How to store excess energy?

Sunnuntai 21.7.2024 klo 19.21 - Mikko Nikinmaa

The problem with both solar and wind energy is that the production is necessarily intermittent. Day and night follow each other, and some days are cloudy. Some days are windy and others are calm. Consequently, sometimes energy is produced much over consumption and at other times renewable energy production remains at much lower level than what is needed. Because of this, it has often been said that wind and solar energy production need constant energy production, such as nuclear power. Also, the intermittence makes it difficult to become completely free from natural gas, oil and coal.

However, the situation would be much better if all the excess energy produced could be stored for later use. The immediate idea is to use batteries. Although batteries are a common solution for small scale storage, they are relatively expensive and a lot of natural resources are needed for making them. A less expensive, large scale storage solution would be to utilize gravity. For a long period of time this has been almost completely restricted to pumping water to reservoirs uphill when excess energy has been available, and then letting water flow downwards when energy production is needed. Instead of pumping water, any material can be moved upward with excess energy, and the potential energy thus stored released when the weight is moved downwards. Such gravity-utilizing energy storage systems are, in principle, cheap and easy to operate. Consequently, they should become an important feature of wind and solar power plants

Kommentoi kirjoitusta. Avainsanat: wind energy, solar power, gravity

Energy Production to Mitigate Climate Change

Maanantai 30.5.2022 klo 16.53 - Mikko Nikinmaa

We must get rid of burning fossil fuels. Especially two things have happened in recent past, which speed up the conversion from fossil fuels to other ways of energy production. As terrible as it is, the attack of Russia to Ukraine is the first. Russian economy has been centered around oil and gas export. With the attack, Europe, by far the biggest market, is decreasing its dependence on Russian energy. Putin’s Russia is imagining that China’s huge market will offer an alternative. However, there is not available transport infrastructure, and building it would take years during which China is investing mainly on decreasing fossil fuel use. So, what is happening to Russia is that it is rapidly becoming a huge loser in everything: it is currently under heavy sanctions, and soon nobody will buy oil and gas from it. And innovative people have emigrated which precludes the generation of new products, which would be bought after the sanctions are lifted. Second, the elections in Australia threw out the climate denialist Morrison and gave clear support to candidates who were for climate actions. Because of this, one can expect that Australia changes from being one of the biggest per capita carbon dioxide polluters (only behind some small Arabian oil producers) to a country that is actively promoting the use of fossil-free energy.

As one is moving away from fossil fuels, nuclear power has been advocated as an important alternative. At the moment the only place, where this is already happening is China, where more than 50 nuclear power plants are in different stages of construction. One cannot expect that any nuclear power plants which are not already being built will make a contribution at the time that fossil fuels need to be replaced, i.e., next ten years. Approximately only 30 % of the power plants, where construction was started 10 years ago, produce energy today. Besides, the traditional nuclear power plants are excessively expensive, with the cost of several billion €. As an alternative, the nuclear power lobbyists advocate the production of small, modular power plants, which could be placed to the sites liberated from coal power plants. However, there is the problem that no such power plant currently exists except in the planners’ drawing tables, although according to the lobbyists the first should have been in use already several years ago.

The reason for advocating nuclear power is that energy production from them is constant, not fluctuating as that from the much cheaper wind and solar energy. In view of this, one should either find ways of producing green energy at constant level or storing it so that the excess energy can be used during the time that production is limited. Both alternatives are already known, and the needed infrastructure is certainly much cheaper and more rapidly built than a full-scale nuclear power plant. With regard to constant fossil-free energy production, the use of geothermal energy is easily done. In fact, Iceland’s energy production depends almost fully on it, and  its use is possible everywhere. The expense for kWh may presently exceed that of using fossil fuels, but it will most likely get cheaper as wind energy has. Tidal energy and ocean current energy are constant. It has been estimated that about 30 % of total energy demand in UK could be produced with tidal energy quite easily. Also, turbines for ocean current utilization would be quite similar to those in hydroelectric power plants.

The simplest way of achieving effective energy storage is to pump water to a storage site during the time that more energy is produced than is needed. When the stored energy is required, the storage site can function as hydroelectric power plant. The second good alternative is not actually storage, but utilizing the fact that the wind blows and sun shines always somewhere. Making electric grids interconnected so that electricity can be transported from where it is overproduced to where it is needed is a way of stabilizing global production/utilization. While this way of making ends need appears vulnerable today with Russian aggression, such globalism is required if we are to effectively combat climate change.

So, probably nuclear power is not needed because of its heavy investment costs and long building time. The alternatives can be built much more rapidly and do not require as extensive investments. However, if fusion power ever comes into controlled being, that changes everything. After all, the sun is only a massive fusion power plant.

Kommentoi kirjoitusta. Avainsanat: nuclear power, wind energy, hydroelectric power, energy storage, fossil fuels