draft.
The problem: Additional grid connections for renewables.
New grid connections are needed for renewables, largely because the right location for wind and solar is often not same as the location of existing power generators.
The Australian opposition has just launched a plan for nuclear power generators, mostly at the sites of existing coal powered stations, but in all cases where power is fed into the grid. In theory, the logic for the plan is that the savings on putting in new grid connections can offset the cost of the nuclear power plants. Regardless of whether this makes sense, it highlights the role of the cost of new grid connections needed for renewables.
The main reason the new grid connections become so expensive is because of the cost of acquiring the land for these new connections. The problem with existing technology, is that it requires acquiring and maintaining corridors around 100 metres wide that house huge towers that affect the scenery and thus devalue the real estate for kilometres.
Australia’s complex tangle of electricity grid connection, congestion and system strength issues is quickly becoming a major barrier to the next big wave of renewable energy investment, a panel of industry insiders has warned.
In a webinar hosted by the Clean Energy Council on Tuesday afternoon, panellists ranging from CEFC CEO Ian Learmonth to Octopus Investments managing director Sam Reynolds said increasing uncertainty around connection and commissioning of large-scale solar and wind energy projects were acting as a major dampener on new investment in the sector.
The webinar, which featured a keynote address from the head of the Macquarie-owned Green Investment Group, Mark Dooley, heard about the “tremendous opportunity” for investment in the renewable energy sector as development ramps up to meet Paris climate targets.
Grid problems now the biggest turnoff for renewable energy investment in Australia | RenewEconomy
High voltage DC underground as significant alternative.
I am using data from this paper from 2011, but it is a least a start.
Consider the comparison with AC:
Not only is the actual land required reduced by up to a factor of 8, reducing the cost of acquisition and maintenance by a factor of 8, but the impact on the environment and surrounding districts puts the scope for objections into a completely different scale.
While which solution works best will be a matter of comparing components of the cost, the scope for solutions that add up is highly significant.
How does it fit with the grid?
Most installations assume the HVDC cabling will be connecting two points on the grid that a currently high voltage AC, but when connection renewables, the cost is even lower.
Most are aware that solar arrays produce DC, which means normally there would be converter to high voltage AC required at the solar farm.
Plus, while wind turbines do generate AC power, unless the turbines operate at one fixed speed, the power will not be the correct frequency for transmission, which means the power is normally converted to DC at the turbine site and then reconverted to appropriate AC.
The generator in wind turbines produces Alternating Current (AC) electricity. Some turbines convert this AC electricity to Direct Current (DC) with a rectifier, and then back to AC using an inverter. The purpose of this, is so the frequency and phase of the electricity is in line with that supplied by the grid.
By converting the variable speed AC current, produced by the generator, to DC current and then back to AC, the electrical signal is converted to a phase and frequency like that produced by the grid. Most electrical equipment in your home runs on predefined electrical conditions, and an unstable supply can damage your electrical equipment.
How does a wind turbine work? – Action Renewables
Ultra high voltage DC power.
It did not take much research to find other people in Australia talking about High Voltage DC for power, with one video pointing out how high voltage DC is playing a big role in connecting renewables to the grid in China, where the distances are similar to those in Australia.
This video highlights the use of Ultra High Voltage DC and shows how widespread this technology is in China. While Ultra HVDC may have a role, it is for fewer and longer distance links, like one from solar in WA to provide evening power on the eastern seaboard where the sun sets and rises around 2hrs 20 minutes later than it does in Sydney.
Interesting, but I suspect not the main focus for now.
updates:
- 2020 June 20 : First draft (push back date)
