increase below 2 ^oC is already unlikely according to the latest IPCC report from 2021.

The carbon footprint of Czech residents is among the highest in the world, reaching up to 10 tonnes of CO_2,eq/person/year overall, twice the global average. The Czech Republic has the highest share of industry in GDP generation among EU countries and is a major subcontractor for larger economies. Around 40 % of all Czech greenhouse-gas emissions come from the power sector. Some studies, for example here, here, here and here, state that an energy mix based almost 100 % on RES can be assembled and that this is merely a matter of political priorities and funding. However, under the climatic and geographical conditions of the Czech Republic, fossil fuels can only be partially replaced by RES:

• Solar and wind sources depend on weather and the time of day and year, and cannot be controlled according to current energy consumption. Hydropower is significantly limited by the Czech Republic's geographical conditions and the continuous availability of water. Biomass (forests, agricultural production) is also limited and is nowhere near sufficient for the sustainable operation of all combined heat and power plants and power stations.
• Although the Czech Republic has been intensively building photovoltaic and wind power plants for 15 years, RES generation in the country falls to as little as 0.3 % of electricity consumption on winter nights with inversion conditions. Average RES output during the winter period is approximately 1 % of total consumption, and available storage capacity must be charged from other sources; see Fig. 1.
• The capacity of all Czech electricity storage facilities can meet only 10 % of Czech consumption. The Czech Republic has no mountain rivers with dams capable of storing the required amount of energy, while pumped-storage power plants are the dominant storage facility. However, no further construction is currently under consideration. Construction of the most recent one, Dlouhé stráně, took 18 years. Battery systems can be purchased more quickly, but these investments are highly loss-making due to batteries' short lifetimes. This is why 99 % of all electricity stored worldwide is stored in pumped-storage hydropower plants.

The inability to efficiently store generated energy is a critical limitation of all Czech solar and wind sources. What matters is not only whether the same amount of energy is generated annually as is consumed, but also whether enough is generated to cover total consumption at every moment of the day and night, 24 hours a day, 365 days a year. Electricity availability at any moment is an important characteristic of the power sector, playing a significant role in all areas of human life, from the everyday comfort of households and strategic infrastructure (mobile and data networks, water utilities, hospitals, street lighting, public transport, railways, etc.) to national security issues. Every energy scenario must therefore guarantee this availability and rule out electricity supply outages.

Current situation

Let us look at the chart of electricity consumption and generation in the Czech Republic in January 2019 in Fig. 1. January tends to be the most critical month due to minimal sunshine and maximum heating demand. The red curve of total Czech consumption shows midday increases of approximately 20 % compared with nighttime levels, as well as similar weekend declines. Despite intensive construction of PV and WPP, most electricity consumed was generated by fossil, nuclear, hydro and biomass sources, while photovoltaic and wind sources supplied only 1 % of total consumption that month.

Fig. 1 - Electricity generation and consumption in the Czech Republic in January 2019 in [GWe]. 79 % of electricity was generated at coal-fired and nuclear power plants, while photovoltaic and wind power plants generated approximately 1 % of electricity.Total Czech annual generation of 80.8 TWh exceeded consumption of 66 TWh, with the surplus exported (dashed line). Exports of this predominantly “coal-fired” electricity made a significant contribution to greenhouse-gas emissions of 3954 kg CO_2,eq/person/year. However, the positive electricity generation trade balance will end in 2023 with the planned closure of several coal-fired power plants, reducing Czech greenhouse-gas emissions to 2972 kg CO_2,eq/person/year.The second part of the article can be found here.