Could the UK’s tides help wean us off fossil fuels?
Could the
UK’s tides help wean us off fossil fuels?
Kelsey Ramp
There is an increasing global need for renewable energy sources
which can be practically implemented into our modern society. Alongside solar
and wind energy, tidal stream energy could replace fossil fuels for a fraction
of our energy needs. Tidal streams could become a reliable source of energy
generation by using predictable tidal waves to turn a turbine which generates
electricity. Tidal energy is not a new concept and has been used to mill grain
for 1,000 years, however, it has not been implemented on a large scale due to
cost and other environmental or engineering challenges. Despite the costs and
challenges, tidal energy remains a viable option for energy generation in areas
with powerful tides, such as the UK which experiences some of the world’s most
powerful tides.
The BBC news article, Could the UK's
tides help wean us off fossil fuels? - BBC News, by Justin Rowlatt summarizes
how tidal power generation works, how the tides are produced, how much of the
UK’s annual electricity demand could be met using tidal energy, current turbine
designs, and the pros and cons of this form of energy generation. Rowlatt does
a nice job of summarizing how tidal energy generation works and why it is a
promising source of renewable energy for the UK, including discussion of how
water is 1000 times denser than air allowing it to provide more concentrated
energy. The article also discusses the predictability of the tides based on the
moon’s gravity and Earth’s rotation. This a major plus as it is a guaranteed
source of energy and does not require “back up” reserves such as with wind or
solar energy. The article mentions a review put together by many top UK
institutions, suggesting the study says tidal generation could meet as much as
11% of the UK’s annual electricity demand.
Important challenges with tidal energy generation using
turbines are also discussed by Rowlatt including scaring animals out of their
natural habitat, expense, difficult maintenance conditions due to waves, and
the corrosive effect of sea water on metals. The article also mentions that
proponents of tidal energy generation suggest it will not reach the same scale
of energy generation compared to wind and solar due to the fact tidal turbines
are restricted in size due to the depth of water. Several different turbine
designs being implemented across the UK are also discussed including turbines
moored to the sea floor and a ‘kite,’ that flies underwater (turbines pictured
below).
The review mentioned by the news article, A review
of the UK and British Channel Islands practical tidal stream energy resource |
Proceedings of the Royal Society A: Mathematical, Physical and Engineering
Sciences (royalsocietypublishing.org), was published in 2021 and provides
an assessment of the potential impact tidal stream energy could make to the UK
and British Channel Islands future energy sources. The review discusses a
Carbon Trust study which estimated an initial practical resource potential of
21 TWh/year, which is equivalent to 6.5% of the UK’s current annual electricity
demand. Due to the reconsideration of some economic and environmental
constraints, the study re-estimated this potential to be closer to 34 THh/year
which is 11% of the UK’s current annual electricity demand. The review
highlights sources of error and uncertainty in this estimate by the Carbon
trust which contribute to an uncertainty of -50/+20 %, due to factors such as
excluding sites with unavailable field data or underestimation due to not using
hydrodynamic models with site specific geometry and forcing. The review also
discusses some environmental impacts not mentioned in the news article, such as
decreasing the energy of tidal mixing by perturbing the balance between
horizontal and vertical mixing processes, and sediment transport. The general
consensus of the review article is that 34 TWh/year of tidal energy is
achievable if 11.5 GW of capacity is installed, which depends on up and coming
sites. The review supports that 34 TWh/year is achievable, but site-specific
hydrodynamic modeling and enhanced model validation should be implemented. The
review concluded that tidal energy does not have significant detrimental
environmental impacts, but that site-specific environmental impact studies
should be implemented.
Overall, I think the news article does a good job of
summarizing important background information, representing the study it cited,
and giving a good overview of the pros and cons associated with this form of
renewable energy. The news article correctly cites the review in saying tidal
energy could have a practical resource contribution of 11% to the UK’s current total
energy needs, however, does not speak of the very large uncertainty associated
with this number or the fact that energy needs are suspected to increase to
between 550 and 680 TWh/year by 2050. The news article also does not mention
that a practical resource contribution considers the annual energy yield
potential that can be harnessed after consideration of economic, environmental,
regulatory, and social constraints. The article also does not mention some of
the other main environmental concerns mentioned by the review such as changes
in sediment dynamics. Considering all of this, I would give this news article an
8/10, I think it does a good job summarizing the information for the general
public, doesn’t oversell anything, and only comes up short in a few areas that
could have also made the article more confusing.
Hi Kelsey, thank you for sharing this great article with us which effectively communicates the main points about tidal energy, with some room for improvement in providing a more comprehensive view, particularly in terms of environmental concerns and the associated uncertainties in the estimates. However, it appears to be a good starting point for those looking to understand the potential of tidal energy as a renewable resource.
ReplyDeleteHi Bishvanwesha,
DeleteI agree this article does a nice job of providing a starting point for understanding the potential of tidal energy as a renewable resource. The news article does not include some environmental concerns associated with this type of energy harvesting such as sediment dynamics and effects on mixing regimes. However, it does mention some of the easier to understand environmental concerns such as scaring animals away from what could be their natural feeding grounds. I would have liked to see the news article mention that when employing this type of renewable energy, doing site specific environmental impact studies are of great importance, as this was one of the main conclusions drawn in the review article.
This analysis is very informative and interesting. I had never considered that the tides could be used as a source of renewable energy. It makes sense though; the tides move on a predictable cycle and the movement is caused by an outside force that doesn’t require human intervention to activate. i.e. the pull of the moon. I can see how this could have some limitations, but it’s not like theres any perfect energy source out there. As they say, perfect is the enemy of the good. If we can have one more type of renewable energy to add to our arsenal, its only contributes to helping us move away from unrenewable sources like fossil fuels.
ReplyDeleteHi Giana,
ReplyDeleteI agree that although not perfect, tidal stream energy is an interesting possibility that could be practically employed and efficient at certain site locations.