Facts and Issues of Energy Production

Solar panel
A solar photovoltaic system array on a rooftop in Hong Kong (Image: Wikipedia user - Wpcpey)

Dr Lou Sai LEONG

Present situation

There is a variety of developments for energy production in the world. A lot of opinions are given and discussions are made: fossil fuels (coal, oil or gas) pollute the atmosphere and produce a lot of CO2 which largely contributes to global warming; renewable energies are infinite resources that produce very few greenhouse gases, but have the constraints of meteorological variability which means that the energy production is intermittent; nuclear energy produces a huge amount of energy without emitting CO2, but draws unfavourable public opinion because of safety issues. Scientists as well as politicians have their own opinions and their own interests to support different types of energy development. However, one of the main parameters for sustainable development is not limited only by the capabilities of each technology, but also by the efficiency of production.

So far, there is no large-scale storage system that can store a huge quantity of electricity. Therefore, in theory, the more electricity we can produce, the more we should consume. In that case, it is necessary to manage and control the energy production rate and the consumption rate based on the needs of the different countries and the technologies. However, we can reconvert the energy back to other resources details of which as follows.

Coal power plant
Coal power plant in Datteln, Germany (Image: Wikimedia Commons)


Why is the efficiency of energy production important?

The demand of electricity changes throughout the day. It increases largely generally at 8 am, and this level of consumption remains high until 8 pm. Energy demand peaks at around 6:30 pm. In the evening, the demand decreases by around 30% , compared to that during the day. To meet this fluctuation in demand during the day, can the power plants provide a stable supply at different energy consumption times?

In fact, we can stop the production at a fossil fuel power station or only decrease its production immediately, due to its fast response. Hence, if we produce 100% our energy through fossil fuel , there is no need to worry about the energy storage because we can synchronize the quantity of energy produced and consumed. But, because of the global warming issue, it is now absolutely necessary to find an alternative option.

Nuclear power plants provide very large-scale energy production for us. If we produce electricity by nuclear power for the whole world, our resource will last hundreds and thousands of years , depending on the type of reactor we use. As a matter of fact, the production of nuclear energy is very stable. Eventhough nuclear power plant cannot be completely stopped within a short period of time like fossil fuel power plant, the production rate can be decreased to less than 40% during the time of low electricity demand. Due to the safety reason, the public is against nuclear energy for long-term energy development.

Renewable energies e.g. sunlight, wind, rain and waves are based on natural resources that are safe and there is no CO2 emission. Global renewable energy consumption has risen for the last ten years (RNE21). Technologies like solar panel, photovoltaic, wind power have been improved a lot. Several projects to build these power stations in mass have been started in Europe and US. Some people suggest hat we should build more power plants to increase the output. However, the main issue of developing these technologies is more related to energy storage.

For example, we need wind that is able to turn the wind turbines 24 hours a day 7/7. There is no place on earth where the sun shines all year for power production. Most of the rivers flow every year but water level might change depending on the season. In fact, the meteorological conditions are the same across some continents. For example, if wind is lacking in Germany, it is also lacking in Spain (same for sunshine), so that the mutual exchange is very limited. Also, the capabilities to develop hydraulic power are very limited in certain countries. We cannot guarantee the energy production with a stable supply from these natural resources, especially during peak time of energy consumption. Without a storage system for storing electricity generated by the power plants in full production, it is difficult to overcome the intermittence of power production of renewable energies, and to advance these technologies.

As it stands now, multi-energy production remains the best option but we must generate and manage the energy in more efficient way.

Nuclear power plant
Bellefonte nuclear power plant in Alabama, USA (Image: Tennessee Valley Authority)

Smart energy and its future

As mentioned, there is no large-scale storage system that is able to store a high quantity of energy, but we may possibly convert an energy resource to another one, like convert the energy to hydraulics. For example, in France, 80% of electricity comes from nuclear, others from fossil fuel (5%) or renewable energy (mostly hydraulics and some wind power). As nuclear production rate is stable and that only twenty percent of production comes from renewable power plant, the impact from the variability of public demand will not be so significant because nuclear energy has the stability comparable to fossil fuel power. In the evening, the need is largely reduced, and nuclear power plant has a capability to vary the energy production to 40% and more, despite 30% difference of energy consumption between high and low peak during the same day. Unused energy is sold to Switzerland for increasing water level of its dam for hydropower.

In Germany, thanks to its geographic position, 50% of its energy is produced with renewable power. However, due to political reasons, after the shutdown of nuclear power plant, the other 50% of its energy is replaced by coal fuel.

Consequently, CO2 emission has increased since the shutdown of all the nuclear power plants. In case of shortage of electricity, clean energy is imported from the hydraulic power station in Switzerland.

In any case, renewable energy requires a lot of a country’s resources. In Europe, the technologies are very advance, but due to geographic constraints (rivers, wind or sunlight) , each country cannot develop diverse types of energy power. Countries like China or United States which cover large land area can build diverse power stations to adapt to the variability of public demand and actually they are now doing so.

Last but not least, it is difficult to say which is the best sustainable development strategy for each country. “How to manage the energy in a more efficient way” is the key for future development. For the future, we should invest more on the research of efficient energy production. But for now, we should save as much as possible in our daily energy consumption.

About the author

Dr Lou Sai LEONG studied nuclear physics at Unversité de Paris Sud in Paris, France.