Time for Joined-up Thinking on Renewables, Natural Gas

By Matti Rautkivi, Wartsila

If the latest market outlook projections from Bloomberg New Energy Finance (BNEF) are anything to go by, renewables are here for the long run and will turn the screws on energy budgets for the foreseeable future.

Of the $1.3 trillion the Americas is predicted to spend on new power generation between now and 2030, more than $430 billion will be spent on onshore wind and rooftop photovoltaics, with further slices of the budget allocated to offshore wind, biomass-to-power and large-scale solar.

Quisqueya Power Plant
Quisqueya Power Plant in the Dominican Republic uses internal combustion engine technology to start in one minute and reach full load in less than five minutes, enabling the integration of intermittent renewable energy.

Renewables are the poster fuel for the decarbonized energy sector, but BNEF’s projections also reflect the continued role of fossil fuels in meeting increased power demand in developing countries amid the need for a highly flexible thermal fleet to integrate intermittent solar and wind power. Coal-fired capacity may be in rapid decline because of increasingly stringent environmental regulations, but gas-fired power plants stand to receive the second-largest portion of the Americas’ new energy infrastructure purse. Thanks mostly to the shale gas boom, which has triggered sustained low gas prices in North America, new gas facilities will be developed in the region to the tune of $314 billion during the next 15 years, according to BNEF.

The influx of renewable generators’ coming online will alter the design and operation of gas power plants. According to the International Energy Agency’s (IEA’s) “Energy Technology Perspectives 2014,” thermal generators will be called upon increasingly to operate more flexibly. Conventional open-cycle gas turbines (OCGT) and combined-cycle gas turbines (CCGT) that operate in part load might adapt, but this strategy is inefficient and expensive; it doubles power plant operators’ costs per kilowatt-hour if their facility is run at 50 percent load. Instead, the IEA suggests that another mature technology, internal combustion engines (ICEs), will challenge traditional balancing techniques.

ICE technology has developed rapidly into a plausible option in large-scale power generation, reaching plant sizes up to 600 MW with fuel efficiency of up to 48 percent. Key to ICE power plants’ flexibility is the ultrafast reaction time: They can ramp up from zero to 100 percent output in less than five minutes regardless of size. This is essential in following the variable output of wind and solar power efficiently. Another advantage is the superior part-loading efficiency, which derives from modular plant design. Each of the example 10-MW engines can be operated independently.

ICEs can increase fuel security by burning any gaseous and liquid fuels and can be built in less than a year. In many locations, a significant added value is the superior efficiency in extreme temperatures and high altitudes compared with OCGT and CCGT plants. The key to future ICE success lies in the synergies between gas technology and renewable energy generators. When combined in the future energy mix, both can unlock greater emissions reductions and cost savings than either technology alone. Renewables must be backed up by highly flexible alternative energy sources. ICE’s fast-reacting system starts from a standstill and reaches full load in just a few minutes.

With ICE plants in the capacity mix, conventional fossil-fueled plants no longer must part load to balance fluctuations in renewables. Instead, the fossil-fueled plants can operate efficiently at full load, leaving ICEs to handle normal system variations and production forecast errors of wind and solar. This creates more carbon savings, promotes fuel efficiency, reduces curtailment of renewables and decreases the number of generators needed on the system.

The Wind Enabler
A Wartsila plant in Texas, known locally as “The Wind Enabler,” includes a modular solution of 24 combustion engines that allow the plant to follow wind turbine output precisely, sustaining top fuel efficiency at any load.

IEA investigations show growth in ICE plants exceeds that of gas turbines and reveal the technology is cost-competitive with OCGTs. Risk, however, remains a key barrier. According to the IEA, this is partly because of the electric utilities work force. Many workers have expertise in gas turbines and perceive the switch to a new technology as a risk that should be avoided unless the investment opportunity is considerable. As a result, even some of the most pro-renewable regions have been slow to take up ICEs. To counter these prejudices, Wartsila commissioned DNV KEMA (now DNV GL) to investigate the impact of gas technologies on the California Independent System Operator (CAISO). The state’s renewable portfolio standard (RPS) requires utilities to obtain a progressively incremental proportion of their electricity from renewable energy sources: from 14 percent in 2010 to 33 percent by 2020. The state could save up to $890 million annually by 2020 if 5.5 GW of planned new OCGT and CCGT capacity were replaced with the equivalent number of ICEs.

In addition, a further study by Wartsila and global energy market modeling firm Energy Exemplar concluded California could reduce its annual water consumption by 25.5 million gallons and its carbon dioxide emissions by more than half a million tons annually by 2022 by adopting ICEs in the state’s Long-Term Planning and Procurement Plan.

These benefits are results of engine design features such as closed-loop radiator cooling that eliminates the need for process water consumption, single-cycle efficiency of between 46 and 48 percent and minimum stable loads as low as 1 percent.

Although the cost or savings associated with renewable energy integration differs by system and varies depending on how well system components fit together, a similar U.K. study by Redpoint Energy also demonstrated the potential for substantial savings through ICE technology. By 2020, the 4.8 GW of new gas generation sources the U.K. plans to install will provide enough electricity to power nearly 5 million of the country’s 26 million homes. Plans outlined by the U.K. Department of Energy and Climate Change (DECC) dictate that this added capacity will come from new efficient CCGT. If replaced with the equivalent amount of 200-MW ICE, however, U.K. power plants could save up to 545 million pounds a year by 2020 while meeting the U.K. government’s target of 30 percent of overall electricity requirements from renewable sources by 2030. The study investigated the U.K.’s gas generation capacity mixes under two wind energy scenarios: one with a high wind, based on National Grid’s Gone Green scenario of around 20 GW of offshore wind in 2020 and close to 40 GW in 2030; and one with a base wind, consistent with the central scenario of the U.K. government’s Updated Emissions Projections, including 10 GW of offshore wind in 2020 and some 15 GW in 2030. The overall findings revealed the U.K. could save between 381 million pounds and 545 million pounds annually by 2020, increasing to between 587 million pounds and 1.5 billion pounds by 2030 (based on base wind and high wind calculations, respectively).

Today the fossil fuel and renewables industries operate predominately in isolation, lobbying for their technologies to be championed and implemented as crucial elements of the energy transition. Studies that look sideways into the benefits of operating one generation type alongside another to optimize affordability, cost efficiency and environmental benefits are in their infancy and seldom debated. As this absence of lateral thinking continues, renewables are moving quickly from a hyped yet small contributor to total electric capacity into one of comparative significance, with BNEF’s predicting more than one-quarter of total generation capacity in the Americas will come from intermittent sources by 2030.

Without flexible backup to provide electricity when clean sources are unavailable, vital building blocks of the aspiring decarbonized energy system remain absent. Wartsila proposes an end to the “us and them” culture that could prevent billions of dollars in cost savings and invaluable emissions reductions from being realized, as evidenced in the synergies between renewables and ICE. A new environment should be fostered by utilities, policymakers and investors that reduces the risks of new technology adoption and rewards those market design strategies that propose the greatest flexibility. Renewables can contribute significantly to future electricity systems and overall emissions reduction if operated as part of an integrated grid with the support of fast-reacting, ICE power plants.

Author

Matti Rautkivi is general manager of the Liaison Office and is responsible for electricity market development in Wärtsilä Power Plants. Before joining Wärtsilä, Rautkivi worked for Pöyry Management Consulting participating in Pöyry’s intermittency studies and several power plant feasibility studies globally. He has a master’s degree in industrial engineering and energy systems.

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