Heat from the sun evaporates vast amounts of water from the oceans which fall as rain and snow, creating large rivers and lakes. This process of evaporation creates potential energy when stored in lakes and kinetic energy in flowing rivers. Kinetic energy can be used to turn millstones or turbines to create electricity. Countries that have large water surpluses can harness this energy as renewable energy, albeit at varying environmental cost. Note that pumped hydro is a method of energy storage. It is not hydro energy as some other primary source is stored. If pumped with coal energy it is stored coal energy. If pumped with solar it is stored solar.
About 16% of the world’s electricity is produced from hydro. The top producers are China, Canada, Brazil, US, Russia and Norway with China producing about 20% of the worlds hydro power and Norway about 5%. Around 15 countries can produce 90% plus of their electricity needs from hydro (and other renewables) in a good year, including Norway, New Zealand, Iceland, Bhutan, Albania, Paraguay and Costa Rica.
Costa Rica is often portrayed as a renewable energy poster child as it can run its electricity needs as 100 % renewable with about 80 % of this from hydro and the remainder from geothermal, wind and solar. The accolades are largely deserved as Costa Rica has built on its natural assets and is investing in their development. Geothermal energy is readily accessible as it is also an active volcanic province ( as are New Zealand and Iceland). Another blog will review geothermal possibilities around the world.
Costa Rica is a special case with hydro though, as it is in one of the world’s highest rainfall areas with plenty of rapidly flowing rivers. It also has little industry requirement for electricity and domestic usage is low. It does however suffer severe droughts as rainfall is not consistent. During droughts it needs to import fossil fuels. Tasmania also suffers from this problem, having to run diesel generators to supplement its electricity supply in recent times (exacerbated by an outage of the underwater electricity cable from the mainland).
On the other side of the equation are the environmental and social impacts of hydro. Large dams, necessary for a constant supply, flood vast areas of land and displace local populations. They also play havoc with fish migration, water quality and local environments. Again Tasmania is a good example, with the outcry over damming the Franklin River.
Costa Rica still has a serious issue with its highly polluting, outdated road transport system. Electricity production is generally about 40% of energy use in any country, so most of its energy requirement is still from fossil fuels. Costa Rica is legislating greater use of electric vehicles but affordability and freight transport are problems.
In Australia we have some hydro on the East coast and Tasmania with little potential elsewhere (other than possibly in the far north). Tasmania is an interesting case as it is an island with limited energy sources. In an average year in recent times Tasmania sources its electricity needs with 60% hydro, 10% wind and 30% imported via the Basslink cable from Victoria. The cable essentially supplies cheap baseload electricity from burning brown coal on the mainland. South Australia similarly uses this baseload electricity to back up its high wind and solar supply. In December 2015 the Basslink connection was broken and is not expected to be repaired until mid year 2016.
In the meantime the Tamar Valley gas fired (imported) power station has been restarted and with the hydro power Tasmania should have been OK. However Tasmania is experiencing a drought with dams down to an unprecedented 12% fill, requiring restrictions in hydro output. Tasmania is currently running on about 12% diesel fired power,10% wind, 35% imported gas and 43% hydro. With dams that low environmental problems are also on the increase.
Norway is a hydro success story. They can produce up to 100% of their energy needs from hundreds of hydroelectric power stations across the country. They operate in an open energy market connected to the rest of Europe via Sweden. The mix of hydro, Swedish nuclear energy and Danish wind works well for renewables / nuclear in the area.
Norway is also about the eighth largest producer and exporter of oil, with much of its GDP and lifestyle coming from this resource. They have the third best GDP per capita in the world and with about 30% government ownership of their industries the local population do well. Norway is also sitting on some of the world’s largest coal resource. This means that Norway is still responsible for a large amount of CO2 entering the atmosphere now and possibly into the future. Norway also has one of the highest CO2 emission rates per capita in Europe due to their hydrocarbon production.
Norway is moving away from hydro power and freeing up some rivers. They are moving on to floating windmills, tidal power and salt water osmosis. The latter is an intriguing power supply where salt and fresh water are stored separated by a semi porous membrane. This allows osmotic pressure to build up and the pressurised water is used to turn a turbine! Only useful I guess where you have large amounts of fresh and salt water together.
China is the biggest hydroelectric producer however and their new Three Gorges Dam the biggest of them all (although the managers of the Brazil / Paraguay Itaipu dam might argue). While the project is helping to clean up China’s environmental act it displaced 1.3 million people in doing so. The dammed water reservoir is 660 km in length and an average of just over a km wide to give 1045 sq km surface area (compared to 1350 sq km at Itaipu). The project cost about US$25 billion but is expected to pay that off within 10 years.
The dam has been said to reduce coal consumption by 31 million tonnes per year, avoiding 100 million tonnes of greenhouse gases. Additionally transport along the dam has significantly reduced trucking requirements again saving millions of tonnes of GHGs.
On the downside, such a large body of water is weighing on the earth’s crust in the region and is a reason significant earthquakes have been recorded. This is not helped by 2 major fault zones running through the area. Landslides are also common on the banks of the dam. The rate of sedimentation has also changed downstream and this will affect the city of Shanghai built on the Yangtze delta.
Hydro dams around the world have and are still creating many disputes. The Franklin River dam divided Australia. The Grand Renaissance Dam in Ethiopia is causing major headaches downstream in Sudan and Egypt. The Belo Monte dam in Brazil is under fire for burying large areas of rainforest (and creating significant methane by its decomposition). India and Pakistan are fighting over water rights and the right to build hydroelectric dams on shared rivers.
So while hydro is considered a great renewable energy source it creates many other problems. It seems that any energy source comes with its own peculiar set of issues. It is also worth noting that it is only available in particular areas and we may have reached a maximum for hydro generation.
Igniting CSG in rivers
Videos have appeared recently showing how the Condamine river is leaking methane and this can be ignited. The CSIRO has declared it a natural phenomenon even though it is within a region exploiting CSG. Some have declared fraccing responsible.
From a scientific viewpoint any rivers flowing along Australia’s east coast are likely to erode into coal seams which are prevalent. Once a coal seam is eroded methane gas will leak and be dissolved in the flowing waters. Every coal mine along the east coast is allowing many times the amount of methane in the Condamine to escape into the atmosphere every day. The Great Artesian Basin waters are similarly exposed to methane from coal beds and can be ignited in the many bores along norther NSW.
Only about 8 percent of CSG wells have been fracced in Australia – most don’t need it. I do not know if any wells in the area have been fracced or the methodology. Wells drilled into coal seams are dewatered to allow the gas to flow. Flowing water out of the seams lowers the pressure enabling CSG to flow. Droughts and water bores have the same effect.
The gas in the Condamine is likely to come from eroded coals, particularly if the local water pressure has dropped from the CSG mining, drought or water bore pumping. Local fault movement may assist this process.
Methane is not poisonous but is a GHG. For this reason its release needs to be controlled. Coal mines are by far the major local contributor.