But hurdles exist, as with any profound break with the nation's fossil-fuel past.
Transmission must be planned, financed and built for the estimated 190GW of new wind projects still required for the 20% scenario. "Right now, wind development is ahead of (what is needed for) 20% by 2030," says Michael Goggin, AWEA's transmission manager. "Transmission has improved, but not to the extent - so far - that we could get to 20%." Around 68GW of wind-oriented transmission is currently proposed, he notes, but many of the plans are likely be dropped due to a lack of financing or regulatory approval, or simply because demand for electricity has risen slower than expected.
Generation and transmission needs by 2030 were assessed in three scenarios by planning authorities of the Eastern Interconnection, the largest interconnected electrical grid in the US, covering 39 states, Washington DC and eastern Canada. Published in December 2012, it concluded that for a renewables-heavy future in the region - with 215GW of new wind in Nebraska and in the areas of two regional transmission organisations, and with energy efficiencies — investment of $99 billion would be needed. This would cover transmission in generation interconnection, constraint relief and voltage support.
For a moderate renewables growth driven by state policies, $67 billion would be needed to fund expansion and upgrades. The third scenario, which is a business-as-usual future where dirty electricity continues to dominate, the cost would be $15 billion.
The study by Eastern Interconnection Planning Collaborative (EIPC) also calculated operations-and-maintenance costs in 2013. For the renewables-heavy future $2.9 billion would be needed for variable-resource integration, and the second and third options would cost only $2.5 billion and $1 billion respectively.
Balance tips with emissions
Yet although more wind power requires pricier transmission and integration, fuel costs are far lower, stresses Bob Fagan, co-author of a recent analysis of EIPC's assessment by research and consultancy firm Synapse Energy Economics. Fagan says that by 2040, the overall cost for the cleanest and the dirtiest scenarios are similar — and once emissions costs are included, the scenario with the most wind is far cheaper.
The majority of the US grid is more than 25 years old, fragmented and poorly planned. There are three huge inter-connected regional grids, and within those are seven regional transmission organisations (RTOs) and independent system operators (ISOs), which co-ordinate transmission regionally (see map, below). Vast areas, especially in the west and south, have resisted co-ordination because of a perceived loss of local control or profitability, and thus they are not in RTOs or ISOs, says Goggin.
Improved transmission planning and financing, however, is being prompted by the groundbreaking Order No 1000 issued by the Federal Energy Regulatory Commission (Ferc) in July 2011. Operators will be required to plan regionally and allocate new project costs to the beneficiaries regardless of location. Yet the order, which could transform the grid, is being challenged in the US court of appeals in Washington DC. "If Ferc is reversed, it could delay (transmission) projects being approved," says Christi Tezak, managing director of research at investment research firm Clear View Energy Partners.
Another piece of the puzzle is integrating large amounts of wind on to the grid, which is cheaper with updated market structures and rules. Generation and load must be balanced over time for grid reliability, a more costly prospect when more electricity comes from a variable or remote source that cannot be accessed on demand, say experts. Changes include larger, more geographically diverse balancing areas and - outside the territories of RTOs and ISOs — creation of energy imbalance markets (EIMs) to enable trading across the grid.
An EIM — which enables faster exchange of electricity over a larger area — has been under way successfully for six years at Southwest Power Pool, and one was initiated between Californian grid operator CAISO and PacifiCorp in Oregon in February using computer technology to exchange electricity at five-minute intervals instead of hourly by telephone.
More frequent dispatching is needed, every five or 15 minutes rather than hourly so generators can change their output more frequently, says AWEA's Goggin. Integrating wind forecasting into systems operation is also important, says Erik Ela, acting manager of the transmission and grid integration group at the National Renewable Energy Laboratory (NREL).
Transformative grid projects are clearly needed. This is why internet giant Google invested 37.5% equity in development of the $5 billion Atlantic Wind Connection, the high-voltage direct-current backbone planned for up to 6GW of offshore wind. "It's a project's audaciousness, not just the returns that we look at," says Rick Needham, director of green business operations at Google, which has so far invested more than $1 billion in renewables.
The project is high-risk, he admits, but could be a first step towards the super-grid renewable energy needs. Will Google invest further in renewables-friendly transmission? Needham says yes, especially if a project is transformative. And that is exactly the sort of attitude needed to get the US to 20% wind by 2030.
HIGH VALUE — SETTING UP AND FINANCING LONG-DISTANCE TRANSMISSION LINES
Clean Line Energy is one of the few merchant developers of long-distance transmission for renewables in the US that builds lines and then sells them on.
Traditionally, transmission has been built by incumbent utilities with scant interest in inter-regional models, says Michael Skelly, Clean Line's president.
What is missing in the US are long-distance lines that can shift wind from the remote and windiest areas to load centres hungry for electricity, says Skelly.
Houston-based Clean Line is developing four inter-regional high-voltage direct-current (HVDC) transmission lines that will each carry about 3.5GW of wind power. (HVDC transports electricity more efficiently long-distance.) The firm is also behind New Mexico's Western Spirit project, a proposed 200-mile (322-kilometre), 345kv alternating-current line for 1.5GW of wind power.
Last year, UK grid operator National Grid invested $40 million in Clean Line, which will ultimately charge fees for use of its transmission lines, similar to toll roads or oil pipelines. The "anchor shipper" approach, where the early investor usually receives a lower rate in return for committing up front, will be used to attract customers, says Skelly. This kick-starts finance and should make the line more likely to be built, says investment research firm Clear View Energy Partners.
Developing transmission is slow, and Clean Line faces hurdles typically encountered by any long-distance transmission developer: having to secure many regulatory approvals and planning permits, as well as dealing with numerous landowners. "We need a patient set of investors and a patient (development) team," says Skelly. The first of its projects are expected to be online by 2018, and all should be finished by the early 2020s, says Skelly.
By building the right long-distance lines, thousands of megawatts of renewables will be made possible, he says. For example, Clean Line maintains that its $2 billion Plains and Eastern Line should enable more than $7 billion of investment in new wind farms in the Oklahoma/Texas Panhandle.
The line will run from the windy Panhandle to the markets of utilities in Tennessee, Arkansas and elsewhere in the mid-south and south-east, which currently rely heavily on coal and other dirty power. In response to a request, wind developers with rights to 16GW of projects - more than four times the line's capacity - have expressed interest, says Clean Line. And two big utilities, TVA and Southern Company, would like to buy more wind, says Skelly.