Solar Thermal Electrochemical Production STEP process at George Washington University in Ashburn, Virginia.

They say it is also zero carbon emission process. Scientists also add that the STEP process could be extended beyond cement
production to other applications that convert limestone to lime, such as
purifying iron and aluminum; producing glass, paper, sugar, and
agriculture; cleaning smoke stacks; softening water; and removing
phosphates from sewage.Main paper behind a paywall http://pubs.rsc.org/en/content/articlelanding/2012/CC/C2CC31341C. I believe OSE is firmly for solar thermal solutions.

From Physorg

"As the scientists explain, 60-70% of CO₂ emissions during cement production occurs during the conversion of limestone into lime. This conversion involves decarbonation, or removing the carbon atom and two oxygen atoms in limestone (CaCO₃) to obtain lime (CaO) with CO₂ as the byproduct. The remainder of the emissions comes from burning fossil fuels, such as coal, to heat the kiln reactors that produce the heat required for this decarbonation process.

The STEP process addresses both issues, starting by replacing the fossil fuel heat source
with solar thermal energy. The solar heat is not only applied directly
to melt the limestone, it also provides heat to assist in the
electrolysis of the limestone. In electrolysis, a current applied to the
limestone changes the chemical reaction so that instead of separating
into lime and CO₂, the limestone separates into lime and some
other combination of carbon and oxygen atoms, depending on the
temperature of the reaction. When electrolyzed below 800°C, the molten
limestone forms lime, C, and O₂. When electrolyzed above 800°C, the product is lime, CO, and ½O₂.

“Electrolysis changes the product of the reaction of the limestone as
it is converted to lime,” coauthor Stuart Licht, a chemistry professor
at George Washington University, told Phys.org. “Rather than
producing carbon dioxide, it reduces the carbon dioxide (adds electrons)
and produces only oxygen and graphite (which can be readily stored as
solid carbon) or CO for fuels, plastics or pharmaceuticals. This is
accomplished at low energy and high throughput.”

When separated, the carbon and oxygen atoms no longer pose the threat to the atmosphere that they do as CO₂.
As Licht explained, the carbon monoxide byproduct in the higher
temperature reaction can be used in other industries, such as to produce
fuels, purify nickel, and form plastics and other hydrocarbons. Plus,
the carbon monoxide is produced significantly below market value by this
solar thermal electrolytic process. The main product, lime, doesn't
react with the other byproducts, but instead forms a slurry at the
bottom of the vessel where it can easily be removed.

“This study presents a low-energy, entirely new synthetic route to
form CaO without any carbon dioxide emission, and is based on unexpected
solubility behavior in molten salts,” Licht said. “This synthesis can
be accomplished without solar energy, and without our new STEP process,
but is particularly attractive when combined with this new solar
process. Alternatively, the new synthesis could be used by industry to
produce cement using any non-solar renewable or nuclear energy without
any CO₂ release, or greatly decrease CO₂ if fossil fuels
were used to drive the new cement production (in the latter, worst-case
scenario, the products are lime, graphite and oxygen; there is still no
CO₂ product, but CO₂ would be used in the energy to drive the process).”