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Cost of electricity by source

Comparison of costs of different electricity generation sources

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Wholesale costs include initial capital, operations and maintenance (O&M), transmission, and costs of decommissioning. Depending on the local regulatory environment, some or all wholesale costs may be passed through to consumers. These are costs per unit of energy, typically represented as dollars/megawatt hour (wholesale). The calculations also assist governments in making decisions regarding energy policy.

Cost metrics

Levelized cost of electricity

The levelized cost of electricity (LCOE) is a metric that attempts to compare the costs of different methods of electricity generation irrespective of dispatchability. Though LCOE is often presented as the minimum constant price at which electricity must be sold to break even over the lifetime of the project, such a cost analysis requires assumptions about the value of various non-financial costs (environmental impacts, local availability, others), and is therefore controversial. Roughly calculated, LCOE is the net present value of all costs over the lifetime of the asset divided by an appropriately discounted total of the energy output from the asset over that lifetime. On average the levelized cost of electricity from utility scale solar power and onshore wind power is less than from coal and gas-fired power stations, but this varies greatly by location. Levelized full system costs of electricity include the cost of grid balancing.

Levelized avoided cost of electricity

The metric levelized avoided cost of energy (LACE) addresses some of the shortcomings of LCOE by considering the economic value that the source provides to the grid. The economic value takes into account the dispatchability of a resource, as well as the existing energy mix in a region.

In 2014, the US Energy Information Administration recommended that levelized costs of non-dispatchable sources such as wind or solar be compared to the "levelized avoided cost of energy" (LACE) rather than to the LCOE of dispatchable sources such as fossil fuels or geothermal. LACE is the total discounted avoided costs divided by the total discounted lifetime output. The EIA hypothesized that fluctuating power sources might not avoid capital and maintenance costs of backup dispatchable sources. The ratio of LACE to LCOE is referred to as the value-cost ratio. When LACE (value) is greater than LCOE (cost), then value-cost ratio is greater than 1, and the project is considered economically feasible.

Value-adjusted levelized cost of electricity

The value-adjusted levelized cost of electricity (VALCOE) is a metric devised by the International Energy Agency which includes both the cost of the electricity and the value to the electricity system. For example, the same amount of electricity is more valuable at a time of peak demand.

Capture rate

The capture rate is the volume-weighted average market price (or capture price) that a source receives divided by the time-weighted average price for electricity over a period. For example, a dammed hydro plant might only generate when prices are high and so have a capture rate of 200%, whereas a source that is not dispatchable, such as a wind farm without batteries, would typically have a capture rate under 100%.

Typically, the more of a single type of renewable that is built in a pricing area (such as Great Britain) the lower the capture rate will become for that type. For example, if many wind farms generate a lot at the same time the price at that time will go down. There can be curtailment if grid connectivity is lacking across the pricing area – for example from wind power in Scotland to consumers in England – resulting in the capture rate not reflecting the true cost.

Levelized cost of storage

The levelized cost of storage (LCOS) is analogous to LCOE, but applied to energy storage technologies such as batteries. Regardless of technology, storage is but a secondary source of electricity dependent on a primary source of generation. Thus, a true cost accounting demands that the costs of both primary and secondary sources be included when the cost of storage is compared to the cost of generating electricity in real time to meet demand.

A cost factor unique to storage are losses that occur due to inherent inefficiencies of storing electricity, as well as increased CO2 emissions if any component of the primary source is less than 100% carbon-free. In the US, a comprehensive 2015 study found that net system CO2 emissions resulting from storage operation are nontrivial when compared to the emissions from electricity generation [in real time to meet demand], ranging from 104 to 407 kg/MWh of delivered energy depending on location, storage operation mode, and assumptions regarding carbon intensity.

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