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Tag Archives: electricity grid

Wiill the lights stay on?

by Dave Elliott

There has been a long and sometimes heated debate over UK grid security issues, with some claiming that the spread of wind power and PV will undermine it.  Ofgem’s 2013 Electricity Capacity Assessment says ‘Wind generation, onshore and offshore, is expected to grow rapidly in the period of analysis and especially after 2015/16, rising from around 9GW of installed capacity now to more than 20GW by 2018/19. Given the variability of wind speeds, we estimate that only 17% of this capacity can be counted as firm (i.e. always available) for security of supply purposes by 2018/19.’ https://www.ofgem.gov.uk/ofgem-publications/75232/electricity-capacity-assessment-report-2013.pdf

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Nuclear and renewables: back-up and grid costs

By Dave Elliott

A study by the OECD Nuclear Energy Agency (NEA), Nuclear Energy and Renewables: System Effects in Low-carbon Electricity Systems, looks at the interactions of variable renewables and “dispatchable” energy technologies, such as nuclear power, in terms of their effects on electricity systems. The report focuses on “grid-level system costs”, the subset of system costs mediated by the electricity grid, which includes the costs of extending and reinforcing transport and distribution grids, as well as connecting new capacity, and the costs of increased short-term balancing and maintaining the long-term adequacy of supply.

While all technologies generate system costs, those of dispatchable generators are seen as at least an order of magnitude lower than those of variable renewables. The study says that “the system costs of variable renewables at the level of the electricity grid increases the total costs of electricity supply by up to one-third, depending on country, technology and penetration levels”. While grid-level system costs for dispatchable technologies are claimed to be lower than $3/MWh, they can reach up to $40/MWh for onshore wind, up to $45/MWh for offshore wind and up to $80/MWh for solar.

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Electric grid flexibility and costs of integrating wind and solar

By Carey King

This week I’m at the American Society of Mechanical Engineers 5th Annual Engineering Sustainability conference.

As indicated by Paul, the limit of system flexibility in the grid will limit integration of renewable generation before pure capacity constraints will occur. This is because the renewable generation will begin to get curtailed before load mathematically exceeds the capacity on the grid due to the fact that the combination of dispatchable sources (hydropower, nuclear, coal, and the various natural gas prime movers) will run into difficult economic choices regarding staying on at minimum levels. That is to say, thermal generators, primarily nuclear and coal, are not inclined to turn completely off at some point during the day and then come back online during another part of the same day (or 24-hr period).

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