Former ALP Senator Don Farrell's return to politics shows now, more than ever, why South Australians needs strong progressive representation in the Senate, Greens marriage equality spokesperson Senator Robert Simms says.

"South Australian voters are faced with a predicament. High-profile candidates on both the ALP and Liberal senate tickets are vehemently against marriage equality. Together with Family First's Bob Day, Cory Bernardi and Don Farrell would work to stymie this progress in the parliament.

Transitioning to a renewable economy and building a solar thermal plant in the mid-north should be prioritised as Port Augusta's coal-fired power stations are today shut down for good, The Australian Greens say.

Greens Senator Robert Simms has said that the choice for voters in South Australia could come down to the Greens or Family First.

"In South Australia, the numbers in the Senate are pretty tight and it looks like it may come down to a race between myself and Family First's Bob Day for that final position," Greens sexuality spokesperson Senator Robert Simms said.

"So for South Australians it's a case of ‘Rob or Bob': the Greens agenda of equality for LGBTI people versus the homophobia and transphobia of Family First.

Greens Sexuality spokesperson Senator Robert Simms has welcomed the approval of PrEP (pre-exposure prophylaxis) by the Therapeutic Goods Administration and called on the Government to now list it under the PBS.

"This is positive development in HIV prevention in our country. The Greens have been advocating for some time for Australians to have access to this effective HIV prevention tool and I'm relieved to see it's finally been granted approval," said Senator Simms.

The Australian Greens are calling on the Government to apologise to Mr Marco Bulmer-Rizzi following revelations of more poor treatment by a government department.

"Mr Bulmer-Rizzi has had his grief compounded by the poor treatment from the government, starting with the failure to name him as next-of-kin on his late husband's death certificate in January," Greens sexuality spokesperson Senator Robert Simms said.

In senate estimates today Attorney-General George Brandis has ruled out seeking a temporary suspension of anti-discrimination laws during any marriage equality plebiscite, in response to questioning from Greens marriage equality spokesperson Senator Robert Simms. But, he left the door open to the Australian Christian Lobby receiving public funds to run a ‘no' campaign.

"The idea of public funds being given to an organisation like the ACL to campaign against marriage equality will horrify all Australians who believe in equality," Senator Simms said.

Australian Greens marriage equality spokesperson Senator Robert Simms is calling on Prime Minister Malcolm Turnbull to ditch the $160 million plebiscite after it was placed in the budget contingency fund.

"It's absurd that after harping on for years about a so-called budget emergency the Liberals are progressing with a $160 million plebiscite on marriage equality," Senator Simms said.

"Now for the first time we are seeing this costly plebiscite factored into the budget. Australians want marriage equality and they want to see this matter dealt with by the parliament.

The Australian Greens have called out the Liberal party for its smoke-and-mirrors approach to higher education after last night's budget announcement revealed plans to cut 20 per cent of funding from the university sector in the 2017 forward estimates and beyond.

The Australian Greens have slammed the Labor and Liberal parties for teaming up to defeat a motion (below) calling on the Government to acknowledge Adnyamathanha traditional owners' opposition to a radioactive waste dump in the Flinders Ranges and refusing to remove Barndioota as a nominated site for such a facility.

Australian Greens sexuality spokesperson Senator Robert Simms's and Liberal Senator for WA Dean Smith's motion (below) to offer the Senate's deepest condolences to the family of LGBTI magazine editor Xulhaz Mannan, who was killed last week, has been supported in Parliament today.