Can heat and power be sustainably generated and should it be?
The energy infrastructure in most countries has been a state-owned, centralised power generation system, supplying electricity from large scale combustion plants and generally located near fuel sources. The remote location of plants has led to a requirement to transport electricity across vast areas of land through the use of a grid system, comprising of high voltage power cables suspended from pylons or buried in the ground, which creates energy loss and unusable heat.
The total power produced in Germany each year from non-renewable sources was almost 90 GW in 2018, renewables provided a further 117 GW of electricity (Datasource: AGEE, BMWi, Bundesnetzagentur). Although this is a positive step in which renewables are contributing more than their fossil fuel equivalents, the energy is still being generated far from where it is needed.
How much energy is required to be produced in order to cover line losses?
Over long distances the loss is minimal due to the high voltages required. When the energy enters urban areas a step-down is required, the efficiency drops and the loss increases. The biggest loss, however, is from the generation of energy from coal or uranium-fuelled power stations (gas is more efficient). This is not a problem in the same way for wind and solar, but it does mean more units are required to cover the losses of energy. So what are the options? Completely change to renewable sources where efficiency is not so detrimental? Move away from a centralised system and locate power sources close to the user? Or a mixture of both?
The problem with maintaining dependence on non-renewable energy sources is the waste gases and the use of a finite fuel, or highly dangerous one. When existing plants were built they were located close to their fuel source and helped to sustain a local economy from, for example, mining. But now most coal, gas and nuclear fuel sources are located around the world: Germany imported around 46 million tonnes of anthracite coal in 2018 (VDKi). This in itself is not a sustainable method of fuel sourcing as anthracite coal requires transporting by sea from countries such as Australia, Columbia and the USA, natural gas needs energy to be pumped across vast areas of land, lignite coal and nuclear fuels by rail. Not only are there environmental issues, but economical and political ones too; the desire for fuel independence is frequently voiced by nations.
Completely changing from fossil fuel sources to renewables would in the long term be the most beneficial and desirable. However, our existing way of life has developed from these fuels allowing products to be created and energy to be derived from them. There is still a great resistance to this shift as the financial implications to those involved with the current system are huge, however the power industry needs to change and alter its focus; electricity will still be needed and therefore remain a commodity to be bought and sold. Over time the infrastructure costs would reduce and efficiencies increase, investment in the distribution and management of energy would be required in order to maximise their potential. Current renewable sources are more limited by their locations: biomass burners need to be near forests in order to reduce transportation, location in windy areas and away from obstructions (or out at sea) is required for wind, solar needs open land or better still existing roofs, tidal requires coastline, therefore creative thinking is required to adapt the energy generation to the location of the user.
Modern technologies are allowing sustainable energy generation to move closer to urban areas and deal with other issues such as waste. E.g. anaerobic digestion of sewage and food waste creates methane, which is then used to fuel engines in order to generate electricity; these are relatively small scale and can be located easily on brown field sites once the supply chain is installed.
Improvements in energy management, weather predictions, advances in efficiencies and energy storage solutions can make renewables work.
So, in the short term, the slow speed at which the wheels of industry and governments turn will dictate the development of renewables and the replacement of fossil fuelled energy generation, but maybe the implications of climate change and the social pressure to prevent it will make the transition take place faster.