energy storage (why & how)

ENERGY STORAGE

Digajerla Suresh

M TECH-CTM

14CM43F

PRESENTATION STRUCTURE

• Why Do We Want Storage?• Benefits of Storage • Storage options• Challenges for storage• Alternatives

Data Sources for Today’s Presentation

• The Ontario generation (except for solar) and customer demand data was obtained from the IESO website (http://www.ieso.ca). Detailed analysis was done in 2011 but load data for 2012 and 2013 has not changed much.

• Solar flux data comes from the Canadian Weather for Energy Calculations (CWEC) dataset for Toronto, Environment Canada. Solar generation output simulations were produced courtesy of Carbon Free Technology using PV system simulation software.

• Electricity production cost data was obtained from Ontario 2013 FIT rates and the Projected Costs of Generating Electricity, 2010 Edition, Organization for Economic Co-operation and Development, median case with carbon tax removed.

• www.eolien.qc.ca

DISADVANTAGES OF RE

• Diffuse Nature Of RenewablesSolar panels and wind turbines need to become cheaper than raw fossil fuels.• Intermittent Nature Of RenewablesStorage solutions need to become cheaper than fossil fuel refineries (e.g. power plants).

COST COMPARISONRENEWABLE ENERGY

• Deployment cost = $1.44/ W

• Lead Acid batteries = $ 0.34 / kWh

• Li ion = $ 0.4/kWh

CONVENTIONAL ENERGY• Deployment cost = $ 0.34/W

• Final cost per unit = $ 0.06/kWh

• Fuel cost = $ 0.015/kWh• Refining cost = $ 0.045 /kWh

Why do we want storage?

• Customer load varies significantly over time. The summer peak is almost 250% higher than the spring low.

• Some generation technologies cannot adjust output to match demand (limited ramp rates, minimum loads, etc.).

• Some generation technologies (wind and solar) are intermittent and can change output very quickly opposite to demand and can disappear for extended periods of time across the province.

• Storage is an integrating technology – enables supply to better match demand.

Benefits of storage

• Storage provides renewables with a zero GHG emission backup.

• Storage can support voltage regulation and grid frequency regulation.

• Storage reduces the amount of dispatching (load following) imposed on generators (improves plant capacity factors)

• Storage reduces the natural gas plant capacity needed to meet peak demand and reserves.

• Storage enables better utilization of base-load nuclear plants. • Storage can reduce the required capacity of transmission and distribution lines if it is located optimally

Storage Options

Short term storage: • Batteries,• Flywheels, • Compressed air (tanks & underwater volumes). • Dam and pumped hydroelectric (with small reservoirs – eg Niagara Pumped Generating Station).

Longer term storage: • Compressed air in underground caverns, • Dam and pumped hydroelectric (with very large reservoirs – eg: Quebec’s James Bay development).

Challenges- Solutions

• Large electrical demand variation increases the required peak power rating of storage in kW and the integrated capacity rating in kWh.

- Improved demand management & load shifting • Seasonal storage (shifting production from spring to summer and autumn to winter) is the most valuable but it is also the most expensive and environmentally disruptive.

-Modifying flood management systems Flood routing and storage in retention basins

The Challenges for Storage

• EfficiencyAll storage options lose some of the stored energy over

time (5 to 50% depending on technology and storage duration).

• Hydroelectric storage Is the cheapest large scale storage but you need ideal geography

The Challenges for Storage

• Cost is prohibitive – see 2010 EPRI Report 1020675 • Batteries: 1 to 5 k$/kW & 0.2 to 5.0 k$/kWh (short life, 3 to 12 yrs)

• Flywheels: 2 k$/kW & 2 to 9 k$/kWh (10 hrs max storage)

• Compressed Gas: 1 to 2 k$/kW & 0.1 to 0.5 k$/kWh (low efficency)

• Pumped Hydro: 1 to 9 k$/kW & 0.2 to 0.9 k$/kWh (uses large land areas)

Alternatives Without Storage

• Improved demand management & load shifting

• Improved load following at existing plants

• Surplus steam to district industrial process steam system

• Produce hydrogen during off-peak hours

• Export energy at below the cost of production.

No energy is wasted with these options.

Alternatives Without Storage

• Hydroelectric spill • Dispatch Solar and wind generation down

• Improve nuclear steam bypass capability

Energy is wasted with these options.

Summary

• Storage is an elegant solution. • Much too expensive now to deploy on a large scale. • Other non-storage options are available to manage supply-demand balance until storage costs drop.