Environmental Impact of Renewable Energy Technologies
The purpose of using renewable energy is to provide energy with reduced emissions of greenhouse gases. The concentration of CO2 in the atmosphere remained below 280 parts per million (ppm) for 800 thousand years until the start of the Industrial Revolution in the eighteenth century.
The concentration has risen from 280 ppm in 1780 up to 400 ppm in 2013. The effects of this accelerating trend on our future environment are unknown, but scientists are debating the effects of these trends and the risks of reaching tipping points that may not be reversible.
So we need to come back down to the present and consider the environmental impact of any new project.
Adopting renewable energy technologies is one way of reducing the environmental impact of what we do.
However, we have to consider the environmental impact of any renewable energy technologies we adopt. There are some environmental costs to most of the renewable energy technologies, so it is worth examining these.
The good news is that wind turbines can convert the power of the wind into electricity. Wind power produces no toxic pollution or global warming emissions in use.
The bad news is that there is a groundswell of objection to the unsightly nature of wind turbines – especially in areas of outstanding natural beauty. Governments have tried to counter these objections by offering large subsidies to those who install wind turbines. This, in turn, enrages some taxpayers who are effectively being required to pay for machines to which they object strongly on environmental grounds.
There are also objections from taxpayers who are required to subsidize machines that are rarely used at more than 30% of their potential capacity.
There are objections from those who observe the mortal impact on birds and bats and objections from those who have to endure the noise of the turbine blades. The accountants solemnly calculate the embedded carbon of constructing the concrete platforms and masts for the blades to be mounted on.
Photovoltaic arrays convert sunlight to electricity. The environmental limitations are to the use of scare resources in manufacturing them and the inefficiencies of operation: this requires substantial taxpayer subsidy to encourage the up take of PVs.
The good news is that burning biomass is an alternative to burning fossil fuels. The limitation is that burning biomass releases 66% more CO2 than burning gas for the equivalent amount of heat. The debate progresses to questioning whether this CO2 should not count because it is releasing CO2 that has been captured over the last, say, fifteen years or whether there is an assumption that the CO2 released may be recaptured by biomass growth somewhere else over the next generation of growth.
Incomplete combustion yields carbon monoxide – a poisonous gas – soot and particulates, the precursors of acid rain. See Air Quality.
There are also suggestions that only waste biomass should be counted – because growing biomass, merely to burn it, prevents land being used for food production. The accountants also calculate the embedded carbon of transporting wood chips across the oceans to satisfy legislative diktats.
Hydro electric stations generate electricity from exploiting the natural forces of gravity and meteorology. Some issues are raised about altering the natural environment and loss of habitat for certain species.
Solar thermal panels generate hot water from the natural energy in sunlight. The environmental impact is small, although some people object to the visual impact, especially on historic houses.
Road solar collectors
A road solar collector also generates hot water from the natural energy in sunlight. The technology is embedded into roads and is invisible. There is no environmental cost of collecting heat from roads.
Air source heat pumps
An air source heat pump recovers heat from ambient air and transfers it into buildings to provide efficient heating. There is environmental impact from the noise created by fans circulating air through the heat exchange elements, but the effect can be moderated by careful siting of the external equipment, as can the visual aspects.
Ground source heat pumps
A ground source heat pump recovers heat from the ground and transfers it into buildings to provide very efficient heating. There is no environmental impact at all because a ground source heat pump installation provides an invisible heating system with no emissions of carbon (or any other gas at all).
Interseasonal Heat Transfer
Interseasonal Heat Transfer is an integration of renewable heat technologies that captures solar energy in summer, stores it in the ground in ThermalBanks over the autumn and delivers it to buildings in winter to provide very efficient heating. IHT uses ground source heat pumps to provide invisible heating systems. It also uses road solar collectors to generate heat in the summer to charge ThermalBanks with solar energy so that its GSHPs can providing heating more efficiently than an unassisted ground source heat pump in winter.
It is now possible to chose a very efficient system for renewable heating – and renewable cooling – with no adverse environmental impact.
The district energy approach of E-Hub allows for sharing of energy supply and demand between the residents of a district. The use of seasonal thermal energy storage allows for the extension of sharing of heating and cooling across the seasons as well. These approaches reduce the overal demand for energy – and the environmental impact of providing it.