ScienceDaily (Mar. 27, 2009) — Engineers at the University of Liverpool claim that building estuary barrages in the North West could provide more than 5% of the UK’s electricity.
How much energy and raw material is used to build a tidal barrage? How much Carbon Dioxide is produced in building a tidal barrage? What is the payback time for the CO2 produced in construction? Will it be offset in other ways? What is the impact of tidal barrages on the carbon budgets of estuary systems? What are the consequences to the economy of the disruption of major ecosystems? In quoting figures such as 5% of UK's electricity demand are we referring to today's demand or projected future demand?
Howard Odum articulated his concept of embodied energy and coined the term Emergy (spelt with an M). This is a calculation of all the energy from all sources that has been used to produce a product or service. It recognises the true value of a product or yield because it quantifies the amount of effort used in producing the yield, including the contributions of natural systems as well as human systems in the upstream processes. It thus provides a basis for valuing the work of ecosystems and human economies in equivalent terms. It also provides a means for quantifying the impacts of economic decisions on natural systems and follows these through to their impacts on the economies that generated them. In other words it provides a quantification of the maxim "what you sow so shall you reap". This is in contrast to the current economic paradigm which externalises costs related to environmental degradation and fails to account for the consequential cost of abatement and repair to human and natural systems.
What would contemporary emergy analysis tell us about tidal barrages?
When engineers boast of meeting 5% of the UK's energy demands, they are missing the point. The Point is this: the future will be darker. It has to be. The sums just don't add up. We are all going to have to use less energy. We will travel less, eat more locally grown food and see more stars in the sky above darkened cities and towns. Its going to be different. People don't like change but building barrages is not the answer. Managing expectation is.
This is the personal opinion of Rhodri Thomas and is not representative of any official position held by Cynnal Cymru-Sustain Wales on the Severn or any other barrage. Comment is encouraged and welcome.